U.S. patent application number 09/836613 was filed with the patent office on 2003-02-27 for synthetic mammalian alpha-n-acetylglucosaminidase and genetic sequences encoding same.
Invention is credited to Anson, Donald Stewart, Blanch, Lianne, Hopwood, John Joseph, Scott, Hamish Steele, Weber, Birgit.
Application Number | 20030039643 09/836613 |
Document ID | / |
Family ID | 3791070 |
Filed Date | 2003-02-27 |
United States Patent
Application |
20030039643 |
Kind Code |
A1 |
Hopwood, John Joseph ; et
al. |
February 27, 2003 |
Synthetic mammalian alpha-N-acetylglucosaminidase and genetic
sequences encoding same
Abstract
An efficient architecture for an interpolator (100) disposed to
process oversampled data is disclosed herein. The interpolator
(100) includes an input divider circuit (104) configured to receive
an input data word over an input data line. A register (108) is
provided for latching the divided input data word from the divider
(104). The divided input data word is added within a summer (112)
to a latched divided data word from the register, thereby forming a
summed data word. A multiplexer (116) produces an interpolated
output by multiplexing the summed data word with an input data
word. In a preferred implementation, the register (108) is latched
at a first clock rate, and the multiplexer (116) is clocked at
twice the first clock rate. The efficient filter architecture
allows interpolation to be performed in the absence of multipliers,
and in a manner using filter coefficients equivalent to powers of
two. This enables the interpolator (100) to be realized
inexpensively, and renders the filter particularly suitable for
implementation within integrated circuits.
Inventors: |
Hopwood, John Joseph;
(Stonyfell, AU) ; Scott, Hamish Steele; (Geneve,
CH) ; Weber, Birgit; (Hackney, AU) ; Blanch,
Lianne; (Grange, AU) ; Anson, Donald Stewart;
(Thebarton, AU) |
Correspondence
Address: |
ANN R. POKALSKY, ESQ.
DILWORTH & BARRESE
333 EARLE OVINGTON BLVD.
UNIONDALE
NY
11553
US
|
Family ID: |
3791070 |
Appl. No.: |
09/836613 |
Filed: |
April 17, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09836613 |
Apr 17, 2001 |
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09077354 |
Apr 22, 1999 |
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6255096 |
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09077354 |
Apr 22, 1999 |
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PCT/US96/00747 |
Nov 22, 1996 |
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Current U.S.
Class: |
424/94.61 ;
435/201; 435/320.1; 435/6.15; 536/23.2 |
Current CPC
Class: |
C12N 9/2402 20130101;
A61K 38/00 20130101; C12Y 302/0105 20130101; A61P 3/00
20180101 |
Class at
Publication: |
424/94.61 ;
536/23.2; 435/320.1; 435/201; 435/6 |
International
Class: |
A61K 038/47; C12Q
001/68; C12N 009/24; C12N 015/56 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 23, 1995 |
AU |
PN 6748 |
Claims
What is claimed is:
1. An isolated nucleic acid molecule comprising a sequence of
nucleotides which encodes or is complementary to a sequence which
encodes a mammalian .alpha.-N-acetylglucosaminidase or fragment or
derivative thereof.
2. The isolated nucleic acid molecule according to claim 1 wherein
the nucleotides are dcoxyribonucleoticles.
3. The isolated nucleic acid molecule according to claim 2 wherein
said molecule is a cDNA.
4. The isolated nucleic acid molecule according to claim 2 wherein
said molecule is a genomic DNA molecule.
5. The isolated nucleic acid according to claim 1 wherein the
mammal is a human.
6. The isolated nucleic acid according to claim 5 wherein the
.alpha.-N-acetylglucosaminidase is of liver, kidney or placenta
origin.
7. The isolated nucleic acid molecule according to claim 1 having a
nucleotide sequence substantially as set forth in SEQ ID NO: I or
complementary thereto or having at least 40% similarity to all or
part thereof.
8. The isolated nucleic acid molecule according to claim 1 having a
nucleotide sequence substantially as set forth in SEQ ID NO:3 or
complementary thereto or having at least 40% similarity to all or
part thereof.
9. The isolated nucleic acid molecule according to claim 7 wherein
the percentage similarity is at least 60%.
10. The isolated nucleic acid molecule according to claim 9 wherein
the percentage homology is at least 80%.
11. The isolated nucleic acid molecule according to claim 1 wherein
the .alpha.-N-acetylglucosaminidase or fragment or derivative
thereof encoded by said molecule comprises an amino acid sequence
substantially identical to SEQ ID NO:2 or is at least 0.40% similar
to all or a part thereof.
12. The isolated nucleic acid molecule according to claim 11
wherein the percentage similarity to SEQ ID NO: 2 is at least
60%.
13. The isolated nucleic acid molecule according to claim 12
wherein the percentage similarity to SEQ ID NO:2 is at least
80%.
14. The isolated nucleic acid molecule according to claim 1 wherein
said molecule is carried by a vector capable of replication in a
eukaryotic cell and/or a prokaryotic cell.
15. The isolated nucleic acid molecule according to claim 14
wherein the vector is an expression vector.
16. The isolated nucleic acid molecule according to claim 15
wherein the expression vector is capable of being expressed in
cells derived from a eukaryote.
17. The isolated nucleic acid molecule according to claim 16
wherein the expression vector is further capable of being expressed
in cells derived from a mammal.
18. The isolated nucleic acid molecule according to claim 17
wherein the expression vector is further capable of being expressed
in CHO cells.
19. A recombinant mammalian .alpha.-N-acetylglucosaminidase or
fragment or derivative thereof.
20. The recombinant mammalian .alpha.-N-acetylglucosaminidase
according to claim 19 in substantially pure form.
21. The recombinant mammalian .alpha.-N-acetylglucosaminidase
according to claim 19 when expressed in mammalian, yeast or insect
cells.
22. The recombinant mammalian .alpha.-N-acetylglucosaminidase
according to claim 21 when expressed in mammalian cells.
23. The recombinant mammalian .alpha.-N-acetylglucosaminidase
according to claim 21, wherein the cells are capable of
glycosylating said recombinant mammalian
.alpha.-N-acetylglucosaminidase.
24. The recombinant mammalian .alpha.-N-acetylglucosaminidase
according to claim 23 wherein the cells are capable of
N-glycosylating said recombinant mammalian
.alpha.-N-acetylglucosaminidase.
25. The recombinant mammalian .alpha.-N-acetylglucosaminidase
according to claim 24 wherein the cells are CHO cells.
26. The recombinant mammalian .alpha.-N-acetylglucosaminidase
according to claim 19 wherein said recombinant
.alpha.-N-acetylglucosaminidase is in a glycosylated form.
27. The recombinant mammalian .alpha.-N-acetylglucosaminidase
according to claim 26 wherein the molecular weight of the
glycosylated form as determined using SDS/PAGE is at least
approximately 79 kDa.
28. The recombinant .alpha.-N-acetylglucosaminidase according to
claim 26 wherein the molecular weight of the glycosylated form as
determined using SDS/PAGE is at least approximately 79 kDa to 89
kDa.
29. The recombinant mammalian .alpha.-N-acetylglucosaminidase
according to claim 19 comprising a sequence of amino acids
substantially the same as a human
.alpha.-N-acetylglucosaminidase.
30. The recombinant mammalian .alpha.-N-acetylglucosaminidase
according to claim 19 when fused to another proteinaceous
molecule.
31. The recombinant mammalian .alpha.-N-acetylglucosaminidase
according to claim 30 wherein the other proteinaceous molecule is
an enzyme, reporter molecule, purification site and/or a signal
sequence.
32. The recombinant mammalian .alpha.-N-acetylglucosaminidase
according to claim 19 comprising an amino acid sequence
substantially as set forth in SEQ ID NO:2 or having at least 40%
similarity to all or part thereof.
33. The recombinant mammalian .alpha.-N-acetylglucosaminidase
according to claim 32 wherein the percentage similarity to SEQ ID
NO:2 is at least 60%.
34. The recombinant mammalian .alpha.-N-acetylglucosaminidase
according to claim 33 wherein the percentage similarity to SEQ ID
NO:2 is at least 80%.
35. A recombinant .alpha.-N-acetylglucosaminidase produced by
expression of a nucleic acid molecule which encodes or is
complementary to a sequence which encodes a mammalian
.alpha.-N-acetylglucosaminidase or fragment thereof and wherein the
molecule is carried by a vector capable of replication in a
eukaryotic or prokaryotic cell.
36. The recombinant .alpha.-N-acetylglucosaminidase according to
claim 35 when glycosylated.
37. A method of diagnosing a mutation in a gene which encodes
.alpha.-N-acetylglucosaminidase in a human patient said method
comprising contacting genomic DNA or RNA derived from said patient
with one or more isolated DNA molecules or oligonucleotides
comprising at least 10 contiguous nucleotides derived from SEQ ID
NO: 1 or SEQ ID NO:3 or a complementary strand thereof for a time
and under conditions sufficient for hybridisation to occur and then
detecting said hybridisation using a detection means.
38. The method according to claim 37 wherein the detection means is
a reporter molecule covalently attached to the isolated DNA
molecule or oligonucleotide.
39. The method according to claim 38 wherein the reporter molecule
is .sup.31P, .sup.35S or biotin.
40. The method according to claim 37 wherein the detection means is
a polyrnerase chain reaction format.
41. The method according to claim 40 wherein the polymerase chain
reaction format is selected from the list comprising SSCP, AMD,
AFLP, IRS-PCR, iPCR or RT-PCR, amongst others.
42. The method according to claim 41 wherein the polymerase chain
reaction format is SSCP.
43. The method according to claim 42 wherein the isolated DNA
molecule or oligonucleotide comprises at least 20 contiguous
nucleotides derived from SEQ ID NO: 1 or SEQ ID NO:3 or a
complementary strand thereof.
44. The method according to claim 43 wherein the isolated DNA
molecule or oligonucleotide comprises at least 50 contiguous
nucleotides derived from SEQ ID NO: 1 or SEQ ID NO: 3 or a
complementary strand thereof.
45. The method according to claim 44 wherein the isolated DNA
molecule or oligonucleotide comprises at least 7 contiguous
nucleotides derived from SEQ ID NO: 1 or SEQ ID NO:3 or a
complementary strand thereof.
46. A method for treating a patient suffering from
.alpha.-N-acetylglucosa- minidase efficiency said method comprising
administering to said patient an effective amount of recombinant
mammalian .alpha.-N-acetylglucosaminid- ase or an active fragment
or derivative thereof.
47. The method according to claim 46 wherein the mammalian
.alpha.-N-acetylglucosaminidase comprises a sequence of amino acids
substantially the same as the amino acid, sequence of human
.alpha.-N-acetylglucosaminidase.
48. The method according to claim 47 wherein the patient is
suffering from mucopolysaccharidosis type IIIB.
49. The method according to claim 46 wherein the recombinant
.alpha.-N-acetylglucosaminidase is produced in mammalian cells.
50. The method according to claim 49 wherein the mammalian cells
are capable of glycosylating the recombinant
.alpha.-N-acetylglucosaminidase produced therein.
51. The method according to claim 50 wherein the recombinant
.alpha.-N-acetylglucosaminidase is in a glycosylated form.
52. The method according to claim 51 wherein the glycosylated form
of the recombinant .alpha.-N-acetylglucosaminidase has a molecular
weight as determined using SDS/PAGE of at least approximately 79
kDa.
53. The method according to claim 52 wherein the glycosylated form
of the recombinant .alpha.-N-acetylglucosaminidase has a molecular
weight as determined using SDS/PAGE of at least approximately 79
kDa to 89 kDa.
54. The method according to claim 46 wherein the recombinant
.alpha.-N-acetylglucosaminidase comprises a sequence of amino acids
substantially as set forth in SEQ ID NO:2 or having at least 40%
similarity to all or a part thereof.
55. The method according to claim 54 wherein the percentage
similarity to SEQ ID NO:2 is at least 60%.
56. The method according to claim 55 wherein the percentage
similarity to SEQ ID NO:2 is at least 80%.
57. A method for treating a patient suffering from
.alpha.-N-acetylglucosa- minidase deficiency said method comprising
administering to said patient an effective amount of recombinant
mammalian .alpha.-N-acetylglucosaminid- ase or an active fragment
or derivative thereof, wherein said recombinant mammalian
.alpha.-N-acetylglucosaminidase is produced by expression of a
nucleic acid molecule according to claim 14.
58. The method according to claim 46 wherein administration of the
recombinant mammalian .alpha.-N-acetylglucosaminidase is by oral,
intravenous, suppository, intraperitoneal intramuscular,
intranasal, intradermal or subcutaneous administration by infusion
or implantation or by enzyme replacement therapy or by gene
therapy.
59. The method according to claim 58 wherein the method of
administration is by enzyme replacement therapy.
60. A pharmaceutical composition comprising a recombinant mammalian
.alpha.-N-acetylglucosaminidase or an active fragment or derivative
thereof and one or more pharmaceutically acceptable carriers and/or
diluents.
61. The pharmaceutical composition according to claim 60 wherein
the recombinant mammalian .alpha.-N-acetylglucosaminidase comprises
a sequence of amino acids substantially the same as human
.alpha.-N-acetylglucosaminidase.
62. The pharmaceutical composition according to claim 60 wherein
the recombinant mammalian .alpha.-N-acetylglucosaminidase is
produced in a mammalian cell.
63. The pharmaceutical composition according to claim 62 wherein
the mammalian cell is a CHO cell line which is capable of
glycosylating the recombinant mammalian
.alpha.-N-acetylglucosaminidase.
64. The pharmaceutical composition according to claim 60 wherein
the .alpha.-N-acetylglucosaminidase is glycosylated.
65. The pharmaceutical composition according to claim 64 wherein
the recombinant .alpha.-N-acetylglucosaminidase has a molecular
weight as determined using SDS/PAGE of at least approximately 79
kDa.
66. The pharmaceutical composition according to claim 65 wherein
the recombinant .alpha.-N-acetylglucosaminidase has a molecular
weight as determined using SDS/PAGE of approximately 79 kDa to 89
kDa.
67. The pharmaceutical composition according to claim 60 wherein
the recombinant .alpha.-N-acetylglucosaminidase comprises a
sequence of amino acids substantially as set forth in SEQ ID NO: 2
or having at least 40% similarity to all or part thereof.
68. The pharmaceutical composition according to claim 67 wherein
the percentage similarity to SEQ ID NO:2 is at least 60%.
69. The pharmaceutical composition according to claim 68 wherein
the percentage similarity to SEQ ID NO:2 is at least 80%.
70. A pharmaceutical composition comprising recombinant mammalian
.alpha.-N-acetylglucosaminidase or an active fragment or derivative
thereof and one or more pharmaceutically acceptable carriers and/or
diluents wherein said recombinant mammalian
.alpha.-N-acetylglucosaminida- se is produced by expression of a
nucleic acid molecule according to claim 35.
71. A pharmaceutical composition comprising recombinant mammalian
.alpha.-N-acetylglucosaminidase or an active fragment or derivative
thereof and one or more pharmaceutically acceptable carriers and/or
diluents when used in the method for treating a patient suffering
from .alpha.-N-acetylglucosaminidase.
72. Use of recombinant mammalian .alpha.-N-acetylglucosaminidase or
an active fragment or derivative thereof in the manufacture of a
medicament for the treatment of .alpha.-N-acetylglucosaminidase
deficiency in a patient.
73. The use according to claim 72 wherein the recombinant mammalian
.alpha.-N-acetylglucosaminidase comprises a sequence of amino acids
substantially the same as the amino acid sequence of human
.alpha.-N-acetylglucosaminidase.
74. The use according to claim 72 wherein the patient is suffering
from mucopolysaccharidosis type IIIB.
75. The use according to claim 74 wherein the recombinant is
.alpha.-N-acetylglucosaminidase expressed in mammalian cells.
76. The use according to claim 75 wherein the cells are CHO
cells.
77. The use according to claim 72 wherein the
.alpha.-N-acetylglucosaminid- ase is glycosylated.
78. The use according to claim 77 wherein the recombinant
.alpha.-N-acetylglucosaminidase has a molecular weight as
determined using SDS/PAGE of at least approximately 79 kDa.
79. The use according to claim 78 wherein the recombinant
.alpha.-N-acetylglucosaminidase has a molecular weight as
determined using SDS/PAGE of approximately 79 kDa to 89 kDa.
80. The use according to claim 72 wherein the recombinant
.alpha.-N-acetylglucosaminidase comprises a sequence of amino acids
substantially as set forth in SEQ ID NO:2 or has at least 40%
similarity to all or a part thereof.
81. The use according to claim 80 wherein the percentage similarity
to SEQ ID NO:2 is at least 60%.
82. The use according to claim 80 wherein the percentage similarity
to SEQ ID NO:2 is at least 80%.
83. A nucleic acid molecule comprising a sequence of nucleotides
encoding or complementary to a sequence encoding a polypeptide
capable of hydrolyzing the terminal .alpha.-N-acetylglucosaminidase
residues present at the non-reducing terminus of fragments of
heparan sulphate and heparin and wherein said nucleotide sequence
is capable of hybridising under at least low stringency conditions
to the nucleotide sequence set forth in SEQ ID NO:1.
84. A nucleic acid molecule comprising a sequence of nucleotides
encoding or complementary to a sequence encoding a polypeptide
capable of hydrolysing the terminal .alpha.-N-acetylglucosaminidase
residues present at the non-reducing terminus of fragments of
heparan sulphate and heparin and wherein said nucleotide sequence
is capable of hybridising under at least low stringency conditions
to the nucleotide sequence set forth in SEQ ID NO:3.
85. A recombinant polypeptide comprising a sequence of amino acids
corresponding to the amino sequence set forth in SEQ ID NO:2 or
having at least 40% similarity thereto and encoded by a nucleic
acid molecule which is capable of hybridising to the nucleotide
sequence set forth in SEQ ID NO:1 or SEQ ID NO:3 under at least low
stringency conditions.
86. A genetic construct comprising the nucleic acid molecule
according to claim 1, operably connected in the sense orientation
to a promoter sequence such that said genetic construct is capable
of being expressed in a eukaryotic or prokaryotic cell to produce a
recombinant mammalian .alpha.-N-acetylglucosaminidase or a fragment
or derivative thereof.
87. The genetic construct according to claim 86 wherein the
promoter is capable of regulating expression of the recombinant
.alpha.-N-acetylglucosaminidase in a mammalian cell.
88. The genetic construct according to claim 87 wherein the
promoter is the CMV promoter sequence or a promoter derived
therefrom.
89. The genetic construct according to claim 86 further comprising
a transcription terminator sequence.
90. The genetic construct according to claim 86 when used to
express or over-express .alpha.-N-acetylglucosaminidase in a
eukaryotic or prokaryotic cell.
91. An antibody to .alpha.-N-acetylglucosaminidase or a recombinant
.alpha.-N-acetylglucosaminidase according to claim 19 or an
antigenic fragment thereof.
92. The antibody according to claim 91 further defined as a
polyclonal antibody molecule.
93. The antibody according to claim 91 further defined as a
monoclonal antibody molecule.
94. The isolated nucleic acid molecule according to claim 8 wherein
the percentage similarity is at least 60%.
95. The isolated nucleic acid molecule according to claim 94
wherein the percentage homology is at least 80%.
96. A recombinant mammalian .alpha.-N-acetylglucosaminidase or
fragment thereof wherein the .alpha.-N-acetylglucosaminidase or
fragment thereof is in glycosylated form and comprises a sequence
of amino acids substantially the same as a human
.alpha.-N-acetylglucosaminidase.
97. The recombinant mammalian .alpha.-N-acetylglucosaminidase
according to claim 96 when fused to another proteinaceous
molecule.
98. The recombinant mammalian .alpha.-N-acetylglucosaminidase
according to claim 97 wherein the other proteinaceous molecule is
an enzyme, reporter molecule, purification site and/or a signal
sequence.
99. The recombinant mammalian .alpha.-N-acetylglucosaminidase
according to claim 96 comprising an amino acid sequence
substantially as set forth in SEQ ID NO:2 or having at least 40%
similarity to all or part thereof.
100. The method according to claim 57 wherein administration of the
recombinant mammalian .alpha.-N-acetylglucosaminidase is by oral,
intravenous, suppository, intraperitoneal, intramuscular.
intranasal. intradermal or subcutaneous administration by infusion
or implantation or by enzyme replacement therapy or by gene
therapy.
101. A pharmaceutical composition comprising recombinant mammalian
.alpha.-N-acetylglucosaminidase or an active fragment or derivative
thereof and one or more pharmaceutically acceptable carriers and/or
diluents when used in the method according to claim 57.
102. A pharmaceutical composition comprising recombinant mammalian
.alpha.-N-acetylglucosaminidase or an active fragment or derivative
thereof and one ore more pharmaceutically acceptable carriers
and/or diluents when used in the method according to claim 58.
103. A genetic construct comprising the nucleic acid molecule
according to claim 83. operably connected in the sense orientation
to a promoter sequence such that said genetic construct is capable
of being expressed in a eukaryotic or prokaryotic cell to produce a
recombinant mammalian .alpha.-N-acetylglucosaminidase or a fragment
or derivative thereof.
104. A genetic construct comprising the nucleic acid molecule
according to claim 84, operably connected in the sense orientation
to a promoter sequence such that said genetic construct is capable
of being expressed in a eukaryotic or prokaryotic cell to produce a
recombinant mammalian .alpha.-N-acetylglucosaminidase or a fragment
or derivative thereof.
105. An antibody to .alpha.-N-acetylglucosaminidase or a
recombinant .alpha.-N-acetylglucosaminidase according to claim 28
or an antigenic fragment thereof.
106. The antibody according to claim 15 further defined as a
polyclonal antibody molecule.
107. The antibody according to claim 15 further defined as a
monoclonal antibody molecule.
108. An antibody to .alpha.-N-acetylglucosaminidase or a
recombinant .alpha.-N-acetylglucosaminidase according to claim 35
or an antigenic fragment thereof.
109. The antibody according to claim 108 further defined as a
polyclonal antibody molecule.
110. The antibody according to claim 108 further defined as a
monoclonal antibody molecule.
Description
FIELD OF THE INVENTION
[0001] The present invention relates generally to mammalian
.alpha.-N-acetylglucosaminidase and to genetic sequences encoding
same and to the use of these in the investigation, diagnosis and
treatment of subjects suspected of or suffering from
.alpha.-N-acetylglucosaminidase deficiency.
[0002] Bibliographic details of the publications referred to by
author in this specification are collected at the end of the
description. Sequence Identity Numbers (SEQ ID NOs.) for the
nucleotide and amino acid sequences referred to in the
specification are defined following the bibliography.
[0003] Throughout this specification, unless the context requires
otherwise, the word "comprise", or variations such as "comprises"
or "comprising", will be understood to imply the inclusion of a
stated element or integer or group of elements or integers but not
the exclusion of any other element or integer or group of elements
or integers.
BACKGROUND TO THE INVENTION
[0004] The increasing sophistication of recombinant DNA technology
is greatly facilitating the efficacy of many commercially important
industries including areas of medical and pharmaceutical research
and development. The ability to purify native proteins and
subsequently clone genetic sequences encoding these proteins is an
important first step in the development of a range of therapeutic
and diagnostic procedures. However, practitioners have faced many
difficulties in purifying target molecules to an extent sufficient
to determine amino acid sequences to permit the development of
oligonucleotide probes to assist in the cloning of genetic
sequences encoding the target molecules.
[0005] Such difficulties have been particularly faced in the
research and development of lysosomal enzymes. An important
lysosomal enzyme is .alpha.-N-acetylglucosaminidase (EC 2.1.50).
This enzyme acts as a exoglycosidase in lysosomes to hydrolyse the
terminal .alpha.-N-acetylglucosamine residues present at the
non-reducing terminus of fragments of heparan sulphate and heparin
(Hopwood, 1989). A deficiency in this lysosomal hydrolase is
responsible for the pathogenesis of Sanfilippo B
(Mucopolysaccharidosis type IIIB [MPS-IIIB]) syndrome (von-Figura
and Kresse, 1972; O'Brien, 1972). This is an autosomal recessive
disorder of glycosaminoglycan catabolism leading to storage and
excretion of excessive amounts of heparan sulphate and a variety of
clinical phenotypes, but classically presenting with progressive
mental retardation in conjunction with skeletal deformities
(McKusick and Neufeld, 1983).
[0006] There is a need, therefore, to purify
.alpha.-N-acetylglucosaminida- se and to clone genetic sequences
encoding same to permit development of a range of therapeutic and
diagnostic procedures to assist in the diagnosis and treatment of
disease conditions arising from .alpha.-N-acetylglucosam- inidase
deficiency.
SUMMARY OF THE INVENTION
[0007] One aspect of the invention provides an isolated nucleic
acid molecule comprising a sequence of nucleotides which encodes or
is complementary to a sequence which encodes a mammalian
.alpha.-N-acetylglucosaminidase or fragment or derivative
thereof.
[0008] A second aspect of the invention provides an isolated
nucleic acid molecule comprising a sequence of nucleotides which is
capable of hybridising under at least low stringency conditions to
a nucleotide sequence set forth in SEQ ID NO:1 or SEQ ID NO:3 or a
complementary strand or a homologue, analogue or derivative
thereof.
[0009] Another aspect of the invention is directed an isolated
nucleic acid molecule which is at least 40% identical to the
nucleotide sequence set forth in SEQ ID NO:1 or SEQ ID NO:3 or to a
complementary strand thereof or a homologue, analogue or derivative
thereof.
[0010] A further aspect of the present invention provides a nucleic
acid molecule comprising a sequence of nucleotides encoding or
complementary to a sequence encoding a polypeptide capable of
hydrolysing the terminal .alpha.-N-acetylglucosamine residues
present at the non-reducing terminus of fragments of heparan
sulphate and heparin residues and wherein said nucleotide sequence
is capable of hybridising under low stringency conditions to the
nucleotide sequence set forth in SEQ ID NO:1.
[0011] A further aspect of the invention is directed to a genetic
construct comprising a sense molecule, for the expression or
over-expression of .alpha.-N-acetylglucosaminidase in prokaryotic
or eukaryotic cells.
[0012] A further aspect of the present invention is directed to
synthetic .alpha.-N-acetylglucosaminidase or like molecule.
[0013] A further aspect of the invention contemplates antibodies to
.alpha.-N-acetylglucosaminidase and preferably synthetic
.alpha.-N-acetylglucosaminidase or a like molecule.
[0014] In still yet another aspect of the present invention there
is contemplated a method of diagnosing a mutation or other
abberations in the .alpha.-N-acetylglucosaminidase gene in a human
or animal patient.
[0015] Another aspect contemplates a method of treating patients
suffering from .alpha.-N-acetylglucosaminidase deficiency, such as
in MPS-IIIB, said method comprising administering to said patient
an effective amount of .alpha.-N-acetylglucosaminidase or active
like form thereof.
[0016] Another aspect of the present invention is directed to a
pharmaceutical composition comprising a recombinant mammalian
.alpha.-N-acetylglucosaminidase or an active fragment or derivative
thereof and one or more pharmaceutically acceptable carriers and/or
diluents.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 is a photographic representation of
.alpha.-N-acetylglucosam- inidase purified from human placenta
following SDS/PAGE. Lane 1: M.sub.r standards (kDa); Lanes 2 and 3:
purified .alpha.-N-acetylglucosaminidase from human placenta. Lane
4 and 5, bovine serum albumin.
[0018] FIG. 2 is a photographic representation of an
SDS/polyacrylamide gel showing the molecular weights of recombinant
.alpha.-N-acetylglucosam- inidase polypeptides produced in CHO
cells before (-) and after (+) PNGase F digestion. The 50 mM NaCl
and 75 mM NaCl fractions are indicated. Molecular weights of
.alpha.-N-acetylglucosaminidase polypeptides are indicated on the
left of the figure. Molecular weights of marker proteins are
indicated on the right hand side of the figure (lane 5).
[0019] Single and three letter abbreviations of conventional amino
acid residues as used herein are defined in Table 1.
[0020] Suitable amino acid substitutions referred to herein are
defined in Table 2.
[0021] Codes for non-conventional amino acid residues as used
herein are defined in Table 3.
1 TABLE 1 Three-letter One-letter Amino Acid Abbreviation Symbol
Alanine Ala A Arginine Arg R Asparagine Asn N Aspartic acid Asp D
Cysteine Cys C Glutamine Gln Q Glutamic acid Glu E Glycine Gly G
Histidine His H Isoleucine Ile I Leucine Leu L Lysine Lys K
Methionine Met M Phenylalanine Phe F Proline Pro P Serine Ser S
Threonine Thr T Tryptophan Trp W Tyrosine Tyr Y Valine Val V Any
residue Xaa X
[0022]
2TABLE 2 Suitable residues for amino acid substitutions Original
Residue Exemplary Substitutions Ala Ser Arg Lys Asn Gln; His Asp
Glu Cys Ser Gln Asn Glu Asp Gly Pro His Asn; Gln Ile Leu; Val Leu
Ile; Val Lys Arg; Gln; Glu Met Leu; Ile Phe Met; Leu; Tyr Ser Thr
Thr Ser Trp Tyr Tyr Trp; Phe Val Ile; Leu
[0023]
3 TABLE 3 Non-conventional amino acid Code .alpha.-aminobutyric
acid Abu .alpha.-amino-.alpha.-methylbutyrate Mgabu
aminocyclopropane- Cpro carboxylate aminoisobutyric acid Aib
aminonorbornyl- Norb carboxylate cyclohexylalanine Chexa
cyclopentylalanine Cpen D-alanine Dal D-arginine Darg D-aspartic
acid Dasp D-cysteine Dcys D-glutamine Dgln D-glutamic acid Dglu
D-histidine Dhis D-isoleucine Dile D-leucine Dleu D-lysine Dlys
D-methionine Dmet D-ornithine Dorn D-phenylalanine Dphe D-proline
Dpro D-serine Dser D-threonine Dthr D-tryptophan Dtrp D-tyrosine
Dtyr D-valine Dval D-.alpha.-methylalanine Dmala
D-.alpha.-methylarginine Dmarg D-.alpha.-methylasparagine Dmasn
D-.alpha.-methylaspartate Dmasp D-.alpha.-methylcysteine Dmcys
D-.alpha.-methylglutamine Dmgln D-.alpha.-methylhistidine Dmhis
D-.alpha.-methylisoleucine Dmile D-.alpha.-methylleucine Dmleu
D-.alpha.-methyllysine Dmlys D-.alpha.-methylmethionine Dmmet
D-.alpha.-methylornithine Dmorn D-.alpha.-methylphenylalanine Dmphe
D-.alpha.-methylproline Dmpro D-.alpha.-methylserine Dmser
D-.alpha.-methylthreonine Dmthr D-.alpha.-methyltryptophan Dmtrp
D-.alpha.-methyltyrosine Dmty D-.alpha.-methylvaline Dmval
D-N-methylalanine Dnmala D-N-methylarginine Dnmarg
D-N-methylasparagine Dnmasn D-N-methylaspartate Dnmasp
D-N-methylcysteine Dnmcys D-N-methylglutamine Dnmgln
D-N-methylglutamate Dnmglu D-N-methylhistidine Dnmhis
D-N-methylisoleucine Dnmile D-N-methylleucine Dnmleu
D-N-methyllysine Dnmlys N-methylcyclohexylalanine Nmchexa
D-N-methylornithine Dnmorn N-methylglycine Nala
N-methylaminoisobutyrate Nmaib N-(1-methylpropyl)glycine Nile
N-(2-methylpropyl)glycine Nleu D-N-methyltryptophan Dnmtrp
D-N-methyltyrosine Dnmtyr D-N-methylvaline Dnmval
.gamma.-aminobutyric acid Gabu L-t-butylglycine Tbug L-ethylglycine
Etg L-homophenylalanine Hphe L-.alpha.-methylarginine Marg
L-.alpha.-methylaspartate Masp L-.alpha.-methylcysteine Mcys
L-.alpha.-methylglutamine Mgln L-.alpha.-methylhistidine Mhis
L-.alpha.-methylisoleucine Mile L-.alpha.-methylleucine Mleu
L-.alpha.-methylmethion- ine Mmet L-.alpha.-methylnorvaline Mnva
L-.alpha.-methylphenylalanine Mphe L-.alpha.-methylserine Mser
L-.alpha.-methyltryptophan Mtrp L-.alpha.-methylvaline Mval
N-(N-(2,2-diphenylethyl) Nnbhm carbamylmethyl)glycine
1-carboxy-1-(2,2-diphenyl- Nmbc ethylamino)cyclopropane
L-N-methylalanine Nmala L-N-methylarginine Nmarg
L-N-methylasparagine Nmasn L-N-methylaspartic acid Nmasp
L-N-methylcysteine Nmcys L-N-methylglutamine Nmgln
L-N-methylglutamic acid Nmglu L-N-methylhistidine Nmhis
L-N-methylisolleucine Nmile L-N-methylleucine Nmleu
L-N-methyllysine Nmlys L-N-methylmethionine Nmmet
L-N-methylnorleucine Nmnle L-N-methylnorvaline Nmnva
L-N-methylornithine Nmorn L-N-methylphenylalanine Nmphe
L-N-methylproline Nmpro L-N-methylserine Nmser L-N-methylthreonine
Nmthr L-N-methyltryptophan Nmtrp L-N-methyltyrosine Nmtyr
L-N-methylvaline Nmval L-N-methylethylglycine Nmetg
L-N-methyl-t-butylglycine Nmtbug L-norleucine Nle L-norvaline Nva
.alpha.-methyl-aminoisobutyrate Maib .alpha.-methyl-.gamma.-amino-
butyrate Mgabu .alpha.-methylcyclohexylalanine Mchexa
.alpha.-methylcylcopentylalanine Mcpen .alpha.-methyl-.alpha.-nap-
thylalanine Manap .alpha.-methylpenicillamine Mpen
N-(4-aminobutyl)glycine Nglu N-(2-aminoethyl)glycine Naeg
N-(3-aminopropyl)glycine Norn N-amino-.alpha.-methylbutyrate Nmaabu
.alpha.-napthylalanine Anap N-benzylglycine Nphe
N-(2-carbamylethyl)glycine Ngln N-(carbamylmethyl)glycine Nasn
N-(2-carboxyethyl)glycine Nglu N-(carboxymethyl)glycine Nasp
N-cyclobutylglycine Ncbut N-cycloheptylglycine Nchep
N-cyclohexylglycine Nchex N-cyclodecylglycine Ncdec
N-cylcododecylglycine Ncdod N-cyclooctylglycine Ncoct
N-cyclopropylglycine Ncpro N-cycloundecylglycine Ncund
N-(2,2-diphenylethyl) Nbhm glycine N-(3,3-diphenylpropyl) Nbhe
glycine N-(3-guanidinopropyl) Narg glycine
N-(1-hydroxyethyl)glycine Nthr N-(hydroxyethyl))glycine Nser
N-(imidazolylethyl)) Nhis glycine N-(3-indolylyethyl) Nhtrp glycine
N-methyl-.gamma.-aminobutyrate Nmgabu D-N-methylmethionine Dnmmet
N-methylcyclopentylalanine Nmcpen D-N-methylphenylalanine Dnmphe
D-N-methylproline Dnmpro D-N-methylserine Dnmser
D-N-methylthreonine Dnmthr N-(1-methylethyl)glycine Nval
N-methyla-napthylalanine Nmanap N-methylpenicillamine Nmpen
N-(p-hydroxyphenyl)glycine Nhtyr N-(thiomethyl)glycine Ncys
penicillamine Pen L-.alpha.-methylalanine Mala
L-.alpha.-methylasparagine Masn L-.alpha.-methyl-t-butylglycine
Mtbug L-methylethylglycine Metg L-.alpha.-methylglutamate Mglu
L-.alpha.-methylhomo Mhphe phenylalanine N-(2-methylthioethyl) Nmet
glycine L-.alpha.-methyllysine Mlys L-.alpha.-methylnorleucine Mnle
L-.alpha.-methylornithine Morn L-.alpha.-methylproline Mpro
L-.alpha.-methylthreonine Mthr L-.alpha.-methyltyrosine Mtyr
L-N-methylhomo Nmhphe phenylalanine N-(N-(3,3-diphenylpropyl) Nnbhe
carbamylmethyl)glycine
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0024] The present invention provides an isolated nucleic acid
molecule comprising a sequence of nucleotides which encodes, or are
complementary to a sequence which encodes, a mammalian
.alpha.-N-acetylglucosaminidase or fragment or derivative thereof
or its like molecule.
[0025] Preferably, the mammal is a human, livestock animal,
companion animal, wild animal or laboratory test animal (e.g.
rabbit, rat, mouse or guinea pig). Most preferably, the mammal is a
human. Conveniently, the .alpha.-N-acetylglucosaminidase is
isolatable from the liver, kidney or placenta. However, the present
invention extends to all mammalian .alpha.-N-acetylglucosaminidase
enzymes and from any anatomical or cellular source and/or any
biological fluid source, such as but not limited to plasma, serum,
cell extract or lymph fluid.
[0026] Although a preferred embodiment of the present invention
contemplates the use of human .alpha.-N-acetylglucosaminidase or
genomic or recombinant (e.g. cDNA) genetic sequences encoding same
in the investigation, diagnosis and/or treatment of human subjects
(i.e. homologous system), one skilled in the art will appreciate
that the enzyme or genetic sequences encoding same from a non-human
animal may also be useful. Such a heterologous system is
encompassed by the present invention.
[0027] The term "nucleic acid molecule" as used herein shall be
taken to refer to any RNA or DNA (eg. cDNA) molecule, whether
single-stranded or double-stranded or in a linear or
covalently-closed form. The nucleic acid molecule may also be DNA
corresponding to the entire genomic gene or a substantial portion
thereof or a fragment or derivative thereof.
[0028] The nucleic acid molecule of the present invention may
constitute solely the nucleotide sequence encoding
.alpha.-N-acetylglucosaminidase or a
.alpha.-N-acetylglucosaminidase-like molecule or may be part of a
larger nucleic acid molecule. Accordingly, the present invention
extends to the isolated genomic .alpha.-N-acetylglucosaminidase
gene. The non-translated sequences in a larger nucleic acid
molecule may include vector, transcriptional and/or translational
regulatory sequences, promoter, terminator, enhancer, replication
or signal sequences or non-coding regions (eg intron sequences) of
an isolated genomic gene.
[0029] Reference herein to a "gene" is to be taken in its broadest
context and includes:
[0030] (i) a classical genomic gene consisting of transcriptional
and/or translational regulatory sequences and/or a coding region
and/or non-translated sequences (i.e. introns, 5'- and
3'-untranslated sequences);
[0031] (ii) mRNA or cDNA corresponding to the coding regions (i.e.
exons) optionally comprising 5'- or 3'-untranslated sequences of
the gene; or
[0032] (iii) synthetic, amplified DNA fragments or other
recombinant nucleic acid molecules produced in vitro and comprising
all or a part of the coding region and/or 5'- or 3'-untranslated
sequences of the gene.
[0033] The term "gene" is also used to describe synthetic or fusion
molecules encoding all or part of a functional product. A
functional product is one which comprises a sequence of nucleotides
or is complementary to a sequence of nucleotides which encodes a
functional polypeptide, in particular a polypeptide having the
catalytic activity of .alpha.-N-acetylglucosaminidase or a
homologue, analogue or derivative thereof.
[0034] For the present purpose, "homologues" of a nucleotide
sequence shall be taken to refer to an isolated nucleic acid
molecule which is substantially the same as the nucleic acid
molecule of the present invention or its complementary nucleotide
sequence, notwithstanding the occurrence within said sequence, of
one or more nucleotide substitutions, insertions, deletions, or
rearrangements.
[0035] "Analogues" of a nucleotide sequence set forth herein shall
be taken to refer to an isolated nucleic acid molecule which is
substantially the same as a nucleic acid molecule of the present
invention or its complementary nucleotide sequence, notwithstanding
the occurrence of any non-nucleotide constituents not normally
present in said isolated nucleic acid molecule, for example
carbohydrates, radiochemicals including radionucleotides, reporter
molecules such as, but not limited to DIG, alkaline phosphatase or
horseradish peroxidase, amongst others.
[0036] "Derivatives" of a nucleotide sequence set forth herein
shall be taken to refer to any isolated nucleic acid molecule which
contains significant sequence similarity to said sequence or a part
thereof. Generally, the nucleotide sequence of the present
invention may be subjected to mutagenesis to produce single or
multiple nucleotide substitutions, deletions and/or insertions.
Nucleotide insertional derivatives of the nucleotide sequence of
the present invention include 5' and 3' terminal fusions as well as
intra-sequence insertions of single or multiple nucleotides or
nucleotide analogues. Insertional nucleotide sequence variants are
those in which one or more nucleotides or nucleotide analogues are
introduced into a predetermined site in the nucleotide sequence of
said sequence, although random insertion is also possible with
suitable screening of the resulting product being performed.
Deletional variants are characterised by the removal of one or more
nucleotides from the nucleotide sequence. Substitutional nucleotide
variants are those in which at least one nucleotide in the sequence
has been removed and a different nucleotide or nucleotide analogue
inserted in its place.
[0037] Preferably, a homologue, analogue or derivative of an
.alpha.-N-acetylglucosaminidase gene according to any embodiments
described herein, comprises a sequence of nucleotides of at least
10 contiguous nucleotides derived from SEQ ID NO:1 or SEQ ID NO:3
or a complementary strand thereof, wherein the sequence of said
homologue, analogue or derivative is at least 40% identical to SEQ
ID NO:1 or SEQ ID NO:3 or a complementary strand thereof or wherein
said homologue, analogue or derivative is capable of hybridising to
said sequence under at least low stringency hybridisation
conditions.
[0038] For the purposes of nomenclature, the nucleotide sequence
set for in SEQ ID NO: 1 relates to the cDNA encoding the human
.alpha.-N-acetylglucosaminidase enzyme.
[0039] The nucleotide sequence set forth in SEQ ID NO:3 relates to
the genomic gene equivalent of the cDNA encoding the human liver
.alpha.-N-acetylglucosaminidase enzyme. Those skilled in the art
will be aware that the specific exon sequences described in SEQ ID
NO:3 correspond to the coding regions of the
.alpha.-N-acetylglucosaminidase gene, said exon regions further
comprising the entire open reading frame of the cDNA sequence set
forth in SEQ ID NO:1, when aligned in a head-to-tail configuration.
The intron sequences of SEQ ID NO:3, which correspond to non-coding
regions of the gene which are spliced from the primary
transcription product thereof, although not explicitly defined, may
be readily deduced by those skilled in the art, when provided with
the exon sequence data provided in the nucleotide sequence
listing.
[0040] The nucleotide sequence of the present invention may
correspond to the sequence of the naturally-occurring
.alpha.-N-acetylglucosaminidase gene or may comprise a homologue,
analogue or derivative thereof which contains single or multiple
nucleotide substitutions, deletions and/or additions. All such
homologues, analogue or derivatives encode
.alpha.-N-acetylglucosaminidase or
.alpha.-N-acetylglucosaminidase-like molecules or a homologue,
analogue or derivative thereof as contemplated by the present
invention. The length of the nucleotide sequence may-vary-from a
few bases, such as-in nucleic acid probes or primers, to a full
length sequence.
[0041] The present invention is particularly directed to the
nucleic acid in cDNA form and particularly when inserted into an,
expression vector. The expression vector may be replicable in a
eukaryotic or prokaryotic cell and may either produce mRNA or the
mRNA may be subsequently translated into
.alpha.-N-acetylglucosaminidase or like molecule. Particularly
preferred eukaryotic cells include CHO cells but may be in any
other suitable mammalian cells or cell lines or non-mammalian cells
such as yeast or insect cells.
[0042] In an alternative embodiment, the present invention provides
a nucleic acid molecule comprising a sequence of nucleotides which
encodes or are complementary to a sequence which encodes a
polypeptide capable of hydrolysing the .alpha.-N-acetylglucosamine
residues from the non-reducing terminus of heparan sulphate and
heparin fragments and wherein said nucleotide sequence is capable
of hybridising under at least low stringency conditions to a
nucleotide sequence set forth in SEQ ID NO:1 or SEQ ID NO:3 or a
homologue, analogue or derivative thereof.
[0043] A second aspect of the invention provides an isolated
nucleic acid molecule comprising a sequence of nucleotides which is
capable of hybridising under at least low stringency conditions to
a nucleotide sequence set forth in SEQ ID NO:1 or SEQ ID NO:3 or a
complementary strand or a homologue, analogue or derivative
thereof.
[0044] Preferably, hybridisation is possible under at least medium
stringent conditions. More preferably, hybridisation is possible
under high stringent conditions.
[0045] For the purposes of defining the level of stringency,
reference can conveniently be made to Sambrook et al (1989) or
Ausubel et al (1987) which are herein incorporated by
reference.
[0046] A low stringency is defined herein as being a hybridisation
and/or wash carried out in 4-6.times. SSC/0.1-0.5% w/v SDS at
37-45.degree. C. for 2-3 hours. A medium stringency hybridisation
and/or wash is carried out in 1-4.times. SSC/0.25-0.5% w/v SDS at
.gtoreq.45.degree. C. for 2-3 hours and a high stringency
hybridisation and/or wash is carried out 0.1-1.times. SSC/0.1% w/v
SDS at 60.degree. C. for 1-3 hours.
[0047] Alternative conditions of stringency may be employed to
those specifically recited herein. Generally, the stringency is
increased by reducing the concentration of SSC buffer, and/or
increasing the concentration of SDS and/or increasing the
temperature of the hybridisation and/or wash. Those skilled in the
art will be aware that the conditions for hybridisation and/or wash
may vary depending upon the nature of the hybridisation membrane or
the type of hybridisation probe used. Conditions for hybridisations
and washes are well understood by one normally skilled in the art.
For the purposes of clarification of parameters affecting
hybridisation between nucleic acid molecules, reference is found in
pages 2.10.8 to 2.10.16. of Ausubel et al. (1987), which is herein
incorporated by reference.
[0048] Those skilled in the art will be aware that the nucleotide
sequences set forth in SEQ ID NO:1 and SEQ ID NO:3 may be used to
isolate the corresponding genes from other human tissues or
alternatively, from the tissues or cells of other species, without
undue experimentation. Means for the isolated of such related
sequences will also be known to those skilled in the art, for
example nucleic acid hybridisation, polymerase chain reaction,
antibody screening of expression libraries, functional screening of
expression libraries, or complementation of mutants, amongst
others. The present invention is not to be limited by the source
from which the specific gene sequences described herein have been
isolated or by the means used to isolate said sequences.
[0049] In one embodiment, a related genetic sequence comprising
genomic DNA, or mRNA, or cDNA is contacted with a hybridisation
effective amount of a genetic sequence which encodes
.alpha.-N-acetylglucosaminidase, or its complementary nucleotide
sequence or a homologue, analogue, derivative or functional part
thereof, and then said hybridisation is detected using a suitable
detection means.
[0050] The related genetic sequence may be in a recombinant form,
in a virus particle, bacteriophage particle, yeast cell, animal
cell, or a plant cell. Preferably, the related genetic sequence
originates from an animal species or a human. More preferably, the
related genetic sequence originates from a human.
[0051] Preferably, the genetic sequence which encodes
.alpha.-N-acetylglucosaminidase (i.e probe or latter genetic
sequence) comprises a sequence of nucleotides of at least 10
nucleotides, more preferably at least 20 nucleotides, even more
preferably at least 50 nucleotides and even still more preferably
at least 100 nucleotides derived from the nucleotide sequence set
forth in SEQ ID NO: 1 or SEQ ID NO:3 or a complementary sequence or
a homologue, analogue or derivative thereof.
[0052] Preferably, the detection means is a reporter molecule
capable of giving an identifiable signal (e.g. a radioisotope such
as .sup.32P or .sup.35S or a biotinylated molecule) covalently
attached to the .alpha.-N-acetylglucosaminidase probe.
[0053] In an alternative embodiment, the detection means is a
polymerase chain reaction. According to this embodiment, two
opposing non-complementary nucleic acid "primer molecules" of at
least 10 nucleotides in length, more preferably at least 20
nucleotides in length, derived from the nucleotide sequence set
forth in SEQ ID NO:1 or SEQ ID NO:3 may be contacted with a nucleic
acid "template molecule" and specific nucleic acid molecule copies
of the template molecule amplified in a polymerase chain
reaction.
[0054] The opposing primer molecules are selected such that they
are each capable of hybridising to complementary strands of the
same template molecule, wherein DNA polymerase-dependant DNA
synthesis occurring from a first opposing primer molecule will be
in a direction toward the second opposing primer molecule.
[0055] Accordingly, both primers hybridise to said template
molecule such that, in the presence of a DNA polymerase enzyme, a
cofactor and appropriate substrate, DNA synthesis occurs in the 5'
to 3' direction from each primer molecule towards the position on
the DNA where the other primer molecule is hybridised, thereby
amplifying the intervening DNA.
[0056] Those skilled in the art are aware of the technical
requirements of the polymerase chain reaction and are capable of
any modifications which may be made to the reaction conditions. For
example, of the polymerase chain reaction may be used in any
suitable format, such as amplified fragment length polymorphism
(AFLP), single-strand chain polymorphism (SSCP), amplification and
mismatch detection (AMD), interspersed repetitive sequence
polymerase chain reaction (IRS-PCR), inverse polymerase chain
reaction (iPCR) and reverse transcription polymerase chain reaction
(RT-PCR), amongst others, to isolate a related
.alpha.-N-acetylglucosaminidase gene sequence or identify a
mutation in an .alpha.-N-acetylglucosaminidase genetic sequence.
Such variations of the polymerase chain reaction are discussed in
detail by McPherson et al (1991), which is incorporated herein by
reference. The present invention encompasses all such variations,
the only requirement being that the final product of the reaction
is an isolated nucleic acid molecule which is capable of encoding
.alpha.-N-acetylglucosaminidase or a homologue, analogue or
derivative thereof.
[0057] In a preferred embodiment, the first primer molecule is
preferably derived from the sense strand of a gene which encodes
.alpha.-N-acetylglucosaminidase, in particular from the nucleotide
sequence set forth in SEQ ID NO:1 or SEQ ID NO:3 or a homologue,
derivative or analogue thereof and the second primer molecule is
preferably derived from the antisense strand of said gene.
[0058] Those skilled in the art will be aware that it is not
essential to the performance of the invention that the primer
molecules be derived from the same gene.
[0059] According to this embodiment, the nucleic acid primer
molecule may further consist of a combination of any of the
nucleotides adenine, cytidine, guanine, thymidine, or inosine, or
functional analogues or derivatives thereof, capable of being
incorporated into a polynucleotide molecule provided that it is
capable of hybridising under at least low stringency conditions to
the nucleic acid molecule set forth in SEQ ID NO:1 or SEQ ID NO:3
or a homologue, analogue or derivative thereof.
[0060] The nucleic acid primer molecules may further be each
contained in an aqueous pool comprising other nucleic acid primer
molecules. More preferably, the nucleic acid primer molecule is in
a substantially pure form.
[0061] The nucleic acid template molecule may be in a recombinant
form, in a virus particle, bacteriophage particle, yeast cell,
animal cell, or a plant cell. Preferably, the related genetic
sequence originates from a cell, tissue, or organ derived from an
animal species or a human. More preferably, the related genetic
sequence originates from a cell, tissue, or organ derived from a
human.
[0062] Accordingly, a third aspect of the present invention extends
to an isolated nucleic acid molecule which is at least 40%
identical to the nucleotide sequence set forth in SEQ ID NO:1 or
SEQ ID NO:3 or to a complementary strand thereof or a homologue,
analogue or derivative thereof.
[0063] Preferably, the percentage identity to SEQ ID NO:1 or SEQ ID
NO:3 is at least about 55%, still more preferably at least about
65%, yet still more preferably at least about 75-80% and even still
more preferably at least about 85-95%.
[0064] In an even more preferred embodiment, the present invention
provides an isolated nucleic acid molecule which is at least 40%
identical to the nucleotide sequence set forth in SEQ ID NO:1 or
SEQ ID NO:3 or to a complementary strand thereof or a homologue,
analogue or derivative thereof and is capable of hybridising under
at least low stringency conditions to a nucleotide sequence set
forth in SEQ ID NO:1 or SEQ ID NO:3.
[0065] In a particularly preferred embodiment, the isolated nucleic
acid molecule described herein is further capable of encoding a
sequence of amino acids which is capable of carrying out the enzyme
reaction catalysed by a .alpha.-N-acetylglucosaminidase enzyme.
[0066] The isolated nucleic acid molecule of the present invention
is also useful for developing a genetic construct comprising a
sense molecule, for the expression or over-expression of
.alpha.-N-acetylglucosaminidase in prokaryotic or eukaryotic cells.
Particularly preferred eukaryotic cells include CHO cells but may
be in any other suitable mammalian cells or cell lines or
non-mammalian cells such as yeast or insect cells.
[0067] The term "sense molecule" as used herein shall be taken to
refer to an isolated nucleic acid molecule of the invention as
described herein, which is provided in a format suitable for its
expression to produce a recombinant polypeptide, when said sense
molecule is introduced into a host cell.
[0068] In a particularly preferred embodiment, a sense molecule
which encodes the .alpha.-N-acetylglucosaminidase comprises a
sequence of nucleotides set forth in SEQ ID NO:1 or SEQ ID NO:3 or
a complementary strand, homologue, analogue or derivative
thereof.
[0069] In a most particularly preferred embodiment, the sense
molecule of the invention comprises the sequence of nucleotides set
forth in SEQ ID NO:1 or a complementary strand, homologue, analogue
or derivative thereof.
[0070] Those skilled in the art will be aware that expression of a
sense molecule may require the nucleic acid molecule of the
invention to be placed in operable connection with a promoter
sequence to produce a "sense construct". The choice of promoter for
the present purpose may vary depending upon the level of expression
of the sense molecule required and/or the tissue-specificity or
developmental-specificity of expression of the sense molecule which
is required. The sense construct may further comprise a terminator
sequence and be introduced into a suitable host cell where it is
capable of being expressed to produce a recombinant polypeptide
gene product.
[0071] In the context of the present invention, a sense molecule
which corresponds to a genetic sequence or isolated nucleic acid
molecule which encodes .alpha.-N-acetylglucosaminidase polypeptide
or a homologue, analogue or derivative thereof, placed operably
under the control of a suitable promoter sequence, is introduced
into a cell using any suitable method for the transformation of
said cell and said genetic sequence or isolated nucleic acid
molecule is expressed therein to produce said polypeptide.
[0072] The present invention clearly extends to genetic constructs
designed to facilitate expression of any nucleic acid molecule
described herein.
[0073] A genetic construct of the present invention comprises the
foregoing sense molecule, placed operably under the control of a
promoter sequence capable of regulating the expression of the said
nucleic acid molecule in a prokaryotic or eukaryotic cell,
preferably a mammalian cell such as a CHO cell, a yeast cell,
insect cell or bacterial cell. The said genetic construct
optionally comprises, in addition to a promoter and sense molecule,
a terminator sequence.
[0074] The term "terminator" refers to a DNA sequence at the end of
a transcriptional unit which signals termination of transcription.
Terminators are 3'-non-translated DNA sequences containing a
polyadenylation signal, which facilitates the addition of
polyadenylate sequences to the 3'-end of a primary transcript.
Terminators active in plant cells are known and described in the
literature. They may be isolated from bacteria, fungi, viruses,
animals and/or plants.
[0075] Reference herein to a "promoter" is to be taken in its
broadest context and includes the transcriptional regulatory
sequences of a classical genomic gene, including the TATA box which
is required for accurate transcription initiation, with or without
a CCAAT box sequence and additional regulatory elements (i.e.
upstream activating sequences, enhancers and silencers) which alter
gene expression in response to developmental and/or external
stimuli, or in a tissue-specific manner. A promoter is usually, but
not necessarily, positioned upstream or 5', of a structural gene,
the expression of which it regulates. Furthermore, the regulatory
elements comprising a promoter are usually positioned within 2 kb
of the start site of transcription of the gene.
[0076] In the present context, the term "promoter" is also used to
describe a synthetic or fusion molecule, or derivative which
confers, activates or enhances expression of said sense molecule in
a cell.
[0077] Preferred promoters may contain additional copies of one or
more specific regulatory elements, to further enhance expression of
the sense molecule and/or to alter the spatial expression and/or
temporal expression of said sense molecule. For example, regulatory
elements which confer copper inducibility may be placed adjacent to
a heterologous promoter sequence driving expression of a sense
molecule, thereby conferring copper inducibility on the expression
of said molecule.
[0078] Placing a sense molecule under the regulatory control of a
promoter sequence means positioning the said molecule such that
expression is controlled by the promoter sequence. Promoters are
generally positioned 5' (upstream) to the genes that they control.
In the construction of heterologous promoter/structural gene
combinations it is generally preferred to position the promoter at
a distance from the gene transcription start site that is
approximately the same as the distance between that promoter and
the gene it controls in its natural setting, i.e., the gene from
which the promoter is derived. As is known in the art, some
variation in this distance can be accommodated without loss of
promoter function. Similarly, the preferred positioning of a
regulatory sequence element with respect to a heterologous gene to
be placed under its control is defined by the positioning of the
element in its natural setting, i.e., the genes from which it is
derived. Again, as is known in the art, some variation in this
distance can also occur.
[0079] Examples of promoters suitable for use in genetic constructs
of the present invention include viral, fungal, bacterial, animal
and plant derived promoters capable of functioning in animal,
human, yeast, insect or bacterial cells. The promoter may regulate
the expression of the said molecule constitutively, or
differentially with respect to the tissue in which expression
occurs or, with respect to the developmental stage at which
expression occurs, or in response to external stimuli such as
physiological stresses, or plant pathogens, or metal ions, amongst
others. Preferably, the promoter is capable of regulating
expression of a sense-molecule in a cell derived from an animal
species or human.
[0080] In a particularly preferred embodiment, the promoter is
derived from the genomic gene encoding
.alpha.-N-acetylglucosaminidase, preferably the human
.alpha.-N-acetylglucosaminidase gene. In a more preferred
embodiment, however, the promoter is derived from the nucleotide
sequence set forth in SEQ ID NO:3 or is at least capable of
hybridising to nucleotide residues 1 to 989 of SEQ ID NO:3 or at
least 20 contiguous nucleotides derived therefrom.
[0081] In an even more particularly preferred embodiment, the
promoter is the CMV promoter sequence or a promoter sequence
derived therefrom.
[0082] An alternative embodiment of the invention is directed to a
genetic construct comprising a promoter or functional derivative,
part fragment, homologue, or analogue thereof, derived from the
.alpha.-N-acetylglucosam- inidase genomic gene defined by SEQ ID
NO: 3.
[0083] Preferably, said genetic construct further comprises the
.alpha.-N-acetylglucosaminidase sequence defined by SEQ ID NO:1
placed in operably connection with said promoter.
[0084] A further aspect of the present invention is directed to
synthetic .alpha.-N-acetylglucosaminidase or like molecule.
[0085] The term "synthetic" as used herein shall be taken to
include both recombinant and chemically-synthesised molecules
produced by the sequential addition of amino acid residues or
groups of amino acid residues in defined order.
[0086] In one embodiment, the invention relates to recombinant
.alpha.-N-acetylglucosaminidase or like molecule encoded by or
expressed from the nucleic acid molecules as hereinbefore
described.
[0087] In another embodiment the synthetic
.alpha.-N-acetylglucosaminidase or like molecule comprises a
sequence of amino acids which is at least 40% identical to the
amino acid sequence set forth in any one of SEQ ID Nos:2, 4, 5 or
6.
[0088] More preferably, the percentage identity is at least 60% and
still more preferably at least 80% or 85-90%.
[0089] A particularly preferred embodiment of the present invention
provides a synthetic .alpha.-N-acetylglucosaminidase as
hereinbefore defined which comprises a sequence of amino acids
substantially as set forth in any one of SEQ ID Nos:2, 4, 5 or 6 or
a homologue, analogue or derivative thereof.
[0090] For the purposes of nomenclature, the amino acid sequence
set forth in SEQ ID NO:2 comprises the full-length translation
product of the human .alpha.-N-acetylglucosaminidase gene (i.e.
hereinafter referred to as the ".alpha.-N-acetylglucosaminidase
polypeptide" or "SEQ ID NO:2") produced by expression of either the
cDNA sequence defined by SEQ ID NO:1 or the genomic gene defined by
SEQ ID NO:3. The .alpha.-N-acetylglucosaminidase polypeptide
comprises at least seven potentially-glycosylated Asn residues, at
positions 261, 272, 435, 503, 513, 526 and 532. Furthermore, the
amino acid sequence of the .alpha.-N-acetylglucosaminidase
polypeptide may comprise a signal peptide of approximately 23 amino
acid residues in length, with a probable site for signal peptide
peptidase cleavage occurring between Gly.sub.23 and Asp.sub.24.
[0091] The amino acid sequences set forth in SEQ ID Nos:4-6 relate
to N-terminal and internal (i.e. CNBr) amino acid sequences derived
from human .alpha.-N-acetylglucosaminidase, purified as described
in Example 1. As described in Example 2, the purified form of the
enzyme comprises two polypeptides having approximate molecular
weights of 82 and 77 kDa. The sequence set forth in SEQ ID NO:4
relates to the N-terminal sequence of the 82 kDa polypeptide, while
SEQ ID NO:5 relates to the N-terminal sequence of the 77 kDa
polypeptide. Furthermore, SEQ ID NO:4 comprises amino acids
residues 24-43 of SEQ ID NO:2, while SEQ ID NO:5 comprises amino
acid residues 59-76 of SEQ ID NO:2.
[0092] The amino acid sequence defined by SEQ ID NO:6 relates to
the CNBr-cleaved peptide of purified human
.alpha.-N-acetylglucosaminidase. This amino acid sequence aligns
with amino acid residues 540-554 of the
.alpha.-N-acetylglucosaminidase polypeptide (SEQ ID NO:2).
[0093] In the present context, "homologues" of a polypeptide refer
to those polypeptides, enzymes or proteins which have a similar
.alpha.-N-acetylglucosaminidase enzyme activity, notwithstanding
any amino acid substitutions, additions or deletions thereto. A
homologue may be isolated or derived from the same or another
animal species.
[0094] Furthermore, the amino acids of a homologous polypeptide may
be replaced by other amino acids having similar properties, for
example hydrophobicity, hydrophilicity, hydrophobic moment, charge
or antigenicity, and so on.
[0095] "Analogues" encompass .alpha.-N-acetylglucosaminidase
polypeptides and peptide derivatives thereof notwithstanding the
occurrence of any non-naturally occurring amino acid analogues
therein.
[0096] The term "derivative" in relation to the polypeptides of the
invention refer to mutants, parts or fragments of a functional
molecule. Derivatives include modified peptides in which ligands
are attached to one or more of the amino acid residues contained
therein, such as carbohydrates, enzymes, proteins, polypeptides or
reporter molecules such as radionuclides or fluorescent compounds.
Glycosylated, fluorescent, acylated or alkylated forms of the
subject peptides are particularly contemplated by the present
invention. Additionally, derivatives of a polypeptide may comprise
fragments or parts of an amino acid sequence disclosed herein and
are within the scope of the invention, as are homopolymers or
heteropolymers comprising two or more copies of the subject
polypeptides. Procedures for derivatizing peptides are well-known
in the art.
[0097] Accordingly, this aspect of the present invention is
directed to any proteinaceous molecule comprising an amino acid
sequence corresponding to the full length mammalian
.alpha.-N-acetylglucosaminidas- e enzyme or to a like molecule. The
like molecule, therefore, comprises parts, derivatives and/or
portions of the .alpha.-N-acetylglucosaminidase enzyme whether
functional or not.
[0098] Preferably, the mammal is human but may be of non-human
origin as contemplated above.
[0099] The synthetic or recombinant .alpha.-N-acetylglucosaminidase
of the present invention may comprise an amino acid sequence
corresponding to the naturally occurring amino acid sequence or may
contain single or multiple amino acid substitutions, deletions
and/or additions. The length of the amino acid sequence may range
from a few residues to a full length molecule.
[0100] Amino acid substitutions are typically of single residues.
Amino acid insertions will usually be in the order of about 1-10
amino acid residues and deletions will range from about 1-20
residues. Preferably, deletions or insertions are made in adjacent
pairs, i.e. a deletion of two residues or insertion of two
residues.
[0101] Amino acid insertional derivatives of
.alpha.-N-acetylglucosaminida- se of the present invention include
amino and/or carboxyl terminal fusions as well as intra-sequence
insertions of single or multiple amino acids. Insertional amino
acid sequence variants are those in which one or more amino acid
residues are introduced into a predetermined site in the protein
although random insertion is also possible with suitable screening
of the resulting product. Deletional variants are characterised by
the removal of one or more amino acids from the sequence.
Substitutional amino acid variants are those in which at least one
residue in the sequence has been removed and a different residue
inserted in its place. Typical substitutions are those made in
accordance with the following Table 2:
[0102] The amino acid variants referred to above may readily be
made using peptide synthetic techniques well known in the art such
as solid phase peptide synthesis (Merrifield synthesis) and the
like, or by recombinant DNA manipulations. Techniques for making
substitution mutations at predetermined sites in DNA having known
or partially known sequence are well known and include, for
example, M13 mutagenesis. The manipulation of DNA sequence to
produce variant proteins which manifest as substitutional,
insertional or deletional variants are conveniently elsewhere
described such as Sambrook et al, 1989 Molecular Cloning: A
Laboratory Manual Cold Spring Harbor Laboratories, Cold Spring
Harbor, N.Y.
[0103] The derivatives or like molecules include single or multiple
substitutions, deletions and/or additions of any component(s)
naturally or artificially associated with the
.alpha.-N-acetylglucosaminidase enzyme such as carbohydrate, lipid
and/or other proteinaceous moieties. For example, the present
invention extends to glycosylated and non-glycosylated forms of the
molecule. All such molecules are encompassed by the expression
"mutants", "derivatives", "fragments", "portions" and "like"
molecules. These molecules may be active or non-active and may
contain specific regions, such as a catalytic region. Particularly,
preferred derivative molecules include those with altered
glycosylation patterns relative to the naturally occurring
molecule. Even more particularly, the recombinant molecule is more
highly glycosylated than the naturally occurring molecule. Such
highly glycosylated derivatives may have improved take-up
properties and enhanced half-lives.
[0104] As indicated in the Examples, the molecular weight of
purified human .alpha.-N-acetylglucosaminidase (i.e. 82 kDa and 77
kDa) and recombinant mammalian .alpha.-N-acetylglucosaminidase
produced in CHO cells (i.e. 89 kDa and 79 kDa) are greater than the
deduced molecular weight of the .alpha.-N-acetylglucosaminidase
polypeptide set forth in SEQ ID No:2 (i.e. 70 kDa), suggesting that
the purified and recombinant polypeptide are post-translationally
modified. The data presented in Example 8 indicate further that the
recombinant .alpha.-N-acetylglucosami- nidase enzyme produced in
CHO cells, at least, is glycosylated and that the difference in
molecular weight determined for the recombinant polypeptides and
the polypeptide of SEQ ID No: 2 is due almost entirely to
glycosylation of the recombinant polypeptide by CHO cells. As shown
in Example 9, the glycosylated recombinant
.alpha.-N-acetylglucosaminidase polypeptide exhibits enzymatic
activity.
[0105] The present invention also extends to synthetic
.alpha.-N-acetylglucosaminidase or like molecules when fused to
other proteinaceous molecules. The latter may include another
enzyme, reporter molecule, purification site or an amino acid
sequence which facilitates transport of the molecule out of a cell,
such as a signal sequence.
[0106] The present invention extends further to post-translational
modifications to the .alpha.-N-acetylglucosaminidase enzyme. The
modifications may be made to the naturally occurring enzyme or
following synthesis by recombinant techniques. The modifications
may be at the structural level or at, for example, the
electrochemical level such as modifying net charge or structural
conformation of the enzyme.
[0107] Such modification may be important to facilitate entry or
penetration of the enzyme into selected tissues such as cartilage
or blood brain barriers or to increase circulation half-life.
[0108] Analogues of .alpha.-N-acetylglucosaminidase contemplated
herein include, but are not limited to, modifications to side
chains, incorporation of unnatural amino acids and/or their
derivatives during peptide synthesis and the use of crosslinkers
and other methods which impose conformational constraints on the
enzyme.
[0109] Examples of side chain modifications contemplated by the
present invention include modifications of amino groups such as by
reductive alkylation by reaction with an aldehyde followed by
reduction with NaBH.sub.4; amidination with methylacetimidate;
acylation with acetic anhydride; carbamoylation of amino groups
with cyanate; trinitrobenzylation of amino groups with
2,4,6-trinitrobenzene sulphonic acid (TNBS); acylation of amino
groups with succinic anhydride and tetrahydrophthalic anhydride;
and pyridoxylation of lysine with pyridoxal-5'-phosphate followed
by reduction with NaBH.sub.4.
[0110] The guanidino group of arginine residues may be modified by
the formation of heterocyclic condensation products with reagents
such as 2,3-butanedione, phenylglyoxal and glyoxal.
[0111] The carboxyl group may be modified by carbodiimide
activation via O-acylisourea formation followed by subsequent
derivatisation, for example, to a corresponding amide.
[0112] Sulphydryl groups may be modified by methods such as
carboxymethylation with iodoacetic acid or iodoacetamide; performic
acid oxidation to cysteic acid; formation of a mixed disulphides
with other thiol compounds; reaction with maleimide, maleic
anhydride or other substituted maleimide; formation of mercurial
derivatives using 4-chloromercuribenzoate,
4-chloromercuriphenylsulphonic acid, phenylmercury chloride,
2-chloromercuric-4-nitrophenol and other mercurials; carbamoylation
with cyanate at alkaline pH.
[0113] Tryptophan residues may be modified by, for example,
oxidation with N-bromosuccinimide or alkylation of the indole ring
with 2-hydroxy-5-nitrobenzyl bromide or sulphenyl halides. Tyrosine
residues on the other hand, may be altered by nitration with
tetranitromethane to form a 3-nitrotyrosine derivative.
[0114] Modification of the imidazole ring of a histidine residue
may be accomplished by alkylation with iodoacetic acid derivatives
or N-carbethoxylation with diethylpyrocarbonate.
[0115] Examples of incorporating unnatural amino acids and
derivatives during peptide synthesis include, but are not limited
to, use of norleucine, 4-amino butyric acid,
4-amino-3-hydroxy-5-phenylpentanoic acid, 6-aminohexanoic acid,
t-butylglycine, norvaline, phenylglycine, ornithine, sarcosine,
4-amino-3-hydroxy-6-methylheptanoic acid, 2-thienyl alanine and/or
D-isomers of amino acids. Non-naturally occurring amino acids
contemplated by the present invention are incorporated herein, as
Table 3.
[0116] Crosslinkers can be used, for example, to stabilise 3D
conformations, using homo-bifunctional crosslinkers such as the
bifunctional imido esters having (CH.sub.2).sub.n spacer groups
with n=1 to n=6, glutaraldehyde, N-hydroxysuccinimide esters and
hetero-bifunctional reagents which usually contain an
amino-reactive moiety such as N-hydroxysuccinimide and another
group specific-reactive moiety such as maleimido or dithio moiety
(SH) or carbodiimide (COOH). In addition, the enzyme could be
conformationally constrained by, for example, incorporation of
C.sub..alpha. and N.sub..alpha.-methylamino acids, introduction of
double bonds between C.sub..alpha. and C.sub..beta. atoms of amino
acids and the formation of cyclic peptides or analogues by
introducing covalent bonds such as forming an amide bond between
the N and C termini, between two side chains or between a side
chain and the N or C terminus.
[0117] Electrochemical modifications of
.alpha.-N-acetylglucosaminidase include interaction with polylysine
or polyethylene glycol or other agent which effects an overall
change to the net charge of the enzyme.
[0118] Advantageously, the recombinant
.alpha.-N-acetylglucosaminidase is a biologically pure preparation
meaning that it has undergone some purification away for other
proteins and/or non-proteinaceous material. The purity of the
preparation may be represented as at least 40% of the enzyme,
preferably at least 60%, more preferably at least 75%, even more
preferably at least 85% and still more preferably at least 95%
relative to non-.alpha.-N-acetylglucosaminidase material as
determined by weight, activity, amino acid homology or similarity,
antibody reactivity or other convenient means.
[0119] Particularly preferred methods-for the preparation and
purification of recombinant .alpha.-N-acetylglucosaminidase are
provided in Examples 7 and 8.
[0120] Those skilled in the art will be aware of the means of
purifying a synthetic or recombinant
.alpha.-N-acetylglucosaminidase from several sources without undue
experimentation and for expressing the degree of purity of such a
purified preparation of the enzyme.
[0121] The present invention further contemplates antibodies to
.alpha.-N-acetylglucosaminidase and preferably synthetic
.alpha.-N-acetylglucosaminidase or like molecule. The antibodies
may be polyclonal or monoclonal, naturally occurring or synthetic
(including recombinant, fragment or fusion forms). Such antibodies
will be useful in developing immunoassays for
.alpha.-N-acetylglucosaminidase and for identifying additional
genetic sequences which are capable of expressing
.alpha.-N-acetylglucosaminidase polypeptides or homologues,
analogues or derivatives thereof.
[0122] Both polyclonal and monoclonal antibodies are obtainable by
immunisation with an appropriate synthetic or recombinant gene
product, or epitope, or peptide fragment of a gene product, in
particular a .alpha.-N-acetylglucosaminidase polypeptide or a
homologue, analogue or derivative thereof.
[0123] Alternatively, fragments of antibodies may be used, such as
Fab fragments. The present invention extends further to encompass
recombinant and synthetic antibodies and to antibody hybrids. A
"synthetic antibody" is considered herein to include fragments and
hybrids of antibodies.
[0124] A further aspect of the present invention contemplates a
method of screening for mutations or other abberations in the
.alpha.-N-acetylglucosaminidase gene in a human or animal patient.
Such a method may be accomplished in a number of ways including
isolating a source of DNA to be tested or mRNA therefrom and
hybridising thereto a nucleic acid molecule as hereinbefore
described. Generally, the nucleic acid is probe or primer size and
polymerase chain reaction is a convenient means by which to analyse
the RNA or DNA. Other suitable assays include the ligation chain
reaction and the strand displacement amplification methods. The
.alpha.-N-acetylglucosaminidase sequence can also be determined and
compared to the naturally occurring sequence. Such methods may be
useful in adults and children and may be adapted for a pre-natal
test The DNA to be tested includes a genomic sample carrying the
.alpha.-N-acetylglucosaminidase gene, a cDNA clone and/or
amplification product.
[0125] In accordance with this aspect of the present invention
there is provided a method for screening for abberations in the
.alpha.-N-acetylglucosaminidase gene including the absence of such
a gene or a portion or a substantial portion thereof comprising
isolating a sample of DNA or mRNA corresponding to a region of said
DNA and contacting same with an oligonucleotide probe capable of
hybridising to one or more complementary sequences within the
.alpha.-N-acetylglucosamin- idase gene and then detecting the
hybridisation, the extent of hybridisation or the absence of
hybridisation.
[0126] Alternatively, the probe is a primer and capable of
directing amplification of one or more regions of said
.alpha.-N-acetylglucosaminid- ase gene and the amplification
products and/or profile of amplification products is compared to an
individual carrying the full gene or to a reference date base.
[0127] Conveniently, the amplification products are sequenced to
determine the presence or absence of the full gene.
[0128] The present invention extends to the use of any and all
DNA-based or nucleic acid-based hybridisation and/or polymerase
chain reaction formats as described herein, for the diagnosis of a
disorder involving the .alpha.-N-acetylglucosaminidase gene in a
human or animal patient.
[0129] The present invention further extends to a method of
treating patients suffering from .alpha.-N-acetylglucosaminidase
deficiency, such as in MPS-IIIB, said method comprising
administering to said patient an effective amount of
.alpha.-N-acetylglucosaminidase or active like form thereof.
[0130] Preferably, the .alpha.-N-acetylglucosaminidase is in
recombinant form. Such a method is referred to as "enzyme therapy".
Alternatively, gene therapy can be employed including introducing
an active gene (i.e. a nucleic acid molecule as hereinbefore
described) or to parts of the gene or other sequences which
facilitate expression of a naturally occurring
.alpha.-N-acetylglucosaminidase gene.
[0131] Administration of .alpha.-N-acetylglucosaminidase for enzyme
therapy may be by oral, intravenous, suppository, intraperitoneal,
intramuscular, intranasal, intradermal or subcutaneous
administration or by infusion or implantation. The
.alpha.-N-acetylglucosaminidase is preferably as hereinbefore
described including active mutants or derivatives thereof and
glycosylation variants thereof. Administration may also be by way
of gene therapy including expression of the gene by inclusion of
the gene in viral vectors which are introduced into the animal
(e.g. human) host to be treated. Alternatively, the gene may be
expressed in a bacterial host which is then introduced and becomes
part of the bacterial flora in the animal to be tested.
[0132] Still yet another aspect of the present invention is
directed to a pharmaceutical composition comprising synthetic (e.g.
recombinant) .alpha.-N-acetylglucosaminidase or like molecule,
including active derivatives and fragments thereof, alone or in
combination with other active molecules. Such other molecules may
act synergistically with the enzyme or facilitates its entry to a
target cell. The composition will also contain one or more
pharmaceutically acceptable carriers and/or diluents. The
composition may alternatively comprise a genetic component useful
in gene therapy.
[0133] The active ingredients of the pharmaceutical composition
comprising the synthetic or recombinant
.alpha.-N-acetylglucosaminidase or mutants or fragments or
derivatives thereof are contemplated to exhibit excellent activity
in treating patients with a deficiency in the enzyme when
administered in an amount which depends on the particular case. The
variation depends, for example, on the patient and the
.alpha.-N-acetylglucosaminidase used. For example, from about 0.5
ug to about 20 mg of enzyme per animal body or, depending on the
animal and other factors, per kilogram of body weight may be
administered. Dosage regima may be adjusted to provide the optimum
therapeutic response. For example, several divided doses may be
administered daily, weekly, monthly or in other suitable time
intervals or the dose may be proportionally reduced as indicated by
the exigencies of the situation. Accordingly, alternative dosages
in the order of 1.0 .mu.g to 15 mg, 2.0 .mu.g to 10 mg or 10 .mu.g
to 5 mg may be administered in a single or as part of multiple
doses. The active compound may be administered in a convenient
manner such as by the oral, intravenous (where water soluble),
intramuscular, subcutaneous, intranasal, intradermal or suppository
routes or implanting (eg using slow release molecules). Depending
on the route of administration, the active ingredients which
comprise a synthetic (e.g. recombinant)
.alpha.-N-acetylglucosaminidase or fragments, derivatives or
mutants thereof may be required to be coated in a material to
protect same from the action of enzymes, acids and other natural
conditions which may inactivate said ingredients. For example, the
low lipophilicity of .alpha.-N-acetylglucosaminidase will allow it
to be destroyed in the gastrointestinal tract by enzymes capable of
cleaving peptide bonds and in the stomach by acid hydrolysis. In
order to administer the vaccine by other than parenteral
administration, the enzyme will be coated by, or administered with,
a material to prevent its inactivation. For example, the enzyme may
be administered in an adjuvant, co-administered with enzyme
inhibitors or in liposomes. Adjuvant is used in its broadest sense
and includes any immune stimulating compound such as interferon.
Adjuvants contemplated herein include resorcinols, non-ionic
surfactants such as polyoxyethylene oleyl ether and n-hexadecyl
polyethylene ether. Conveniently, the adjuvant is Freund's Complete
or Incomplete Adjuvant. Enzyme inhibitors include pancreatic
trypsin inhibitor, diisopropylfluorophosphate (DEP) and trasylol.
Liposomes include water-in-oil-in-water emulsions as well as
conventional liposomes.
[0134] The active compound may also be administered in dispersions
prepared in glycerol, liquid polyethylene glycols, and/or mixtures
thereof and in oils. Under ordinary conditions of storage and use,
these preparations contain a preservative to prevent the growth of
microorganisms.
[0135] The pharmaceutical forms suitable for injectable use include
sterile aqueous solutions (where water soluble) or dispersions and
sterile powders for the extemporaneous preparation of sterile
injectable solutions or dispersion. In all cases the form must be
sterile and must be fluid to the extent that easy syringability
exists. It must be stable under the conditions of manufacture and
storage and must be preserved against the contaminating action of
microorganisms such as bacteria and fungi. The carrier can be a
solvent or dispersion medium containing, for example, water,
ethanol, polyol (for example, glycerol, propylene glycol, and
liquid polyethylene glycol, and the like), suitable mixtures
thereof, and vegetable oils. The proper fluidity can be maintained,
for example, by the use of a coating such as lecithin, by the
maintenance of the required particle size in the case of dispersion
and by the use of superfactants. The prevention of the action of
microorganisms can be brought about by various antibacterial and
antifungal agents, for example, parabens, chlorobutanol, phenol,
sorbic acid, thirmerosal, and the like. In many cases, it will be
preferable to include isotonic agents, for example, sugars or
sodium chloride. Prolonged absorption of the injectable
compositions can be brought about by the use in the compositions of
agents delaying absorption, for example, aluminum monostearate and
gelatin.
[0136] Sterile injectable solutions are prepared by incorporating
the active compound in the required amount in the appropriate
solvent with various of the other ingredients enumerated above, as
required, followed by filtered sterilization. Generally,
dispersions are prepared by incorporating the various sterilized
active ingredient(s) into a sterile vehicle which contains the
basic dispersion medium and the required other ingredients from
those enumerated above. In the case of sterile powders for the
preparation of sterile injectable solutions, the preferred methods
of preparation are vacuum drying and the freeze-drying technique
which yield a powder of the active ingredient plus any additional
desired ingredient from previously sterile-filtered solution
thereof.
[0137] When the .alpha.-N-acetylglucosaminidase of the present
invention is suitably protected as described above, the composition
may be orally administered, for example, with an inert diluent or
with an assimilable edible carrier, or it may be enclosed in hard
or soft shell gelatin capsule, or it may be compressed into
tablets, or it may be incorporated directly with the food of the
diet. For oral therapeutic administration, the active compound may
be incorporated with excipients and used in the form of ingestible
tablets, buccal tablets, troches, capsules, elixirs, suspensions,
syrups, wafers, and the like. Such compositions and preparations
should contain at least 1% by weight of active compound. The
percentage of the compositions and preparations may, of course, be
varied and may conveniently be between about 5 to about 80% of the
weight of the unit. The amount of active compound in the vaccine
compositions is such that a suitable dosage will be obtained.
Preferred compositions or preparations according to the present
invention are prepared, so that an oral dosage unit form contains
between about 0.5 ug and 20 mg of active compound.
[0138] The tablets, troches, pills, capsules and the like may also
contain the following: a binder such as gum gragacanth, acacia,
corn starch or gelatin; excipients such as dicalcium phosphate; a
disintegrating agent such as corn starch, potato starch, alginic
acid and the like; a lubricant such as magnesium stearate; and a
sweetening agent such a sucrose, lactose or saccharin may be added
or a flavoring agent such as peppermint, oil of wintergreen, or
cherry flavouring. When the dosage unit form is a capsule, it may
contain, in addition to materials of the above type, a liquid
carrier. Various other materials may be present as coatings or to
otherwise modify the physical form of the dosage unit. For
instance, tablets, pills, or capsules may be coated with shellac,
sugar or both. A syrup or elixir may contain the active compound,
sucrose as a sweetening agent, methyl and propylparabens as
preservatives, a dye and flavoring such as cherry or orange flavor.
Of course, any material used in preparing any dosage unit form
should be pharmaceutically pure and substantially non-toxic in the
amounts employed. In addition, the active compound may be
incorporated into sustained-release reparations and
formulations.
[0139] As used herein "pharmaceutically acceptable carriers and/or
diluents" include any and all solvents, dispersion media, aqueous
solutions, coatings, antibacterial and antifungal agents, isotonic
and absorption delaying agents, and the like. The use of such media
and agents for pharmaceutical active substances is well known in
the art. Except insofar as any conventional media or agent is
incompatible with the active ingredient, use thereof in the
pharmaceutical compositions is contemplated. Supplementary active
ingredients can also be incorporated into the compositions.
[0140] The present invention further relates to the use of
.alpha.-N-acetylglucosaminidase or active fragment, mutant or
derivative thereof in the manufacture of a medicament for the
treatment of patients suffering from a deficiency in the naturally
occurring enzyme (e.g. MPS-IIIB).
[0141] The present invention is further described with reference to
the following non-limiting Examples.
EXAMPLE 1
Purification of .alpha.-N-acetylglucosaminidase
[0142] .alpha.-N-acetylglucosaminidase was purified according to
the method described in Weber et al. (1996). Enzyme was purified to
homogeneity from human placenta. Evidence of purity is shown
following SDS/PAGE which is represented in FIG. 1. All samples were
reduced with dithiothreitol prior to electrophoresis.
EXAMPLE 2
Characterisation of .alpha.-N-acetylglucosaminidase
[0143] Results presented in FIG. 1 show two polypeptides of about
82 kDa and 77 kDa molecular weight, which correspond to
.alpha.-N-acetylglucosam- inidase polypeptides purified from human
placenta according to Example 1.
EXAMPLE 3
Amino Acid Sequence Determination
[0144] The N-terminal amino acid sequences the 77 kDA and 82 kDa
.alpha.-N-acetylglucosaminidase polypeptides, in addition to the
amino acid sequence of an internal CNBr cleavage product of these
peptides, were determined using the methods of Weber et al.
(1996).
[0145] The amino acid sequences are shown in Table 4.
4TABLE 4 N-Terminal Amino Acid Sequences (SEQ ID NO:4 and SEQ ID
No:5) and CNBr peptide sequence (SEQ ID No:6) determined from
Purified Human .alpha.-N-Acetylglucosaminida- se polypeptide 82 kDa
DEAREAAAVRALVARLLGPG polypeptide 77 kDa KPGLDTYSLGGGGAAX.sup.1 VR
CNBr peptide WRLLLTSAPSLX.sup.1TX.sup.1P
[0146] X.sup.1 no residue could be identified for this position,
indicating that this residue could be phosphorylated or
glycosylated.
EXAMPLE 4
Cloning of .alpha.-N-acetylglucosaminidase cDNA
[0147] Oligonucleotide probes were prepared based on the partial
amino acid sequences obtained for the purified
.alpha.-N-acetylglucosaminidase polypeptides (Example 3). The
probes were subsequently used to screen a human peripheral blood
leukocyte cDNA library. An approximately 2.6 kbp cDNA clone was
isolated encoding most of the sequence of human
.alpha.-N-acetylglucosaminidase (SEQ ID NO:1).
[0148] The remaining .alpha.-N-acetylglucosaminidase coding
sequence was obtained from the nucleotide sequence of the
corresponding genomic gene (SEQ ID NO:3), isolated by hybridisation
to a human chromosome 17 library (Weber et.al. 1996).
[0149] The complete open reading frame is 2232 nucleotides long and
encodes a 743 (plus stop codon) amino acid protein. The predicted
molecular mass of the longest mature protein (minus the 23 amino
acid N-terminal signal peptide) is about 79,622 daltons.
[0150] The amino acid sequence of .alpha.-N-acetylglucosaminidase
is shown in SEQ ID NO:2. The deduced molecular weight of the
desired amino acid sequence of .alpha.-N-acetylglucosaminidase is
approximately 70 kDa. The probable site of signal peptide peptidase
cleavage is between amino acids 23 and 24. There are seven
potential N-glycosylation sites in the sequence.
[0151] The nucleotide sequence of the corresponding
.alpha.-N-acetylglucosaminidase genomic gene (SEQ ID No:3)
comprises 10380 bp including 889 bp of 5' upstream sequence
corresponding to at least at part of the
.alpha.-N-acetylglucosaminidase promoter sequence, in addition to
the nucleotide sequences of introns I, II, II, IV, V, in addition
to 1326 bp of 3'-untranslated sequence.
EXAMPLE 5
Construction of an Expression Vector Comprising the
.alpha.-N-acetylglucosaminidase cDNA Sequence
[0152] The cDNA insert of 1 clone pbl 33, containing bases 107 to
2575 of the .alpha.-N-acetylglucosaminidase cDNA was excised with
EcoRI and subcloned into pBluescript II SK-(Stratagene). A 178 bp
XmaI fragment (bases 1 to 178 of the
.alpha.-N-acetylglucosaminidase cDNA) from cosmid sub-clone 6.3,
containing the start codon, was cloned into the pBluescript
subclone to produce a full-length cDNA sequence in addition to 101
bp of 5' non-translated sequence as well as 245 bp of 3'
non-translated region including the polyadenylation-site, the
polyA-tail and linkerDNA. The full length cDNA was directionally
cloned into the pCDNA3 expressionvector (Invitrogen) via the EcoRI
and BamHI sites.
EXAMPLE 6
Expression of Recombinant .alpha.-N-acetylglucosaminidase
[0153] Chinese Hamster Ovary (CHO) cells were transfected with
expressionvector using the DOTAP transfection reagent (Boehringer
Mannheim) according to the manufacturers instructions. Cells were
grown in Ham's F12 medium, 10% (v/v) fetal calf serum, penicillin
and streptomycin sulfate at 100 .mu.g/ml each. Cells were grown in
nonselective medium for 48 h and then incubated in medium
containing 750 .mu.g/ml G418 sulfate (Geniticin) until resistant
colonies emerged.
[0154] Single cell clones were grown up and 26 of them were tested
for expression of recombinant .alpha.-N-acetylglucosaminidase with
a fluorogenic .alpha.-N-acetylglucosaminidase substrate. (i.e.
N-acetylglucosamine .alpha.-linked to 4-methylumbelliferone)
EXAMPLE 7
Large Scale .alpha.-N-acetylglucosaminidase Production
[0155] 2 g of Cytodex 2 microcarrier beads were swollen in 250 ml
of PBS for 3 h at 37.degree. C. with three changes of PBS and then
autoclaved for 15 min at 120.degree. C. (wet cycle). The beads were
then rinsed with sterile growth medium (Coons/DMEM, 10% v/v fetal
calf serum, penicillin and streptomycin sulfate at 100 .mu.g/ml
each and 0.1% w/v Pluronic F68) and transferred into a Techne
stirrer culture flask. The microcarrier beads were inoculated with
seven confluent 175 flasks of the cell clone showing the highest
expression of recombinant .alpha.-N-acetylglucosamini- dase, Growth
medium was added up to 200 ml and the culture incubated with a
stirrer speed of 20 rpm to achieve an even distribution of cells on
the beads. The cells were allowed to attach to the beads for 16 h
at low speed then medium was added up to 500 ml and the stirrer
speed increased to 30 rpm. After a growth phase of 48 to 72 h with
daily aerating to allow gas exchange the beads were completely
covered with cells and the medium was exchanged for production
medium (Coons/DMEM, no fetal calf serum, penicillin and
streptomycin sulfate at 100 .mu.g/ml each, 0.1% w/v Pluronic F68
and 5 mM NH.sub.4Cl). The glucose concentration was monitored daily
and the medium replaced, when glucose fell below 5 mM every 203
days. The harvested medium contained approximately 2 mg
.alpha.-N-acetylglucosaminidase protein per dm.sup.3 of production
medium.
EXAMPLE 8
Purification of Recombinant .alpha.-N-acetylglucosaminidase
[0156] Production medium was dialysed against 50 mM NaAc pH 5.5 and
loaded onto a heparin-agarose column equilibrated in the same
buffer. After washing with NaAc buffer and NaAc/50 mM NaCl the
column was eluted with 75 mM NaCl in NaAc buffer. The eluate was
dialysed against 20 mM Tris/HCl pH 7.5, loaded onto a DEAE Scphacel
column, washed with 25 mM NaCl in 20 mM Tris/HCl and then eluted
with 50 and 75 mM NaCl in 20 mM Tris/HCl respectively.
[0157] SDS-PAGE of the two eluates showed two polypeptide bands
associated with enzyme activity with apparent molecular weights of
79 and 89 kDa. The smaller .alpha.-N-acetylglucosaminidase was
eluted predominantly in the 50 mM NaCl fraction whereas the 89 kDa
.alpha.-N-acetylglucosaminidas- e polypeptide was enriched in the
75 mM NaCl fraction (FIG. 2).
[0158] The difference in apparent molecular weight of the
recombinant .alpha.-N-acetylglucosaminidase polypeptides is due to
the presence of additional carbohydrate side chains, since a digest
with PNGase F, which cleaves off N-glycosylation groups, reduced
both the 79 kDa and 89 kDa polypeptides to the polypeptide band
having an apparent molecular weight of about 70 kDa (FIG. 2), which
corresponds to the approximate molecular weight deduced from
primary amino acid sequence data (SEQ ID No:2).
EXAMPLE 9
Characteristics of Recombinant .alpha.-N-acetylglucosaminidase
[0159] No differences were observed between the enzyme activities
of the 79 and 89 kDa recombinant .alpha.-N-acetylglucosaminidase
polypeptides produced in CHO cells according to Example 7 and 8.
With the fluorogenic N-acetylglucosamine .alpha.-linked to
4-methylumbelliferone (4-MU) substrate, the enzyme has a pH-optimum
of 4.6 with a k.sub.M of 5.34 mM and a V.sub.max of
3.97.times.10.sup.6 pmol/min/mg. Towards a .sup.3H-labelled
disaccharide substrate it should a pH-optimum of 4.1 with a k.sub.M
of 0.0166 mM and a V.sub.max of 4.48.times.10.sup.4
pmol/min/mg.
EXAMPLE 10
Mutational Analysis of Sanfilippo B Patients
[0160] Genomic DNA is isolated from cultivated skin fibroblasts of
patients by extraction with Phenol/Chloroform and used to amplify
the eight exons and adjacent intronic sequences individually by
PCR.
[0161] Primer sequences used in the amplification reaction are
readily determined from the nucleotide sequences of the
.alpha.-N-acetylglucosami- nidase cDNA and genomic clones. set
forth in SEQ ID No:1 or SEQ ID No:3. Amplification conditions are
also readily determined without undue experimentation. Procedures
for the design of PCR primers and amplification conditions are
described in detail, for example, by McPherson et al. (1991).
Differences in the primary sequence can be identified by separating
the PCR products on a polyacrylamide gel under non-denaturing
conditions (SSCP gels). Base changes, insertions and deletions will
lead to a different band pattern compared with the wildtype in most
of the cases, which can be visualised either by autoradiography of
the gel after labelling the DNA during the PCR or by staining
unlabelled DNA in the gel with silver. PCR products which show a
different band pattern are sequences to identify the change. Other
patient samples can be tested for mutations and polymorphism that
were found by hybridisation with wildtype- and mutation-specific
oligonucleotides (ASO).
[0162] Those skilled in the art will appreciate that the invention
described herein is susceptible to variations and modifications
other than those specifically described. It is to be understood
that the invention includes all such variations and modifications.
The invention also includes all of the steps, features,
compositions and compounds referred to or indicated in this
specification, individually or collectively, and any and all
combinations of any two or more of said steps or features.
REFERENCES
[0163] 1. Ausubel, F. M., Brent, R, Kingston, R E, Moore, D. D.,
Seidman, J. G., Smith, J. A., and Struhl, K. (1987). In: Current
Protocols in Molecular Biology. Wiley Interscience (ISBN
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[0164] 2. Hopwood J J (1989) In: "Heparin: Chemical and Biological
Properties, Clinical Applications" (Lane D W and Lindahl U, eds.),
190-229, Edward Arnold, London.
[0165] 3. McKusick V and Neufeld E (1983) In: "The Metabolic Basis
of Inherited Disease" (Stanbury J B, Wyngaarden J B, Fredrickson D
S, Goldstein J L and Brown M S, eds), 5th Ed., 751-771,
McGraw-Hill, New York.
[0166] 4. McPherson, M. J., Quirke, P. and Taylor, G. R, (1991) In:
PCR A Practical Approach. Oxford University Press, Oxford. (ISBN
0-19-96322L-X).
[0167] 5. O'Brien J S, (1972) Proc. Natl. Acad. Sci. USA 69:
1720-1722.
[0168] 6. Sambrook, J., Fritsch, E., and Maniatis, T. (1989)
In:"Molecular Cloning" a laboratory manual, Cold Spring
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[0169] 7. Von Figura, K, and Kresse K (1972) Biochem Biophys. Res.
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[0170] 8. Weber B, Scott H, Blanch L, Clements P, Morris C P, Anson
D, Hopwood J, (1996) Nature Genetics (submitted)
Sequence CWU 0
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