U.S. patent application number 10/466941 was filed with the patent office on 2004-10-28 for method for secretory production of glycoprotein having human-type sugar chain using plant cell.
Invention is credited to Fujiyama, Kazuhito, Tatsuji, Seki, Yoshida, Toshiomi.
Application Number | 20040214273 10/466941 |
Document ID | / |
Family ID | 18879514 |
Filed Date | 2004-10-28 |
United States Patent
Application |
20040214273 |
Kind Code |
A1 |
Fujiyama, Kazuhito ; et
al. |
October 28, 2004 |
Method for secretory production of glycoprotein having human-type
sugar chain using plant cell
Abstract
A method for the secretory production of a glycoprotein having a
human-type sugar chain, comprising a step of introducing a gene of
an enzyme capable of performing a transfer reaction of a galactose
residue to a non-reducing terminal acetylglucosamine residue, and a
gene of heterologous glycoprotein, to obtain a transformed plant
cell, a step of culturing the plant cell, and a step of recovering
the culture medium of the plant cell.
Inventors: |
Fujiyama, Kazuhito; (Osaka,
JP) ; Tatsuji, Seki; (Toyonaka-shi, JP) ;
Yoshida, Toshiomi; (Osaka, JP) |
Correspondence
Address: |
Graham E Taylor
The Dow Chemical Company
Intellectual Property
P O Box 1967
Midland
MI
48641-1967
US
|
Family ID: |
18879514 |
Appl. No.: |
10/466941 |
Filed: |
July 18, 2003 |
PCT Filed: |
January 18, 2002 |
PCT NO: |
PCT/JP02/00361 |
Current U.S.
Class: |
435/69.1 ;
435/419; 435/468; 530/395 |
Current CPC
Class: |
C12N 9/0065 20130101;
C12N 15/8257 20130101; C12N 9/1051 20130101; C12P 21/005 20130101;
C12N 9/00 20130101; C07K 14/47 20130101 |
Class at
Publication: |
435/069.1 ;
435/419; 435/468; 530/395 |
International
Class: |
C12P 021/02; C12N
005/04; C07K 014/47 |
Claims
1. A method for the secretory production of a glycoprotein having a
human-type sugar chain, comprising: a step of introducing a gene of
an enzyme capable of performing a transfer reaction of a galactose
residue to a non-reducing terminal acetylglucosamine residue and a
gene of a heterologous glycoprotein, to obtain a transformed plant
cell, and a step of culturing said plant cell.
2. The method according to claim 1, wherein said glycoprotein
having a human-type sugar chain comprises a core sugar chain and an
outer sugar chain, said core sugar chain substantially comprises a
plurality of mannoses and acetylglucosamines, and said outer sugar
chain has a terminal sugar chain moiety containing a non-reducing
terminal galactose.
3. The method according to claim 2, wherein said outer sugar chain
has a linear structure.
4. The method according to claim 2, wherein said outer sugar chain
has a branched structure.
5. The method according to claim 4, wherein said branched structure
is a mono-, bi-, tri- or tetra-structure.
6. The method according to claim 1, wherein said glycoprotein is
free of fucose or xylose.
7. The method according to claim 1, which further comprises a step
of recovering the culture solution of said plant cells.
8. The method according to claim 1, which further comprises a step
of adding sugar or a sugar chain in vitro.
9. A plant cell which comprises a sugar chain adding mechanism
capable of performing a transfer reaction of a galactose residue to
a non-reducing terminal acetylglucosamine residue and can secrete a
protein with an added sugar chain added by said sugar chain-adding
mechanism, wherein said sugar chain-adding mechanism adds a sugar
chain comprising a core sugar chain and an outer sugar chain, said
core sugar chain substantially comprises a plurality of mannoses
and acetylglucosamines, and said outer sugar chain has a terminal
sugar chain moiety containing a non-reducing terminal
galactose.
10. A glycoprotein having a human-type sugar chain obtained by the
method according to claim 1.
11. A method for the secretory production of a glycoprotein having
human-type sugar chain, comprising: a step of introducing a gene
for an enzyme capable of performing a transfer reaction of a
galactose residue to a non-reducing terminal acetylglucosamine
residue and a gene for a heterologous glycoprotein, to obtain a
transformed plant cell, and a step of expressing said enzyme within
an intracellular organelle.
12. A plant cell transformed with a gene for an enzyme capable of
performing a transfer reaction of a galactose residue to a
non-reducing terminal acetylglucosamine residue, wherein said
enzyme is localized in the plant cell such that the plant cell is
capable of synthesizing a glycoprotein having a human-type sugar
chain structure.
13. A plant cell according to claim 12, wherein said sugar chain
structure includes an added galactose residue.
14. A plant cell according to claim 13, wherein said sugar chain
structure is free of .beta.1,2-xylose or .alpha.1,3-fucose.
15. A plant cell according to claim 12, wherein said sugar chain
structure includes an galactose residue added to a N-linked type
sugar chain of
(N-acetylglucosamine).sub.1-2(Mannose).sub.2-5(N-acetylglucosamine).sub.2
selected from the group consisting of
GlcNAc.sub.1Man.sub.3GlcNAc.sub.2,
GlcNAc.sub.1Man.sub.5GlcNAc.sub.2,
GlcNAc.sub.2Man.sub.3GlcNAc.sub.2 and
GlcNAc.sub.1Man.sub.4GlcNAc.sub.2.
16. A plant cell according to claim 12, wherein said enzyme is
localized within an intracellular organelle in the plant cell.
17. A plant regenerated from the plant cell of claim 12.
18. A seed produced from the plant of claim 16.
19. The method according to claim 5, wherein said glycoprotein is
free of fucose or xylose.
20. The method according to claim 5, which further comprises a step
of adding sugar or a sugar chain in vitro.
21. A glycoprotein having a human-type sugar chain obtained by the
method according to claim 5.
Description
TECHNICAL FIELD
[0001] The present invention relates to a method for the secretory
production of a heterologous glycoprotein having a human-type sugar
chain using a plant cell, a plant cell capable of secreting this
glycoprotein, and a glycoprotein having a human-type sugar chain
secreted by this plant cell.
BACKGROUND ART
[0002] Production of extraneous proteins using plant cultured cells
is proceeding. For example, attempts are being made to produce the
following proteins useful for humans using tobacco cultured
cell:
[0003] GM-CSF (see, E. A. James, C. Wang, Z. Wang, R. Reeves, J. H.
Shin, N. S. Magnuson and J. M. Lee, "Production and
Characterization of Biologically Active Human GM-CSF Secreted by
Genetically Modified Plant Cells", Protein Expr. Purif., 19,
131-138 (2000)), IL-2 and IL-4 (see, N. S. Magnuson, P. M.
Linzmaier, R. Reeves, G. An, K. HayGlass and J. M. Lee, "Secretion
of Biologically Active Human Interleukin-2 and Interleukin-4 from
Genetically Modified Tobacco Cells in Suspension Culture", Protein
Expr. Purif., 13, 45-52 (1998)), immunoglobulin (see, N. S.
Magnuson, P. M. Linzmaier, J. W. Gao, R. Reeves, G. An and J. M.
Lee, "Enhanced Recovery of a Secreted Mammalian Protein from
Suspension Culture of Genetically Modified Tobacco Cells", Protein
Expr. Purif., 7, 220-228 (1996)), erythropoietin (see, S.
Matsumoto, A. Ishii, K. Ikura, M. Ueda and R. Sasaki, "Expression
of Human Erythropoietin in Cultured Tobacco Cells", Biosci.
Biotechnol. Biochem., 57, 1249-1252 (1993)), and
.alpha.1-antitrypsin (see, M. Terashima, Y. Murai, M. Kawamura, S.
Nakanishi, T. Stoltz, L. Chen, W. Drohan, R. L. Rodriguez and S.
Katoh, "Production of Functional Human .alpha.1-Antitrypsin by
Plant Cell Culture", Appl. Microbiol. Biotechnol., 52, 516-523
(1999)).
[0004] On other hand, it is reported that plant cultured cells
secrete many proteins or glycoproteins (see, A. Sturm,
"Heterogeneity of the Complex N-Linked Oligosaccharides at Specific
Glycosylation Sites of Two Secreted Carrot Glycoproteins", Eur. J.
Biochem., 199, 169-179 (1991); Y. Okushima, N. Koizumi, T. Kusano
and H. Sano, "Secreted Proteins of Tobacco Cultured BY2 Cells:
Identification of A New Member of Pathogenesis-Related Proteins",
Plant Mol. Biol., 42, 479-488 (2000); and Y. Okushima, N. Koizumi,
T. Kusano and H. Sano, "Glycosylation and Its Adequate Processing
is Critical for Protein Secretion in Tobacco BY2 Cells", J. Plant
Physiolo., 154, 623-627 (1999)). Of these, in the case of tobacco
BY2 cultured cells, two kinds of peroxidases are purified and their
genes have been cloned (see, H. Narita, Y. Asaka, K. Ikura, S.
Matsumoto and R. Sasaki, "Isolation, Characterization and
Expression of Cationic Peroxidase Isozymes Released into the Medium
of Cultured Tobacco Cells", Eur. J. Biochem., 228, 855-862 (1995)).
It is also reported that by adding polyvinylpyrrolidone (PVP) to
the medium, the concentration of protein secreted in the medium
could be increased (see, N. S. Magnuson, P. M. Linzmaier, J. W.
Gao, R. Reeves, G. An and J. M. Lee, "Enhanced Recovery of A
Secreted Mammalian Protein from Suspension Culture of Generically
Modified Tobacco Cells", Protein Expr. Purif., 7, 220-228 (1996))
and by Y. Okushima et al., supra. (1999) that from tobacco BY2
strain cultured cells, hundreds of proteins are extracellularly
secreted. Among these, extracellular secretion of many
glycoproteins are confirmed because of their reaction with lectin
(concanavalin A) which recognizes high mannose-type sugar chains
(see, Y. Okushima, supra. (1999)).
[0005] With respect to these glycoproteins, in particular,
immunoglobulin, interleukin and GM-CSF, produced within plant
cells, a signal peptide of each glycoprotein itself is also
recognized in the secretion mechanism within the plant cell, and is
secreted in the culture solution (see, E. A. James et al., supra.;
N. S. Magnuson et al., supra. (1998): and N. S. Magnuson et al.,
supra. (1996)). In any of these glycoproteins, it is suggested, the
sugar chain participates in the determination of half-life in
blood, sensitivity to protease and stability. However, the sugar
chain structures of recombinant proteins actually produced within
plant cells and purified have not been examined and these proteins
are presumed to have a plant-type sugar chain structure.
[0006] In the analysis of sugar chain structure, the secretion-type
antibody molecule sIgA, produced from tobacco plants is revealed to
have a plant-type sugar chain (see, M. Cabanes-Macheteau, A. C.
Fitchette-Laine, C. Loutelier-Bourhis, C. Lange, N. D. Vine, J. K.
Ma, P. Lerouge and L. Faye, "N-Glycosylation of a Mouse IgG
Expressed in Transgenic Tobacco Plants", Glycobiology, 9, 365-372
(1999)). Furthermore, in the case where another antibody molecule
is produced from the same tobacco plant body, the antibody protein
produced within the cell is decomposed by the protease and is
unstable (see, L. H. Stevens, G. M. Stoopen, I. J. Elbert, J. W.
Molthoff, H. A. Bakker, A. Lommen, D. Bosch and W. Jordi, "Effect
of Climate Conditions and Plant Developmental Stage on the
Stability of Antibodies Expressed in Transgenic Tobacco", Plant
Physiol., 124, 173-182 (2000)). By the Western method using an
antiplant-type sugar chain antibody, addition of a plant-type sugar
chain to this antibody is confirmed. Although it is reported that
the .beta.1,4-linked galactose residue present in the sugar chain
of an antibody molecule produced by human or mouse contributes to
the stabilization of antibody protein, this sugar residue is absent
in the antibody molecule produced by plant cells. Because of this,
the antibodies produced by tobacco plants are considered to be
prone to decomposition by the protease.
[0007] In the case where erythropoietin is produced by tobacco
cultured cells, the biological activity is recognized in vitro, but
the activity in vivo is not detected (see, S. Matsumoto, K. Ikura,
M. Uedaand R. Sasaki, "Characterization of a Human Glycoprotein
(Erythropoietin) Produced in Cultured Tobacco Cells", Plant Mol.
Biol., 27 1163-1172 (1995). This is concluded to occur because
erythropoietin of which sugar chain is considered to greatly
participate in the biological activity, has a largely different
sugar chain structure when produced by plant cells.
[0008] On the other hand, it is suggested that the plant-type sugar
chain may be an allergen in mammals including humans. That is, the
sugar chain structure peculiar to plants, such as .beta.1,2-xylose
and .alpha.1,3-fucose which are not seen in glycoproteins of
mammals, are reported to act as an allergen (see, K. Fotisch, F.
Altmann, D. Haustein and S. Vieths, Involvement of Carbohydrate
Epitopes in the IgE Response of Celery-Allergic Patients, Int.
Arch. Allergy Immunol., 120, 30-42(1999); I. B. Wilson, J. E.
Harthill, N. P. Mullin, D. A. Ashford and F. Altmann, "Core
.alpha.1,3-Fucose is a Key Part of the Epitope Recognized by
Antibodies Reacting Against Plant N-Linked Oligosaccharides and is
Present in a wide Variety of Plant Extracts", Glycobiology, 8,
651-661 (1998); and R. van Ree, M. Cabanes-Macheteau, J. Akkerdaas,
J. P. Milazzo, C. Loutelier-Bourhis, C. Rayon, M. Villalba, S.
Koppeiman, R. Aalberse, R. Rodriguez, L. Faye and P. Lerouge,
".beta.(1,2)-Xylose and .alpha.(1,3)-Fucose Residues Have a Strong
Contribution in IgE Binding to Plant Glycoallergens", J. Biol.
Chem., 275(15), 11451-11458 (Apr. 14, 2000). Accordingly, proteins
for medical uses must have a sugar chain structure free of
.beta.1,2-xylose or .alpha.1,3-fucose.
DISCLOSURE OF THE INVENTION
[0009] The object of the present invention is to solve the
above-described problems in conventional techniques and provide a
method for the secretory production, in plant cells, of a
glycoprotein which is stable, maintains its original physiological
activity and is not an allergen, a plant cell capable of secreting
such glycoprotein, and a glycoprotein having a human-type sugar
chain secreted by this plant cell.
[0010] As a result of extensive investigations, the present
inventors have found that when a human-derived galactose
transferred enzyme gene cDNA is expressed in a tobacco cultured
cell BY2 strain, galactose is added to sugar chains of most
glycoproteins secreted to the exterior medium and the glycoproteins
have a sugar chain structure free of .beta.1,2-xylose or
.alpha.1,3-fucose. The present invention has been accomplished
based on this finding. Accordingly, when a human-derived useful
protein is produced using this genetic recombinant tobacco cultured
cell, the objective protein having a sugar structure which is not
an allergen, can be secreted in the extracellular fluid.
[0011] The present invention relates to a method for the secretory
production of a glycoprotein having a human-type sugar chain. This
method comprises a step of introducing a gene of an enzyme capable
of performing a transfer reaction of a galactose residue to a
non-reducing terminal acetylglucosamine residue and a gene of a
heterologous glycoprotein, into a plant cell to obtain a
transformed plant cell, and a step of culturing the obtained plant
cell.
[0012] In the method above, the glycoprotein having a human-type
sugar chain may comprise a core sugar chain and an outer sugar
chain, the core sugar chain may substantially comprise a plurality
of mannoses and acetylglucosamines, and the outer sugar chain may
have a terminal sugar chain moiety containing a non-reducing
terminal galactose.
[0013] In the method above, the outer sugar chain may have a linear
or branched structure.
[0014] In the method above, the branched sugar chain moiety may be
a mono-, bi-, tri- or tetra-structure
[0015] In the method above, the glycoprotein may be free of fucose
or xylose.
[0016] The method above for the secretory production may preferably
further comprise a step of recovering the medium of the plant
cells.
[0017] In one embodiment, the method above for the secretory
production may further comprise a step of adding sugar or sugar
chain in vitro.
[0018] In one aspect, the present invention relates to a plant cell
which comprises a sugar chain-adding mechanism capable of
performing a transfer reaction of a galactose residue to a
non-reducing terminal acetylglucosamine residue and can secrete a
protein with an added sugar chain added by the sugar chain-adding
mechanism, wherein the sugar chain-adding mechanism adds a sugar
chain comprising a core sugar chain and an outer sugar chain, the
core sugar chain substantially comprises a plurality of mannoses
and acetylglucosamines, and the outer sugar chain has a terminal
sugar chain moiety containing a non-reducing terminal
galactose.
[0019] The present invention further relates to a glycoprotein
having a human-type sugar chain obtained by the method described
above.
[0020] The present invention still further relates to a method for
the secretory production of a glycoprotein having a human-type
sugar chain, comprising a step of introducing a gene for an enzyme
capable of performing a transfer reaction of a galactose residue to
a non-reducing terminal acetylglucosamine residue and a gene for a
heterologous glycoprotein, to obtain a transformed plant cell, and
a step of expressing the enzyme within an intracellular
organelle.
[0021] The present invention still further relates to a plant cell
transformed with a gene for an enzyme capable of performing a
transfer reaction of a galactose residue to a non-reducing terminal
acetylglucosamine residue, wherein the enzyme is localized in the
plant cell such that the plant cell is capable of synthesizing a
glycoprotein having a human-type sugar chain structure.
[0022] In one aspect, in the plant cell above, the sugar chain
structure includes an added galactose residue.
[0023] In one aspect, in the plant cell above, the sugar chain
structure is free of .beta.1,2-xylose or .alpha.1,3-fucose.
[0024] In one aspect, in the plant cell above, the sugar chain
structure includes an galactose residue added to a N-linked type
sugar chain of
(N-acetylglucosamine).sub.1-2(Mannose).sub.2-5(N-acetylglucosamine).sub.2
selected from the group consisting of
GlcNAc.sub.1Man.sub.3GlcNAc.sub.2,
GlcNAc.sub.1Man.sub.5GlcNAc.sub.2,
GlcNAc.sub.2Man.sub.3GlcNAc.sub.2 and
GlcNAc.sub.1Man.sub.4GlcNAc.sub.2.
[0025] In one aspect, in the plant cell above, the enzyme is
localized within an intracellular organelle in the plant cell.
[0026] The present invention still further relates to a plant
regenerated from the plant cell above.
[0027] The present invention still further relates to a seed
produced from the plant above.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] FIG. 1 is a schematic view showing a process for cloning
hGT.
[0029] FIG. 2 is a schematic view showing a process for
constructing vector pGAhGT for expressing hGT.
[0030] FIG. 3 is a photograph showing the Southern analysis of
genome of transformant tobacco cultured cell. FIG. 3(A) shows the
results when genomic DNA (40 .mu.g) was digested by EcoRI and
HindIII and then electrophoresed. The numerals in the left side
show the sites of the DNA molecular weight marker. FIG. 3(B) shows
a schematic view of fragment 2.2 kb containing promoter, hGT and
terminator integrated into each transformant.
[0031] FIG. 4A is a view showing the analysis of PA-sugar chain
prepared from GT6 strain culture medium by high-performance liquid
chromatography.
[0032] FIG. 4B is a view showing the analysis of PA-sugar chain
prepared from GT6 strain culture medium by high-performance liquid
chromatography.
[0033] FIG. 5 is a view showing the structures and analysis results
of sugar chains in the glycoprotein secreted in the GT6 strain
culture medium. The numerals in parentheses in the Figure show the
molar ratio of sugar chain having each structure shown in the
Figure.
[0034] FIG. 6 is a view showing the analysis of PA-sugar chain
prepared from GT6 strain culture medium and the exoglycosidase
digestion product thereof by high-performance liquid
chromatography.
[0035] FIG. 7 is a view showing the analysis of PA-sugar chain
prepared from GT6 strain culture medium and the exoglycosidase
digestion product thereof by high-performance liquid
chromatography.
[0036] FIG. 8 is a view showing the analysis of PA-sugar chain
prepared from GT6 strain culture medium and the exoglycosidase
digestion product thereof by high-performance liquid
chromatography.
[0037] FIG. 9 is a view showing the analysis of PA-sugar chain
prepared from GT6 strain culture medium and the exoglycosidase
digestion product thereof by high-performance liquid
chromatography.
[0038] FIG. 10 is a view showing the IS-MS/MS analysis of PA-sugar
chain prepared from GT6 strain culture medium. B is a partial
enlarged view of A.
[0039] FIG. 11 is a view showing the analysis of PA-sugar chain
prepared from GT6 strain culture medium and the exoglycosidase
digestion product thereof by high-performance liquid
chromatography.
[0040] FIG. 12 is a view showing the analysis of PA-sugar chain
prepared from GT6 strain culture medium and the exoglycosidase
digestion product thereof by high-performance liquid
chromatography.
[0041] FIG. 13 is a photograph showing the results of stalic acid
transferase reaction in vitro using GT6 stain culture
medium-derived glycoprotein, BY2 strain culture medium-derived
glycoprotein or asialo fetuin as the substrate.
[0042] FIG. 14A is a view showing the analysis of PA-sugar salt
prepared from BY2 strain culture medium by high-performance liquid
chromatography.
[0043] FIG. 14B is a view showing the analysis of PA-sugar salt
prepared from BY2 strain culture medium by high-performance liquid
chromatography.
[0044] FIG. 15A is a view showing the structures and analysis
results of sugar chains in the glycoprotein secreted in the GT6
strain culture medium. The numerals in parentheses in the Figure
show the molar ratio of sugar chain having each structure shown in
the Figure.
[0045] FIG. 15B is a view showing the structures and analysis
results of sugar chains in the glycoprotein secreted in the GT6
strain culture medium. The numerals in parentheses in the Figure
show the molar ratio of sugar chain having each structure shown in
the Figure.
[0046] FIG. 16 is a view showing the analysis of PA-sugar chain
prepared from BY2 strain culture medium.
[0047] FIG. 17 is a view showing the analysis of PA-sugar chain
prepared from BY2 strain culture medium and the exoglycosidase
digestion product thereof by high-performance liquid
chromatography.
[0048] FIG. 18A is a view showing the analysis of PA-sugar chain
prepared from BY2 strain culture medium and the exoglycosidase
digestion product thereof by high-performance liquid
chromatography.
[0049] FIG. 18B is a view showing the analysis of PA-sugar chain
prepared from BY2 strain culture medium and the exoglycosidase
digestion product thereof by high-performance liquid
chromatography.
[0050] FIG. 19 is a photograph showing the results of isoelectric
focusing electrophoresis. Proteins in the spent media of cultured
tobacco cells were analyzed by isoelectric focusing and stained for
peroxidase activity. Wild Type denotes BY2 strain. WT-HRP denotes
transformant of BY2 strain with HRP. GT-HRP denotes the
transformant of GT6 strain with HRP gene.
[0051] FIG. 20 is a photograph showing the results of lectin
staining of proteins in the spent media of transgenic cultured
tobacco cells. Proteins were fractionated by SDS-PAGE and stained
with Coomassie brilliant blue (A), or transfered to nitrocellulose
membrane and treated with ConA(B), and RCA120(C). Wild Type denotes
BY2 strain. WT-HRP-2 denotes one of the transformants of BY2 strain
with HRP gene. GT-HRP-5 denotes one of the transformants of GT6
strain with HRP gene.
BEST MODE FOR CARRYING OUT THE INVENTION
[0052] The present invention is described in detail below.
[0053] Herein, unless otherwise specified, protein separating and
analyzing methods and immunological techniques known in the art can
be employed. These techniques can be performed using commercially
available kits, antibodies, marker substances and the like.
[0054] The method of the present invention is a method for
producing a glycoprotein having a human type sugar chain. In the
present invention, the "human-type sugar chain" means a sugar chain
having a galactose residue bonded to an N-acetylglucosamine
residue. The galactose residue in the human-type sugar chain may be
a terminal of the sugar chain or a sialic acid residue may further
be bonded to the outer side of the galactose residue. In the
glycoprotein having a human-type sugar chain comprising a core
sugar chain moiety, a branched sugar chain moiety and a terminal
sugar chain moiety of the present invention, at least one of xylose
and fucose is preferably not bonded in one or more of the moieties,
more preferably in any of the moieties. Most preferably, the
human-type sugar chain contains neither xylose nor fucose.
[0055] The plant cell may be any plant cell. The plant cell may
have any form of cultured cell, cultured tissue, cultured organ and
plant body. Among these, preferred are cultured cell, cultured
tissue and cultured organ, more preferred is cultured cell. The
plant species which can be used in the production method of the
present invention may be any plant species which can perform the
genetic transduction. Examples of the plant species which can be
used in the production method of the present invention include
plants belonging to Solanaceae, Gramineae, Cruciferae, Rosaceae,
Leguminosae, Cucurbi taceae, Labiatae, Liliaceae, Chenopodiaceae
and Umbelliferae.
[0056] Examples of the Solanaceae plant include plants belonging to
Nicotlana, Solanum, Datura, Lycopersion or Petunia, such as
tobacco, egg-plant, potato, tomato, red pepper and petunia.
[0057] Examples of the Gramineae plant include plants belonging to
Oryza, Hordenum, Secale, Scocharum, Echinochloa or Zea, such as
rice, barley, rye, barnyard millet, sorghum and corn.
[0058] Examples of the Cruciferae plant include plants belonging to
Raphanus, Brassica, Arabidopsis, Wasabia or Capsella, such as
radish, rape, whitlowgrass, horseradish and shepherd's purse.
[0059] Examples of the Rosaceae plant include plants belonging to
Orunus, Malus, Pynus, Fragaria or Rosa, such as Japanese apricot,
peach, apple, pear, strawberry and rose.
[0060] Examples of the Leguminosae plant include plants belonging
to Glycine, Vigna, Phaseolus, Pisum, Vioia, Arachis, Trifolium,
Alphalfa or Medicago, such as soybean, red bean, kidney bean, green
pea, horsebean, peanut, clover and bur clover.
[0061] Examples of the Cucurbitaceae plant include plants belonging
to Luffa, Cucurbita or Cucumis, such as luff a, cushaw, cucumber
and melon.
[0062] Examples of the Labiatae plant include plants belonging to
Lavandula, Mentha or Perilla, such as lavender, mint and
perilla.
[0063] Examples of the Liliaceae plant include plants belonging to
Allium, Lilium or Tulipa, such as Welsh onion, garlic, lily and
tulip.
[0064] Examples of the Chenopodiaoeae plant include plants
belonging to Spinacia, such as spinach.
[0065] Examples of the Umbelliferae plant include plants belonging
to Angelica, Daucus, Cryptotaenia or Apitum, such as Angelica
polyclada, carrot, trefoil and celery.
[0066] Among these plants for use in the production method of the
present invention, preferred are tobacco, tomato, potato, rice,
corn, radish, soybean, green pea, bur clover and spinach, more
preferred are tobacco, tomato, potato, corn and soybean.
[0067] The "enzyme capable of performing a transfer reaction of a
galactose residue to a non-reducing terminal acetylglucosamine
residue" means an enzyme which can transfer a galactose residue to
a non-reducing terminal acetylglucosamine residue generated at the
addition of a sugar chain after the synthesis of the protein moiety
of a glycoprotein within a plant cell. Examples of such an enzyme
include galactosyl transferase, lactose synthase and
.beta.-galactosidase. Such an enzyme may be derived from any animal
species but is preferably derived from mammals, more preferably
from human.
[0068] This enzyme is preferably localized in an intracellular
organelle. Although restriction to a specific theory is not
intended, the present inventors consider that this enzyme being
present in an intracellular organelle, such as endoplasmic
reticulum and Golgi body, thereby acting on a protein or sugar
chain before a fucose or xylose residue is added, or acting so as
to inhibit the addition of a fucose or xylose residue, at the time
of expression and secretion of a heterologous glycoprotein in plant
cells.
[0069] The "enzyme gene capable of performing a transfer reaction
of a galactose residue to a non-reducing terminal acetylglucosamine
residue" may be isolated from any animal cell using a nucleotide
sequence known to code this enzyme, or a commercially available
enzyme may be purchased or may be used after modifying it to suit
to the expression in plants.
[0070] Herein, the "gene" means the structural gene moiety. In
order to facilitate the expression in plants, a regulator sequence
such as promoter, operator and terminator may be linked to the
gene.
[0071] The "heterologous glycoprotein" means a glycoprotein which
is originally not expressed in plants for use in the present
invention. Examples of the heterologous glycoprotein include
enzyme, hormone, cytokine, antibody, vaccine, receptor and serum
protein. Examples of the enzyme include horseradish peroxidase,
kinase, glucocerebrosidase, .alpha.-galactosidase, phytase, TPA
(tissue-type plasminogen activator) and HMG-COA reductase. Examples
of the hormone and cytokine include enkephalin, interferon alpha,
GM-CSF, G-CSF, chorionic gonadotropic hormone, interleukin-2,
interferon beta, interferon gamma, erythropoietin, vascular
endothelial growth factor, human chorionic gonadotropin (HCG),
luteinizing hormone (LH), thyroid-simulating hormone (TSH),
prolactin and follicle-stimulating hormone. Examples of the
antibody include IgG, scFv and secretory IgA. Examples of the
vaccine include hepatitis B surface antigen, rotavirus antigen,
Escherichia coli enterotoxin, malaria antigen, G protein of rabies
virus, and HIV virus glycoprotein (e.g., gp120). Examples of the
receptor and matrix protein include EGF receptor, fibronectin,
.alpha.1-antitrypsin and coagulation factor VI II. Examples of the
serum protein include albumin, complement system protein,
plasminogen, corticosteroid-binding globulin, Thyroxine-binding
globulin and protein C.
[0072] The "gene of heterologous glycoprotein" may be isolated from
any cell using a nucleotide sequence known to code the objective
heterologous glycoprotein or a commercially available gene may be
purchased or may be used after modifying it to suit to the
expression in plants.
[0073] The gene of an enzyme capable of performing a transfer
reaction of a galactose residue to a non-reducing terminal
acetylglucosamine residue and the gene of heterologous glycoprotein
are introduced into a plant cell by a method known in the art.
These genes may be introduced separately or simultaneously. Those
skilled in the art will appreciate that the choice of method might
depend on the type of plant targeted for transformation.
[0074] Suitable methods of transforming plant cells include
microinjection (Crossway et al., BioTechniques 4:320-334 (1986)),
electroporation (Riggs et al., Proc. Natl. Acad. Sci. USA
83:5602-5606 (1986), Agrobacterium-mediated transformation (Hinchee
et al., Biotechnology 6:915-921 (1988); See also, Ishida et al.,
Nature Biotechnology 14:745-750 (June 1996) for maize
transformation), direct gene transfer (Paszkowski et al., EMBO J.
3:2717-2722 (1984); Hayashimoto et al., Plant Physiol 93:857-863
(1990)(rice)), and ballistic particle acceleration using devices
available from Agracetus, Inc., Madison, Wis. and Dupont, Inc.,
Wilmington, Del. (see, for example, Sanfordet al., U.S. Pat. No.
4,945,050; and McCabe et al., Biotechnology 6:923-926 (1988)). See
also, Weissinger et al., Annual Rev. Genet. 22:421-477 (1988);
Sanford et al., Particulate Science and Technology 5.27-37
91987)(onion); Svab et al., Proc. Natl. Acad. Sci. USA 87:8526-8530
(1990) (tobacco chloroplast); Christou et al., Plant Physiol.
87:671-674 (1988)(soybean); McCabe et al., Bio/Technology 6.923-926
(1988)(soybean); Klein et al., Proc. Natl. Acad. Sci. USA,
85:4305-4309 (1988)(maize); Klein et al., Bio/Technology 6:559-563
(1988) (maize); Klein et al., Plant Physiol. 91:440-444 (1988)
(maize); Fromm et al., Bio/Technology 8:833-839 (1990); and
Gordon-Kamm et al., Plant Cell 2: 603-618 (1990) (maize); Koziel et
al., Biotechnology 11: 194-200 (1993) (maize); Shimamoto et al.,
Nature 338: 274-277 (1989) (rice); Christou et al., Biotechnology
9: 957-962 (1991) (rice); Datta et al., Biol/Technology 3:736-740
(1990) (rice); European Patent Application EP 0 332 581
(orchardgrass and other Pooideae); Vasil et al., Biotechnology 11:
1553-1558 (1993) (wheat); Weeks et al., Plant Physiol. 102:
1077-1084 (1993) (wheat); Wan et al., Plant Physiol. 104: 37-48
(1994) (barley); Jahne et al., Theor. Appl. Genet. 89:525-533
(1994)(barley); Umbeck et al., Bio/Technology 5: 263-266 (1987)
(cotton); Casas et al., Proc. Natl. Acad. Sci. USA 90:11212-11216
(December 1993) (sorghum); Somers et al., Bio/Technology
10:1589-1594 (December 1992) (oat); Torbert et al., Plant Cell
Reports 14:635-640 (1995) (oat); Weeks et al., Plant Physiol.
102:1077-1084 (1993) (wheat); Chang et al., WO 94/13822 (wheat) and
Nehra et al., The Plant Journal 5:285-297 (1994) (wheat). A
particularly preferred set of embodiments for the introduction of
recombinant DNA molecules into maize by microprojectile bombardment
can be found in Koziel et al., Biotechnology 11: 194-200 (1993),
Hill et al., Euphytica 85:119-123 (1995) and Koziel et al., Annals
of the New York Academy of Sciences 792:164-171 (1996). An
additional preferred embodiment is the protoplast transformation
method for maize as disclosed in EP 0 292 435. Transformation of
plants can be undertaken with a single DNA species or multiple DNA
species (i.e. co-transformation) and both these techniques are
suitable for use with the peroxidase coding sequence.
[0075] The gene product expressed and secreted by the plant cell
having incorporated thereinto the above-described genes can be
identified by a method known in the art. Examples of the
identification method include silver staining, Western blotting,
Northern hybridization and detection of enzymatic activity.
[0076] The transformed cell expressing an enzyme capable of
performing a transfer reaction of a galactose residue into a
non-reducing terminal acetylglucosamine residue and expressing a
heterologous glycoprotein, expresses and secretes a heterologous
glycoprotein having a human-type sugar chain. In other words; the
thus-obtained transformed plant has a human-type sugar chain-adding
mechanism and by culturing this transformed cell, human-type
glycoprotein can be expressed and secreted in a large amount in the
medium.
[0077] This human-type glycoprotein comprises a core sugar chain
and an outer sugar chain, and the core sugar chain substantially
comprises a plurality of mannoses and acetylglucosamines. The outer
sugar chain of the glycoprotein obtained contains a non-reducing
terminal sugar chain moiety. The outer sugar chain may have a
linear structure or a branched structure. The branched sugar chain
moiety may be any of mono-, bi-, tri- and tetra-structures. The
glycoprotein produced by the transformed cell preferably is free of
fucose or xylose.
[0078] The resulting transformed plant cell may be maintained in
the state of cultured cell, may be differentiated into a specific
tissue or organ, or may be regenerated in a complete plant body or
in a part such as seed, fruit, leaf, root, stem or flower obtained
from a complete plant body.
[0079] For the culture, differentiation or regeneration of the
transformed plant cell, means and culture mediums known in the art
are used. Examples of the medium include Murashige-Skoog (MS)
medium, Gamborg B5 (B) medium, White medium and Nitsch & Nitsch
(Nitsch) medium, however, the present invention is not limited
thereto. These mediums are usually used after adding thereto an
appropriate amount of a plant growth control substance (e.g., plant
hormone) and the like.
[0080] Application of these systems to different plant strains
depends upon the ability to regenerate that particular plant strain
from protoplasts. Illustrative methods for the regeneration of
cereals from protoplasts are described (Fujimura et al., Plant
Tissue Culture Letters, 2:74, 1985; Toriyama et al., Theor. Appl.
Genet., 73:16, 1986; Yamada et al., Plant Cell Rep., 4:85, 1986;
Abdullah et al., Biotechnology, 4:1087, 1986).
[0081] To transform plant strains that cannot be successfully
regenerated from protoplasts, other ways to introduce DNA into
intact cells or tissues can be utilized. For example, regeneration
of cereals from immature embryos or explants can be effected as
described (Vasil, Biotechnology, 6:397, 1988).
[0082] Agrobacterium-mediated transfer is also a widely applicable
system for introducing genes into plant cells because the DNA can
be introduced into whole plant tissues, thereby bypassing the need
for regeneration of an intact plant from a protoplast. The use of
Agrobacterium-mediated plant integrating vectors to introduce DNA
into plant cells is well known in the art. See, for example, the
methods described above.
[0083] Fundamentally, as long as the transformed plant cell grows
and then expresses and secretes the desired gene product, a culture
medium having any composition containing trace nutrients necessary
for the growth of plant cells, such as carbon source, nitrogen
source, vitamins and salts, may be used for the secretory
production of a glycoprotein having a human-type sugar chain. Also,
polyvinylpyrrolidone, protease inhibitor and the like may be added
so as to stabilize the secreted heterologous protein and attain
efficient secretion of the heterologous protein.
[0084] The glycoprotein having a human-type sugar chain expressed
and secreted by the transformed plant cell can be typically
isolated from the medium of plant cells. The isolation of
glycoprotein from the medium of plant cells can be performed using
a method well-known to one skilled in the art. For example, the
glycoprotein can be purified to isolate it from the medium using,
individually or in combination, techniques such as salting out
(e.g., ammonium sulfate precipitation, sodium phosphate
precipitation), solvent precipitation (e.g., protein fractional
precipitation by acetone or ethanol), dialysis, gel filtration, ion
exchange, column chromatography such as reverse phase,
ultrafiltration, and high-performance chromatography (HPLC).
[0085] Alternatively, the glycoprotein of the present invention may
also be isolated or extracted from plant cells. Furthermore, the
glycoprotein of the present invention, which is contained in
transformed cells, can be used as it is for food. The glycoprotein
of the present invention has a human-type sugar chain addition and
therefore, is free of antigenicity and suitable for the
administration to animals including humans.
[0086] Further also included within the present invention, the
plant cell or the plant body transformed with a gene of an enzyme
capable of performing a transfer reaction of a galactose residue to
a non-reducing terminal acetylglucosamine residue, may have
inactivated or suppressed activity of .beta.1,2-xylose transfer
enzyme or a 1,3-fucose transfer enzyme.
[0087] Strasser et al. has isolated cDNA encoding
.beta.1,2-xylosyltransfe- rase from Arabidopsis thaliana (Strasser
R, Mucha J, Mach L, Altmann F, Wilson I B, Glossl J, Steinkellner
H, Molecular cloning and functional expression of
.beta.1,2-xylosyltransferase cDNA from Arabidopsis thaliana. FEBS
Lett. (2000) 472:105-108). Homology searching against databases
such as NIH GenBank may show nucleotide sequences corresponding to
some EST (expression sequence tag) clones and genome sequence in
some plants, are similar to the nucleotide sequence encoding
Arabidopsis .beta.1,2-xylosyltransferase. Based on these sequences,
nucleic acid encoding .beta.1,2-xylosyltransferase may be cloned
from the host plant and used to establish a plant cell or plant
with reduced xylosyltransferase activity by repressing
.beta.1,2-xylosyltransferase gene expression. Repression of
.beta.1,2-xylosyltransferase gene expression may be carried out by
an antisense method, co-suppression method, RNAi method or so
on.
[0088] Alternatively, a plant cell or plant with reduced
xylosyltransferase activity may be established by chemical
mutagenesis, site-directed mutagenesis using oligonucleotides,
tagging methods or so on. In said plant, introduction and
expression of one or more glycosyltransferase genes encoding
galactose transferase together with a gene encoding a heterologous
polypeptide may produce a heterologous polypeptide with humanized
glycan structure or excrete a heterologous polypeptide with
humanized glycan structure.
[0089] Similarly, Wilson et al. isolated cDNA encoding
.alpha.1,3-fucosyltransferase from Arabidopsis thaliana (Wilson I
B, Rendic D, Freilinger A, Dumic J, Altmann F, Mucha J, Muller S,
Hauser M T Cloning and expression of cDNAs encoding a
1,3-fucosyltransferase homologues from Arabidopsis thaliana.
Biochim Biophys Acta (2001) 1527:88-96). Leiter et al. isolated
cDNA encoding .alpha.1,3-fucosyltrans- ferase from mung bean
(Leiter, H., Mucha, J., Staudacher, E., Grimm, R., Glossl, J.,
Altmann, F. Purification, cDNA cloning, and expression of
GDP-L-Fuc:Asn-linked GlcNAc .alpha.1,3-fucosyltransferase from mung
beans. J. Biol. Chem. (1999) 274:21830-21839). Homology searching
against databases such as NIH GenBank may show nucleotide sequences
corresponding to some EST (expression sequence tag) clones and
genome sequence in some plants, are similar to the nucleotide
sequence encoding Arabidopsis .alpha.1,3-fucosyltransferase. Based
on these sequences, nucleic acid encoding
.alpha.1,3-fucosyltransferase may be cloned from the host plant and
used to establish a plant cell or plant with reduced
fucosyltransferase activity by repressing
.alpha.1,3-fucosyltransferase gene expression. Repression of
.alpha.1,3-fucosyltransferase gene expression can be carried out by
an antisense method, co-suppression method, RNAi method or so
on.
[0090] Alternatively, a plant cell or plant with reduced
fucosyltransferase activity may be established by chemical
mutagenesis, site-directed mutagenesis using oligonucleotides,
tagging methods or so on. In said plant, introduction and
expression of one or more glycosyltransferase genes encoding
galactose transferase together with a gene encoding a heterologous
polypeptide may produce a heterologous polypeptide with humanized
glycan structure or excrete a heterologous polypeptide with
humanized glycan structure.
EXAMPLES
[0091] The present invention is described below by referring to the
Examples. The following Examples are only to illustrate but not to
limit the present invention.
[0092] 1. Cloning of Human .beta.1-4 Galactose Transferase Gene
[0093] The .beta.1-4 galactose transferase (hGt) (EC2.4.1.38) has
been already cloned and a primary structure comprising 400 amino
acids has been revealed (K. A. Masri et al., Biochem. Biophys. Res.
Commun., 157, 657-663 (1988)).
[0094] (1) Primer Preparation and Template DNA
[0095] By referring to the report of Masri et al., the following
primer were prepared.
1 hGT-5Eco: 5'-AAAGAATTCGCGATGCCAGGC (SEQ. ID NO: 1) GCGCGTCCCT-3'
hGT-2Sal: 3'-TCGATCGCAAAACCATGTGCA (SEQ. ID. NO: 2) GCTGATG-5'
hGT-7Spe: 3'-ACGGGACTCCTCAGGGGCGAT (SEQ. ID. NO: 3) GATCATAA-5'
hGT6Spe: 5'-AAGACTAGTGGGCCCCATGCT (SEQ. ID. NO: 4 GATTGA-3'
[0096] As the template DNA, human genomic DNA, human placenta cDNA
and human kidney cDNA purchased from Clontech were used.
[0097] (2) Cloning of hGT Gene cDNA
[0098] Using two combinations of (i) template of human genomic DNA
with primers of hGT-5Eco and hGT-7Spe and (ii) template of human
placenta cDNA with primers of hGT-2Sal and hGT6Spe, a PCR reaction
was performed under the following conditions to obtain fragments of
0.4 kb and 0.8 kb containing an hGT-coding region.
[0099] (PCR Reaction System)
[0100] Water was added to 1 .mu.l of template DNA, 5 .mu.l of
10.times.PCR buffer, 4 .mu.l of dNTPs (200 .mu.M), primer (10 pmol)
and 0.5 .mu.L.sup.1 of Tag polymerase (produced by Takara Shuzo)
(in the case of Tub polymerase, 0.2 .mu.l) to make 50 .mu.L.
[0101] (PCR Reaction Condition)
[0102] First Stage:
[0103] cycle number: 1, denaturation (94.degree. C.): 5 min.,
annealing (55.degree. C.): 1 min., extension (72.degree. C.): 2
min.
[0104] Second Stage:
[0105] cycle number: 30, denaturation (94.degree. C.): 1 min.,
annealing (55.degree. C.): 1 min., extension (72.degree. C.): 2
min.
[0106] Third Stage:
[0107] cycle number: 1, denaturation (94.degree. C.): 1 min.,
annealing (55.degree. C.): 2 min., extension (72.degree. C.): 5
min.
[0108] Two fragments obtained were combined to construct hGT gene
cDNA and subcloned into pBluescriptIISK+(SK). The
pBluescriptIISK+(SK) was purchased from Stratagene. FIG. 1 shows
the construction of plasmid containing hGT gene cDNA. SEQ. ID. NO:5
shows the base sequence of the obtained hGT gene and SEQ. ID. NO:6
shows the presumed amino acid sequence.
[0109] The obtained sequence was different from the hGT sequence
disclosed in Masri et al. supra. in the following points: a) A at
the position 528, C at the position 562 and A at the position 1047
were changed to G, T and G, respectively, but the amino acids coded
were not changed; b) 9 bases at the positions 622 to 630 were
deleted; and c) in order to connect the above-described fractions
of 0.4 kb and 0.8 kb, G at the position 405 and T at the position
408 were transformed to A and A, respectively, at the preparation
of primer.
[0110] Incidentally, the hGT gene cDNA which has two initiation
codons (ATG), was designed in this experimentation such that the
translation starts from the second initiation codon (position
37).
[0111] 2. Introduction of hGT Gene Into Tobacco Cultured Cell (1)
hGT has been reported to be Escherichia coli expressed as an active
type (see, D. Aoki et al., EMBO J., 9, 3171 (1990) and K. Nakazawa
et al., J. Biochem., 113, 747 (1993)).
[0112] In order to express hGT in tobacco cultured cells, a vector
pGAhGT for expression was constructed as shown in FIG. 2. The
promoter used was cauliflower mosaic virus 35S promoter (CaMV 35S
promoter) and the selectable marker used was kanamycin resistant
gene. The pGAhGT was introduced into tobacco cultured cells through
Agrobacterium.
[0113] The transformation of Agrobacterium was performed using a
triparental mating method by Bevan et al (see, M. Bevan, Nucleic
Acid Res., 12, 8711 (1984)). Escherichia coli DH 5.alpha. strain
(suE44, .DELTA.lacU169 (.phi.801acZ.DELTA.M15), hsdR17) (Bethesda
Research Laboratories Inc., Focus 8(2), 9(1986)) having pGA-type
plasmid (see, G. An, Methods Enzymol. 153, 292 (1987)) and
Escherichia coli HB101 having helper plasmid pRK2013 (see, M.
Bevan, Nucleic Acid Res., 12, 8711 (1984)) each was cultured at
37.degree. C. overnight in 2.times.YT medium containing 12.5 mg/L
of tetracycline and 50 mg/L of kanamycin, and Agrobacterium
tumefaciens EHA101 strain (see, E. H. Elizabeth, J. Bacteriol.,
168, 1291 (1986)) was cultured at 28.degree. C. over two nights in
2.times.YT medium containing 50 mg/L of kanamycin and 25 mg/L of
chloramphenicol. From each culture medium, 1.5 ml was transferred
into an Eppendorf tube and cells were collected and washed three
times with LB medium. The obtained cells of each species were
suspended in 100 .mu.l of 2.times.YT medium, these three kinds of
cells were mixed, the mixture was smeared on 2.times.YT agar medium
and cultured at 28.degree. C. to conjugation-transmit the pGA-type
plasmid from Escherichia coli to Agrobacterium. After 2 days, a
part of cells grown throughout the surface of the 2.times.YT agar
medium were scraped by a loop and coated on LB agar medium
containing 50 mg/L of kanamycin, 12.5 mg/L of tetracycline and 25
mg/L of chloramphenicol. After culturing at 28.degree. C. for 2
days, a single colony was selected.
[0114] The transformation of tobacco cultured cells was performed
by the method described in G. An, Plant Mol. Bio. Manual, A3, 1. A
suspension of Agrobacterium (EHA101 strain having pGA-type plasmid)
cultured at 28.degree. C. for 36 hours in LB medium containing 12.5
mg/L of tetracycline and a suspension of tobacco cultured cells
(Nicotiana tabacum L. cv. bright yellow 2) after culturing for 4
days (purchased under Cell Name of BY-2 in catalogue No. RPC1 from
The Institute of Physical and Chemical Research, Riken Gene Bank,
Plant Cell Bank) were placed in a petri dish in amounts of 100
.mu.l and 4 ml, respectively, then thoroughly mixed and left
standing at 25.degree. C. in a dark place. After 2 days, the
culture medium in the petri dish was transferred into a
centrifugation tube and the supernatant was removed by the
centrifugal separation (1,000 rpm, 5 minutes). Subsequently, a
fresh medium was added and after the centrifugal separation, the
cells were smeared on a plate of modified LS agar medium containing
from 150 to 200 mg/L of kanamycin and 250 mg/L of carbenicillin and
left standing at 25.degree. C. in the dark. After about 2 to 3
weeks, the callused cells were implanted on a new plate and the
growing clones were selected. After further 2 to 3 weeks, the
clones were transferred to 30 ml of modified LS medium having added
thereto kanamycin and carbenicillin and subjected to passage
culture. For about 1 month, the selection was repeated. From some
resistant strains obtained, 6 resistant strains (GT1, 4, 5, 6, 8
and 9) were randomly selected.
[0115] (2) Identification of Introduced hGT Gene
[0116] The resistant strains obtained were analyzed by the Southern
analysis and it was confirmed that the fragment of 2.2 kb
containing CaMV35S promoter-hGT gene cDNA-NOS terminator in T-DNA
was integrated into genomic DNA of tobacco cultured cell. From each
resistant strain obtained above, genomic DNA was prepared, digested
using EcoRI, HindIII, and analyzed by Southern analysis.
[0117] The preparation of chromosome DNA from tobacco cultured
cells was performed according to the Watabe method (see, K. Watabe,
"Cloning to Sequence (Cloning and Sequence)", Shokubutsu
Biotechnology Jikken Manual (Plant Biotechnology Experimentation
Manual), Noson Bunka Sha). 10 ml of Tobacco cultured cells were
frozen by liquid nitrogen and ground into the powder form using
mortar and pestle. Before liquefaction started, about 5 g of the
thus-obtained powder was added to 5 ml of 2.times.CTAB
(cetyltrimethylammonium bromide) solution preheated to 60.degree.
C. in a centrifugal tube (40 ml) and gradually well-mixed and while
occasionally mixing at 60.degree. C. for 10 minutes or more, the
temperature was maintained. Thereto, 5 ml of chloroform:isoamyl
alcohol (24:1) was added and thoroughly mixed until an emulsion was
formed, and the emulsion was then centrifuged (2,800 rpm, 15
minutes, room temperature). The upper layer was transferred to a
new 40 ml-volume centrifugal tube and the extraction operation
using chloroform:isoamyl alcohol (24:1) was repeated. To the
obtained upper layer, {fraction (1/10)} volume of 10% CTAB was
added and thoroughly mixed and centrifuged (2,800 rpm, 15 minutes,
room temperature). The upper layer was transferred to a new
centrifugal tube and 1 volume of cold isopropanol was added
thereto, well mixed and centrifuged (4,500 rpm, 20 minutes, room
temperature). After removing the supernatant by an aspirator, a TE
buffer solution containing 5 ml of 1M sodium chloride was added and
completely dissolved at 55 to 60.degree. C. Thereto, 5 ml of cold
isopropanol was added and when DNA was observed, the DNA was taken
up using the end of a stick, transferred to an Eppendorf tube
(containing 80% cold ethanol) and rinsed. The DNA was further
rinsed with 70% ethanol and the dry precipitate was dissolved in an
appropriate amount of TE buffer. Thereto, 5 .mu.l of RNAaseA (10
mg/ml) was added and reacted at 37.degree. C. for 1 hour. The
2.times.CTAB solution had a composition of 2% CTAB, 0.1M Tris-HCl
(pH: 8.0), 1.4M sodium chloride and 1% polyvinyl pyrrolidone (PVP),
and the 10% CTAB solution had a composition of 10% CTAB and 0.7M
sodium chloride.
[0118] The Southern analysis was performed as follows.
[0119] (i) Electrophoresis and Alkali Modification of DNA:
[0120] After completely degrading 40 .mu.g of the obtained
chromosome DNA using a restriction enzyme, 1.5% agarose gel
electrophoresis (50 V) was performed by a standard method. The gel
was stained with ethidium bromide, photographed and shaken for 20
minutes in 400 ml of 0.25M HCl. Thereafter, the solution was
discarded and the gel was immersed in 400 ml of modified solution
(1.5M, NaCl, 0.5M, NaOH) and gradually shaken for 45 minutes.
Subsequently, the solution was discarded and 400 ml. of a
neutralization solution (1.5M NaCl, 0.5M Tris-Cl (pH: 7.4)) was
added and gradually shaken for 15 minutes. After discarding the
solution, 400 ml of the neutralization solution was again added and
gradually shaken for 15 minutes.
[0121] (ii) Transfer:
[0122] The DNA after the electrophoresis was transferred to a nylon
membrane (Hybond-N Amersham) using 20.times.SSC. The transfer was
performed for 12 hours or more. The blotted membrane was dried at
room temperature for 1 hour and subjected to UV fixing for 5
minutes. The 20.times.SSC had a composition of 3M NaCl and 0.3M
sodium citrate.
[0123] (iii) Preparation of DNA Probe
[0124] The DNA probe was prepared using Random prime Labeling Kit
(produced by Takara Shuzo). In an Eppendorf tube, a reaction
solution shown below was prepared and after heating at 95.degree.
C. for 3 minutes, rapidly cooled in ice: template DNA 25 ng, Random
Primer 2 .mu.l, water added to make 5 .mu.l. 10.times.Buffer and
DNTP each in 1.5 .mu.l and [.alpha.-.sup.32P]dCTP (1.85 MBq, 50
mCi) in 5 .mu.l were added, followed by filling up to 24 .mu.l with
H.sub.2O. Thereto, 1 .mu.l of Klenow fragment was added and after
keeping at 37.degree. C. for 10 minutes, eluted through NAP10
column (produced by Pharmacia) to purify the DNA. This purified DNA
was heated at 95.degree. C. for 3 minutes and then rapidly cooled
in ice to obtain a hybridization probe.
[0125] (iv) Hybridization:
[0126] To the following prehybridization solution, 0.05 mg/ml of
0.5% (w/v) SDS was added. In the resulting solution, the membrane
of (ii) above was immersed and the prehybridization was performed
at 42.degree. C. for 2 hours or more. Thereafter, the DNA probe
prepared in (iii) was added and the hybridization was performed at
42.degree. C. for 12 hours or more. The prehybridization solution
had a composition of 5.times.SSC. 50 mM sodium phosphate, 50% (w/v)
formamide, 5.times. Denhardt's solution (obtained by diluting
100.times. Denhardt's solution), 0.1% (w/v) SDS. The 100.times.
Denhardt's solution had a composition of 2% (w/v) BSA, 2% (w/v)
Ficol 400, 2% (w/v) polyvinyl pyrrolidone (PVP).
[0127] (v) Autoradiography:
[0128] After the cleaning in the following sequence, the
autoradiography was performed by a standard method. Twice in
2.times.SSC and 0.1% SDS at 65.degree. C. for 15 minutes and then,
once in 0.1.times.SSC and 0.1% SDS at 65.degree. C. for 15
minutes.
[0129] FIG. 3 shows the results of the Southern analysis of genomic
DNA prepared each resistant strain obtained above. As seen from
FIG. 3, it was confirmed that the hGT gene was integrated in four
strains of GT1, 6, 8 and 9.
[0130] 3. Analysis of Glycoprotein Secreted by Galactosyl
Transferase Transformant
[0131] (Preparation of Glycoprotein by Extracellular Secretion of
Tobacco Cultured Cell GT6 Strain)
[0132] A culture medium of tobacco cultured cell GT6 strain
resulting from culturing in modified Murashige-Skoog medium
prepared using mixed salts for Murashige-Skoog medium (produced by
Wako Junyaku) for 7 days was centrifuged at 2,000 rpm for 10
minutes at room temperature and the obtained supernatant was
recovered as the GT6 strain culture medium and used in this
Example. The obtained supernatant was dialyzed against dH.sub.2O
(deionized water) (1.times.10.sup.5 times dilution) and then
freeze-dried.
[0133] (Preparation of N-Linked Type Sugar Chain)
[0134] The sample obtained by the freeze-drying was hydrazinolyzed
at 100.degree. C. for 10 hours to excise the sugar chain. To the
hydrazinolysis product, excess acetone was added and by
centrifugation at 4.degree. C. and 10,000 rpm for 20 minutes, sugar
chains were precipitated. The sugar chains were N-acetylated in the
presence of an aqueous saturated sodium hydrogencarbonate solution
and acetic anhydride, then desalted using Dowex 50.times.2
(produced by Muromachi Kagaku Kogyo), and passed through Sephadex
G-25 super fine gel filter column (1.8.times.180 cm) equilibrated
with 0.1N aqueous ammonia, thereby recovering the N-linked sugar
chains.
[0135] (Preparation of Pyridylaminated (PA) Sugar Chain)
[0136] The recovered N-linked sugar chains were PA-formed. The
PA-sample was passed through Sephadex G-25 super fine gel filter
column (1.8.times.180 cm) equilibrated with an aqueous 3% acetic
acid solution to purify the PA-sugar chains.
[0137] (Fractionation and Analysis of PA-Sugar Chains by HPLC)
[0138] The PA-sugar chain structure was analyzed by reversed-phase
(RP) and size-fractionation (SF) HPLC, two-dimensional sugar chain
mapping using the exoglycosidase digestion, and IS-MS/MS analysis.
In the HPLC (high-performance liquid chromatography) analysis.
Jasco 880-PU HPLC having Jasco 821-FP Intelligent
Spectrofluorometer was used and the fluorescence intensity was
measured at excitation wavelength of 310 nm and fluorescence
wavelength of 380 nm.
[0139] In the RP-HPLC analysis using Cosmosil 5C18-P column
(6.times.250 mm, produced by Nakaraitesc), the concentration of
acetonitrile in an aqueous 0.02% TFA solution was increased from 0%
to 6% over 40 minutes at a flow rate of 1.2 ml/min and thereby
PA-sugar chains were eluted. In the SF-HPLC analysis using Asahipak
NH2P-50 column (4.6.times.250 mm, produced by Showa Denko K.K.),
the concentration of acetonitrile in a dH.sub.2O-acetonitrile mixed
solution was increased from 26% to 50% over 25 minutes at a flow
rate of 0.7 ml/min and thereby PA-sugar chains were eluted.
[0140] (Analysis of PA-Sugar Chains by Exoglycosidase
Digestion)
[0141] In the enzymatic digestion reaction using
.beta.-galactosidase (Diplococcus pneumoniae, Roche), each PA-sugar
chain was reacted at 37.degree. C. for 2 days in a 0.1M sodium
acetate buffer (pH: 5.5) containing 5 mU of .beta.-galactosidase.
Similarly, in the enzymatic digestion reaction using
N-acetylglucosamidase (Diplococcus pneumoniae, Roche), each
PA-sugar chain was reacted at 37.degree. C. for 2 days in a 0.1M
sodium acetate buffer (pH: 5.5) containing 5 mU of
N-acetylglucosamidase. Furthermore, in the enzymatic digestion
reaction using .alpha.-mannosidase (Jack bean, Sigma), each
PA-sugar chain was reacted at 37.degree. C. for 2 days in a 0.1M
sodium acetate buffer (pH: 3.88) containing 10 mM zinc acetate and
10 .mu.U of .alpha.-mannosidase. Each enzymatic digestion reaction
was stopped by boiling the solution at 100.degree. C. for 3
minutes. Then, the reaction solution was centrifuged at 12,000 rpm
for 10 minutes and the supernatant was subjected to HPLC. The
elution time of each sample sugar chain was compared with the
elution time of a known sugar chain.
[0142] (IS-MS/MS Analysis)
[0143] The IS-MS/MS Analysis was performed using Perkin-Elmer Sciex
API-III triple-quadrupole mass spectrometer. The scan interval was
0.5 Da.
[0144] (Sialic Acid Transferase Reaction In Vitro)
[0145] The GT6 strain cell culture medium-derived glycoprotein
prepared above after the dialysis and freeze-drying was used as the
substrate. A sialic acid transferase reaction was performed at
37.degree. C. for 5 hours in 62.5 mM sodium cacodylate buffer
solution (pH: 6.0) containing 1 mg/ml of BSA, 0.5% of Triton CF-54,
2 .mu.M of CMP-sialic acid, 6 mU of .alpha.2,6-sialyl transferase
(derived from rat liver) (produced by Wako Junyaku) and 400 .mu.g
of GT6 strain cell culture medium-derived glycoprotein. In the
control test, 400 .mu.g of BY2 strain cell culture medium-derived
glycoprotein and 40 .mu.g of asialo fetuin fetal (fetal bovine
serum, Sigma) were used as the substrate.
[0146] (Lectin Staining)
[0147] The sialic acid transferase reaction product was subjected
to SDS-PAGE at 130 V for 2 hours using 12.5% polyacrylamide gel and
then transferred to nitrocellulose membrane at a constant current
of 1 mA/cm.sup.2 for 50 minutes. In the lectin blotting,
horseradish peroxidase-linked SNA lectin (produced by EY
Laboratories, Inc.) 200-fold diluted with a PBS solution containing
0.05% of Tween-20 was used. After the blotting, the staining was
performed using POD Immunostain Kit (produced by Wako Junyaku).
[0148] (Purification of Tobacco Cultured Cell GT6 Strain Culture
Medium-Derived PA-Sugar Chain)
[0149] The PA-sugar chain prepared from the GT6 strain culture
medium was purified using RP-HPLC and SF-HPLC (shown in FIG. 4A and
FIG. 4B, respectively). FIG. 4A shows the peak of PA-product by
RP-HPLC. After the recovery of peaks (1 to 6), each was subjected
to SF-HPLC (see, FIG. 4B).
[0150] Exclusive of 6 peaks (shown by A to F in FIG. 4B) obtained
by the SF-HPLC, the peaks were not an N-linked sugar chain. This
was verified because, in IS-MS/MS analysis, signals agreeing with
m/z 299.33 (GlcNAc-PA) and m/z 502.52 (GlcNAc.sub.2-PA) were not
obtained. FIG. 5 shows N-linked sugar chain structures analyzed on
the peaks (A-F). In FIG. 5, the numerals in parentheses indicate
the molar ratio of sugar chain having each structure shown in the
Figure.
[0151] As shown in FIG. 5, A to F are all a human-type sugar chain
having a galactose residue bound to an N-acetylglucosamine residue,
contain no fucose residue and except for B and D, have no xylose
residue.
[0152] (Structural Analysis of Tobacco Cultured Cell GT6 Culture
Medium-Derived PA-Sugar Chain)
[0153] The molecular weight (m/z 1354.8) obtained by the IS-MS
analysis of the peak A (I in FIG. 6) agreed with
GalGlcNAcMan.sub.3GlcNAc.sub.2-PA (1354.27). The signals obtained
by the IS-MS/MS analysis, namely, m/z 1192.5, m/z 990.5, m/z 827.5,
m/z 665.5, m/z 503.0, m/z 300.0, are presumed to be
GlcNAcMan.sub.3GlcNAC.sub.2-PA (1192.13), Man.sub.3GlcNAc.sub.2-PA
(988.94), Man.sub.2GlcNAc.sub.2-PA (826.80), ManGlcNAc.sub.2-PA
(664.66), GlcNAc.sub.2-PA (502.52) and GlcNAc-PA (299.33),
respectively, and this suggests that the peak A contains these
structures (the data are not shown).
[0154] The .beta.-galactosidase digestion product from the peak A
was GlcNAcMan.sub.3GlcNAc.sub.2-PA (II in FIG. 6) and the
N-acetylglucosaminidase digestion product thereof was
Man.sub.3GlcNAc.sub.2-PA (III in FIG. 6).
[0155] The molecular weight (m/z 1486.8) obtained by the IS-MS
analysis of the peak B (I in FIG. 7) agreed with
GalGlcNAcMan.sub.3XylGlcNAc.sub.2-PA (1486.38). The signals
obtained by the IS-MS/MS analysis, namely, m/z 1354.5, m/z 1324.0,
m/z 1324.0, m/z 1122.0, m/z 991.5. m/z 960.0, m/z 666.0, m/z 503.0
and m/z 300.0, are presumed to be GalGlcNAcMan.sub.3GlcNAc.sub.2-PA
(1354.27), GlcNAcMan.sub.3XylGlcNAc.sub- .2-PA (1324.24),
Man.sub.3XylGlcNAc.sub.2-PA (1121.05), Man.sub.3GlcNAc.sub.2-PA
(988.94), Man.sub.2XylGlcNAc.sub.2-PA (958.91), ManGlcNAc.sub.2-PA
(664.66), GlcNAC.sub.2-PA (502.52) and GlcNAc.sub.2-PA (299.33),
respectively, and this suggests that the peak B contains these
structures (the data are not shown).
[0156] The .beta.-galactosidase digestion product from the peak B
was GlcNAcMan3XylGlcNAc.sub.2-PA (II in FIG. 7) and the
N-acetylglucosaminidase digestion product thereof was
Man.sub.3XylGlcNAc.sub.2-PA (III in FIG. 7).
[0157] The molecular weight (m/z 1355.0) obtained by the IS-MS
analysis of the peak C (I in FIG. 8) agreed with
GalGlcNAcMan.sub.3GlcNAc.sub.2-PA (m/z 1354.27). The signals
obtained by the IS-MS/MS analysis, namely, m/z 1193.5, m/z 989.0.
m/z 827.0, m/z 665.5, m/z 503.0, m/z 300.0, are presumed to be
GlcNAcMan.sub.3GlcNAc.sub.2-PA (m/z 1192.13),
Man.sub.3GlcNAc.sub.2-PA (m/z 988.94), Man.sub.2GlcNAc.sub.2-PA
(m/z 826.80). ManGlcNAc.sub.2-PA (m/z 664.66), GlcNAc.sub.2-PA (m/z
502.52) and GlcNAc-PA (m/z 299.33), respectively, and this suggests
that the peak C contains these structures (the data are not
shown).
[0158] The .beta.-galactosidase digestion product from the peak C
was GlcNAcMan.sub.3GlcNAc.sub.2-PA (II in FIG. 8) and the
N-acetylglucosaminidase digestion product thereof was
Man.sub.3GlcNAc.sub.2-PA (III in FIG. 8).
[0159] The molecular weight (m/z 1487.0, A in FIG. 10) obtained by
the IS-MS analysis of the peak D (I in FIG. 9) agreed with
GalGlcNAcMan.sub.3XylGlcNAc.sub.2-PA (m/z 1486.38). The signals
obtained by the IS-MS/MS analysis, namely, m/z 1354.0, m/z 1325.0,
m/z 1191.0, m/z 1121.5, m/z 989.5, m/z 828.5, m/z 503.0 and m/z
300.5, are presumed to be GalGlcNAcMan.sub.3GlcNAc.sub.2-PA (m/z
1354.27), GlcNAcMan.sub.3XylGlcNAc- .sub.2-PA (m/z 1324.24),
GlcNAcMan.sub.3GlcNAc.sub.2-PA (m/z 1192.13),
Man.sub.3XylGlcNAc.sub.2-PA (m/z 1121.05), Man.sub.3GlcNAc.sub.2-PA
(m/z 988.94), Man.sub.2GlcNAc.sub.2-PA (m/z 826.80),
GlcNAc.sub.2-PA (m/z 502.52) and GlcNAc-PA (m/z 299.33),
respectively, and this suggests that the peak D contains these
structures (B in FIG. 10).
[0160] The .beta.-galactosidase digestion product from the peak D
was GlcNAcMan.sub.3XylGlcNAc.sub.2-PA (II in FIG. 9) and the
N-acetylglucosaminidase digestion product thereof was
Man.sub.3XylGlcNAc.sub.2-PA (III in FIG. 9).
[0161] The molecular weight (m/z 1516.6) obtained by the IS-MS
analysis of the peak E (I in FIG. 11) agreed with
GalGlcNAcMan.sub.4GlcNAc.sub.2-PA (1516.41). The signals obtained
by the IS-MS/MS analysis, namely, m/z 1355.0, m/z 1193.0, m/z
990.0, m/z 826.5, m/z 665.0, m/z 503.5 and m/z 300.0, are presumed
to be GalGlcNAcMan.sub.3GlcNAc.sub.2-PA (m/z 1354.27),
GalNAcMan.sub.3GlcNAc.sub.2-PA (m/z 1192.13),
Man.sub.3GlcNAc.sub.2-PA (m/z 988.94), Man.sub.2GlcNAc.sub.2-PA
(m/z 826.80), ManGlcNAc.sub.2-PA (m/z 664.66) GlcNAc.sub.2-PA (m/z
502.52) and GlcNAc-PA (m/z 299.33), respectively, and this suggests
that the peak E contains these structures (the data are not
shown).
[0162] The .beta.-galactosidase digestion product from the peak E
was GlcNAcMan.sub.4GlcNAc.sub.2-PA (II in FIG. 11) and the
N-acetylglucosaminidase digestion product thereof was
Man.sub.4GlcNAc.sub.2-PA (III in FIG. 11).
[0163] The molecular weight (m/z 1679.8) obtained by the IS-MS
analysis of the peak F (I in FIG. 12) agreed with
GalGlcNAcMan.sub.5GlcNAc.sub.2-PA (1678.55). The signals obtained
by the IS-MS/MS analysis, namely, m/z 1517.5, m/z 1313.5, m/z
1152.0, m/z 827.5, m/z 665.5, m/z 503.0 and m/z 300.0, are presumed
to be GlcNAcMan.sub.3GlcNAc.sub.2-PA (m/z 1516.41).
Man.sub.2GlcNAc.sub.2-PA (1313.22), Man.sub.4GlcNAC.sub.2-PA
(1151.08), Man.sub.2GlcNAc.sub.2-PA (826.80), ManGlcNAc.sub.2-PA
(664.66), GlcNAc.sub.2-PA (502.52) and GlcNAc-PA (m/z 299.33),
respectively, and this suggests that the peak F contains these
structures (the data are not shown).
[0164] The .beta.-galactosidase digestion product from the peak F
was GlcNAcMan.sub.5GlcNAc.sub.2-PA (II in FIG. 12) and the
N-acetylglucosaminidase digestion product thereof was
Man.sub.5GlcNAc.sub.2-PA (III in FIG. 12).
[0165] From these results, the peak A or C is considered to be
either .alpha.-D-Man-(1.fwdarw.6)
[.beta.-D-Gal-(1.fwdarw.4)-.beta.-D-GlcNAc-(1.-
fwdarw.2)-.alpha.-D-Man-(1.fwdarw.3)]
.beta.-D-Man-(1.fwdarw.4)-.beta.-D-G-
lcNAc-(1.fwdarw.4)-GlcNAc-PA(GalGNlM3-PA) or
[.beta.-D-Gal-(1.fwdarw.4)-.b-
eta.-D-GlcNAc(1.fwdarw.2)-.alpha.-D-Man-(1.fwdarw.6)]
.alpha.-D-Man-(1.fwdarw.3)
.beta.-D-Man-(1.fwdarw.4)-.beta.-D-GlcNAc-(14)- -GlcNAc-PA
(GalGN.sup.1M3-PA).
[0166] The peak B or D is considered to be either
.alpha.-D-Man-(1.fwdarw.- 6)
[.beta.-D-Gal-(1.fwdarw.4)-D-GlcNAc-(1.fwdarw.2)-.alpha.-D-Man-(1.fwdar-
w.3)] [.beta.-D-Xyl-(1.fwdarw.2)]
.beta.-D-Man-(1.fwdarw.4)-.beta.-D-GlcNA- c-(1.fwdarw.4)-GlcNAc-PA
(GalGN.sup.1M3X-PA) or [.beta.-D-Gal-(1.fwdarw.4)-
-.beta.-D-GlcNAc(1.fwdarw.2)-.alpha.-D-Man-(1.fwdarw.6)]
[.alpha.-D-Man-(1.fwdarw.3)] [.beta.-D-Xyl-(1.fwdarw.2)]
.beta.-D-Man-(1.fwdarw.4)--D-GlcNAc-(1.fwdarw.4)-GlcNAC-PA
(GalGN.sup.1M3X-PA).
[0167] The peak E is considered to be either
.alpha.-D-Man-(1.fwdarw.6)-.a- lpha.-D-Man-(1.fwdarw.6)
[.beta.-D-Gal-(1-4)-.beta.-D-GlcNAc-(1.fwdarw.2)--
.alpha.-D-Man-(1.fwdarw.3)] .beta.-D-Man-(1.fwdarw.4)
.beta.-D-GlcNAc-(1.fwdarw.4)-GlcNAc-PA (GalGNM4-PA) or
.alpha.-D-Man-(1.fwdarw.3)-.alpha.-D-Man-(1.fwdarw.6)
[.beta.-D-Gal-(1.fwdarw.4)-.beta.-D-GlcNAc(1>2)-.alpha.-D-Man-(1.fwdar-
w.3)]
.beta.-D-Man-(1.fwdarw.4)-.beta.-D-GlcNAc-(1.fwdarw.4)-GlcNAc-PA
(GalGNM4-PA).
[0168] The peak F is considered to be .alpha.-D-Man-(1.fwdarw.6)
[.alpha.-D-Man-(1.fwdarw.3) .alpha.-D-Man-(1.fwdarw.6)
[.beta.-D-Gal-(1.fwdarw.4)-.beta.-D-GlcNAc(1.fwdarw.2)-.alpha.-D-Man-(1.f-
wdarw.3)]
.beta.-D-Man-(1.fwdarw.4)-.beta.-D-GlcNAc-(1.fwdarw.4)-GlcNAc-PA
(GalGNM5-PA).
[0169] (Sialic Acid Transferase Reaction In Vitro)
[0170] A sialic acid transferase reaction in vitro was performed
using GT6 strain culture medium-derived glycoprotein, BY2 strain
culture medium-derived glycoprotein or asialo fetuin as the
substrate. Each reactant was transferred to nitrocellulose membrane
and subjected to lectin staining. As a result, the lectin staining
was positive in the case where the substrate was asialo fetuin
(lane 1 in FIG. 13) or GT6 strain culture medium-derived
glycoprotein (lane 2 in FIG. 13), and the lectin staining was
negative in the case where the substrate was BY2 strain culture
medium-derived glycoprotein (lane 3, FIG. 13). From this, it is
revealed that tobacco cultured cell GT6 strain culture
medium-derived glycoprotein acts as the substrate in the sialic
acid transferase reaction.
COMPARATIVE EXAMPLE
[0171] (Analysis of Glycoprotein Secreted by Non-Transformant BY2
Strain Cultured Cell)
[0172] (Preparation of Glycoprotein by Extracellular Secretion)
[0173] A freeze-dried culture supernatant sample was obtained by
the same method as in GT6 strain except for using BY2 strain in
place of GT6 strain.
[0174] (Preparation of N-Linked Sugar Chain)
[0175] N-Linked sugar chains were recovered by the same method as
in GT6 strain except for using TSK gel TOYO PERAL HW-40 (produced
by TOSO) gel filter column (2.5.times.30 cm) in place of the
Sephadex G-25 super fine gel filer column (1.8.times.180 cm).
[0176] (Preparation of Pyridylaminated (PA) Sugar Chain)
[0177] The recovered N-linked sugar chains were PA-formed using
2-aminopyridine. The PA-sample was filtered through TSK gel TOYO
PERAL HW-40 (produced by TOSO) gel filter column (2.5.times.30 cm)
to purify the PA-sugar chains.
[0178] (Fractionation and Analysis of PA-Sugar Chain by HPLC)
[0179] The fractionation and analysis of PA-sugar chains were
performed in the same manner as in GT6 strain except for using
HITACHI HPLC system having a HITACHI FL Detector L-7480 in place of
Jasco 880-PU HPLC having a Jasco 821-FP Intelligent
Spectrofluorometer.
[0180] (Analysis of PA-Sugar Chain by Exoglycosidase Digestion)
[0181] In the enzymatic digestion reaction using
N-acetylglucosaminidase (Diplococcus pneumoniae, Roche), each
PA-sugar chain was reacted at 37.degree. C. for 2 days in a 0.1M
sodium acetate buffer (pH: 5.45) containing 3 mU of
N-acetylglucosaminidase. In the enzymatic digestion reaction using
.alpha.-mannosidase (Jack bean, Sigma), each PA-sugar chain was
reacted at 37.degree. C. for 2 days in a 0.1M sodium acetate buffer
(pH: 4.0) containing 10 mM zinc acetate and 10 .mu.U of
.alpha.-mannosidase. Each enzymatic digestion reaction was stopped
by boiling the solution at 100.degree. C. for 3 minutes. Then, the
reaction solution was centrifuged at 12,000 rpm for 10 minutes and
the supernatant was subjected to HPLC. The elution time of each
sample sugar chain was compared with the elution time of a known
sugar chain.
[0182] (IS-MS/MS Analysis)
[0183] This analysis was performed in the same manner as in GT6
strain.
[0184] (Preparation of BY2 Strain Culture Medium-Derived PA-Sugar
Chain)
[0185] The PA-sugar chains prepared from BY2 culture medium were
also purified using RP-HPLC and SF-HPLC (FIGS. 14A and 14B). FIG.
14A shows the peaks of PA-product by RP-HPLC. After the recovery,
each fraction (I to X) was subjected to SF-HPLC (FIG. 14B).
[0186] In the fractions (I, II and III) shown in FIG. 14A, N-linked
sugar chain was not detected by SF-HPLC analysis. This was verified
because in IS-MS/MS analysis, signals agreeing with m/z 299.33
(GlcNAc-PA) and m/z 502.52 (GlcNAc.sub.2-PA) were not obtained. The
peaks of fractions IV to X were analyzed by SF-HPLC, as a result,
21 peaks were obtained (see, FIG. 14B). FIGS. 15A and 15B show
analyzed N-linked sugar chain structures.
[0187] (Structural Analysis of BY2 Strain Culture Medium-Derived
PA-Sugar Chain)
[0188] As a result of IS-MS/MS analysis of the peaks V-4, VII-3 and
VIII-4 shown in FIG. 14B, the molecular weights (m/z) were 1639.0,
1476.5 and 1314.5, respectively and, on considering the elution
sites in SF-HPLC together, the sugar chain structures present in
the peaks agreed with PA-high mannose sugar chain
Man.sub.7GlcNAc.sub.2-PA, Man.sub.6GlcNAc.sub.2-PA and
Man.sub.5GlcNAc.sub.2-PA, respectively (the data are not
shown).
[0189] Also, as a result of SF-HPLC analysis, the
.alpha.-mannosidase digestion product of sugar chain of each peak
agreed with Man GlcNAc.sub.2-PA (M1) (the data are not shown). When
the isomers M7A, M7B and M7D of Man.sub.7GlcNAc.sub.2-PA were
compared, the elution site of the peak V-4 agreed with the elution
site of M7A. Among the isomers M6B and M6C of
Man.sub.6GlcNAc.sub.2-PA, the peak VII-3 agreed with M6B. Also, the
isomer M5A of Man.sub.5GlcNAc.sub.2-PA and the peak VIII-4
agreed.
[0190] From these data, the peaks V-4, VII-3 and VIII-4 shown in
FIG. 14B were, as shown in FIG. 15A,
.alpha.-D-Man-(1-2)-.alpha.-D-Man-(1.fwdarw.6- )
[.alpha.-D-Man-(1.fwdarw.3)] .alpha.-D-Man-(1.fwdarw.6)
[.alpha.-D-Man-(1.fwdarw.2)-.alpha.-D-Man-(1.fwdarw.3)]
.beta.-D-Man-(1.fwdarw.4)-.beta.-D-GlcNAc-(1-4)-GlcNAc-PA (M7A),
.alpha.-D-Man-(1-6) [.alpha.-D-Man-(1.fwdarw.3)]
.alpha.-D-Man-(1.fwdarw.- 6)
[.alpha.-D-Man(1.fwdarw.2)-.alpha.-D-Man-(1.fwdarw.3)]
.alpha.-D-Man-(1.fwdarw.4)-.beta.-D-GlcNAc-(1.fwdarw.4)-GlcNAc-PA
(M6A), and .alpha.-D-Man-(1.fwdarw.6) [.alpha.-D-Man-(1.fwdarw.3)]
.alpha.-D-Man-(1.fwdarw.6) [.alpha.-D-Man-(1.fwdarw.3)]
.beta.-D-Man-(1.fwdarw.4)-.beta.-D-GlcNAc-(1-4)-GlcNAc-PA (M5A). In
the figure, the numerals in parentheses indicate the molar ratio of
sugar chain having each structure shown in the Figure.
[0191] The molecular weight (m/z 1267.5) determined by the IS-MS
analysis of the peaks IV-1 and V-1 shown in FIG. 14B agreed with
the calculated value of Man.sub.3XylFucGlcNAc.sub.2-PA (M3FX:
1267.19). Also, the elution site in HPLC completely agreed with
M3FX standard product on the two-dimensional sugar chain map.
Furthermore, as a result of SF-HPLC analysis and IS-MS/MS analysis,
the .alpha.-mannosidase digestion product of sugar chain of each
peak agreed with the calculated value of ManXylFucGlcNAc.sub.2-PA
(MFX: 942.91) (see, FIGS. 17A and 17B).
[0192] From these data, the peaks IV-1 and V-1 shown in FIG. 14B
were, as shown in FIG. 15B, .alpha.-D-Man-(1.fwdarw.6)
[.alpha.-D-Man-(1.fwdarw.3)- ] [.beta.-D-Xyl-(1>2)]
P-D-Man-(114)-.beta.-D-GlcNAc-(1.fwdarw.4)-[.alp-
ha.-L-Fuc-(1.fwdarw.3)]GlcNAc-PA (M3FX).
[0193] The molecular weight (m/z 1417.0) determined by the IS-MS
analysis of the peak VII-2 shown in FIG. 14B agreed with the
calculated value of GlcNACMan.sub.3XylFucGlcNAc.sub.2-PA (GNM3FX:
1470.38). Also, as a result of SF-HPLC analysis and IS-MS/MS
analysis, the N-acetylglucosaminidase digestion product of sugar
chain of the peak agreed with Man.sub.3XylFucGlcNAc.sub.2-PA (M3FX:
1267.19). Furthermore, after the digestion by .alpha.-mannosidase,
the SF-HPLC analysis and IC-MS/MS analysis revealed that the
product agreed with ManXylFucGlcNAc.sub.2-PA (MFX: 942.91) (C to E
in FIG. 17). On the two-dimensional sugar chain map, the elution
site in RP-HPLC of the peak VII-2 (D-2 in FIG. 16) completely
agreed with the standard product GN.sup.1M3FX,
.beta.-D-GlcNAc-(1.fwdarw.2)-.alpha.-D-Man-(1.fwdarw.6)
[.alpha.-D-Man-(1.fwdarw.3)] (.beta.-D-Xyl-(1.fwdarw.2)]
.beta.-D-Man-(1.fwdarw.4)-.beta.-D-GlcNAc-(1.fwdarw.4)-[.alpha.-L-Fuc-(1--
3)]GlcNAc-PA (D-1 in FIG. 16).
[0194] From these data, the peak VII-2 was, as shown in FIG. 15B,
.beta.-D-GlcNAc-(1.fwdarw.2)-.alpha.-D-Man-(1.fwdarw.6)
[.alpha.-D-Man-(1.fwdarw.3)] [.beta.-D-Xyl-(1.fwdarw.2)]
.beta.-D-Man-(1.fwdarw.4)-.beta.-D-GlcNAc-(1.fwdarw.4)-[.alpha.-L-Fuc-(1.-
fwdarw.3)]GlcNAc-PA (GN.sup.1M3FX).
[0195] The molecular weight (m/z 1324.0) of the peaks VII-1 and
VIII-3 shown in FIG. 14B agreed with the calculated value of
GlcNAcMan.sub.3XylGlcNAc.sub.2-PA (GNM3FX: 1324.24). Also, as a
result of SF-HPLC analysis and IS-MS/MS analysis, the
N-acetylglucosaminidase digestion product of the peak VIII-1 agreed
with Man.sub.3XylGlcNAc.sub.2- -PA (M3X: 1121.05) (B in FIG. 18A).
Furthermore, after the digestion by .alpha.-mannosidase, the
SF-HPLC analysis and IC-MS/MS analysis revealed that the product
agreed with ManXylGlcNAc.sub.2-PA (MX: 796.77) (C in FIG. 18A). As
the structure of GNM3X, two isomer types are considered, that is,
.alpha.-D-Man-(1.fwdarw.6) [.beta.-D-GlcNAc-(1.fwdarw.2)-.alpha.-
-D-Man-(1.fwdarw.3)] [.beta.-D-Xyl-(1.fwdarw.2)]
.beta.-D-Man-(1.fwdarw.4)- -.beta.-D-GlcNAc-(1.fwdarw.4)-GlcNAc-PA
(GN.sub.1M3X) and
.beta.-D-GlcNAc-(1.fwdarw.2)-.alpha.-D-Man-(1>6)
[.alpha.-D-Man-(1>3)] [.beta.-D-Xyl-(1.fwdarw.2)]
.beta.-D-Man-(1.fwdarw.4)-.beta.-D-GlcNAc-(1.fwdarw.4)-GlcNAc-PA
(GN.sup.1M3X). On the ODS column, it has been reported that
GN.sub.1M3X elutes in advance of GN.sup.1M3X. When the elution
sites of the peaks VII-1 and VIII-3 are considered, as shown in
FIG. 15B, the peak VII-1 was .alpha.-D-Man-(1-6)
[.beta.-D-GlcNAc-(1.fwdarw.2)-.alpha.-D-Man-(1.fwdarw- .3)]
[.beta.-D-Xyl-(1.fwdarw.2)]
.beta.-D-Man-(1.fwdarw.4)--O-D-GlcNAc-(1.- fwdarw.4)-GlcNAc-PA
(GN.sub.1M3X) and the peak VIII-3 was
.beta.-D-GlcNAc-(1.fwdarw.2)-.alpha.-D-Man-(1.fwdarw.6)
[.alpha.-D-Man-(1.fwdarw.3) [ ]-D-Xyl-(1.fwdarw.2)]
.beta.-D-Man-(1.fwdarw.4)--O-D-GlcNAc-(1.fwdarw.4)-GlcNAc-PA
(GN.sup.1M3X).
[0196] The elution site of the peak X-1 shown in FIG. 14B in HPLC
completely agreed with the standard GN2M3 (1395.32) on the
two-dimensional sugar chain map. Also, as a result of SF-HPLC
analysis and IS-MS/MS analysis, the N-acetylglucosaminidase
digestion product of sugar chain of the peak agreed with
Man.sub.3GlcNAc.sub.2-PA (M3: 988.94). Furthermore, after the
digestion by .alpha.-mannosidase, the SF-HPLC analysis and IC-MS/MS
analysis revealed that the product agreed with ManGlcNAc.sub.2-PA
(M1: 664.66) (the data are not shown). From these results, the peak
X-1 was, as shown in FIGS. 15A and 15B,
.beta.-D-GlcNAc-(1.fwdarw.2)-.alpha.-D-Man-(1.fwdarw.6)
[.beta.-D-GlcNAc-(1.fwdarw.2)-.alpha.-D-Man-(1.fwdarw.3)]
P-D-Man-(1.fwdarw.4)-.beta.-D-GlcNAc-(1-4)-GlcNAc-PA (GN2M3).
[0197] The molecular weight (m/z 1529.5) of the peak X-2 shown in
FIG. 14B agreed with the calculated value of
GlcNAc.sub.2Man.sub.3XylGlcNAc.sub.2-- PA (GN2M3FX: 1527.43). Also,
the elution site in HPLC completely agreed with the M3FX standard
product on the two-dimensional sugar chain map. Furthermore, the
elution site of the .alpha.-mannosidase digestion product of sugar
chain of this peak was not changed by the HPLC analysis. However,
as a result of the SF-HPLC analysis and IC-MS/MS analysis, the
N-acetylglucosaminidase digestion product agreed with
Man.sub.3XylGlcNAc.sub.2-PA (M3X: 1121.05) (B in FIG. 18B). After
further digestion by .alpha.-mannosidase, the SF-HPLC analysis and
IC-MS/MS analysis revealed that the product agreed with
ManXylGlcNAc.sub.2-PA (MX: 796.77) (C in FIG. 18A). From these
data, the peak X-2 was, as shown in FIG. 15B,
.beta.-D-GlcNAc-(1.fwdarw.2)-.alpha.-D-Man-(1.fwdarw.6)
[.beta.-D-GlcNAc-(1.fwdarw.2)-.alpha.-D-Man-(1.fwdarw.3)]
[.beta.-D-Xyl-(1.fwdarw.2)]
.beta.-D-Man-(1.fwdarw.4)-.beta.-D-GlcNAc-(1.- fwdarw.4)-GlcNAc-PA
(GN2M3X).
[0198] Other peaks IV-2, IV-3, V-2, V-3, V-5, VI-1, VI-2, VI-3,
VI-4, VIII-2 and 1.times.shown in FIG. 14B were not an N-linked
sugar chain, because as a result of the IS-MS/MS analysis, signals
agreeing with m/z 299.33 (GlcNAC-PA) and m/z 502.52
(GlcNAc.sub.2-PA) were not obtained.
[0199] 4. Secretion of Horse Radish Peroxidase (HRP)
[0200] A foreign gene, horseradish peroxidase gene, which was
obtained from 35S-C1a (Kawaoka et al., J. Ferment. Bioeng., 78,
49-53 (1994)), was inserted at Hind III and SacI site of vector
pBI101 HmB (Akama et al., Plant Cell Rep.12,7-11(1992)) and
introduced into GT6 Strain. After cultivating the obtained clones
of GT6 Strain (GT-HRP-5, GT-HRP-19), the supernatant was collected,
and subjected to a standard isoelectric focusing electrophoresis.
As a result, as indicated in FIG. 19, electrophoresis band of pI
7.8 of HRP was detected in the supernatant of clones GT-HRP-5,
GT-HRP-19, and thus confirmed that an foreign protein was also
secreted from the plant cell transformed with the Ga1T gene.
Further, FIG. 20 indicates the results of lectin staining of
secreted proteins by clone GT-HRP-5, separated by standard SDS-PAGE
electrophoresis as described above. RCA120 staining indicates that
GT-HRP-5 has a positive signal (FIG. 20(c)), and thus it was
indicated that secreted HRP had a galactose added sugar chain
structure.
INDUSTRIAL APPLICABILITY
[0201] According to the present invention, a method for the
secretory production of a heterologous glycoprotein having a
human-type sugar chain using a plant cell, a plant cell which can
secrete this glycoprotein, and a glycoprotein having a human-type
sugar chain which is secreted by a plant cell. The glycoprotein of
the present invention has a human-type sugar chain and therefore,
is free of antigenicity and is useful for the administration to
animals including human.
Sequence CWU 1
1
6 1 31 DNA Artificial Sequence Description of Artificial
Sequenceprimer hGT-5Eco 1 aaagaattcg cgatgccagg cgcgcgtccc t 31 2
28 DNA Artificial Sequence Description of Artificial Sequenceprimer
hGT-2Sal 2 tcgatcgcaa aaccatgtgc agctgatg 28 3 29 DNA Artificial
Sequence Description of Artificial Sequenceprimer hGT-7Spe 3
acgggactcc tcaggggcga tgatcataa 29 4 27 DNA Artificial Sequence
Description of Artificial Sequenceprimer hGT-6Spe 4 aagactagtg
ggccccatgc tgattga 27 5 1158 DNA Homo sapiens CDS (1)..(1155) 5 atg
cca ggc gcg tcc cta cag cgg gcc tgc cgc ctg ctc gtg gcc gtc 48 Met
Pro Gly Ala Ser Leu Gln Arg Ala Cys Arg Leu Leu Val Ala Val 1 5 10
15 tgc gct ctg cac ctt ggc gtc acc ctc gtt tac tac ctg gct ggc cgc
96 Cys Ala Leu His Leu Gly Val Thr Leu Val Tyr Tyr Leu Ala Gly Arg
20 25 30 gac ctg agc cgc ctg ccc caa ctg gtc gga gtc tcc aca ccg
ctg cag 144 Asp Leu Ser Arg Leu Pro Gln Leu Val Gly Val Ser Thr Pro
Leu Gln 35 40 45 ggc ggc tcg aac agt gcc gcc gcc atc ggg cag tcc
tcc ggg gag ctc 192 Gly Gly Ser Asn Ser Ala Ala Ala Ile Gly Gln Ser
Ser Gly Glu Leu 50 55 60 cgg acc gga ggg gcc cgg ccg ccg cct cct
cta ggc gcc tcc tcc cag 240 Arg Thr Gly Gly Ala Arg Pro Pro Pro Pro
Leu Gly Ala Ser Ser Gln 65 70 75 80 ccg cgc ccg ggt ggc gac tcc agc
cca gtc gtg gat tct ggc cct ggc 288 Pro Arg Pro Gly Gly Asp Ser Ser
Pro Val Val Asp Ser Gly Pro Gly 85 90 95 ccc gct agc aac ttg acc
tcg gtc cca gtg ccc cac acc acc gca ctg 336 Pro Ala Ser Asn Leu Thr
Ser Val Pro Val Pro His Thr Thr Ala Leu 100 105 110 tcg ctg ccc gcc
tgc cct gag gag tcc ccg cta cta gtg ggc ccc atg 384 Ser Leu Pro Ala
Cys Pro Glu Glu Ser Pro Leu Leu Val Gly Pro Met 115 120 125 ctg att
gag ttt aac atg cct gtg gac ctg gag ctc gtg gca aag cag 432 Leu Ile
Glu Phe Asn Met Pro Val Asp Leu Glu Leu Val Ala Lys Gln 130 135 140
aac cca aat gtg aag atg ggc ggc cgc tat gcc ccc agg gac tgc gtc 480
Asn Pro Asn Val Lys Met Gly Gly Arg Tyr Ala Pro Arg Asp Cys Val 145
150 155 160 tct cct cac aag gtg gcc atc atc att cca ttc cgc aac cgg
cag gag 528 Ser Pro His Lys Val Ala Ile Ile Ile Pro Phe Arg Asn Arg
Gln Glu 165 170 175 cac ctc aag tac tgg cta tat tat ttg cac cca gtc
ctg cag cgc cag 576 His Leu Lys Tyr Trp Leu Tyr Tyr Leu His Pro Val
Leu Gln Arg Gln 180 185 190 cag ctg gac tat ggc atc tat gtt atc aac
cag gcg gga gac act ata 624 Gln Leu Asp Tyr Gly Ile Tyr Val Ile Asn
Gln Ala Gly Asp Thr Ile 195 200 205 ttc aat cgt gct aag ctc ctc aat
gtt ggc ttt caa gaa gcc ttg aag 672 Phe Asn Arg Ala Lys Leu Leu Asn
Val Gly Phe Gln Glu Ala Leu Lys 210 215 220 gac tat gac tac acc tgc
ttt gtg ttt agt gac gtg gac ctc att cca 720 Asp Tyr Asp Tyr Thr Cys
Phe Val Phe Ser Asp Val Asp Leu Ile Pro 225 230 235 240 atg aat gac
cat aat gcg tac agg tgt ttt tca cag cca cgg cac att 768 Met Asn Asp
His Asn Ala Tyr Arg Cys Phe Ser Gln Pro Arg His Ile 245 250 255 tcc
gtt gca atg gat aag ttt gga ttc agc cta cct tat gtt cag tat 816 Ser
Val Ala Met Asp Lys Phe Gly Phe Ser Leu Pro Tyr Val Gln Tyr 260 265
270 ttt gga ggt gtc tct gct cta agt aaa caa cag ttt cta acc atc aat
864 Phe Gly Gly Val Ser Ala Leu Ser Lys Gln Gln Phe Leu Thr Ile Asn
275 280 285 gga ttt cct aat aat tat tgg ggc tgg gga gga gaa gat gat
gac att 912 Gly Phe Pro Asn Asn Tyr Trp Gly Trp Gly Gly Glu Asp Asp
Asp Ile 290 295 300 ttt aac aga tta gtt ttt aga ggc atg tct ata tct
cgc cca aat gct 960 Phe Asn Arg Leu Val Phe Arg Gly Met Ser Ile Ser
Arg Pro Asn Ala 305 310 315 320 gtg gtc ggg agg tgt cgc atg atc cgc
cac tca aga gac aag aaa aat 1008 Val Val Gly Arg Cys Arg Met Ile
Arg His Ser Arg Asp Lys Lys Asn 325 330 335 gaa ccc aat cct cag agg
ttt gac cga att gca cac aca aag gag aca 1056 Glu Pro Asn Pro Gln
Arg Phe Asp Arg Ile Ala His Thr Lys Glu Thr 340 345 350 atg ctc tct
gat ggt ttg aac tca ctc acc tac cag gtg ctg gat gta 1104 Met Leu
Ser Asp Gly Leu Asn Ser Leu Thr Tyr Gln Val Leu Asp Val 355 360 365
cag aga tac cca ttg tat acc caa atc aca gtg gac atc ggg aca ccg
1152 Gln Arg Tyr Pro Leu Tyr Thr Gln Ile Thr Val Asp Ile Gly Thr
Pro 370 375 380 agc tag 1158 Ser 385 6 385 PRT Homo sapiens 6 Met
Pro Gly Ala Ser Leu Gln Arg Ala Cys Arg Leu Leu Val Ala Val 1 5 10
15 Cys Ala Leu His Leu Gly Val Thr Leu Val Tyr Tyr Leu Ala Gly Arg
20 25 30 Asp Leu Ser Arg Leu Pro Gln Leu Val Gly Val Ser Thr Pro
Leu Gln 35 40 45 Gly Gly Ser Asn Ser Ala Ala Ala Ile Gly Gln Ser
Ser Gly Glu Leu 50 55 60 Arg Thr Gly Gly Ala Arg Pro Pro Pro Pro
Leu Gly Ala Ser Ser Gln 65 70 75 80 Pro Arg Pro Gly Gly Asp Ser Ser
Pro Val Val Asp Ser Gly Pro Gly 85 90 95 Pro Ala Ser Asn Leu Thr
Ser Val Pro Val Pro His Thr Thr Ala Leu 100 105 110 Ser Leu Pro Ala
Cys Pro Glu Glu Ser Pro Leu Leu Val Gly Pro Met 115 120 125 Leu Ile
Glu Phe Asn Met Pro Val Asp Leu Glu Leu Val Ala Lys Gln 130 135 140
Asn Pro Asn Val Lys Met Gly Gly Arg Tyr Ala Pro Arg Asp Cys Val 145
150 155 160 Ser Pro His Lys Val Ala Ile Ile Ile Pro Phe Arg Asn Arg
Gln Glu 165 170 175 His Leu Lys Tyr Trp Leu Tyr Tyr Leu His Pro Val
Leu Gln Arg Gln 180 185 190 Gln Leu Asp Tyr Gly Ile Tyr Val Ile Asn
Gln Ala Gly Asp Thr Ile 195 200 205 Phe Asn Arg Ala Lys Leu Leu Asn
Val Gly Phe Gln Glu Ala Leu Lys 210 215 220 Asp Tyr Asp Tyr Thr Cys
Phe Val Phe Ser Asp Val Asp Leu Ile Pro 225 230 235 240 Met Asn Asp
His Asn Ala Tyr Arg Cys Phe Ser Gln Pro Arg His Ile 245 250 255 Ser
Val Ala Met Asp Lys Phe Gly Phe Ser Leu Pro Tyr Val Gln Tyr 260 265
270 Phe Gly Gly Val Ser Ala Leu Ser Lys Gln Gln Phe Leu Thr Ile Asn
275 280 285 Gly Phe Pro Asn Asn Tyr Trp Gly Trp Gly Gly Glu Asp Asp
Asp Ile 290 295 300 Phe Asn Arg Leu Val Phe Arg Gly Met Ser Ile Ser
Arg Pro Asn Ala 305 310 315 320 Val Val Gly Arg Cys Arg Met Ile Arg
His Ser Arg Asp Lys Lys Asn 325 330 335 Glu Pro Asn Pro Gln Arg Phe
Asp Arg Ile Ala His Thr Lys Glu Thr 340 345 350 Met Leu Ser Asp Gly
Leu Asn Ser Leu Thr Tyr Gln Val Leu Asp Val 355 360 365 Gln Arg Tyr
Pro Leu Tyr Thr Gln Ile Thr Val Asp Ile Gly Thr Pro 370 375 380 Ser
385
* * * * *