Isolation of a mutant Arabidopsis plant that lacks N-aetyl glucosaminyl transferase I and is unable to synthesize Golgi-modified complex N-linked glycans
- Univ. of California, San Diego, La Jolla, CA (United States)
- Friedrich Miescher Institute, Basel (Switzerland)
The complex asparagine-linked glycans of plant glycoproteins, characterized by the presence of [beta]1[yields]2 xylose and [alpha]1[yields]3 fucose residues, are derived from typical mannose[sub 9](N-acetylglucosamine)[sub 2] (Man[sub 9]GlcNAc[sub 2]) N-linked glycans through the activity of a series of glycosidases and glycosyl transferases in the Golgi apparatus. By screening leaf extracts with an antiserum against complex glycans, we isolated a mutant of Arbidopsis thaliana that is blocked in the conversion of high-manne to complex glycans. In callus tissues derived from the mutant plants, all glycans bind to concanavalin A. These glycans can be released by treatment with endoglycosidase H, and the majority has the same size as Man[sub 5]GlcNAc[sub 1] glycans. In the presence of deoxymannojirimycin, an inhibitor of mannosidase I, the mutant cells synthesize Man[sub 9]GlcNAc[sub 2] and Man[sub 8]GlcNAc[sub 2] glycans, suggesting that the biochemical lesion in the mutant is not in the biosynthesis of high-mannose glycans in the endoplasmic reticulum but in their modification in the Golgi. Direct enzyme assays of cell extracts show that the mutant cells lack N-acetyl glucosaminyl transferase I, the first enzyme in the pathway of complex glycan biosynthesis. The mutant plants are able to complete their development normally under several environmental conditions, suggesting that complex glycans are not essential for normal developmental processes. By crossing the complex-glycan-deficient strain of A. thaliana with a transgenic strain that expresses the glycoprotein phytohemagglutinin, a unique strain was obtained that synthesizes phytohemagglutinin with two high-mannose glycans, instead of one high-mannose and one complex glycan. 42 refs., 8 figs., 1 tab.
- OSTI ID:
- 5815233
- Journal Information:
- Plant Physiology; (United States), Journal Name: Plant Physiology; (United States) Vol. 102:4; ISSN PLPHAY; ISSN 0032-0889
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
59 BASIC BIOLOGICAL SCIENCES
AGGLUTININS
ALDEHYDES
AMIDES
AMINO ACIDS
ANTIBODIES
ARABIDOPSIS
ASPARAGINE
BIOCHEMISTRY
BIOSYNTHESIS
CARBOHYDRATES
CARBOXYLIC ACIDS
CELL CONSTITUENTS
CHEMISTRY
CONCANAVALIN A
ENDOPLASMIC RETICULUM
ENZYMES
GLYCOPROTEINS
GLYCOSYL TRANSFERASES
GROWTH
HEMAGGLUTININS
HEXOSES
LECTINS
MAGNOLIOPHYTA
MAGNOLIOPSIDA
MANNOSE
MITOGENS
MONOSACCHARIDES
MUCOPROTEINS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PENTOSES
PHYTOHEMAGGLUTININ
PLANT GROWTH
PLANTS
POLYSACCHARIDES
PROTEINS
SACCHARIDES
SYNTHESIS
TRANSFERASES
XYLOSE