title: Arabidopsis thaliana alpha1,2-glucosyltransferase (ALG10) is required for efficient N-glycosylation and leaf growth.
abstract: Assembly of the dolichol-linked oligosaccharide precursor (Glc(3) Man(9) GlcNAc(2) ) is highly conserved among eukaryotes. In contrast to yeast and mammals, little is known about the biosynthesis of dolichol-linked oligosaccharides and the transfer to asparagine residues of nascent polypeptides in plants. To understand the biological function of these processes in plants we characterized the Arabidopsis thaliana homolog of yeast ALG10, the α1,2-glucosyltransferase that transfers the terminal glucose residue to the lipid-linked precursor. Expression of an Arabidopsis ALG10-GFP fusion protein in Nicotiana benthamiana leaf epidermal cells revealed a reticular distribution pattern resembling endoplasmic reticulum (ER) localization. Analysis of lipid-linked oligosaccharides showed that Arabidopsis ALG10 can complement the yeast Δalg10 mutant strain. A homozygous Arabidopsis T-DNA insertion mutant (alg10-1) accumulated mainly lipid-linked Glc(2) Man(9) GlcNAc(2)  and displayed a severe protein underglycosylation defect. Phenotypic analysis of alg10-1 showed that mutant plants have altered leaf size when grown in soil. Moreover, the inactivation of ALG10 in Arabidopsis resulted in the activation of the unfolded protein response, increased salt sensitivity and suppression of the phenotype of α-glucosidase I-deficient plants. In summary, these data show that Arabidopsis ALG10 is an ER-resident α1,2-glucosyltransferase that is required for lipid-linked oligosaccharide biosynthesis and subsequently for normal leaf development and abiotic stress response.
authors.affiliation: Department of Applied Genetics and Cell Biology, BOKU-University of Natural Resources and Life Sciences, Muthgasse 18, A-1190 Vienna, Austria.
authors.forename: Akhlaq
authors.initials: A
authors.lastname: Farid
authors.forename: Martin
authors.initials: M
authors.lastname: Pabst
authors.forename: Jennifer
authors.initials: J
authors.lastname: Schoberer
authors.forename: Friedrich
authors.initials: F
authors.lastname: Altmann
authors.forename: Josef
authors.initials: J
authors.lastname: Glössl
authors.forename: Richard
authors.initials: R
authors.lastname: Strasser
mesh_terms: D017360:Arabidopsis / Q000196:embryology / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002240:Carbohydrate Sequence; D004721:Endoplasmic Reticulum / Q000201:enzymology / Q000378:metabolism; D005816:Genetic Complementation Test; D005964:Glucosyltransferases / Q000235:genetics / Q000378:metabolism; D006031:Glycosylation; D049452:Green Fluorescent Proteins; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D009844:Oligosaccharides / Q000096:biosynthesis* / Q000737:chemistry; D010641:Phenotype; D018515:Plant Leaves / Q000201:enzymology / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D011105:Polyisoprenyl Phosphate Sugars / Q000096:biosynthesis* / Q000737:chemistry; D011134:Polysaccharides / Q000378:metabolism; D011499:Protein Processing, Post-Translational; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D055049:Salt Tolerance; D013312:Stress, Physiological; D014026:Nicotiana / Q000235:genetics / Q000378:metabolism; D056811:Unfolded Protein Response
chemical_list: D029681:Arabidopsis Proteins; C066723:Glc(3)Man(9)(GlcNAc)(2)-diphosphate-dolichol; D009844:Oligosaccharides; D011105:Polyisoprenyl Phosphate Sugars; D011134:Polysaccharides; D049452:Green Fluorescent Proteins; C586857:ALG10 protein, Arabidopsis; D005964:Glucosyltransferases