Mutants in DEFECTIVE GLYCOSYLATION, an Arabidopsis homolog of an oligosaccharyltransferase complex subunit, show protein underglycosylation and defects in cell differentiation and growth.
A mutant called defective glycosylation1-1 (dgl1-1) was identified in Arabidopsis based on a growth defect of the dark-grown hypocotyl and an abnormal composition of the non-cellulosic cell wall polysaccharides. dgl1-1 is altered in a protein ortholog of human OST48 or yeast WBP1, an essential protein subunit of the oligosaccharyltransferase (OST) complex, which is responsible for the transfer in the ER of the N-linked glycan precursor onto Asn residues of candidate proteins. Consistent with the known function of the OST complex in eukaryotes, the dgl1-1 mutation led to a reduced N-linked glycosylation of the ER-resident protein disulfide isomerase. A second more severe mutant (dgl1-2) was embryo-lethal. Microscopic analysis of dgl1-1 revealed developmental defects including reduced cell elongation and the collapse and differentiation defects of cells in the central cylinder. These defects were accompanied by changes in the non-cellulosic polysaccharide composition, including the accumulation of ectopic callose. Interestingly, in contrast to other dwarf mutants that are altered in early steps of the N-glycan processing, dgl1-1 did not exhibit a cellulose deficiency. Together, these results confirm the role of DGL1 in N-linked glycosylation, cell growth and differentiation in plants.
Lerouxel
Olivier
O
Unité Mixte de Recherche 6037 Centre National de la Recherche Scientifique, IFRMP 23, Faculté des Sciences, Université de Rouen, 76821 Mont Saint Aignan Cedex, France.
Mouille
Grégory
G
Andème-Onzighi
Christine
C
Bruyant
Marie-Pierre
MP
Séveno
Martial
M
Loutelier-Bourhis
Corinne
C
Driouich
Azeddine
A
Höfte
Herman
H
Lerouge
Patrice
P
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000166:cytology / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002454:Cell Differentiation / Q000235:genetics / Q000502:physiology*; D002473:Cell Wall; D015870:Gene Expression; D006031:Glycosylation; D006602:Hexosyltransferases / Q000235:genetics / Q000378:metabolism*; D018546:Hypocotyl / Q000648:ultrastructure; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D010641:Phenotype; D018517:Plant Roots / Q000648:ultrastructure; D030821:Plants, Genetically Modified; D017386:Sequence Homology, Amino Acid
D029681:Arabidopsis Proteins; C502738:DGL1 protein, Arabidopsis; D008565:Membrane Proteins; D006602:Hexosyltransferases; C025620:dolichyl-diphosphooligosaccharide - protein glycotransferase