Arabidopsis glucosidase I mutants reveal a critical role of N-glycan trimming in seed development.
Glycoproteins with asparagine-linked (N-linked) glycans occur in all eukaryotic cells. The function of their glycan moieties is one of the central problems in contemporary cell biology. N-glycosylation may modify physicochemical and biological protein properties such as conformation, degradation, intracellular sorting or secretion. We have isolated and characterized two allelic Arabidopsis mutants, gcs1-1 and gcs1-2, which produce abnormal shrunken seeds, blocked at the heart stage of development. The mutant seeds accumulate a low level of storage proteins, have no typical protein bodies, display abnormal cell enlargement and show occasional cell wall disruptions. The mutated gene has been cloned by T-DNA tagging. It codes for a protein homologous to animal and yeast alpha-glucosidase I, an enzyme that controls the first committed step for N-glycan trimming. Biochemical analyses have confirmed that trimming of the alpha1,2- linked glucosyl residue constitutive of the N-glycan precursor is blocked in this mutant. These results demonstrate the importance of N-glycan trimming for the accumulation of seed storage proteins, the formation of protein bodies, cell differentiation and embryo development.
Boisson
M
M
Laboratoire de Biologie des Semences, INRA-INAPG, Route de St-Cyr, 78026 Versailles, France.
Gomord
V
V
Audran
C
C
Berger
N
N
Dubreucq
B
B
Granier
F
F
Lerouge
P
P
Faye
L
L
Caboche
M
M
Lepiniec
L
L
D000483:Alleles; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000196:embryology / Q000201:enzymology* / Q000235:genetics / Q000648:ultrastructure; D002454:Cell Differentiation; D003001:Cloning, Molecular; D004269:DNA, Bacterial / Q000235:genetics; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D020043:Genes, Essential / Q000235:genetics; D005816:Genetic Complementation Test; D006031:Glycosylation; D006651:Histocytochemistry; D015151:Immunoblotting; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics*; D010641:Phenotype; D011134:Polysaccharides / Q000737:chemistry / Q000378:metabolism*; D012333:RNA, Messenger / Q000032:analysis / Q000235:genetics; D012639:Seeds / Q000196:embryology / Q000201:enzymology* / Q000235:genetics / Q000648:ultrastructure; D017386:Sequence Homology, Amino Acid; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D000520:alpha-Glucosidases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*
D004269:DNA, Bacterial; D011134:Polysaccharides; D012333:RNA, Messenger; C036483:T-DNA; C042059:glucosidase I; D000520:alpha-Glucosidases