Mutations of an alpha1,6 mannosyltransferase inhibit endoplasmic reticulum-associated degradation of defective brassinosteroid receptors in Arabidopsis.
Plant Cell
; 21(12): 3792-802, 2009 Dec.
Article
in En
| MEDLINE
| ID: mdl-20023196
ABSTRACT
Asn-linked glycans, or the glycan code, carry crucial information for protein folding, transport, sorting, and degradation. The biochemical pathway for generating such a code is highly conserved in eukaryotic organisms and consists of ordered assembly of a lipid-linked tetradeccasaccharide. Most of our current knowledge on glycan biosynthesis was obtained from studies of yeast asparagine-linked glycosylation (alg) mutants. By contrast, little is known about biosynthesis and biological functions of N-glycans in plants. Here, we show that loss-of-function mutations in the Arabidopsis thaliana homolog of the yeast ALG12 result in transfer of incompletely assembled glycans to polypeptides. This metabolic defect significantly compromises the endoplasmic reticulum-associated degradation of bri1-9 and bri1-5, two defective transmembrane receptors for brassinosteroids. Consequently, overaccumulated bri1-9 or bri1-5 proteins saturate the quality control systems that retain the two mutated receptors in the endoplasmic reticulum and can thus leak out of the folding compartment, resulting in phenotypic suppression of the two bri1 mutants. Our results strongly suggest that the complete assembly of the lipid-linked glycans is essential for successful quality control of defective glycoproteins in Arabidopsis.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Glycoproteins
/
Receptors, Steroid
/
Arabidopsis
/
Arabidopsis Proteins
/
Endoplasmic Reticulum
/
Mannosyltransferases
Type of study:
Risk_factors_studies
Language:
En
Journal:
Plant Cell
Journal subject:
BOTANICA
Year:
2009
Document type:
Article
Affiliation country: