Related Experiment Videos
The yeast CWH41 gene encodes glucosidase I
P A Romero1, G J Dijkgraaf, S Shahinian
1McGill Cancer Centre, McGill University, Montréal, Québec, Canada.
Glycobiology
|November 18, 1997
Summary
The yeast gene CWH41 encodes glucosidase I, an enzyme crucial for N-glycosylation processing in the endoplasmic reticulum. This enzyme removes glucose residues from newly synthesized glycoproteins, a vital step conserved across eukaryotes.
Area of Science:
- Biochemistry
- Molecular Biology
- Yeast Genetics
Background:
- N-glycosylation is a conserved eukaryotic process involving oligosaccharide precursor synthesis and transfer to proteins.
- Oligosaccharide processing begins with the removal of terminal glucose by glucosidase I in the endoplasmic reticulum.
- The yeast gene encoding glucosidase I remained unidentified despite enzyme isolation.
Purpose of the Study:
- To identify the yeast gene responsible for glucosidase I activity.
- To investigate the function of the yeast endoplasmic reticulum protein Cwh41p in N-glycosylation.
Main Methods:
- Sequence similarity analysis between Cwh41p and human glucosidase I.
- Tetrad analysis of glucosidase I activity in vitro and in vivo using cwh41 delta null mutants.
- High-performance liquid chromatography analysis of N-linked oligosaccharides after [3H]mannose labeling.
Main Results:
- Cwh41p exhibits significant amino acid similarity to human glucosidase I.
- cwh41 delta null mutants lack in vitro glucosidase I activity, failing to cleave glucose from a synthetic trisaccharide.
- In vivo, oligosaccharides from cwh41 delta null mutants remain fully glucosylated, unlike those from wild-type cells.
Conclusions:
- The yeast gene CWH41 encodes glucosidase I.
- Cwh41p is essential for the initial glucose trimming step in N-glycosylation processing in Saccharomyces cerevisiae.
- This finding identifies the specific gene responsible for a critical step in a conserved eukaryotic pathway.