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Processing glycosidases of Saccharomyces cerevisiae
1McGill Cancer Centre, McGill University, 3655 Drummond Street, Montreal, Que. H3G 1Y6, Canada. annette@med.mcgill.ca
Biochimica Et Biophysica Acta
|January 8, 1999
Summary
This study details yeast endoplasmic reticulum glycosidases involved in N-glycan processing. These enzymes, including alpha-glucosidases and alpha-mannosidase, play roles in cell wall formation and quality control.
Area of Science:
- Biochemistry
- Molecular Biology
- Yeast Genetics
Background:
- Endoplasmic reticulum (ER) glycosidases are crucial for N-glycan processing in Saccharomyces cerevisiae.
- Specific enzymes like alpha-glucosidase I (CWH41), alpha-glucosidase II (ROT2), and alpha1,2-mannosidase (MNS1) modify the Glc3Man9GlcNAc2 precursor.
Purpose of the Study:
- To describe the properties of N-glycan processing glycosidases in yeast ER.
- To investigate the roles of these enzymes in cell wall beta1,6-glucan formation and ER quality control.
- To present structure-function studies of yeast alpha1,2-mannosidase as a conserved eukaryotic model.
Main Methods:
- Enzyme characterization of N-glycan processing glycosidases.
- Analysis of mutant yeast strains lacking specific glycosidases.
- Structure-function studies of recombinant yeast alpha1,2-mannosidase.
Main Results:
- Alpha-glucosidase I and II trim glucose residues from the N-glycan precursor.
- Alpha1,2-mannosidase generates a specific Man8GlcNAc2 isomer.
- Mutant studies reveal indirect roles in cell wall beta1,6-glucan synthesis and ER quality control.
Conclusions:
- Yeast ER glycosidases are essential for proper N-glycan processing.
- These enzymes have significant implications for cell wall integrity and protein folding quality control.
- Yeast alpha1,2-mannosidase serves as a valuable model for conserved eukaryotic enzymes.