acid-phosphatase and galactomannan

The oligosaccharide of glycoproteins in the fission yeast Schizosaccharomyces pombe is unique in containing galactose. We isolated four mutants that had reduced amounts of galactose residues on their cell surface glycoproteins by fluorescence-activated cell sorter. The isolated four recessive mutants, gmd1 to gmd4, showed a defect in glycosylation of acid phosphatase, a cell surface glycoprotein. In gmd3 mutant cells, the amounts of both mannose and galactose residues were decreased on the cell surface galactomannoproteins, suggesting an underglycosylation of galactomannoproteins. The gmd3(+) gene encodes a protein that has significant similarity with Saccharomyces cerevisiae Alg11p and is likely to be involved in N-linked core oligosaccharide synthesis. ALG11 suppressed the gmd3 mutation, indicating that gmd3(+) gene is a functional homologue of the ALG11 gene. We therefore designated gmd3(+) as alg11(+).

Topics: Acid Phosphatase; Amino Acid Sequence; Carbohydrate Conformation; Cell Membrane; Cloning, Molecular; Fungal Proteins; Galactose; Genes, Fungal; Genetic Complementation Test; Glycosylation; Mannans; Molecular Sequence Data; Mutation; Oligosaccharides; Phenotype; Saccharomyces cerevisiae; Schizosaccharomyces; Schizosaccharomyces pombe Proteins; Sequence Alignment

In a search for Schizosaccharomyces pombe mutants resistant to the antifungal agent papulacandin B, a morphological mutant was isolated. The mutant is round shaped in contrast to the rod shaped parental strain. This morphological defect segregated as a recessive Mendelian character and was not observed in other papulacandin B resistant mutants belonging to the same complementation group. The mutation mapped in the right arm of S. pombe chromosome III very close to pap1 marker. Mutant cell walls were more susceptible to alkali extraction and Novozyme degradation than those from the wild-type. A specific reduction in the cell wall galactomannan fraction was the only significant difference detected as compared to the wild-type strain. Levels of beta (1,3)-glucan and mannan synthases as well as other enzymic periplasmic mannoproteins were very similar in wild type and mutant strains.

Topics: Acid Phosphatase; Aminoglycosides; Anti-Bacterial Agents; beta-Fructofuranosidase; Cell Fractionation; Cell Wall; Drug Resistance, Microbial; Enzymes; Ethyl Methanesulfonate; Galactose; Glucans; Glucosyltransferases; Glycoside Hydrolases; Hexoses; Mannans; Mannosyltransferases; Membrane Proteins; Mutation; Pancreatitis-Associated Proteins; Schizosaccharomyces; Schizosaccharomyces pombe Proteins