Previously, we showed that chitin synthase 2 (Chs2) is required for septum formation in Saccharomyces cerevisiae, whereas chitin synthase 1 (Chs1) does not appear to be an essential enzyme. However, in strains carrying a disrupted CHS1 gene, frequent lysis of buds is observed. Lysis occurs after nuclear separation and appears to result from damage to the cell wall, as indicated by osmotic stabilization and by a approximately 50-nm orifice at the center of the birth scar. Lysis occurs at a low pH and is prevented by buffering the medium above pH 5. A likely candidate for the lytic system is a previously described chitinase that is probably involved in cell separation. The chitinase has a very acidic pH optimum and a location in the periplasmic space that exposes it to external pH. Accordingly, allosamidin, a specific chitinase inhibitor, substantially reduced the number of lysed cells. Because the presence of Chs1 in the cell abolishes lysis, it is concluded that damage to the cell wall is caused by excessive chitinase activity at acidic pH, which can normally be repaired through chitin synthesis by Chs1. The latter emerges as an auxiliary or emergency enzyme. Other experiments suggest that both Chs1 and Chs2 collaborate in the repair synthesis of chitin, whereas Chs1 cannot substitute for Chs2 in septum formation.
|Evidence ID||Analyze ID||Interactor||Interactor Systematic Name||Interactor||Interactor Systematic Name||Type||Assay||Annotation||Action||Modification||Phenotype||Source||Reference||Note|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Gene Ontology Term||Gene Ontology Term ID||Qualifier||Aspect||Method||Evidence||Source||Assigned On||Reference||Annotation Extension|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Phenotype||Experiment Type||Experiment Type Category||Mutant Information||Strain Background||Chemical||Details||Reference|
|Evidence ID||Analyze ID||Regulator||Regulator Systematic Name||Target||Target Systematic Name||Experiment||Conditions||Strain||Source||Reference|