Independent regulation of chitin synthase and chitinase activity in Candida albicans and Saccharomyces cerevisiae.
Chitin is an essential structural polysaccharide in fungi that is required for cell shape and morphogenesis. One model for wall synthesis at the growing cell surface suggests that the compliance that is necessary for turgor-driven expansion of the cell wall involves a delicate balance of wall synthesis and lysis. Accordingly, de novo chitin synthesis may involve coordinated regulation of members of the CHS chitin synthase and CHT chitinase gene families. To test this hypothesis, the chitin synthase and chitinase activities of cell-free extracts were measured, as well as the chitin content of cell walls isolated from isogenic mutant strains that contained single or multiple knock-outs in members of these two gene families, in both Candida albicans and Saccharomyces cerevisiae. However, deletion of chitinase genes did not markedly affect specific chitin synthase activity, and deletion of single CHS genes had little effect on in vitro specific chitinase activity in either fungus. Chitin synthesis and chitinase production was, however, regulated in C. albicans during yeast-hypha morphogenesis. In C. albicans, the total specific activities of both chitin synthase and chitinase were higher in the hyphal form, which was attributable mainly to the activities of Chs2 and Cht3, respectively. It appeared, therefore, that chitin synthesis and hydrolysis were not coupled, but that both were regulated during yeast-hypha morphogenesis in C. albicans.
Selvaggini
Serena
S
School of Medical Sciences, University of Aberdeen, Institute of Medical Sciences, Foresterhill, Aberdeen AB25 2ZD, UK.
Munro
Carol A
CA
School of Medical Sciences, University of Aberdeen, Institute of Medical Sciences, Foresterhill, Aberdeen AB25 2ZD, UK.
Paschoud
Serge
S
University Hospital Lausanne (CHUV), Institute of Microbiology, CH-1011 Lausanne, Switzerland.
Sanglard
Dominique
D
University Hospital Lausanne (CHUV), Institute of Microbiology, CH-1011 Lausanne, Switzerland.
Gow
Neil A R
NAR
School of Medical Sciences, University of Aberdeen, Institute of Medical Sciences, Foresterhill, Aberdeen AB25 2ZD, UK.
D001557:Benzenesulfonates / Q000494:pharmacology; D002176:Candida albicans / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D002473:Cell Wall / Q000378:metabolism; D002686:Chitin / Q000378:metabolism; D002687:Chitin Synthase / Q000235:genetics / Q000378:metabolism*; D002688:Chitinases / Q000235:genetics / Q000378:metabolism*; D005456:Fluorescent Dyes / Q000494:pharmacology; D017353:Gene Deletion; D015966:Gene Expression Regulation, Fungal; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics
D001557:Benzenesulfonates; D005456:Fluorescent Dyes; D002686:Chitin; C007061:C.I. Fluorescent Brightening Agent 28; D002687:Chitin Synthase; D002688:Chitinases