Down-regulation of the expression of PKC1 and SRB1/PSA1/VIG9, two genes involved in cell wall integrity in Saccharomyces cerevisiae, causes flocculation

• Published in: Microbiology (Society for General Microbiology) 1999-02, Vol.145 (2), p.309-316
• Main Authors: Zhang, Nianshu, Gardner, David C. J, Oliver, Stephen G, Stateva, Lubomira I
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Cell Wall - genetics; Cell Wall - metabolism; Down-Regulation; Enzyme Repression; Flocculation; Fundamental and applied biological sciences. Psychology; Fungal Proteins - genetics; Fungal Proteins - metabolism; Gene Expression Regulation, Fungal; Genes, Fungal; Growth, nutrition, metabolism, transports, enzymes. Molecular biology; Methionine - metabolism; Microbiology; Mycology; Promoter Regions, Genetic; Protein Kinase C; Saccharomyces cerevisiae; Saccharomyces cerevisiae - genetics; Saccharomyces cerevisiae - growth & development; Saccharomyces cerevisiae - physiology; Transcription, Genetic
• ISSN: 1350-0872; 1465-2080
• DOI: 10.1099/13500872-145-2-309

Department of Biomolecular Sciences, UMIST, PO Box 88, Manchester M60 1QD, UK Author for correspondence: Lubomira I. Stateva. Tel: [phone]. Fax: [phone]. e-mail: [e-mail] ABSTRACT Summary: The cell wall integrity determinants PKC1 and SRB1/PSA1/VIG9 of Saccharomyces cerevisiae were expressed under the control of the tightly regulated promoter p MET3. Substitution of the cell-cycle-regulated SRB1/PSA1 native promoter with p MET3 led to faster cell growth, larger cell volumes, and a twofold reduction of the steady-state SRB1/PSA1 mRNA level. In addition, the new pattern of expression of SRB1/PSA1 resulted in a dominant flocculation phenotype at all phases of batch growth. By contrast, expression of PKC1 from p MET3 increased the flocculation capacity of cells only at stationary phase. Methionine-mediated repression of either PSA1/SRB1 or PKC1 resulted in enhanced cell clumping. Cells in which both these genes had been replaced with their respective p MET3 -regulated cassettes were highly flocculent under both expression and repression conditions. These results suggest that greater exposure of flocculin on the cell surface, caused by either cell wall distortion (through depletion of Pkc1p) or aberrant regulation of mannosylation (through constitutive production of Srb1p), results in an increased flocculation ability. Keywords: MET3 promoter, SRB1/PSA1 , PKC1 , cell wall, yeast flocculation