Dissection of upstream regulatory components of the Rho1p effector, 1,3-beta-glucan synthase, in Saccharomyces cerevisiae.
In the budding yeast Saccharomyces cerevisiae, one of the main structural components of the cell wall is 1,3-beta-glucan produced by 1,3-beta-glucan synthase (GS). Yeast GS is composed of a putative catalytic subunit encoded by FKS1 and FKS2 and a regulatory subunit encoded by RHO1. A combination of amino acid alterations in the putative catalytic domain of Fks1p was found to result in a loss of the catalytic activity. To identify upstream regulators of 1,3-beta-glucan synthesis, we isolated multicopy suppressors of the GS mutation. We demonstrate that all of the multicopy suppressors obtained (WSC1, WSC3, MTL1, ROM2, LRE1, ZDS1, and MSB1) and the constitutively active RHO1 mutations tested restore 1,3-beta-glucan synthesis in the GS mutant. A deletion of either ROM2 or WSC1 leads to a significant defect of 1,3-beta-glucan synthesis. Analyses of the degree of Mpk1p phosphorylation revealed that among the multicopy suppressors, WSC1, ROM2, LRE1, MSB1, and MTL1 act positively on the Pkc1p-MAPK pathway, another signaling pathway regulated by Rho1p, while WSC3 and ZDS1 do not. We have also found that MID2 acts positively on Pkc1p without affecting 1,3-beta-glucan synthesis. These results suggest that distinct networks regulate the two effector proteins of Rho1p, Fks1p and Pkc1p.
Sekiya-Kawasaki
Mariko
M
Department of Integrated Biosciences, Graduate School of Frontier Science, University of Tokyo, Kashiwanoha, Kashiwa, Chiba 277-8562, Japan.
Abe
Mitsuhiro
M
Saka
Ayaka
A
Watanabe
Daisuke
D
Kono
Keiko
K
Minemura-Asakawa
Masayo
M
Ishihara
Satoru
S
Watanabe
Takahide
T
Ohya
Yoshikazu
Y
D002135:Calcium-Binding Proteins / Q000378:metabolism; D054714:Echinocandins; D015966:Gene Expression Regulation, Fungal; D005936:Glucans / Q000096:biosynthesis; D005964:Glucosyltransferases / Q000378:metabolism*; D047908:Intracellular Signaling Peptides and Proteins; D008562:Membrane Glycoproteins; D008565:Membrane Proteins / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D008954:Models, Biological; D011493:Protein Kinase C / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism; D029702:Schizosaccharomyces pombe Proteins; D013696:Temperature; D047071:beta-Glucans; D020741:rho GTP-Binding Proteins / Q000235:genetics*
D002135:Calcium-Binding Proteins; D054714:Echinocandins; D005936:Glucans; D047908:Intracellular Signaling Peptides and Proteins; C091625:MID2 protein, S cerevisiae; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D029701:Saccharomyces cerevisiae Proteins; D029702:Schizosaccharomyces pombe Proteins; D047071:beta-Glucans; C033363:beta-1,3-glucan; D005964:Glucosyltransferases; C020570:1,3-beta-glucan synthase; C091618:FKS1 protein, S cerevisiae; D011493:Protein Kinase C; D020928:Mitogen-Activated Protein Kinases; C051302:RHO1 protein, S cerevisiae; D020741:rho GTP-Binding Proteins; C511156:rho1 protein, S pombe