title: Profilin is required for Ca2+ homeostasis and Ca2+-modulated bud formation in yeast.
abstract: A cls5-1 mutant of Saccharomyces cerevisiae is specifically sensitive to high concentrations of Ca2+, with elevated intracellular calcium content and altered cell morphology in the presence of 100 mM Ca2+. To reveal the mechanisms of the Ca2+-sensitive phenotype, we investigated the gene responsible and its interacting network. We demonstrated that CLS5 is identical to PFY1, encoding profilin. Involvement of profilin in the maintenance of intracellular Ca2+ homeostasis was supported by the fact that both exchangeable and non-exchangeable intracellular Ca2+ pools in the cls5-1 mutant are higher than those of the wild-type strain. Several mutations of the genes whose proteins physically interact with profilin resulted in the Ca2+-sensitive phenotype. Examination of the intracellular Ca2+ pools indicated that Bni1p, Bem1p, Rho1p, and Cla4p are also required for the maintenance of Ca2+ homeostasis. Quantitative morphological analysis revealed that the Ca2+-induced morphological changes in cls5-1 cells are similar to bem1 and cls4-1 cells. Common Ca2+-induced morphological changes were an increase in cell size and a decrease of the ratio of budded cells in the population. Since a mutation allele of cls4-1 is located in the CDC24 gene, we suggest that profilin, Bem1p, and Cdc24p are required for Ca2+-modulated bud formation. Thus, profilin is involved in Ca2+ regulation in two ways: the first is Ca2+ homeostasis by coordination with Bni1p, Bem1p, Rho1p, and Cla4p, and the second is the requirement of Ca2+ for bud formation by coordination with Bem1p and Cdc24p.
authors.affiliation: Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, Building FBS-101, 5-1-5 Kashiwanoha, Kashiwa, Chiba, 277-8561, Japan.
authors.forename: Mitsunori
authors.initials: M
authors.lastname: Yoshida
authors.forename: Shinsuke
authors.initials: S
authors.lastname: Ohnuki
authors.forename: Yoko
authors.initials: Y
authors.lastname: Yashiroda
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Ohya
mesh_terms: D002118:Calcium / Q000378:metabolism*; D016000:Cluster Analysis; D006706:Homeostasis; D008954:Models, Biological; D009154:Mutation; D051304:Profilins / Q000235:genetics*; D011485:Protein Binding; D060066:Protein Interaction Maps; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D051304:Profilins; D029701:Saccharomyces cerevisiae Proteins; D002118:Calcium