Calcium-sensitive cls Mutants of Saccharomyces cerevisiae Showing a Pet- Phenotype Are Ascribable to Defects of Vacuolar Membrane H'-ATPase Activity*

摘要: Ca(2+)-sensitive mutants of the yeast Saccharomyces cerevisiae showing a Pet- phenotype (cls7-cls11) have lesions in system for maintaining intracellular Ca2+ homeostasis (Ohya, Y., Ohsumi, and Anraku, Y. (1986) J. Gen. Microbiol. 132, 979-988). Genetic biochemical studies demonstrated that these cls are related to defects vacuolar membrane H(+)-ATPase. CLS7 CLS8 were found be identical with structural genes encoding subunit c (VMA3) (VMA1), respectively, enzyme. In addition, five all had vma defects; no ATPase activity was detected cells, showed loss ability acidify vacuole vivo. Measurements cytosolic free concentration [( Ca2+]i) individual cells average [Ca2+]i wild-type 150 +/- 80 nM, whereas 900 100 nM. These data consistent observation vesicles prepared from lost ATP-dependent uptake activities. The H(+)-ATPase resulted pleiotropic effects on several cellular activities, including homeostasis, glycerol metabolism, phospholipid metabolism. an inositol-dependent phenotype, possibly due alteration regulation biosynthesis; phosphatidylserine decarboxylase activities 15-50% not repressed by addition inositol. contrast majority previously isolated pet (Tzagoloff, A., Dieckmann, C. L. (1990) Rev. 54, 211-225), detectable mitochondrial defects. Taking findings into account, we suggest at least six genes, VMA1 (CLS8, a), VMA2 (subunit b), VMA3 (CLS7, c), VMA11 (CLS9), VMA12 (CLS10), VMA13 (CLS11), required expression activity.