Basic and Applied Research on tie Roles of Ca^<2+>-Signal-mediated Cell-Cycle Regulation in Budding Yeast.

点击翻译按钮获取中文摘要

Analyses of cell-cycle regulation and investigation of its physiological role For understanding detailed mechanism for the Ca^<2+>-signal mediated cell-cycle regulation in yeast, we isolated mutants (designated scz) defective in this process and performed molecular genetic analyses of the mutants.(1) By the analysis of scz6 mutation, we found that the phenotype is caused by a mutation of PKC1 gene. We further demonstrated that C-kinase and A-kinase antagonistically regulates Cln2, and thereby regulate cell growth and polarized bud growth, suggesting a crosstalk between A-kinase and C-kinase pathways.(2) By the analysis of sczl3 mutation, we found a mutation of Alg9 which is involved in the protein N-glycosylation in the ER lumen is responsible for suppression of the Ca^<2+> phenotype. We found that N-glycosylation of proteins is important for the maintenance of Swel and Cln2 levels.We also developed a procedure to detect bioactive compounds which inhibit Ca^<2+>-signal mediated cell-cycle regulation and screened for active substances from various sources. We investigated action mechanisms of two small-molecule compounds found by the screening.(1) Radicicol, inhibitor of Hsp90, inhibits Ca^<2+>-signal mediated cell-cycle regulation by destabilizing Swel, inhibitory Idnase of Cdc28/Clb.(2) By molecular genetic analysis of the mutants resistant to NKH-7, we identified Tubl α-tubulin as target of this compound. Based on its physiological effect and mutation site of Tub I, we suggested that NKH-7 destabilizes microtubules by binding to Tubl α-tubulin.