Isolation and Characterization of High-Osmolarity-Sensitive Mutants of Fission Yeast
Isolation and Characterization of High-Osmolarity-Sensitive Mutants of Fission Yeast
复制标题
裂殖酵母高渗透压敏感突变体的分离和表征
作者：
H. Aiba;Ryosuke Kawaura;E. Yamamoto;Hisami Yamada;K. Takegawa;T. Mizuno
摘要 对于裂殖酵母粟酒裂殖酵母，对高渗透性培养基的适应是由丝裂原激活蛋白 (MAP) 激酶级联介导的，涉及 Wis1 MAP 激酶激酶和 Sty1 MAP 激酶。 MAP 激酶途径转导渗透信号并相应地调节编码 NADH 依赖性甘油 3-磷酸脱氢酶的下游靶基因 (gpd1+) 的表达，以便在细胞内适应性地积累甘油作为渗透保护剂。我们之前鉴定了一组高渗透压敏感的 S. pombe 突变体，包括 wis1、sty1 和 gpd1。在这项研究中，我们试图进一步分离新的渗透压敏感突变体。对于一些分离的突变体，响应生长培养基渗透压的甘油产生曲线与野生型细胞没有区别，表明它们是新类型。它们在基因上被分为三种不同的类型，因此被指定为hos1、hos2和hos3（高渗透压敏感）突变体。其中一个，hos1 突变体，得到了详细的表征。 hos1 突变体被证明在已知的 ryh1+ 基因中存在突变损伤，该基因编码一个小的 GTP 结合蛋白。 theryh1+ 基因的破坏不仅会导致渗透敏感性，还会导致生长的温度敏感性。还发现Δryh1突变体是严重不育的。这些结果的讨论特别涉及粟酒裂殖酵母的渗透适应。
ABSTRACT For the fission yeast Schizosaccharomyces pombe, adaptation to high-osmolarity medium is mediated by a mitogen-activated protein (MAP) kinase cascade, involving the Wis1 MAP kinase kinase and the Sty1 MAP kinase. The MAP kinase pathway transduces an osmotic signal and accordingly regulates the expression of the downstream target gene (gpd1+) that encodes NADH-dependent glycerol-3-phosphate dehydrogenase, in order to adaptively accumulate glycerol inside the cells as an osmoprotectant. We previously characterized a set of high-osmolarity-sensitive S. pombemutants, including wis1, sty1, andgpd1. In this study, we attempted to further isolate novel osmolarity-sensitive mutants. For some of the mutants isolated, profiles of glycerol production in response to the osmolarity of the growth medium were indistinguishable from that of the wild-type cells, suggesting that they are novel types. They were classified into three distinct types genetically and, thus, were designated hos1,hos2, and hos3 (high osmolarity sensitive) mutants. One of them, the hos1 mutant, was characterized in detail. The hos1 mutant was demonstrated to have a mutational lesion in the known ryh1+ gene, which encodes a small GTP-binding protein. Disruption of theryh1+ gene results not only in osmosensitivity but also in temperature sensitivity for growth. It was also found that the Δryh1 mutant is severely sterile. These results are discussed with special reference to the osmoadaptation of S. pombe.