Isolation and characterization of high-osmolarity-sensitive mutants of fission yeast

• Published in: Journal of Bacteriology Vol. 180; no. 19; pp. 5038 - 5043
• Main Authors: Aiba, H. (Nagoya University, Nagoya, Japan.), Kawaura, R, Yamamoto, E, Yamada, H, Takegawa, K, Mizuno, T
• Format: Journal Article
• Language: English
• Published: United States American Society for Microbiology 01.10.1998
• Subjects: ACCOUPLEMENT; ARN MENSAJERO; ARN MESSAGER; Bacteriology; BINDING PROTEINS; BIOSINTESIS; BIOSYNTHESE; BIOSYNTHESIS; CHLORURE DE POTASSIUM; CLORURO POTASICO; COPULA; COPULATION; Culture Media; Eukaryotic Cells; EXPRESION GENICA; EXPRESSION DES GENES; FENOTIPOS; GENE; GENE EXPRESSION; GENES; Genetic Complementation Test; Genetics; GLICEROL; GLYCEROL; Glycerol - analysis; GLYCEROL-3-PHOSPHATE DEHYDROGENASE; GTP-Binding Proteins - genetics; GUANOSINE TRIPHOSPHATE; MATING; MESSENGER RNA; Monomeric GTP-Binding Proteins; MUTANT; MUTANTES; MUTANTS; Mutation; NUCLEOTIDE; NUCLEOTIDES; NUCLEOTIDOS; OSMOLALIDAD; OSMOLALITE; OSMOLALITY; Osmolar Concentration; Osmotic Pressure; OXIDOREDUCTASES; OXIDORREDUCTASAS; OXYDOREDUCTASE; PHENOTYPE; PHENOTYPES; Phylogeny; POTASSIUM CHLORIDE; PROTEINAS AGLUTINANTES; PROTEINE DE LIAISON; Proteins; RNA, Fungal - biosynthesis; RNA, Messenger - biosynthesis; RYH1+ GENE; Schizosaccharomyces - genetics; Schizosaccharomyces - growth & development; SCHIZOSACCHAROMYCES POMBE; SORBITOL; SUSCEPTIBILITY; Temperature; Yeast
• ISSN: 0021-9193; 1098-5530; 1067-8832
• DOI: 10.1128/jb.180.19.5038-5043.1998

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 characterizd a set of high-osmolarity-sensitive S. pombe mutants, including wis1, sty1, and gpd1. 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 the ryh1+ gene results not only in osmosensitivity but also in temperature sensitivity for growth. It was also found that the delta ryh1 mutant is severely sterile. These results are discussed with special reference to the osmoadaptation of S. pombe