title: Characterization of multicopy suppressor genes that complement a defect in the Wis1-Sty1 MAP kinase cascade involved in stress responses in Schizosaccharomyces pombe.
abstract: The Wis1-Sty1 mitogen-activated protein (MAP) kinase cascade is one of the major signaling systems involved in a wide range of stress responses in Schizosaccharomyces pombe. It is known that Deltawis1 and Deltasty1 mutants exhibit highly pleiotropic phenotypes, including a phenotype of temperature sensitivity for growth. In this study, we screened multicopy suppressor genes that allow both the Deltawis1 and Deltasty1 mutants to grow simultaneously at a non-permissive temperature, 37 degrees C. Two such multicopy suppressors were cloned and characterized as sds23(+) and hxk2(+) genes. The former is known to specify a protein that functions as a multicopy suppressor for mutations of the PP1 protein phosphatase and the 20S cyclosome/anaphase-promoting complex (APC), and the latter encodes hexokinase 2. It was revealed that the multicopy sds231 gene restored a defect in the mating efficiency caused by the Deltawis1 and Deltasty1 mutations, whereas the multicopy hxk2(+) gene suppressed a phenotype of heat-shock sensitivity for growth of these mutant cells. These findings are discussed with special reference to the Wis1-Sty1 MAP kinase signaling pathway in S. pombe.
authors.affiliation: Laboratory of Molecular Microbiology, School of Agriculture, Nagoya University, Chikusa-ku, Nagoya 464, Japan.
authors.forename: Hisami
authors.initials: H
authors.lastname: Yamada
authors.forename: Ryusuke
authors.initials: R
authors.lastname: Ohmiya
authors.forename: Eiji
authors.initials: E
authors.lastname: Yamamoto
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Aiba
authors.forename: Takeshi
authors.initials: T
authors.lastname: Mizuno