title: Genes for a nuclease and a protease are involved in the drastic decrease in cellular RNA amount in fission yeast cells during nitrogen starvation.
abstract: Cellular RNA in Schizosaccharomyces pombe cells drastically decreases in amount during nitrogen starvation. Previously, we found and purified a soluble RNA-degrading enzyme whose activity drastically increased in the cells of S. pombe undergoing nitrogen starvation. The enzyme was a nuclease encoded by pnu1(+). In this study, the increase in the RNA-degrading activity and the decrease in cellular RNA level are examined in a null-mutant of pnu1(+) (pnu1Delta). During nitrogen starvation, wild-type cells show an apparent increase in RNA-degrading activity, whereas the pnu1Delta cells do not. The wild-type cells show a drastic decrease in cellular RNA amount, whereas the pnu1Delta cells show only a slight decrease. These results suggest that Pnu1 nuclease is implicated in the decrease in cellular RNA amount during nitrogen starvation, probably via the RNA-degrading activity. The increase in the RNA-degrading activity is independent of both the Wis1 stress-activated MAP kinase cascade and Tor1 signaling pathway, but it is strongly dependent on isp6(+), a gene for a possible protease, whose expression is induced during nitrogen starvation. A disruption mutant for isp6(+) (isp6Delta) is deficient in both the increase in the RNA-degrading activity and the drastic decrease in the cellular RNA amount during nitrogen starvation, which suggests that isp6(+) is involved in the RNA degradation via regulating the RNA-degrading activity of Pnu1.
authors.affiliation: Department of Chemistry, Faculty of Science, Shizuoka University, Oya, Shizuoka 422-8529, Japan.
authors.forename: Akio
authors.initials: A
authors.lastname: Nakashima
authors.forename: Mayumi
authors.initials: M
authors.lastname: Yoshida
authors.forename: Kazutoshi
authors.initials: K
authors.lastname: Nakayama
authors.forename: Aya
authors.initials: A
authors.lastname: Kato-Furuno
authors.forename: Masaru
authors.initials: M
authors.lastname: Ueno
authors.forename: Takashi
authors.initials: T
authors.lastname: Ushimaru
authors.forename: Masahiro
authors.initials: M
authors.lastname: Uritani
mesh_terms: D010450:Endopeptidases / Q000235:genetics / Q000378:metabolism*; D004789:Enzyme Activation; D009154:Mutation; D009584:Nitrogen / Q000172:deficiency* / Q000378:metabolism; D012331:RNA, Fungal / Q000378:metabolism*; D012260:Ribonucleases / Q000235:genetics / Q000378:metabolism*; D012568:Schizosaccharomyces / Q000166:cytology / Q000235:genetics / Q000378:metabolism*
chemical_list: D012331:RNA, Fungal; D012260:Ribonucleases; D010450:Endopeptidases; D009584:Nitrogen