Complex regulatory role(s) of Atf1 and Pcr1 under nitrosative stress in Schizosaccharomyces pombe

Abstract

Abstract Excess nitric oxide (NO) and reactive nitrogen species produce nitrosative stress in cells. Schizosaccharomyces pombe cells showed intra S-phase check point activation under nitrosative stress. In this study we investigated the role of bZIP transcription factors Atf1 and Pcr1 under nitrosative stress in S. pombe. Δatf1 and Δpcr1 strain of S. pombe showed differential growth sensitivity towards NO donor. Δatf1 strain of S. pombe showed growth acceleration whereas Δpcr1 showed growth retardation in response to NO donor. Mitotic index and flow cytometry data also showed faster mitotic entry and absence of intra S-phase checkpoint activation in Δatf1 strain of S. pombe compared to Δpcr1 strains in response to NO donor. Interestingly, phospho mutant of Atf1 also showed similar effects like the wild type indicating phosphorylation of Atf1 was not essential for inducing nitrosative stress response in S. pombe. Our previous experimental evidences established the fact that Wee1 phosphorylates Cdc2 Tyr15 which leads to replication slowdown in the fission yeast under nitrosative stress. Cdc13 is a B-type cyclin and it forms a complex with Cdc2, and this complex formation is essential for activating Cdc2. To check whether Pcr1 and Cdc13 are involved or not in Δatf1 strain of S. pombe for activating Cdc2 under nitrosative stress, we checked the transcripts of both. Both Pcr1 and Cdc13 expression were significantly increased in S. pombe upon nitrosative stress in the absence of Atf1. From our study it is evident that Atf1 and Pcr1 play complex regulatory role in S. pombe under nitrosative stress.