A Cds1-mediated checkpoint protects the MBF activator Rep2 from ubiquitination by anaphase-promoting complex/cyclosome-Ste9 at S-phase arrest in fission yeast.

ABSTRACT: Transcription of the MluI cell cycle box (MCB) motif-containing genes at G(1) phase is regulated by the MCB-binding factors (MBF) (also called DSC1) in Schizosaccharomyces pombe. Upon S-phase arrest, the MBF transcriptional activity is induced through the accumulation of the MBF activator Rep2. In this study, we show that the turnover of Rep2 is attributable to ubiquitin-mediated proteolysis. Levels of Rep2 oscillate during the cell cycle, with a peak at G(1) phase, coincident with the MBF activity. Furthermore, we show that Rep2 ubiquitination requires the function of the E3 ligase anaphase-promoting complex/cyclosome (APC/C). Ste9 can be phosphorylated by the checkpoint kinase Cds1 in vitro, and its inhibition/phosphorylation at S-phase arrest is dependent on the function of Cds1. Our da

SUBMITTER: Chu Z 

PROVIDER: S-EPMC2738293 | biostudies-literature | 2009 Sep

REPOSITORIES: biostudies-literature