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 data indicate that the Cds1-dependent stabilization of Rep2 is achieved through the inhibition/phosphorylation of APC/C-Ste9 at the onset of S-phase arrest. Stabilization of Rep2 is important for stimulating transcription of the MBF-dependent genes to ensure a sufficient supply of proteins essential for cell recovery from S-phase arrest. We propose that oscillation of Rep2 plays a role in regulation of periodic transcription of the MBF-dependent genes during cell cycle progression.
Publication types
-
Research Support, Non-U.S. Gov't
MeSH terms
-
Amino Acid Sequence
-
Anaphase-Promoting Complex-Cyclosome
-
Cell Cycle Proteins / metabolism*
-
Checkpoint Kinase 2
-
DNA-Binding Proteins / metabolism
-
G1 Phase / drug effects
-
Hydroxyurea / pharmacology
-
Mutation / genetics
-
Phosphorylation / drug effects
-
Proteasome Endopeptidase Complex / metabolism
-
Protein Binding / drug effects
-
Protein Processing, Post-Translational / drug effects
-
Protein Serine-Threonine Kinases / metabolism*
-
Protein Stability / drug effects
-
S Phase* / drug effects
-
Schizosaccharomyces / cytology*
-
Schizosaccharomyces / drug effects
-
Schizosaccharomyces / enzymology*
-
Schizosaccharomyces / genetics
-
Schizosaccharomyces pombe Proteins / chemistry
-
Schizosaccharomyces pombe Proteins / metabolism*
-
Trans-Activators / chemistry
-
Trans-Activators / metabolism*
-
Transcription, Genetic / drug effects
-
Ubiquitin-Protein Ligase Complexes / metabolism*
-
Ubiquitination / drug effects
Substances
-
Cell Cycle Proteins
-
DNA-Binding Proteins
-
Rep2 protein, S pombe
-
Schizosaccharomyces pombe Proteins
-
Trans-Activators
-
res2 protein, S pombe
-
srw1 protein, S pombe
-
Ubiquitin-Protein Ligase Complexes
-
Anaphase-Promoting Complex-Cyclosome
-
Checkpoint Kinase 2
-
Cds1 protein, S pombe
-
Protein Serine-Threonine Kinases
-
Proteasome Endopeptidase Complex
-
Hydroxyurea