Xenopus Cut5 is essential for a CDK-dependent process in the initiation of DNA replication.
Fission yeast Cut5/Rad4 and its budding yeast homolog Dpb11 are required for both DNA replication and the S-phase checkpoint. Here, we have investigated the role of the Xenopus homolog of Cut5 in the initiation of DNA replication using Xenopus egg extracts. Xenopus Cut5, which shows sequence similarity to DmMus101 and HsTopBP1, is essential for DNA replication in the egg extracts. It is required for the chromatin binding of Cdc45 and DNA polymerases, but not for the formation of pre-replicative complexes or the elongation stage of DNA replication. The chromatin binding of Cut5 consists of two distinct modes. S-phase cyclin-dependent kinase (S-CDK)-independent binding is sufficient for DNA replication while S-CDK-dependent binding is dispensable. Further, S-CDK acts after the chromatin binding of Cut5 and before the binding of Cdc45. These results demonstrate that the chromatin binding of Cut5 is required for the action of S-CDK, which in turn triggers the formation of pre-initiation complexes of DNA replication.
Department of Biology, Graduate School of Science, Osaka University, Toyonaka, Japan.
Yoshitami
Y
Hashimoto
Haruhiko
H
Takisawa
D000818:Animals; D002352:Carrier Proteins; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D002474:Cell-Free System; D002843:Chromatin / Q000378:metabolism; D018844:Cyclin-Dependent Kinases / Q000378:metabolism*; D004261:DNA Replication / Q000502:physiology*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D064248:Geminin; D006801:Humans; D009687:Nuclear Proteins; D009865:Oocytes / Q000502:physiology; D011485:Protein Binding; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins; D029702:Schizosaccharomyces pombe Proteins / Q000378:metabolism*; D011503:Transglutaminases / Q000378:metabolism*; D029867:Xenopus Proteins; D014982:Xenopus laevis / Q000502:physiology*
C102209:CDC45 protein, S cerevisiae; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D002843:Chromatin; D004268:DNA-Binding Proteins; C577998:GMNN protein, Xenopus; C577995:GMNN protein, human; D064248:Geminin; D009687:Nuclear Proteins; C082463:RAD4 protein, S pombe; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; D029702:Schizosaccharomyces pombe Proteins; D029867:Xenopus Proteins; D011503:Transglutaminases; D018844:Cyclin-Dependent Kinases