Phosphorylation of MCM3 on Ser-112 regulates its incorporation into the MCM2-7 complex.
During late M and early G(1), MCM2-7 assembles and is loaded onto chromatin in the final step of prereplicative complex (pre-RC) formation. However, the regulation of MCM assembly remains poorly understood. Cyclin-dependent kinase (CDK)-dependent phosphorylation contributes to DNA replication by initially activating pre-RCs and subsequently inhibiting refiring of origins during S and M phases, thus limiting DNA replication to a single round. Although the precise roles of specific MCM phosphorylation events are poorly characterized, we now demonstrate that CDK1 phosphorylates MCM3 at Ser-112, Ser-611, and Thr-719. In vivo, CDK1-dependent phosphorylation of Ser-112 triggers the assembly of MCM3 with the remaining MCM subunits and subsequent chromatin loading of MCMs. Strikingly, loss of MCM3 triggers the destabilization of other MCM proteins, suggesting that phosphorylation-dependent assembly is essential for stable accumulation of MCM proteins. These data reveal that CDK-dependent MCM3 phosphorylation contributes to the regulated formation of the MCM2-7 complex.
The Leonard and Madlyn Abramson Family Cancer Research Institute and Cancer Center, University of Pennsylvania, Philadelphia, PA 19104, USA.
Douglas I
DI
Lin
Priya
P
Aggarwal
J Alan
JA
Diehl
D000818:Animals; D016203:CDC2 Protein Kinase / Q000378:metabolism; D002453:Cell Cycle; D018797:Cell Cycle Proteins / Q000378:metabolism*; D016384:Consensus Sequence; D051357:Cyclin-Dependent Kinase 2 / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism*; D006801:Humans; D051379:Mice; D064126:Minichromosome Maintenance Complex Component 3; D046912:Multiprotein Complexes / Q000378:metabolism*; D041681:NIH 3T3 Cells; D009687:Nuclear Proteins / Q000378:metabolism*; D010766:Phosphorylation; D010768:Phosphoserine / Q000378:metabolism*; D010769:Phosphothreonine / Q000378:metabolism; D013379:Substrate Specificity
D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; C066470:MCM3 protein, human; C513269:Mcm3 protein, mouse; D046912:Multiprotein Complexes; D009687:Nuclear Proteins; D010769:Phosphothreonine; D010768:Phosphoserine; D016203:CDC2 Protein Kinase; D051357:Cyclin-Dependent Kinase 2; D064126:Minichromosome Maintenance Complex Component 3