First Author | You Z | Year | 2008 |
Journal | J Biol Chem | Volume | 283 |
Issue | 36 | Pages | 24469-77 |
PubMed ID | 18606811 | Mgi Jnum | J:142022 |
Mgi Id | MGI:3820193 | Doi | 10.1074/jbc.M803212200 |
Citation | You Z, et al. (2008) Cdt1 forms a complex with the minichromosome maintenance protein (MCM) and activates its helicase activity. J Biol Chem 283(36):24469-77 |
abstractText | Mcm4/6/7 forms a complex possessing DNA helicase activity, suggesting that Mcm may be a central component for the replicative helicase. Although Cdt1 is known to be essential for loading of Mcm onto the chromatin, its precise role in pre-RC formation and replication initiation is unknown. Using purified proteins, we show that Cdt1 forms a complex with Mcm4/6/7, Mcm2/3/4/5/6/7, and Mcm2/4/6/7 in glycerol gradient fractionation through interaction with Mcm2 and Mcm4/6. In the glycerol gradient fractionation, Mcm4/6/7-Cdt1 forms a complex (speculated to be a (Mcm4/6/7)2-Cdt13 assembly) in the presence of ATP, which is significantly larger than the Mcm4/6/7-Cdt1 complex generated in its absence. Furthermore, DNA binding and helicase activities of Mcm4/6/7 are significantly stimulated by Cdt1 protein in vitro. We generated a Cdt1 mutant, which fails to stimulate DNA binding and helicase activities of Mcm4/6/7. This mutant Cdt1 showed reduced interaction with Mcm and is deficient in the formation of a high molecular weight complex with Mcm. Thus, a productive interaction between Cdt1 and MCM appears to be essential for efficient loading of MCM onto template DNA, as well as for the efficient unwinding reaction. |