Helicases unwind duplex DNA ahead of the polymerases at the replication fork. However, the identity of the eukaryotic replicative helicase has been controversial; in vivo studies implicate the ring-shaped heterohexameric Mcm2-7 complex, although only a specific subset of Mcm subunits (Mcm467) unwind DNA in vitro. To address this discrepancy, we have compared both Mcm assemblies and find that they differ in their linear single-stranded DNA association rate and their ability to bind circular single-stranded DNA. These differences depend upon the Mcm2/5 interface, which we hypothesize serves as an ATP-dependent "gate" within Mcm2-7. Importantly, we find that reaction conditions that putatively close the Mcm2-7 "gate" reconstitute Mcm2-7 helicase activity. Unlike Mcm467, Mcm2-7 helicase activity is strongly anion dependent. Our results show that purified Mcm2-7 acts as a helicase, provides functional evidence of a Mcm2/5 gate, and lays the foundation for future mechanistic studies of this critical factor.
|Evidence ID||Analyze ID||Interactor||Interactor Systematic Name||Interactor||Interactor Systematic Name||Type||Assay||Annotation||Action||Modification||Phenotype||Source||Reference||Note|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Gene Ontology Term||Gene Ontology Term ID||Qualifier||Aspect||Method||Evidence||Source||Assigned On||Reference||Annotation Extension|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Phenotype||Experiment Type||Experiment Type Category||Mutant Information||Strain Background||Chemical||Details||Reference|
|Evidence ID||Analyze ID||Regulator||Regulator Systematic Name||Target||Target Systematic Name||Experiment||Conditions||Strain||Source||Reference|