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Cdt1 stabilizes an open MCM ring for helicase loading

DOI: 10.1038/ncomms15720 DOI Help

Authors: Jordi Frigola (The Francis Crick Institute) , Jun He (The Francis Crick Institute) , Kerstin Kinkelin (The Francis Crick Institute) , Valerie E. Pye (The Francis Crick Institute) , Ludovic Renault (The Francis Crick Institute) , Max E. Douglas (The Francis Crick Institute) , Dirk Remus (Memorial Sloan Kettering Cancer Center) , Peter Cherepanov (The Francis Crick Institute) , Alessandro Costa (The Francis Crick Institute) , John F. X. Diffley (The Francis Crick Institute)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Nature Communications , VOL 8

State: Published (Approved)
Published: June 2017
Diamond Proposal Number(s): 9424 , 7299

Open Access Open Access

Abstract: ORC, Cdc6 and Cdt1 act together to load hexameric MCM, the motor of the eukaryotic replicative helicase, into double hexamers at replication origins. Here we show that Cdt1 interacts with MCM subunits Mcm2, 4 and 6, which both destabilizes the Mcm2–5 interface and inhibits MCM ATPase activity. Using X-ray crystallography, we show that Cdt1 contains two winged-helix domains in the C-terminal half of the protein and a catalytically inactive dioxygenase-related N-terminal domain, which is important for MCM loading, but not for subsequent replication. We used these structures together with single-particle electron microscopy to generate three-dimensional models of MCM complexes. These show that Cdt1 stabilizes MCM in a left-handed spiral open at the Mcm2–5 gate. We propose that Cdt1 acts as a brace, holding MCM open for DNA entry and bound to ATP until ORC–Cdc6 triggers ATP hydrolysis by MCM, promoting both Cdt1 ejection and MCM ring closure.

Journal Keywords: DNA; Electron microscopy; Replisome

Subject Areas: Biology and Bio-materials

Instruments: I04-Macromolecular Crystallography

Other Facilities: ESRF

Added On: 12/07/2017 16:15


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