6f0l

S. cerevisiae MCM double hexamer bound to duplex DNA

Loading... Status: waiting for Mol* initialization Structural highlights 6f0l is a 14 chain structure with sequence from Saccharomyces cerevisiae S288C and Synthetic construct. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: Electron Microscopy, Resolution 4.77Å Ligands: ADP Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function MCM2_YEAST Acts as component of the MCM2-7 complex (MCM complex) which is the putative replicative helicase essential for 'once per cell cycle' DNA replication initiation and elongation in eukaryotic cells. The active ATPase sites in the MCM2-7 ring are formed through the interaction surfaces of two neighboring subunits such that a critical structure of a conserved arginine finger motif is provided in trans relative to the ATP-binding site of the Walker A box of the adjacent subunit. The six ATPase active sites, however, are likely to contribute differentially to the complex helicase activity; specifically the MCM2-MCM5 association is proposed to be reversible and to mediate a open ring conformation which may facilitate DNA loading. Once loaded onto DNA, double hexamers can slide on dsDNA in the absence of ATPase activity. Necessary for cell growth. Publication Abstract from PubMed Eukaryotic origins of replication are licensed upon loading of the MCM helicase motor onto DNA. ATP hydrolysis by MCM is required for loading and the post-catalytic MCM is an inactive double hexamer that encircles duplex DNA. Origin firing depends on MCM engagement of Cdc45 and GINS to form the CMG holo-helicase. CMG assembly requires several steps including MCM phosphorylation by DDK. To understand origin activation, here we have determined the cryo-EM structures of DNA-bound MCM, either unmodified or phosphorylated, and visualize a phospho-dependent MCM element likely important for Cdc45 recruitment. MCM pore loops touch both the Watson and Crick strands, constraining duplex DNA in a bent configuration. By comparing our new MCM-DNA structure with the structure of CMG-DNA, we suggest how the conformational transition from the loaded, post-catalytic MCM to CMG might promote DNA untwisting and melting at the onset of replication. Cryo-EM structure of a licensed DNA replication origin.,Abid Ali F, Douglas ME, Locke J, Pye VE, Nans A, Diffley JFX, Costa A Nat Commun. 2017 Dec 21;8(1):2241. doi: 10.1038/s41467-017-02389-0. PMID:29269875 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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