6sko
Cryo-EM Structure of the Fork Protection Complex Bound to CMG at a Replication Fork - conformation 2 MCM CTD:ssDNA
Structural highlights
FunctionMCM6_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. Once loaded onto DNA, double hexamers can slide on dsDNA in the absence of ATPase activity. Required for the entry in S phase and for cell division.[1] [2] Publication Abstract from PubMedThe eukaryotic replisome, organized around the Cdc45-MCM-GINS (CMG) helicase, orchestrates chromosome replication. Multiple factors associate directly with CMG, including Ctf4 and the heterotrimeric fork protection complex (Csm3/Tof1 and Mrc1), which has important roles including aiding normal replication rates and stabilizing stalled forks. How these proteins interface with CMG to execute these functions is poorly understood. Here we present 3 to 3.5 A resolution electron cryomicroscopy (cryo-EM) structures comprising CMG, Ctf4, and the fork protection complex at a replication fork. The structures provide high-resolution views of CMG-DNA interactions, revealing a mechanism for strand separation, and show Csm3/Tof1 "grip" duplex DNA ahead of CMG via a network of interactions important for efficient replication fork pausing. Although Mrc1 was not resolved in our structures, we determine its topology in the replisome by cross-linking mass spectrometry. Collectively, our work reveals how four highly conserved replisome components collaborate with CMG to facilitate replisome progression and maintain genome stability. Cryo-EM Structure of the Fork Protection Complex Bound to CMG at a Replication Fork.,Baretic D, Jenkyn-Bedford M, Aria V, Cannone G, Skehel M, Yeeles JTP Mol Cell. 2020 Apr 29. pii: S1097-2765(20)30254-9. doi:, 10.1016/j.molcel.2020.04.012. PMID:32369734[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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