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Cryo-EM structure of the fork protection complex bound to CMG at a replication fork

DOI: 10.1016/j.molcel.2020.04.012 DOI Help

Authors: Domagoj Baretic (Laboratory of Molecular Biology, Medical Research Council) , Michael Jenkyn-Bedford (Laboratory of Molecular Biology, Medical Research Council) , Valentina Aria (Laboratory of Molecular Biology, Medical Research Council) , Giuseppe Cannone (Laboratory of Molecular Biology, Medical Research Council) , Mark Skehel (Laboratory of Molecular Biology, Medical Research Council) , Joseph T. P. Yeeles (Laboratory of Molecular Biology, Medical Research Council)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Molecular Cell , VOL 78 , PAGES 926 - 940.e13

State: Published (Approved)
Published: June 2020
Diamond Proposal Number(s): 20976 , 17434

Open Access Open Access

Abstract: The 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 Å 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.

Journal Keywords: Fork Protection Complex; Replisome; CMG helicase; DNA replication; Genome Stability; Csm3; Tof1; Mrc1; Timeless-Tipin; Claspin

Subject Areas: Biology and Bio-materials

Instruments: Krios I-Titan Krios I at Diamond

Other Facilities: CM01 at ESRF

Added On: 07/01/2021 11:51


Discipline Tags:

Structural biology Life Sciences & Biotech

Technical Tags:

Microscopy Electron Microscopy (EM) Cryo Electron Microscopy (Cryo EM)