Journal Article

MCM2-7 ring closure involves the Mcm5 C-terminus and triggers Mcm4 ATP hydrolysis

Yuan, Zuanning, Bai, Lin, Winkler, Christian, Mossler, Audrey, Speck, Christian, Barbon, Marta, Faull, Sarah V., Riera, Alberto, Reuter, L. Maximilian, Magdalou, Indiana, Peach, Matthew, Li, Huilin

2025

Overview

The eukaryotic helicase MCM2-7, is loaded by ORC, Cdc6 and Cdt1 as a double-hexamer onto replication origins. The insertion of DNA into the helicase leads to partial MCM2-7 ring closure, while ATP hydrolysis is essential for consecutive steps in pre-replicative complex (pre-RC) assembly. Currently it is unknown how MCM2-7 ring closure and ATP-hydrolysis are controlled. A cryo-EM structure of an ORC-Cdc6-Cdt1-MCM2-7 intermediate shows a remodelled, fully-closed Mcm2/Mcm5 interface. The Mcm5 C-terminus (C5) contacts Orc3 and specifically recognises this closed ring. Interestingly, we found that normal helicase loading triggers Mcm4 ATP-hydrolysis, which in turn leads to reorganisation of the MCM2-7 complex and Cdt1 release. However, defective MCM2-7 ring closure, due to mutations at the Mcm2/Mcm5 interface, leads to MCM2-7 ring splitting and complex disassembly. As such we identify Mcm4 as the key ATPase in regulating pre-RC formation. Crucially, a stable Mcm2/Mcm5 interface is essential for productive ATP-hydrolysis-dependent remodelling of the helicase. The loading of the replicative helicase is vital for replication fork assembly. Here the authors identify Mcm4 as the key ATPase in this process and show that helicase ring closure around DNA promotes Mcm4 ATPase dependent Cdt1 release, while defective ring closure leads to complex disassembly.

• Publisher: Nature Publishing Group UK,Nature Publishing Group,Nature Portfolio
• Subject: 101/28 / 631/337/151/2352 / 631/45/535/1258/1259 / 82/16 / 82/83 / Adenosine triphosphatase / Adenosine Triphosphate - metabolism / C-Terminus / Cell Cycle Proteins - chemistry / Cell Cycle Proteins - genetics / Cell Cycle Proteins - metabolism / Cryoelectron Microscopy / Deoxyribonucleic acid / Dismantling / DNA / DNA biosynthesis / DNA helicase / DNA Helicases - chemistry / DNA Helicases - genetics / DNA Helicases - metabolism / DNA Replication / DNA-Binding Proteins - chemistry / DNA-Binding Proteins - genetics / DNA-Binding Proteins - metabolism / Humanities and Social Sciences / Hydrolysis / Minichromosome Maintenance Complex Component 4 - genetics / Minichromosome Maintenance Complex Component 4 - metabolism / Minichromosome Maintenance Proteins - chemistry / Minichromosome Maintenance Proteins - genetics / Minichromosome Maintenance Proteins - metabolism / multidisciplinary / Mutation / Origin Recognition Complex - chemistry / Origin Recognition Complex - genetics / Origin Recognition Complex - metabolism / Proteins / Replication / Replication origins / Saccharomyces cerevisiae - genetics / Saccharomyces cerevisiae - metabolism / Saccharomyces cerevisiae Proteins - chemistry / Saccharomyces cerevisiae Proteins - genetics / Saccharomyces cerevisiae Proteins - metabolism / Science / Science (multidisciplinary)