9BCX

Cryo-EM structure of the S. cerevisiae ORC-Cdc6-Mcm2-7-DNA complex with a fully closed Mcm2-Mcm5 DNA entry gate

This is a non-PDB format compatible entry.

Summary for 9BCX

• Entry DOI: 10.2210/pdb9bcx/pdb
• EMDB information: 44441
• Descriptor: DNA replication licensing factor MCM2, Origin recognition complex subunit 4, Origin recognition complex subunit 5, ... (18 entities in total)
• Functional Keywords: dna replication, cryo-em, occm-deltac6, replication-dna complex, dna binding protein
• Biological source: Saccharomyces cerevisiae (brewer's yeast); More
• Total number of polymer chains: 16
• Total formula weight: 1173128.88

Authors

Yuan, Z.,Bai, L.,Li, H.,Speck, C. (deposition date: 2024-04-10, release date: 2025-01-01, Last modification date: 2025-01-15)

Primary citation

Faull, S.V.,Barbon, M.,Mossler, A.,Yuan, Z.,Bai, L.,Reuter, L.M.,Riera, A.,Winkler, C.,Magdalou, I.,Peach, M.,Li, H.,Speck, C.
MCM2-7 ring closure involves the Mcm5 C-terminus and triggers Mcm4 ATP hydrolysis.
Nat Commun, 16:14-14, 2025

PubMed Abstract: 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.

PubMed: 39747125
DOI: 10.1038/s41467-024-55479-1

Experimental method

ELECTRON MICROSCOPY (6.1 Å)