9NUH

SsoPfMCM:DNA class 1a from merged particles

This is a non-PDB format compatible entry.

Summary for 9NUH

• Entry DOI: 10.2210/pdb9nuh/pdb
• Related: 9NUI 9NUJ 9NUK 9NUL 9NUM 9NUN 9NUO 9NUP 9NUQ 9NUR 9NUS 9NUT 9NUU 9NUV 9NUW 9NUX 9NUY
• EMDB information: 49806
• Descriptor: Minichromosome maintenance protein MCM,DNA helicase, DNA (60-MER), ADENOSINE-5'-DIPHOSPHATE, ... (6 entities in total)
• Functional Keywords: dna replication, helicase, mcm, replication, hydrolase- dna complex, hydrolase-dna complex, hydrolase/dna
• Biological source: Saccharolobus solfataricus P2; More
• Total number of polymer chains: 8
• Total formula weight: 456919.20

Authors

Enemark, E.J.,Rasouli, S.,Myasnikov, A. (deposition date: 2025-03-19, release date: 2026-03-25, Last modification date: 2026-06-17)

Primary citation

Rasouli, S.,Myasnikov, A.,Enemark, E.J.
Archaeal and eukaryotic MCM rings sequentially melt DNA for replication initiation.
Nat Commun, 17:-, 2026

PubMed Abstract: DNA replication initiation requires local melting of fully base-paired DNA for a helicase to gain a foothold and initiate processive DNA unwinding. In eukaryotes and archaea, the helicase engine is the hexameric ring minichromosome maintenance (MCM) complex. In eukaryotes, a defined biochemical sequence assembles two Cdc45-MCM-GINS (CMG) complexes that provide limited DNA unwinding as the species that immediately precedes extensive unwinding. A prior structure revealed how MCM subunits interact with this form of DNA, but the atomic progression from undistorted DNA to this melted DNA species is unknown. Here, we present a sequential DNA melting mechanism determined by snapshots of an archaeal MCM ring with DNA in varying degrees of melting. In this mechanism, successive ATP-binding at MCM ATPase sites drives sequential discrete DNA melting steps mediated a specific MCM aromatic residue. Analysis of eukaryotic structures shows loaded MCM rings principally adopt only two molecular arrangements at the ATPase: one that does not melt DNA and one tuned to melt DNA with equivalent aromatic residues, indicating a universal sequential mechanism melts DNA in archaea and eukaryotes for replication initiation.

PubMed: 41916983
DOI: 10.1038/s41467-026-70961-8

Experimental method

ELECTRON MICROSCOPY (2.92 Å)