28VY

sCMGE assembled on ARS1 DNA with Sld2 and RPA

This is a non-PDB format compatible entry.

Summary for 28VY

• Entry DOI: 10.2210/pdb28vy/pdb
• EMDB information: 56898
• Descriptor: DNA replication licensing factor MCM2, Cell division control protein 45, DNA polymerase epsilon subunit B, ... (18 entities in total)
• Functional Keywords: macromolecular complex, dna, atpase, helicase mcm2-7, replication
• Biological source: Saccharomyces cerevisiae (brewer's yeast); More
• Total number of polymer chains: 15
• Total formula weight: 1147984.44

Authors

Butryn, A.,Palm, G.,Costa, A. (deposition date: 2026-02-23, release date: 2026-05-13, Last modification date: 2026-07-01)

Primary citation

Puhringer, T.,Canal, B.,Palm, G.,Butryn, A.,Couves, E.C.,Willhoft, O.,Lewis, J.S.,Diffley, J.F.X.,Costa, A.
Structure of the pre-initiation complex explains CMGE biogenesis.
Nature, 2026

PubMed Abstract: When cells enter S phase, bidirectional DNA replication is initiated through the kinase-regulated recruitment of three activators (Cdc45, GINS and Pol ε) to a duplex-DNA-loaded double hexamer of minichromosome maintenance (MCM) ATPases. Together, these proteins form two CMGE helicases that establish divergent replication forks as they become separated. Here, to gain an understanding of CMGE biogenesis, we reconstituted the pre-initiation complex with purified yeast proteins. The cryo-electron-microscopy structure shows a set of firing factors caught in the act of assembling two symmetrical CMGEs. We show how stepwise complex formation reshapes MCM in preparation for DNA opening, and we explain how ATP promotes firing-factor ejection and CMGE maturation. We find that although Sld2 facilitates the recruitment of GINS to MCM, as expected, it also aids the efficient separation of the CMGE dimer, and is essential for the ejection of the lagging strand from MCM. These findings have direct implications for our understanding of the metazoan Sld2 orthologue, RECQL4, and point to a replication-fork establishment mechanism that is conserved across eukaryotes.

PubMed: 42310460
DOI: 10.1038/s41586-026-10657-7

Experimental method

ELECTRON MICROSCOPY (2.7 Å)