8P62

S. cerevisiae ssDNA-sCMGE after DNA replication initiation

Summary for 8P62

• Entry DOI: 10.2210/pdb8p62/pdb
• EMDB information: 17458
• Descriptor: DNA replication licensing factor MCM2, Cell division control protein 45, DNA polymerase epsilon subunit B, ... (18 entities in total)
• Functional Keywords: saccharomyces cerevisiae, helicase, cmge, initiation of dna replication, dna, dna unwinding, replication
• Biological source: Saccharomyces cerevisiae (brewer's yeast); More
• Total number of polymer chains: 14
• Total formula weight: 1135225.89

Authors

Henrikus, S.S.,Willhoft, O. (deposition date: 2023-05-25, release date: 2024-05-29, Last modification date: 2024-08-28)

Primary citation

Henrikus, S.S.,Gross, M.H.,Willhoft, O.,Puhringer, T.,Lewis, J.S.,McClure, A.W.,Greiwe, J.F.,Palm, G.,Nans, A.,Diffley, J.F.X.,Costa, A.
Unwinding of a eukaryotic origin of replication visualized by cryo-EM.
Nat.Struct.Mol.Biol., 31:1265-1276, 2024

PubMed Abstract: To prevent detrimental chromosome re-replication, DNA loading of a double hexamer of the minichromosome maintenance (MCM) replicative helicase is temporally separated from DNA unwinding. Upon S-phase transition in yeast, DNA unwinding is achieved in two steps: limited opening of the double helix and topological separation of the two DNA strands. First, Cdc45, GINS and Polε engage MCM to assemble a double CMGE with two partially separated hexamers that nucleate DNA melting. In the second step, triggered by Mcm10, two CMGEs separate completely, eject the lagging-strand template and cross paths. To understand Mcm10 during helicase activation, we used biochemical reconstitution with cryogenic electron microscopy. We found that Mcm10 splits the double CMGE by engaging the N-terminal homo-dimerization face of MCM. To eject the lagging strand, DNA unwinding is started from the N-terminal side of MCM while the hexamer channel becomes too narrow to harbor duplex DNA.

PubMed: 38760633
DOI: 10.1038/s41594-024-01280-z

Experimental method

ELECTRON MICROSCOPY (3.9 Å)