6RAZ

D. melanogaster CMG-DNA, State 2B

Summary for 6RAZ

• Entry DOI: 10.2210/pdb6raz/pdb
• EMDB information: 4788
• Descriptor: DNA, DNA replication licensing factor Mcm6, DNA replication licensing factor Mcm3, ... (15 entities in total)
• Functional Keywords: helicase, atpase, aaa+, dna unwinding, hydrolase
• Biological source: Drosophila melanogaster (Fruit fly); More
• Total number of polymer chains: 13
• Total formula weight: 717828.37

Authors

Eickhoff, P.,Martino, F.,Costa, A. (deposition date: 2019-04-08, release date: 2019-09-18, Last modification date: 2021-01-20)

Primary citation

Eickhoff, P.,Kose, H.B.,Martino, F.,Petojevic, T.,Abid Ali, F.,Locke, J.,Tamberg, N.,Nans, A.,Berger, J.M.,Botchan, M.R.,Yardimci, H.,Costa, A.
Molecular Basis for ATP-Hydrolysis-Driven DNA Translocation by the CMG Helicase of the Eukaryotic Replisome.
Cell Rep, 28:2673-2688.e8, 2019

PubMed Abstract: In the eukaryotic replisome, DNA unwinding by the Cdc45-MCM-Go-Ichi-Ni-San (GINS) (CMG) helicase requires a hexameric ring-shaped ATPase named minichromosome maintenance (MCM), which spools single-stranded DNA through its central channel. Not all six ATPase sites are required for unwinding; however, the helicase mechanism is unknown. We imaged ATP-hydrolysis-driven translocation of the CMG using cryo-electron microscopy (cryo-EM) and found that the six MCM subunits engage DNA using four neighboring protomers at a time, with ATP binding promoting DNA engagement. Morphing between different helicase states leads us to suggest a non-symmetric hand-over-hand rotary mechanism, explaining the asymmetric requirements of ATPase function around the MCM ring of the CMG. By imaging of a higher-order replisome assembly, we find that the Mrc1-Csm3-Tof1 fork-stabilization complex strengthens the interaction between parental duplex DNA and the CMG at the fork, which might support the coupling between DNA translocation and fork unwinding.

PubMed: 31484077
DOI: 10.1016/j.celrep.2019.07.104

Experimental method

ELECTRON MICROSCOPY (4.46 Å)