3JC6

Structure of the eukaryotic replicative CMG helicase and pumpjack motion

Summary for 3JC6

• Entry DOI: 10.2210/pdb3jc6/pdb
• Related: 3JC5 3JC7
• EMDB information: 6534 6535 6536
• Descriptor: DNA replication licensing factor MCM2, DNA replication complex GINS protein PSF1, DNA replication complex GINS protein PSF3, ... (12 entities in total)
• Functional Keywords: cmg helicase, cryo-em, replication
• Biological source: Saccharomyces cerevisiae (yeast); More
• Total number of polymer chains: 11
• Total formula weight: 788766.32

Authors

Li, H.,Bai, L.,Yuan, Z.,Sun, J.,Georgescu, R.E.,Liu, J.,O'Donnell, M.E. (deposition date: 2015-11-24, release date: 2016-02-10, Last modification date: 2018-07-18)

Primary citation

Yuan, Z.,Bai, L.,Sun, J.,Georgescu, R.,Liu, J.,O'Donnell, M.E.,Li, H.
Structure of the eukaryotic replicative CMG helicase suggests a pumpjack motion for translocation.
Nat.Struct.Mol.Biol., 23:217-224, 2016

PubMed Abstract: The CMG helicase is composed of Cdc45, Mcm2-7 and GINS. Here we report the structure of the Saccharomyces cerevisiae CMG, determined by cryo-EM at a resolution of 3.7-4.8 Å. The structure reveals that GINS and Cdc45 scaffold the N tier of the helicase while enabling motion of the AAA+ C tier. CMG exists in two alternating conformations, compact and extended, thus suggesting that the helicase moves like an inchworm. The N-terminal regions of Mcm2-7, braced by Cdc45-GINS, form a rigid platform upon which the AAA+ C domains make longitudinal motions, nodding up and down like an oil-rig pumpjack attached to a stable platform. The Mcm ring is remodeled in CMG relative to the inactive Mcm2-7 double hexamer. The Mcm5 winged-helix domain is inserted into the central channel, thus blocking entry of double-stranded DNA and supporting a steric-exclusion DNA-unwinding model.

PubMed: 26854665
DOI: 10.1038/nsmb.3170

Experimental method

ELECTRON MICROSCOPY (3.7 Å)