Download MendeleyStructure of the eukaryotic replicative CMG helicase suggests a pumpjack motion for translocation.
Yuan, Z., Bai, L., Sun, J., Georgescu, R., Liu, J., O'Donnell, M.E., Li, H.(2016) Nat Struct Mol Biol 23: 217-224
- PubMed: 26854665 Search on PubMedSearch on PubMed Central
- DOI: https://doi.org/10.1038/nsmb.3170
- Primary Citation Related Structures:
3JC5, 3JC6, 3JC7 - 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.
- Department of Biochemistry &Cell Biology, Stony Brook University, Stony Brook, New York, USA.
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