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Title | Structure of the eukaryotic replicative CMG helicase suggests a pumpjack motion for translocation. |
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Journal, issue, pages | Nat Struct Mol Biol, Vol. 23, Issue 3, Page 217-224, Year 2016 |
Publish date | Feb 8, 2016 |
Authors | Zuanning Yuan / Lin Bai / Jingchuan Sun / Roxana Georgescu / Jun Liu / Michael E O'Donnell / Huilin Li / |
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 ...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. |
External links | Nat Struct Mol Biol / PubMed:26854665 / PubMed Central |
Methods | EM (single particle) |
Resolution | 3.7 - 4.8 Å |
Structure data | EMDB-6534, PDB-3jc6: |
Chemicals | ChemComp-ZN: |
Source |
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Keywords | HYDROLASE / CMG helicase / Cryo-EM / REPLICATION |