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PDBsum entry 3jc6
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Contents |
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241 a.a.
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269 a.a.
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275 a.a.
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254 a.a.
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267 a.a.
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325 a.a.
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553 a.a.
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221 a.a.
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181 a.a.
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208 a.a.
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159 a.a.
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References listed in PDB file
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Key reference
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Title
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Structure of the eukaryotic replicative cmg helicase suggests a pumpjack motion for translocation.
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Authors
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Z.Yuan,
L.Bai,
J.Sun,
R.Georgescu,
J.Liu,
M.E.O'Donnell,
H.Li.
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Ref.
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Nat Struct Biol, 2016,
23,
217-224.
[DOI no: ]
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PubMed id
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Abstract
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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.
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