3JA8: Cryo-em Structure Of The Mcm2-7 Double Hexamer

Citation:
Abstract
DNA replication in eukaryotes is strictly regulated by several mechanisms. A central step in this replication is the assembly of the heterohexameric minichromosome maintenance (MCM2-7) helicase complex at replication origins during G1 phase as an inactive double hexamer. Here, using cryo-electron microscopy, we report a near-atomic structure of the MCM2-7 double hexamer purified from yeast G1 chromatin. Our structure shows that two single hexamers, arranged in a tilted and twisted fashion through interdigitated amino-terminal domain interactions, form a kinked central channel. Four constricted rings consisting of conserved interior beta-hairpins from the two single hexamers create a narrow passageway that tightly fits duplex DNA. This narrow passageway, reinforced by the offset of the two single hexamers at the double hexamer interface, is flanked by two pairs of gate-forming subunits, MCM2 and MCM5. These unusual features of the twisted and tilted single hexamers suggest a concerted mechanism for the melting of origin DNA that requires structural deformation of the intervening DNA.
PDB ID: 3JA8Download
MMDB ID: 131375
PDB Deposition Date: 2015/5/9
Updated in MMDB: 2015/08
Experimental Method:
electron microscopy
Resolution: 3.8  Å
Source Organism:
Similar Structures:
Biological Unit for 3JA8: hexameric; determined by author
Molecular Components in 3JA8
Label Count Molecule
Proteins (6 molecules)
1
Minichromosome Maintenance 2(Gene symbol: MCM2)
Molecule annotation
1
Minichromosome Maintenance 3(Gene symbol: MCM3)
Molecule annotation
1
Minichromosome Maintenance 4(Gene symbol: MCM4)
Molecule annotation
1
Minichromosome Maintenance 5(Gene symbol: MCM5)
Molecule annotation
1
Minichromosome Maintenance 6(Gene symbol: MCM6)
Molecule annotation
1
Minichromosome Maintenance 7(Gene symbol: MCM7)
Molecule annotation
Chemicals (6 molecules)
1
6
* Click molecule labels to explore molecular sequence information.

Citing MMDB
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