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Title | Structural basis of Mcm2-7 replicative helicase loading by ORC-Cdc6 and Cdt1. |
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Journal, issue, pages | Nat Struct Mol Biol, Vol. 24, Issue 3, Page 316-324, Year 2017 |
Publish date | Feb 13, 2017 |
Authors | Zuanning Yuan / Alberto Riera / Lin Bai / Jingchuan Sun / Saikat Nandi / Christos Spanos / Zhuo Angel Chen / Marta Barbon / Juri Rappsilber / Bruce Stillman / Christian Speck / Huilin Li / |
PubMed Abstract | To initiate DNA replication, the origin recognition complex (ORC) and Cdc6 load an Mcm2-7 double hexamer onto DNA. Without ATP hydrolysis, ORC-Cdc6 recruits one Cdt1-bound Mcm2-7 hexamer, thus ...To initiate DNA replication, the origin recognition complex (ORC) and Cdc6 load an Mcm2-7 double hexamer onto DNA. Without ATP hydrolysis, ORC-Cdc6 recruits one Cdt1-bound Mcm2-7 hexamer, thus forming an ORC-Cdc6-Cdt1-Mcm2-7 (OCCM) helicase-loading intermediate. Here we report a 3.9-Å structure of Saccharomyces cerevisiae OCCM on DNA. Flexible Mcm2-7 winged-helix domains (WHDs) engage ORC-Cdc6. A three-domain Cdt1 configuration embraces Mcm2, Mcm4, and Mcm6, thus comprising nearly half of the hexamer. The Cdt1 C-terminal domain extends to the Mcm6 WHD, which binds the Orc4 WHD. DNA passes through the ORC-Cdc6 and Mcm2-7 rings. Origin DNA interaction is mediated by an α-helix within Orc4 and positively charged loops within Orc2 and Cdc6. The Mcm2-7 C-tier AAA+ ring is topologically closed by an Mcm5 loop that embraces Mcm2, but the N-tier-ring Mcm2-Mcm5 interface remains open. This structure suggests a loading mechanism of the first Cdt1-bound Mcm2-7 hexamer by ORC-Cdc6. |
External links | Nat Struct Mol Biol / PubMed:28191893 / PubMed Central |
Methods | EM (single particle) |
Resolution | 3.9 Å |
Structure data | |
Chemicals | ChemComp-AGS: |
Source |
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Keywords | REPLICATION / DNA replication / Cryo-EM / OCCM |