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| Title | The structural basis for MCM2-7 helicase activation by GINS and Cdc45. |
|---|---|
| Journal, issue, pages | Nat Struct Mol Biol, Vol. 18, Issue 4, Page 471-477, Year 2011 |
| Publish date | Mar 6, 2011 |
 Authors | Alessandro Costa / Ivar Ilves / Nele Tamberg / Tatjana Petojevic / Eva Nogales / Michael R Botchan / James M Berger /  |
| PubMed Abstract | Two central steps for initiating eukaryotic DNA replication involve loading of the Mcm2-7 helicase onto double-stranded DNA and its activation by GINS-Cdc45. To better understand these events, we ...Two central steps for initiating eukaryotic DNA replication involve loading of the Mcm2-7 helicase onto double-stranded DNA and its activation by GINS-Cdc45. To better understand these events, we determined the structures of Mcm2-7 and the CMG complex by using single-particle electron microscopy. Mcm2-7 adopts two conformations--a lock-washer-shaped spiral state and a planar, gapped-ring form--in which Mcm2 and Mcm5 flank a breach in the helicase perimeter. GINS and Cdc45 bridge this gap, forming a topologically closed assembly with a large interior channel; nucleotide binding further seals off the discontinuity between Mcm2 and Mcm5, partitioning the channel into two smaller pores. Together, our data help explain how GINS and Cdc45 activate Mcm2-7, indicate that Mcm2-7 loading may be assisted by a natural predisposition of the hexamer to form open rings, and suggest a mechanism by which the CMG complex assists DNA strand separation. |
 External links | Nat Struct Mol Biol / PubMed:21378962 / PubMed Central |
| Methods | EM (single particle) |
| Resolution | 28.0 - 35.0 Å |
| Structure data |  EMDB-1832:  EMDB-1833:  EMDB-1834:  EMDB-1835: |
| Source |
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Drosophila melanogaster (fruit fly)