Article ; Online: Cryo-EM structures of the eukaryotic replicative helicase bound to a translocation substrate.
2016 Volume 7, Page(s) 10708
Abstract: ... cryo-electron microscopy to describe two subnanometre resolution structures of the CMG helicase trapped on a DNA fork ... a set of pre-sensor 1 hairpins that spiral around the translocation substrate. In the second state ... The Cdc45-MCM-GINS (CMG) helicase unwinds DNA during the elongation step of eukaryotic ...
| Abstract | The Cdc45-MCM-GINS (CMG) helicase unwinds DNA during the elongation step of eukaryotic genome duplication and this process depends on the MCM ATPase function. Whether CMG translocation occurs on single- or double-stranded DNA and how ATP hydrolysis drives DNA unwinding remain open questions. Here we use cryo-electron microscopy to describe two subnanometre resolution structures of the CMG helicase trapped on a DNA fork. In the predominant state, the ring-shaped C-terminal ATPase of MCM is compact and contacts single-stranded DNA, via a set of pre-sensor 1 hairpins that spiral around the translocation substrate. In the second state, the ATPase module is relaxed and apparently substrate free, while DNA intimately contacts the downstream amino-terminal tier of the MCM motor ring. These results, supported by single-molecule FRET measurements, lead us to suggest a replication fork unwinding mechanism whereby the N-terminal and AAA+ tiers of the MCM work in concert to translocate on single-stranded DNA. |
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| MeSH term(s) | Cryoelectron Microscopy ; DNA/genetics ; DNA/metabolism ; DNA/ultrastructure ; DNA Helicases/metabolism ; DNA Helicases/ultrastructure ; DNA Replication ; Eukaryota/enzymology ; Eukaryota/genetics ; Eukaryota/ultrastructure |
| Chemical Substances | DNA (9007-49-2) ; DNA Helicases (EC 3.6.4.-) |
| Language | English |
| Publishing date | 2016-02-18 |
| Publishing country | England |
| Document type | Journal Article ; Research Support, Non-U.S. Gov't |
| ZDB-ID | 2553671-0 |
| ISSN | 2041-1723 ; 2041-1723 |
| ISSN (online) | 2041-1723 |
| ISSN | 2041-1723 |
| DOI | 10.1038/ncomms10708 |
| Database | MEDical Literature Analysis and Retrieval System OnLINE |
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