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-Structure paper
Title | DNA is loaded through the 9-1-1 DNA checkpoint clamp in the opposite direction of the PCNA clamp. |
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Journal, issue, pages | Nat Struct Mol Biol, Vol. 29, Issue 4, Page 376-385, Year 2022 |
Publish date | Mar 21, 2022 |
Authors | Fengwei Zheng / Roxana E Georgescu / Nina Y Yao / Michael E O'Donnell / Huilin Li / |
PubMed Abstract | The 9-1-1 DNA checkpoint clamp is loaded onto 5'-recessed DNA to activate the DNA damage checkpoint that arrests the cell cycle. The 9-1-1 clamp is a heterotrimeric ring that is loaded in ...The 9-1-1 DNA checkpoint clamp is loaded onto 5'-recessed DNA to activate the DNA damage checkpoint that arrests the cell cycle. The 9-1-1 clamp is a heterotrimeric ring that is loaded in Saccharomyces cerevisiae by Rad24-RFC (hRAD17-RFC), an alternate clamp loader in which Rad24 replaces Rfc1 in the RFC1-5 clamp loader of proliferating cell nuclear antigen (PCNA). The 9-1-1 clamp loading mechanism has been a mystery, because, unlike RFC, which loads PCNA onto a 3'-recessed junction, Rad24-RFC loads the 9-1-1 ring onto a 5'-recessed DNA junction. Here we report two cryo-EM structures of Rad24-RFC-DNA with a closed or 27-Å open 9-1-1 clamp. The structures reveal a completely unexpected mechanism by which a clamp can be loaded onto DNA. Unlike RFC, which encircles DNA, Rad24 binds 5'-DNA on its surface, not inside the loader, and threads the 3' ssDNA overhang into the 9-1-1 clamp from above the ring. |
External links | Nat Struct Mol Biol / PubMed:35314830 / PubMed Central |
Methods | EM (single particle) |
Resolution | 3.17 - 3.23 Å |
Structure data | EMDB-25121: Cryo-EM 3D map of the yeast Rad24-RFC loader bound to DNA and the closed 9-1-1 clamp EMDB-25122: Cryo-EM 3D map of the yeast Rad24-RFC loader bound to DNA and the open 9-1-1 clamp |
Chemicals | ChemComp-AGS: ChemComp-MG: ChemComp-ADP: ChemComp-PO4: |
Source |
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Keywords | DNA BINDING PROTEIN/DNA / DNA damage repair / Rad24-RFC / 9-1-1 clamp / DNA clamp / alternative clamp loader / DNA damage signaling / DNA BINDING PROTEIN-DNA complex |