7SH2

Structure of the yeast Rad24-RFC loader bound to DNA and the open 9-1-1 clamp

Summary for 7SH2

• Entry DOI: 10.2210/pdb7sh2/pdb
• EMDB information: 25121 25122
• Descriptor: Checkpoint protein RAD24, Crick strand, PHOSPHOTHIOPHOSPHORIC ACID-ADENYLATE ESTER, ... (13 entities in total)
• Functional Keywords: dna damage repair, rad24-rfc, 9-1-1 clamp, dna clamp, alternative clamp loader, dna damage signaling, dna binding protein-dna complex, dna binding protein/dna
• Biological source: Saccharomyces cerevisiae (Baker's yeast); More
• Total number of polymer chains: 10
• Total formula weight: 416868.19

Authors

Zheng, F.,Georgescu, R.,Yao, Y.N.,O'Donnell, M.E.,Li, H. (deposition date: 2021-10-07, release date: 2022-03-23, Last modification date: 2025-05-14)

Primary citation

Zheng, F.,Georgescu, R.E.,Yao, N.Y.,O'Donnell, M.E.,Li, H.
DNA is loaded through the 9-1-1 DNA checkpoint clamp in the opposite direction of the PCNA clamp.
Nat.Struct.Mol.Biol., 29:376-385, 2022

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 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.

PubMed: 35314830
DOI: 10.1038/s41594-022-00742-6

Experimental method

ELECTRON MICROSCOPY (3.23 Å)