Summary information and primary citation

PDB-id
8dr1; SNAP-derived features in text and JSON formats; DNAproDB
Class
replication-DNA
Method
cryo-EM (2.14 Å)
Summary
Consensus closed state of rfc:pcna bound to a 3' ss-dsDNA junction (dna2)
Reference
Schrecker M, Castaneda JC, Devbhandari S, Kumar C, Remus D, Hite RK (2022): "Multistep loading of a DNA sliding clamp onto DNA by replication factor C." Elife, 11. doi: 10.7554/eLife.78253.
Abstract
The DNA sliding clamp proliferating cell nuclear antigen (PCNA) is an essential co-factor for many eukaryotic DNA metabolic enzymes. PCNA is loaded around DNA by the ATP-dependent clamp loader replication factor C (RFC), which acts at single-stranded (ss)/double-stranded DNA (dsDNA) junctions harboring a recessed 3' end (3' ss/dsDNA junctions) and at DNA nicks. To illuminate the loading mechanism we have investigated the structure of RFC:PCNA bound to ATPĪ³S and 3' ss/dsDNA junctions or nicked DNA using cryogenic electron microscopy. Unexpectedly, we observe open and closed PCNA conformations in the RFC:PCNA:DNA complex, revealing that PCNA can adopt an open, planar conformation that allows direct insertion of dsDNA, and raising the question of whether PCNA ring closure is mechanistically coupled to ATP hydrolysis. By resolving multiple DNA-bound states of RFC:PCNA we observe that partial melting facilitates lateral insertion into the central channel formed by RFC:PCNA. We also resolve the Rfc1 N-terminal domain and demonstrate that its single BRCT domain participates in coordinating DNA prior to insertion into the central RFC channel, which promotes PCNA loading on the lagging strand of replication forks in vitro. Combined, our data suggest a comprehensive and fundamentally revised model for the RFC-catalyzed loading of PCNA onto DNA.

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