Mechanism of PCNA loading by Ctf18-RFC for leading-strand DNA synthesis.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 39088616.
- Also identified by DOI 10.1126/science.adk5901 and PMC identifier 11349045.
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Abstract
The proliferating cell nuclear antigen (PCNA) clamp encircles DNA to hold DNA polymerases (Pols) to DNA for processivity. The Ctf18-RFC PCNA loader, a replication factor C (RFC) variant, is specific to the leading-strand Pol (Polε). We reveal here the underlying mechanism of Ctf18-RFC specificity to Polε using cryo-electron microscopy and biochemical studies. We found that both Ctf18-RFC and Polε contain specific structural features that direct PCNA loading onto DNA. Unlike other clamp loaders, Ctf18-RFC has a disordered ATPase associated with a diverse cellular activities (AAA+) motor that requires Polε to bind and stabilize it for efficient PCNA loading. In addition, Ctf18-RFC can pry prebound Polε off of DNA, then load PCNA onto DNA and transfer the PCNA-DNA back to Polε. These elements in both Ctf18-RFC and Polε provide specificity in loading PCNA onto DNA for Polε.
Medical subject headings
- DNA Replication
- Proliferating Cell Nuclear Antigen
- Replication Protein C