Replication Factor C Clamp Loader Subunit Arrangement within the Circular Pentamer and Its Attachment Points to Proliferating Cell Nuclear Antigen

摘要: Replication factor C (RFC) is a heteropentameric AAA+ protein clamp loader of the proliferating cell nuclear antigen (PCNA) processivity factor. The prokaryotic homologue, γ complex, also heteropentamer, and structural studies show subunits are arranged in circle. In this report, Saccharomyces cerevisiae RFC protomers examined for their interaction with each other PCNA. data lead to model subunit order around A characteristic oligomers use bipartite ATP sites which one supplies catalytic arginine residue hydrolysis bound neighboring subunit. We find that RFC(3/4) complex DNA-dependent ATPase, we activity determine RFC3 site RFC4. This information, combined arrangement, defines composition remaining sites. Furthermore, RFC(2/3) subassemblies bind stably PCNA, yet neither RFC2 nor RFC4 tightly indicating forms strong contact point RFC1 binds PCNA tightly, identify two hydrophobic residues important interaction. Therefore, at least make contacts unlike Escherichia coli only makes β clamp. Multiple points may reflect extra demands loading trimeric ring onto DNA compared dimeric ring.