Download MendeleyCryo-EM structures reveal that RFC recognizes both the 3'- and 5'-DNA ends to load PCNA onto gaps for DNA repair.
Zheng, F., Georgescu, R., Yao, N.Y., Li, H., O'Donnell, M.E.(2022) Elife 11
- PubMed: 35829698
- DOI: https://doi.org/10.7554/eLife.77469
- Primary Citation of Related Structures:
7TFH, 7TFI, 7TFJ, 7TFK, 7TFL - PubMed Abstract:
RFC uses ATP to assemble PCNA onto primed sites for replicative DNA polymerases δ and ε. The RFC pentamer forms a central chamber that binds 3' ss/ds DNA junctions to load PCNA onto DNA during replication. We show here five structures that identify a second DNA binding site in RFC that binds a 5' duplex. This 5' DNA site is located between the N-terminal BRCT domain and AAA+ module of the large Rfc1 subunit. Our structures reveal ideal binding to a 7-nt gap, which includes 2 bp unwound by the clamp loader. Biochemical studies show enhanced binding to 5 and 10 nt gaps, consistent with the structural results. Because both 3' and 5' ends are present at a ssDNA gap, we propose that the 5' site facilitates RFC's PCNA loading activity at a DNA damage-induced gap to recruit gap-filling polymerases. These findings are consistent with genetic studies showing that base excision repair of gaps greater than 1 base requires PCNA and involves the 5' DNA binding domain of Rfc1. We further observe that a 5' end facilitates PCNA loading at an RPA coated 30-nt gap, suggesting a potential role of the RFC 5'-DNA site in lagging strand DNA synthesis.
Organizational Affiliation:
Department of Structural Biology, Van Andel Institute, Grand Rapids, United States.
