7TIB

Structure of the yeast clamp loader (Replication Factor C RFC) bound to the open sliding clamp (Proliferating Cell Nuclear Antigen PCNA) and primer-template DNA

Summary for 7TIB

• Entry DOI: 10.2210/pdb7tib/pdb
• EMDB information: 25616
• Descriptor: Replication factor C subunit 1, MAGNESIUM ION, ADENOSINE-5'-DIPHOSPHATE, ... (11 entities in total)
• Functional Keywords: sliding clamp, dna replication, aaa+, clamp loader, replication-dna complex, replication/dna
• Biological source: Saccharomyces cerevisiae (baker's yeast); More
• Total number of polymer chains: 10
• Total formula weight: 355696.15

Authors

Gaubitz, C.,Liu, X.,Pajak, J.,Stone, N.,Hayes, J.,Demo, G.,Kelch, B.A. (deposition date: 2022-01-13, release date: 2022-02-16, Last modification date: 2024-02-28)

Primary citation

Gaubitz, C.,Liu, X.,Pajak, J.,Stone, N.P.,Hayes, J.A.,Demo, G.,Kelch PhD, B.A.
Cryo-EM structures reveal high-resolution mechanism of a DNA polymerase sliding clamp loader.
Elife, 11:-, 2022

PubMed Abstract: Sliding clamps are ring-shaped protein complexes that are integral to the DNA replication machinery of all life. Sliding clamps are opened and installed onto DNA by clamp loader AAA+ ATPase complexes. However, how a clamp loader opens and closes the sliding clamp around DNA is still unknown. Here, we describe structures of the clamp loader Replication Factor C (RFC) bound to its cognate sliding clamp Proliferating Cell Nuclear Antigen (PCNA) en route to successful loading. RFC first binds to PCNA in a dynamic, closed conformation that blocks both ATPase activity and DNA binding. RFC then opens the PCNA ring through a large-scale 'crab-claw' expansion of both RFC and PCNA that explains how RFC prefers initial binding of PCNA over DNA. Next, the open RFC:PCNA complex binds DNA and interrogates the primer-template junction using a surprising base-flipping mechanism. Our structures indicate that initial PCNA opening and subsequent closure around DNA do not require ATP hydrolysis, but are driven by binding energy. ATP hydrolysis, which is necessary for RFC release, is triggered by interactions with both PCNA and DNA, explaining RFC's switch-like ATPase activity. Our work reveals how a AAA+ machine undergoes dramatic conformational changes for achieving binding preference and substrate remodeling.

PubMed: 35179493
DOI: 10.7554/eLife.74175

Experimental method

ELECTRON MICROSCOPY (3.4 Å)