Reverse-chaperoning activity of an AAA+ protein

Biophys J. 2011 Mar 2;100(5):1344-52. doi: 10.1016/j.bpj.2011.01.057.


Speed and processivity of replicative DNA polymerases can be enhanced via coupling to a sliding clamp. Due to the closed ring shape of the clamp, a clamp loader protein, belonging to the AAA+ class of ATPases, needs to open the ring-shaped clamp before loading it to DNA. Here, we developed real-time fluorescence assays to study the clamp (PCNA) and the clamp loader (RFC) from the mesophilic archaeon Methanosarcina acetivorans. Unexpectedly, we discovered that RFC can assemble a PCNA ring from monomers in solution. A motion-based DNA polymerization assay showed that the PCNA assembled by RFC is functional. This PCNA assembly activity required the ATP-bound conformation of RFC. Our work demonstrates a reverse-chaperoning activity for an AAA+ protein that can act as a template for the assembly of another protein complex.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Adenosine Triphosphate / metabolism
  • Archaeal Proteins / metabolism*
  • DNA / chemistry
  • DNA / metabolism
  • Kinetics
  • Methanosarcina*
  • Molecular Chaperones / metabolism*
  • Proliferating Cell Nuclear Antigen / chemistry
  • Proliferating Cell Nuclear Antigen / metabolism
  • Protein Multimerization
  • Protein Structure, Quaternary
  • Replication Protein C / metabolism*


  • Archaeal Proteins
  • Molecular Chaperones
  • Proliferating Cell Nuclear Antigen
  • Adenosine Triphosphate
  • DNA
  • Replication Protein C