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. © 2011 by the Biophysical Society.
Liu, C., McKinney, M. C., Chen, Y. H., Earnest, T. M., Shi, X., Lin, L. J., … Ha, T. (2011). Reverse-chaperoning activity of an AAA+ protein. Biophysical Journal, 100(5), 1344–1352. https://doi.org/10.1016/j.bpj.2011.01.057