title: Reverse-chaperoning activity of an AAA+ protein.
abstract: 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.
authors.affiliation: Department of Physics and the Center for the Physics of Living Cells, University of Illinois at Urbana-Champaign, Champaign, Illinois, USA.
authors.forename: Cheng
authors.initials: C
authors.lastname: Liu
authors.forename: Mary C
authors.initials: MC
authors.lastname: McKinney
authors.forename: Yi-Hsing
authors.initials: YH
authors.lastname: Chen
authors.forename: Emmy E
authors.initials: EE
authors.lastname: Earnest
authors.forename: Xinghua
authors.initials: X
authors.lastname: Shi
authors.forename: Li-Jung
authors.initials: LJ
authors.lastname: Lin
authors.forename: Yoshizumi
authors.initials: Y
authors.lastname: Ishino
authors.forename: Karin
authors.initials: K
authors.lastname: Dahmen
authors.forename: Isaac K O
authors.initials: IK
authors.lastname: Cann
authors.forename: Taekjip
authors.initials: T
authors.lastname: Ha
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D019843:Archaeal Proteins / Q000378:metabolism*; D004247:DNA / Q000737:chemistry / Q000378:metabolism; D007700:Kinetics; D017020:Methanosarcina; D018832:Molecular Chaperones / Q000378:metabolism*; D018809:Proliferating Cell Nuclear Antigen / Q000737:chemistry / Q000378:metabolism; D055503:Protein Multimerization; D020836:Protein Structure, Quaternary; D051818:Replication Protein C / Q000378:metabolism*
chemical_list: D019843:Archaeal Proteins; D018832:Molecular Chaperones; D018809:Proliferating Cell Nuclear Antigen; D000255:Adenosine Triphosphate; D004247:DNA; D051818:Replication Protein C