title: RAD51 protein ATP cap regulates nucleoprotein filament stability.
abstract: RAD51 mediates homologous recombination by forming an active DNA nucleoprotein filament (NPF). A conserved aspartate that forms a salt bridge with the ATP γ-phosphate is found at the nucleotide-binding interface between RAD51 subunits of the NPF known as the ATP cap. The salt bridge accounts for the nonphysiological cation(s) required to fully activate the RAD51 NPF. In contrast, RecA homologs and most RAD51 paralogs contain a conserved lysine at the analogous structural position. We demonstrate that substitution of human RAD51(Asp-316) with lysine (HsRAD51(D316K)) decreases NPF turnover and facilitates considerably improved recombinase functions. Structural analysis shows that archaebacterial Methanococcus voltae RadA(D302K) (MvRAD51(D302K)) and HsRAD51(D316K) form extended active NPFs without salt. These studies suggest that the HsRAD51(Asp-316) salt bridge may function as a conformational sensor that enhances turnover at the expense of recombinase activity.
authors.affiliation: Biophysics Graduate Program, Department of Molecular Virology, Immunology, and Medical Genetics, Ohio State University, Columbus, Ohio 43210, USA.
authors.forename: Ravindra
authors.initials: R
authors.lastname: Amunugama
authors.forename: Yujiong
authors.initials: Y
authors.lastname: He
authors.forename: Smaranda
authors.initials: S
authors.lastname: Willcox
authors.forename: Robert A
authors.initials: RA
authors.lastname: Forties
authors.forename: Kang-Sup
authors.initials: KS
authors.lastname: Shim
authors.forename: Ralf
authors.initials: R
authors.lastname: Bundschuh
authors.forename: Yu
authors.initials: Y
authors.lastname: Luo
authors.forename: Jack
authors.initials: J
authors.lastname: Griffith
authors.forename: Richard
authors.initials: R
authors.lastname: Fishel
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism*; D000595:Amino Acid Sequence; D019843:Archaeal Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D018360:Crystallography, X-Ray; D006801:Humans; D017017:Methanococcus / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics; D008969:Molecular Sequence Data; D009698:Nucleoproteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D055550:Protein Stability; D051135:Rad51 Recombinase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment
chemical_list: D019843:Archaeal Proteins; D009698:Nucleoproteins; D000255:Adenosine Triphosphate; D051135:Rad51 Recombinase