title: Tumor-associated mutations in a conserved structural motif alter physical and biochemical properties of human RAD51 recombinase.
abstract: Human RAD51 protein catalyzes DNA pairing and strand exchange reactions that are central to homologous recombination and homology-directed DNA repair. Successful recombination/repair requires the formation of a presynaptic filament of RAD51 on ssDNA. Mutations in BRCA2 and other proteins that control RAD51 activity are associated with human cancer. Here we describe a set of mutations associated with human breast tumors that occur in a common structural motif of RAD51. Tumor-associated D149N, R150Q and G151D mutations map to a Schellman loop motif located on the surface of the RecA homology domain of RAD51. All three variants are proficient in DNA strand exchange, but G151D is slightly more sensitive to salt than wild-type (WT). Both G151D and R150Q exhibit markedly lower catalytic efficiency for adenosine triphosphate hydrolysis compared to WT. All three mutations alter the physical properties of RAD51 nucleoprotein filaments, with G151D showing the most dramatic changes. G151D forms mixed nucleoprotein filaments with WT RAD51 that have intermediate properties compared to unmixed filaments. These findings raise the possibility that mutations in RAD51 itself may contribute to genome instability in tumor cells, either directly through changes in recombinase properties, or indirectly through changes in interactions with regulatory proteins.
authors.affiliation: Department of Biochemistry, University of Vermont College of Medicine, Burlington, VT 05405, USA.
authors.forename: Jianhong
authors.initials: J
authors.lastname: Chen
authors.affiliation: Department of Biochemistry, University of Vermont College of Medicine, Burlington, VT 05405, USA.
authors.forename: Milagros D
authors.initials: MD
authors.lastname: Morrical
authors.affiliation: Department of Therapeutic Radiology, Yale University School of Medicine, New Haven, CT 06520, USA.
authors.forename: Katherine A
authors.initials: KA
authors.lastname: Donigan
authors.affiliation: Department of Radiation Oncology, University of California-Los Angeles, Los Angeles, CA 90095, USA.
authors.forename: Joanne B
authors.initials: JB
authors.lastname: Weidhaas
authors.affiliation: Department of Microbiology and Molecular Genetics, University of Vermont College of Medicine, Burlington, VT 05405, USA Department of Therapeutic Radiology, Yale University School of Medicine, New Haven, CT 06520, USA.
authors.forename: Joann B
authors.initials: JB
authors.lastname: Sweasy
authors.affiliation: Department of Microbiology and Molecular Genetics, University of Vermont College of Medicine, Burlington, VT 05405, USA.
authors.forename: April M
authors.initials: AM
authors.lastname: Averill
authors.affiliation: Department of Biochemistry, University of Vermont College of Medicine, Burlington, VT 05405, USA.
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Tomczak
authors.affiliation: Department of Biochemistry, University of Vermont College of Medicine, Burlington, VT 05405, USA Department of Microbiology and Molecular Genetics, University of Vermont College of Medicine, Burlington, VT 05405, USA smorrica@uvm.edu.
authors.forename: Scott W
authors.initials: SW
authors.lastname: Morrical
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D020816:Amino Acid Motifs / Q000235:genetics; D004247:DNA / Q000378:metabolism; D006801:Humans; D008958:Models, Molecular; D009154:Mutation; D009369:Neoplasms / Q000235:genetics*; D017510:Protein Folding; D051135:Rad51 Recombinase / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism
chemical_list: D000255:Adenosine Triphosphate; D004247:DNA; D051135:Rad51 Recombinase