title: Disparate requirements for the Walker A and B ATPase motifs of human RAD51D in homologous recombination.
abstract: In vertebrates, homologous recombinational repair (HRR) requires RAD51 and five RAD51 paralogs (XRCC2, XRCC3, RAD51B, RAD51C and RAD51D) that all contain conserved Walker A and B ATPase motifs. In human RAD51D we examined the requirement for these motifs in interactions with XRCC2 and RAD51C, and for survival of cells in response to DNA interstrand crosslinks (ICLs). Ectopic expression of wild-type human RAD51D or mutants having a non-functional A or B motif was used to test for complementation of a rad51d knockout hamster CHO cell line. Although A-motif mutants complement very efficiently, B-motif mutants do not. Consistent with these results, experiments using the yeast two- and three-hybrid systems show that the interactions between RAD51D and its XRCC2 and RAD51C partners also require a functional RAD51D B motif, but not motif A. Similarly, hamster Xrcc2 is unable to bind to the non-complementing human RAD51D B-motif mutants in co-immunoprecipitation assays. We conclude that a functional Walker B motif, but not A motif, is necessary for RAD51D's interactions with other paralogs and for efficient HRR. We present a model in which ATPase sites are formed in a bipartite manner between RAD51D and other RAD51 paralogs.
authors.affiliation: Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA. cwiese@lbl.gov
authors.forename: Claudia
authors.initials: C
authors.lastname: Wiese
authors.forename: John M
authors.initials: JM
authors.lastname: Hinz
authors.forename: Robert S
authors.initials: RS
authors.lastname: Tebbs
authors.forename: Peter B
authors.initials: PB
authors.lastname: Nham
authors.forename: Salustra S
authors.initials: SS
authors.lastname: Urbin
authors.forename: David W
authors.initials: DW
authors.lastname: Collins
authors.forename: Larry H
authors.initials: LH
authors.lastname: Thompson
authors.forename: David
authors.initials: D
authors.lastname: Schild
mesh_terms: D000251:Adenosine Triphosphatases / Q000737:chemistry*; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D004249:DNA Damage; D004260:DNA Repair; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D005816:Genetic Complementation Test; D006801:Humans; D047468:Immunoprecipitation; D008969:Molecular Sequence Data; D009154:Mutation; D051135:Rad51 Recombinase / Q000378:metabolism; D011995:Recombination, Genetic; D020798:Two-Hybrid System Techniques
chemical_list: D004268:DNA-Binding Proteins; C112629:RAD51D protein, human; D051135:Rad51 Recombinase; D000251:Adenosine Triphosphatases