title: The RAD51 family member, RAD51L3, is a DNA-stimulated ATPase that forms a complex with XRCC2.
abstract: The Rad51 protein in eukaryotic cells is a structural and functional homolog of Escherichia coli RecA with a role in DNA repair and genetic recombination. Several proteins showing sequence similarity to Rad51 have previously been identified in both yeast and human cells. In Saccharomyces cerevisiae, two of these proteins, Rad55p and Rad57p, form a heterodimer that can stimulate Rad51-mediated DNA strand exchange. Here, we report the purification of one of the representatives of the RAD51 family in human cells. We demonstrate that the purified RAD51L3 protein possesses single-stranded DNA binding activity and DNA-stimulated ATPase activity, consistent with the presence of "Walker box" motifs in the deduced RAD51L3 sequence. We have identified a protein complex in human cells containing RAD51L3 and a second RAD51 family member, XRCC2. By using purified proteins, we demonstrate that the interaction between RAD51L3 and XRCC2 is direct. Given the requirements for XRCC2 in genetic recombination and protection against DNA-damaging agents, we suggest that the complex of RAD51L3 and XRCC2 is likely to be important for these functions in human cells.
authors.affiliation: Imperial Cancer Research Fund Laboratories, Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DS, Oxfordshire OX11 ORD, United Kingdom.
authors.forename: J P
authors.initials: JP
authors.lastname: Braybrooke
authors.forename: K G
authors.initials: KG
authors.lastname: Spink
authors.forename: J
authors.initials: J
authors.lastname: Thacker
authors.forename: I D
authors.initials: ID
authors.lastname: Hickson
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002460:Cell Line; D004247:DNA / Q000494:pharmacology*; D004249:DNA Damage; D004277:DNA, Single-Stranded / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000276:immunology / Q000302:isolation & purification / Q000378:metabolism*; D006801:Humans; D008297:Male; D008970:Molecular Weight; D011817:Rabbits; D051135:Rad51 Recombinase; D011994:Recombinant Proteins / Q000302:isolation & purification
chemical_list: D004277:DNA, Single-Stranded; D004268:DNA-Binding Proteins; D011994:Recombinant Proteins; C113187:XRCC2 protein, human; D000255:Adenosine Triphosphate; D004247:DNA; C495153:RAD51 protein, human; D051135:Rad51 Recombinase; D000251:Adenosine Triphosphatases