title: p53 suppresses BRCA2-stimulated ATPase and strand exchange functions of human RAD51.
abstract: Although homologous recombination (HR) is an important pathway for DNA repair, it can also be a cause for deleterious genomic rearrangements leading to carcinogenesis. Therefore, cells have evolved elaborate mechanisms to regulate HR, positively as well as negatively. Among many molecular components that regulate HR are tumour suppressors p53, a negative regulator and breast cancer early-onset (BRCA)2, a positive regulator. Both the players not only interact with each other but also directly interact with human RAD51 (hRAD51), the key recombinase in HR. Here, for the first time we studied HR regulation by the combined action of p53 and BRCA2, in vitro. While BRC4 peptide inhibits ATP hydrolysis by hRAD51, BRCA2(BRC1-8) stimulates DNA-independent and double-stranded DNA-dependent ATPase several fold and only marginally single-stranded DNA-dependent ATPase. Pull down assays demonstrated the occurrence of complex comprising of all three proteins and DNA, where p53 tends to compete out hRAD51 and BRCA2(BRC1-8), leading to not only the decline in ATP hydrolysis but also the strand exchange function of hRAD51 that was stimulated by BRCA2(BRC1-8). Our findings suggest a rigorous p53-mediated regulation on hRAD51 functions in HR even in the presence of BRCA2.
authors.affiliation: Department of Biological Sciences, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400 005, Maharashtra, India.
authors.forename: Shalini
authors.initials: S
authors.lastname: Verma
authors.forename: Basuthkar J
authors.initials: BJ
authors.lastname: Rao
mesh_terms: D000251:Adenosine Triphosphatases / Q000235:genetics* / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D024682:BRCA2 Protein / Q000235:genetics* / Q000378:metabolism; D004247:DNA / Q000235:genetics / Q000378:metabolism; D004277:DNA, Single-Stranded / Q000235:genetics / Q000378:metabolism; D004331:Drosophila melanogaster / Q000235:genetics / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D005057:Eukaryotic Cells / Q000166:cytology / Q000378:metabolism; D005786:Gene Expression Regulation; D059765:Homologous Recombination; D006801:Humans; D006868:Hydrolysis; D051135:Rad51 Recombinase / Q000235:genetics* / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D016159:Tumor Suppressor Protein p53 / Q000235:genetics* / Q000378:metabolism
chemical_list: D024682:BRCA2 Protein; C551750:BRCA2 protein, human; D004277:DNA, Single-Stranded; D011994:Recombinant Proteins; D016159:Tumor Suppressor Protein p53; D000255:Adenosine Triphosphate; D004247:DNA; C495153:RAD51 protein, human; D051135:Rad51 Recombinase; D000251:Adenosine Triphosphatases
keywords: ATP hydrolysis; BRCA2; RAD51; homologous recombination; p53