Homologous recombination mediated by RAD51 recombinase helps eliminate chromosomal lesions, such as DNA double-strand breaks induced by radiation or arising from injured DNA replication forks. The tumor suppressors BRCA2 and PALB2 act together to deliver RAD51 to chromosomal lesions to initiate repair. Here we document a new function of PALB2: to enhance RAD51's ability to form the D loop. We show that PALB2 binds DNA and physically interacts with RAD51. Notably, although PALB2 alone stimulates D-loop formation, it has a cooperative effect with RAD51AP1, an enhancer of RAD51. This stimulation stems from the ability of PALB2 to function with RAD51 and RAD51AP1 to assemble the synaptic complex. Our results demonstrate the multifaceted role of PALB2 in chromosome damage repair. Because PALB2 mutations can cause cancer or Fanconi anemia, our findings shed light on the mechanism of tumor suppression in humans.
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We are grateful to R. Buisson and J.-Y. Masson (Centre de Recherche du Centre hospitalier universitaire de Québec) for the communication of results before publication, to S. Begovic, S. Longerich and Y.-C. Kim (Yale University) for assistance, to Y. Kwon (Yale University) for providing ScRad51 protein and to B. Xia (Department of Radiation Oncology, The Cancer Institute of NJ) for providing PALB2-deficient and PALB2-complemented cells, as well as for providing PALB2 antibody. This study was supported by research and program project grants RO1CA120315, RO1ES07061, RO1ES015252, RO1ES015632, PO1CA129186 and PO1CA92584 from the US National Institutes of Health and by postdoctoral fellowship PDF0706844 from the Susan G. Komen for the Cure Foundation.
The authors declare no competing financial interests.
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Dray, E., Etchin, J., Wiese, C. et al. Enhancement of RAD51 recombinase activity by the tumor suppressor PALB2. Nat Struct Mol Biol 17, 1255–1259 (2010). https://doi.org/10.1038/nsmb.1916
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