title: Compensatory functions and interdependency of the DNA-binding domain of BRCA2 with the BRCA1-PALB2-BRCA2 complex.
abstract: BRCA1, BRCA2, and PALB2 are key players in cellular tolerance to chemotherapeutic agents, including camptothecin, cisplatin, and PARP inhibitor. The N-terminal segment of BRCA2 interacts with PALB2, thus contributing to the formation of the BRCA1-PALB2-BRCA2 complex. To understand the role played by BRCA2 in this complex, we deleted its N-terminal segment and generated BRCA2(Δ)(N) mutant cells. Although previous studies have suggested that BRCA1-PALB2 plays a role in the recruitment of BRCA2 to DNA-damage sites, BRCA2(Δ)(N) mutant cells displayed a considerably milder phenotype than did BRCA2(-/-) null-deficient cells. We hypothesized that the DNA-binding domain (DBD) of BRCA2 might compensate for a defect in BRCA2(ΔN) that prevented stable interaction with PALB2. To test this hypothesis, we disrupted the DBD of BRCA2 in wild-type and BRCA2(Δ)(N) cells. Remarkably, although the resulting BRCA2(Δ)(DBD) cells displayed a moderate phenotype, the BRCA2(Δ)(N+ΔDBD) cells displayed a very severe phenotype, as did the BRCA2(-/-) cells, suggesting that the N-terminal segment and the DBD play a substantially overlapping role in the functionality of BRCA2. We also showed that the formation of both the BRCA1-PALB2-BRCA2 complex and the DBD is required for efficient recruitment of BRCA2 to DNA-damage sites. Our study revealed the essential role played by both the BRCA1-PALB2-BRCA2 complex and the DBD in the functionality of BRCA2, as each can compensate for the other in the recruitment of BRCA2 to DNA-damage sites. This knowledge adds to our ability to accurately predict the efficacy of antimalignant therapies for patients carrying mutations in the BRCA2 gene.
authors.affiliation: Authors' Affiliations: Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Sakyo-ku; and Laboratory of Structural Biology, Graduate School of Advanced Science and Engineering, Waseda University, Shinjuku-ku, Tokyo, Japan.
authors.forename: Muthana
authors.initials: M
authors.lastname: Al Abo
authors.forename: Donniphat
authors.initials: D
authors.lastname: Dejsuphong
authors.forename: Kouji
authors.initials: K
authors.lastname: Hirota
authors.forename: Yasukazu
authors.initials: Y
authors.lastname: Yonetani
authors.forename: Mitsuyoshi
authors.initials: M
authors.lastname: Yamazoe
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Kurumizaka
authors.forename: Shunichi
authors.initials: S
authors.lastname: Takeda
mesh_terms: D019313:BRCA1 Protein / Q000378:metabolism*; D024682:BRCA2 Protein / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D002869:Chromosome Aberrations; D004247:DNA / Q000378:metabolism*; D004249:DNA Damage / Q000187:drug effects; D000076164:Fanconi Anemia Complementation Group N Protein; D017353:Gene Deletion; D055786:Gene Knockout Techniques; D005838:Genotype; D006801:Humans; D008938:Mitosis; D046912:Multiprotein Complexes / Q000378:metabolism*; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D010641:Phenotype; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D051135:Rad51 Recombinase / Q000235:genetics / Q000378:metabolism; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D019313:BRCA1 Protein; D024682:BRCA2 Protein; D000076164:Fanconi Anemia Complementation Group N Protein; D046912:Multiprotein Complexes; D009687:Nuclear Proteins; C512790:PALB2 protein, human; D025521:Tumor Suppressor Proteins; D004247:DNA; D051135:Rad51 Recombinase