Dissecting BRCA1-PALB2 Activity in DNA Repair and Development

项目摘要 BRCA 1和PALB 2蛋白通过它们各自的卷曲螺旋（CC）结构域直接异二聚化， 促进形成RAD 51细丝所需的更大的BRCA 1-PALB 2-BRCA 2-RAD 51复合物 阵目前，对BRCA 1-PALB 2相互作用的结构基础知之甚少，包括 物理相互作用的β-螺旋的残基排列和取向。阐明CC分子相互作用是 这对于理解患者中发现的突变如何破坏肽相互作用并促进疾病至关重要。 蛋白质CC结构域能够介导与几个含有CC结构域的配偶体的相互作用。然而，在这方面， BRCA 1和PALB 2形成了唯一已知的由它们各自的CC结构域介导的相互作用。是否 BRCA 1和PALB 2 CC结构域仅相互作用，或者如果存在额外的CC相互作用， 功能不明。本实验室开发了新型BRCA 1和PALB 2 CC结构域突变小鼠 模型来研究这种相互作用在DNA修复和生物体健康中的意义。我们还 纯化的CC肽，以便可以进行生物化学测定，评估突变对复合物的影响。 互动和活动。BRCA 1和PALB 2 CC结构域的唯一已知功能是与一个 因此，另一种BRCA 1CC和PALB 2CC纯合子小鼠可能具有相同的表型。 然而，尽管BRCA 1CC小鼠以亚孟德尔比率出生，新生小鼠表现出一系列的 发育缺陷，PALB 2CC纯合性导致早期胚胎死亡。因为BRCA 1CC和 PALB 2CC小鼠具有不同的表型，我们假设CC结构域促进蛋白质相互作用， 促进DNA修复和胚胎发育BRCA 1-PALB 2异二聚体。我们将解决 以下具体目标：1）确定生物化学CC相互作用和活性; 2）揭示DNA修复， CC突变小鼠的发育缺陷;和3）阐明BRCA 1-PALB 2复合物募集的机制 DNA断裂总的来说，所提出的实验将产生新的见解的机制， BRCA 1-PALB 2复合物保护基因组不稳定性。

PROJECT SUMMARY The BRCA1 and PALB2 proteins directly heterodimerize through their respective coiled-coil (CC) domains, facilitating the formation of a larger BRCA1-PALB2-BRCA2-RAD51 complex that is required for RAD51 filament formation. Currently, little is known about the structural basis of the BRCA1-PALB2 interaction, including the residue alignment and orientation of physically interacting -helices. Elucidating CC molecular interactions is critical for understanding how mutations found in patients disrupt peptide interactions and promote disease. Protein CC domains are capable of mediating interactions with several CC domain containing partners. However, BRCA1 and PALB2 form the only known interaction that is mediated by their respective CC domains. Whether BRCA1 and PALB2 CC domains exclusively interact with one another, or if there are additional CC interactions and functions is unknown. Our laboratory has developed novel BRCA1 and PALB2 CC domain mutant mouse models to investigate the significance of this interaction in DNA repair and organismal health. We have also purified CC peptides so that biochemical assays can be performed assessing the effects of mutations on complex interactions and activity. The only known function of BRCA1 and PALB2 CC domains is to interact with one another, thus, BRCA1CC and PALB2CC homozygous mice might be expected to have identical phenotypes. However, while BRCA1CC mice are born at sub-Mendelian ratios and neo-natal mice demonstrate a range of developmental defects, PALB2CC homozygosity resulted in early embryonic lethality. Because BRCA1CC and PALB2CC mice have distinct phenotypes, we hypothesize that CC domains facilitate protein interactions beyond the BRCA1-PALB2 heterodimer that promote DNA repair and embryonic development. We will address the following Specific Aims: 1) Determine biochemical CC interactions and activity; 2) Uncover DNA repair and developmental defects in CC mutant mice; and 3) Elucidate mechanisms of BRCA1-PALB2 complex recruitment to DNA breaks. Collectively, the proposed experiments will yield new insight into the mechanism by which the BRCA1-PALB2 complex protects from genome instability.