Assembly and disassembly of DNA repair protein complexes at DNA damage sites are essential for maintaining genomic integrity. Investigating factors coordinating assembly of the base excision repair (BER) proteins DNA polymerase β (Polβ) and XRCC1 to DNA lesion sites identifies a role for Polβ in regulating XRCC1 disassembly from DNA repair complexes and, conversely, demonstrates Polβ’s dependence on XRCC1 for complex assembly. LivePAR, a genetically encoded probe for live-cell imaging of poly(ADP-ribose) (PAR), reveals that Polβ and XRCC1 require PAR for repair-complex assembly, with PARP1 and PARP2 playing unique roles in complex dynamics. Further, BER complex assembly is modulated by attenuation/augmentation of NAD⁺ biosynthesis. Finally, SIRT6 does not modulate PARP1 or PARP2 activation but does regulate XRCC1 recruitment, leading to diminished Polβ abundance at sites of DNA damage. These findings highlight coordinated yet independent roles for PARP1, PARP2, and SIRT6 and their regulation by NAD⁺ bioavailability to facilitate BER.

在 DNA 损伤位点组装和拆卸 DNA 修复蛋白复合物对于维持基因组完整性至关重要。调查协调碱基切除修复 (BER) 蛋白 DNA 聚合酶 β (Polβ) 和 XRCC1 组装到 DNA 损伤位点的因素，确定了 Polβ 在调节 XRCC1 从 DNA 修复复合物中解体中的作用，相反，证明 Polβ 对 XRCC1 的复杂组装的依赖. LivePAR 是一种用于聚 (ADP-核糖) (PAR) 活细胞成像的基因编码探针，它揭示了 Polβ 和 XRCC1 需要 PAR 才能进行修复复合物组装，而 PARP1 和 PARP2 在复杂动力学中发挥着独特的作用。^{此外，BER 复合组件通过 NAD +}的衰减/增强来调制生物合成。最后，SIRT6 不调节 PARP1 或 PARP2 激活，但确实调节 XRCC1 募集，导致 DNA 损伤部位的 Polβ 丰度降低。这些发现强调了 PARP1、PARP2 和 SIRT6 的协调但独立的作用，以及它们通过 NAD ⁺生物利用度的调节以促进 BER。