Department of Chemistry, Georgia State University, Atlanta, GA, USA.
Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, GA, USA.
Nat Commun. 2021 Dec 1;12(1):7001. doi: 10.1038/s41467-021-27295-4.
Transcription-coupled repair is essential for the removal of DNA lesions from the transcribed genome. The pathway is initiated by CSB protein binding to stalled RNA polymerase II. Mutations impairing CSB function cause severe genetic disease. Yet, the ATP-dependent mechanism by which CSB powers RNA polymerase to bypass certain lesions while triggering excision of others is incompletely understood. Here we build structural models of RNA polymerase II bound to the yeast CSB ortholog Rad26 in nucleotide-free and bound states. This enables simulations and graph-theoretical analyses to define partitioning of this complex into dynamic communities and delineate how its structural elements function together to remodel DNA. We identify an allosteric pathway coupling motions of the Rad26 ATPase modules to changes in RNA polymerase and DNA to unveil a structural mechanism for CSB-assisted progression past less bulky lesions. Our models allow functional interpretation of the effects of Cockayne syndrome disease mutations.
转录偶联修复对于从转录基因组中去除 DNA 损伤至关重要。该途径由 CSB 蛋白与停滞的 RNA 聚合酶 II 结合启动。破坏 CSB 功能的突变会导致严重的遗传疾病。然而，CSB 如何利用 ATP 驱动 RNA 聚合酶绕过某些损伤，同时触发其他损伤切除的 ATP 依赖性机制仍不完全清楚。在这里，我们构建了结合在酵母 CSB 同源物 Rad26 上的无核苷酸和结合状态的 RNA 聚合酶 II 的结构模型。这使得模拟和图论分析能够将该复合物划分为动态社区，并阐明其结构元件如何协同作用以重塑 DNA。我们确定了一种变构途径，将 Rad26 ATP 酶模块的运动与 RNA 聚合酶和 DNA 的变化联系起来，从而揭示了 CSB 辅助通过较小体积损伤的结构机制。我们的模型允许对 Cockayne 综合征疾病突变的影响进行功能解释。
