DNA–protein crosslinks (DPCs) arise from enzymatic intermediates, metabolism or chemicals like chemotherapeutics. DPCs are highly cytotoxic as they impede DNA-based processes such as replication, which is counteracted through proteolysis-mediated DPC removal by spartan (SPRTN) or the proteasome. However, whether DPCs affect transcription and how transcription-blocking DPCs are repaired remains largely unknown. Here we show that DPCs severely impede RNA polymerase II-mediated transcription and are preferentially repaired in active genes by transcription-coupled DPC (TC-DPC) repair. TC-DPC repair is initiated by recruiting the transcription-coupled nucleotide excision repair (TC-NER) factors CSB and CSA to DPC-stalled RNA polymerase II. CSA and CSB are indispensable for TC-DPC repair; however, the downstream TC-NER factors UVSSA and XPA are not, a result indicative of a non-canonical TC-NER mechanism. TC-DPC repair functions independently of SPRTN but is mediated by the ubiquitin ligase CRL4^CSA and the proteasome. Thus, DPCs in genes are preferentially repaired in a transcription-coupled manner to facilitate unperturbed transcription.

DNA-蛋白质交联 (DPC) 源自酶促中间体、新陈代谢或化疗药物等化学物质。 DPC 具有高度细胞毒性，因为它们会阻碍复制等基于 DNA 的过程，而复制等过程可通过斯巴达 (SPRTN) 或蛋白酶体的蛋白水解介导的 DPC 去除来抵消。然而，DPC 是否影响转录以及转录阻断 DPC 如何修复仍然很大程度上未知。在这里，我们发现 DPC 严重阻碍 RNA 聚合酶 II 介导的转录，并优先通过转录偶联 DPC (TC-DPC) 修复在活性基因中进行修复。 TC-DPC 修复是通过将转录偶联核苷酸切除修复 (TC-NER) 因子 CSB 和 CSA 招募到 DPC 停滞的 RNA 聚合酶 II 来启动的。 CSA和CSB是TC-DPC修复不可缺少的；然而，下游 TC-NER 因子 UVSSA 和 XPA 却不是，这一结果表明了非规范的 TC-NER 机制。 TC-DPC 修复功能独立于 SPRTN，但由泛素连接酶 CRL4 ^CSA和蛋白酶体介导。因此，基因中的 DPC 优先以转录偶联方式修复，以促进不受干扰的转录。