Sensing and Processing of DNA Interstrand Crosslinks by the Mismatch Repair Pathway

• Published in: Cell reports (Cambridge) Vol. 21; no. 5; pp. 1375 - 1385
• Main Authors: Kato, Niyo, Kawasoe, Yoshitaka, Williams, Hannah, Coates, Elena, Roy, Upasana, Shi, Yuqian, Beese, Lorena S., Schärer, Orlando D., Yan, Hong, Gottesman, Max E., Takahashi, Tatsuro S., Gautier, Jean
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 31.10.2017; Elsevier
• Subjects: Animals; DNA - metabolism; DNA Mismatch Repair - physiology; DNA Replication; DNA-Binding Proteins - metabolism; Exodeoxyribonucleases - metabolism; interstrand crosslink; mismatch repair; MutL Proteins - metabolism; Oocytes - metabolism; replication-independent repair; Xenopus; Xenopus - growth & development; Xenopus Proteins - metabolism; Xenopus; mismatch repair; interstrand crosslink; replication-independent repair
• ISSN: 2211-1247; 2211-1247
• DOI: 10.1016/j.celrep.2017.10.032

DNA interstrand crosslinks (ICLs) that are repaired in non-dividing cells must be recognized independently of replication-associated DNA unwinding. Using cell-free extracts from Xenopus eggs that support neither replication nor transcription, we establish that ICLs are recognized and processed by the mismatch repair (MMR) machinery. We find that ICL repair requires MutSα (MSH2–MSH6) and the mismatch recognition FXE motif in MSH6, strongly suggesting that MutSα functions as an ICL sensor. MutSα recruits MutLα and EXO1 to ICL lesions, and the catalytic activity of both these nucleases is essential for ICL repair. As anticipated for a DNA unwinding-independent recognition process, we demonstrate that least distorting ICLs fail to be recognized and repaired by the MMR machinery. This establishes that ICL structure is a critical determinant of repair efficiency outside of DNA replication. [Display omitted] •ICLs are sensed and repaired independently of replication and transcription•MutSα (MSH2–MSH6) binds to ICLs and initiates repair•ICL structure influences recognition and repair efficiency•MMR-dependent ICL repair requires the nuclease activities of MutLα and EXO1 Kato et al. identify a mechanism of ICL recognition that operates independently of DNA replication and transcription. In the absence of these processes, ICLs are recognized and repaired by the MMR machinery. MutSα is critical for ICL recognition, while MutLα and EXO1 contribute to key downstream nucleolytic steps during ICL repair.