CSB promotes transcription-coupled repair of DNA-protein crosslinks

PxP-MS (Purification of x-linked Proteins coupled to Mass Spectrometry) was used to assess the role of CSB in DNA-protein crosslink repair. The CSB protein is a sensor that can detect stalled RNA polymerases at sites of DNA damage, thereby triggering transcription-coupled repair mechanisms. DPCs were induced in WT and CSB knock-out RPE1 cells using a pulse of formaldehyde. To identify crosslinked proteins that specifically require CSB for repair, DNA-protein crosslinks were isolated from cells using PxP either directly after formaldehyde exposure or following a chase in drug-free media and identified by mass spectrometry.