Interactome analysis of elongating RNAPII after induction of DNA damage by IP-MS/MS

Endogenous aldehydes induce inter-strand crosslinks (ICL) and DNA-protein crosslinks (DPC). While DNA-repair and aldehyde-clearance systems cope with cellular toxicity, deficiencies in these mechanisms cause genome-instability disorders. The FA-pathway, defective in Fanconi anemia (FA), specifically removes ICL. In contrast, SPRTN, compromised in Ruijs-Aalfs syndrome, eliminates DPC during replication. However, AMeDS patients lacking aldehyde-detoxification display combined features of FA and Cockayne syndrome, associated with transcription-coupled repair (TCR) deficiency, suggesting a novel repair mechanism for aldehyde-induced DNA lesions in active genes. In this report, we demonstrate efficient resolution of aldehyde-induced transcription-blocking lesions by TCR. Mass-spectrometry and DPC-seq identify the TCR complex and additional factors involved in DPC removal and formaldehyde-induced damage tolerance. Notably, TFIIS-dependent cleavage of stalled-RNAPII transcripts exclusively protects against formaldehyde-induced damage. A mouse-model lacking both aldehyde-clearance and TCR pathways confirms endogenous DPC accumulation in transcribed regions. These findings highlight the importance of DPC removal in preventing transcription-roadblocks and contribute to understanding disorders related to aldehyde clearance and TCR deficiencies.