Visualisation of transcription-coupled repair in live Escherichia coli

Cellular DNA is constantly under threat from exogenous as well as endogenous genotoxic agents that result in DNA damage. Transcription, the first step of gene expression, helps to safeguard the genome via the transcription-coupled repair (TCR) process. During this reaction, transcription complexes stalled at sites of lesions stimulate recruitment of DNA repair factors. In prokaryotes, TCR is mediated by the translocase Mfd. Mfd displaces stalled transcription complexes and subsequently recruits UvrA-UvrB, the damage recognition complex that detects bulky lesions. How TCR is orchestrated in cellular environments remains poorly understood. To further our understanding of TCR in live cells, we developed fluorescent probes to visualise single molecules of Mfd, UvrA and UvrB in the model organism Escherichia coli.