英语翻译

英语翻译
Transcription-coupled DNA repair uses components of the transcription machinery to identify DNA lesions and initiate their repair.These repair pathways are complex,so their mechanistic features remain poorly understood.Bacterial transcription-coupled repair is initiated when RNA polymerase stalled at a DNA lesion is removed by Mfd,an ATP-dependent DNA translocase1,2,3.Here we use single-molecule DNA nanomanipulation to observe the dynamic interactions of Escherichia coli Mfd with RNA polymerase elongation complexes stalled by a cyclopyrimidine dimer or by nucleotide starvation.We show that Mfd acts by catalysing two irreversible,ATP-dependent transitions with different structural,kinetic and mechanistic features.Mfd remains bound to the DNA in a long-lived complex that could act as a marker for sites of DNA damage,directing assembly of subsequent DNA repair factors.These results provide a framework for considering the kinetics of transcription-coupled repair in vivo,and open the way to reconstruction of complete DNA repair pathways at single-molecule resolution.