Dynamic Backtracking Regulates Lesion Bypass by RNAPII

Abstract

Abstract The eukaryotic genome is prone to a high amount of DNA damage from intrinsic and extrinsic sources, causing transcriptional stress, including pausing, backtracking and stalling. If not rectified in time, these damages can further lead to transcriptional arrest and genome instability. Here, we develop a single-molecule FRET based elongation complex which allows us to insert various types of DNA damage into the transcribed region and study the effect they have on the dynamics of RNAPII transcription. We show that different DNA lesions cause a heterogenous effect on RNAPII. In some instances, such as oxidative lesions, RNAPII exhibits a high level of dynamic behaviour often backtracking up to 10 nt. While other damages, such as cyclo-butane pyrimidine dimers and abasic sites, can cause more significant static stalling. Furthermore, the repair factor Rad26 binds to RNAPII and alters these dynamics by pushing RNAPII further over the damage site and preventing long-range backtracking events.