Head-on and co-directional RNA polymerase collisions orchestrate bidirectional transcription termination (Wang et al., Mol Cell 2023)
Schematic showing that a head-on collision between convergent RNAPs prevents transcriptional readthrough, while a trailing RNAP disassembles the collided complex by co-directional collision. As such, a higher RNAP trafficking density results in more efficient bidirectional transcription termination.
Transcription is the first step of gene expression that converts DNA into messenger RNA. It has been a favorite subject for single-molecule studies, which probe either the position of RNA polymerase (RNAP) on the DNA template or the composition/conformation of the transcription complex. Here we aim to simultaneously monitor both by using smCFFM to visualize individual E. coli RNAPs transcribing DNA. We focus on the molecular mechanism of bidirectional transcription termination that we first reported in Ju et al. (2019). Our results show that both head-on and co-directional RNAP collisions are required for dismantling the transcription complex at these bidirectional terminators located between convergent genes. This work suggests that genomic conflicts among molecular machines—long thought to be detrimental to genome stability—can also be utilized to finetune gene expression.