Preprint redefines role of RNA polymerase ω subunit in transcription-replication conflicts

A preprint posted to bioRxiv on 17 May 2026 presents new evidence that the ω subunit of Escherichia coli RNA polymerase (RNAP), encoded by the rpoZ gene, plays a previously unrecognised role in balancing transcriptional processivity against the resolution of transcription-replication conflicts.

The ω subunit — whose homologue in eukaryotes is RPB6 — has conventionally been described either as a chaperone for RNAP assembly or as a modulator of competition between sigma factors. Contrary to earlier assumptions, the researchers report that a ΔrpoZ deletion strain shows no major defects in σS-dependent stress responses, pointing away from a primary role in stress-related transcription.

Using a CRISPRi screen, the team found that loss of ω may instead promote bacterial survival during transcription-replication conflicts — head-on or co-directional collisions between the transcription and replication machineries that are a known source of genome instability. Supporting this interpretation, ω-deficient RNAP was found to be more sensitive to transcriptional termination, suggesting the subunit normally stabilises the elongation complex.

The work offers a revised mechanistic framework for understanding how bacteria manage the competing demands of gene expression and genome duplication. Because RPB6 is conserved across all domains of life, the findings may have broader implications for understanding transcription-replication conflicts in eukaryotes, though the authors note that comparative work remains to be done. This is a preprint and has not yet undergone peer review.