A phage transcription factor displaces the host σ factor and stabilizes its own σ factor.

ABSTRACT: Phages are the most abundant self-replicating entities on earth, and understanding their transcriptional regulation can provide insights into bacterial gene expression mechanisms. The bacterial RNA polymerase core enzyme interacts with various σ factors to recognize and unwind promoter DNA. Gp79, a protein from Escherichia coli phage phiEco32, inhibits host σ70-mediated transcription while simultaneously activating transcription through its own σ factor, gp36. The underlying mechanism of this unusual dual regulatory role has remained unclear. In this study, we present cryo-EM structures of E. coli RNA polymerase (RNAP) in complex with gp79, and of RNAP in complex with gp79, gp36, and a cognate promoter. Structural and biochemical analyses reveal the basis for σ displacement by gp79 and pro

SUBMITTER: Xu L 

PROVIDER: S-EPMC12276001 | biostudies-literature | 2025 Jul

REPOSITORIES: biostudies-literature