title: The Xp10 Bacteriophage Protein P7 Inhibits Transcription by the Major and Major Variant Forms of the Host RNA Polymerase via a Common Mechanism.
abstract: The σ factor is a functionally obligatory subunit of the bacterial transcription machinery, the RNA polymerase. Bacteriophage-encoded small proteins that either modulate or inhibit the bacterial RNAP to allow the temporal regulation of bacteriophage gene expression often target the activity of the major bacterial σ factor, σ70. Previously, we showed that during Xanthomonas oryzae phage Xp10 infection, the phage protein P7 inhibits the host RNAP by preventing the productive engagement with the promoter and simultaneously displaces the σ70factor from the RNAP. In this study, we demonstrate that P7 also inhibits the productive engagement of the bacterial RNAP containing the major variant bacterial σ factor, σ54, with its cognate promoter. The results suggest for the first time that the major variant form of the host RNAP can also be targeted by bacteriophage-encoded transcription regulatory proteins. Since the major and major variant σ factor interacting surfaces in the RNAP substantially overlap, but different regions of σ70and σ54are used for binding to the RNAP, our results further underscore the importance of the σ-RNAP interface in bacterial RNAP function and regulation and potentially for intervention by antibacterials.
authors: MRC Centre for Molecular Microbiology and Infection, Imperial College London, SW7 2AZ, UK. Electronic address: drbrown@imperial.ac.uk.
authors: D R
authors: DR
authors: Brown
authors: MRC Centre for Molecular Microbiology and Infection, Imperial College London, SW7 2AZ, UK.
authors: C M
authors: CM
authors: Sheppard
authors: MRC Centre for Molecular Microbiology and Infection, Imperial College London, SW7 2AZ, UK.
authors: L
authors: L
authors: Burchell
authors: MRC Centre for Molecular Microbiology and Infection, Imperial College London, SW7 2AZ, UK.
authors: S
authors: S
authors: Matthews
authors: MRC Centre for Molecular Microbiology and Infection, Imperial College London, SW7 2AZ, UK. Electronic address: s.r.wig@imperial.ac.uk.
authors: S
authors: S
authors: Wigneshweraraj
mesh_terms: D001426:Bacterial Proteins / Q000037:antagonists & inhibitors*; D001435:Bacteriophages / Q000254:growth & development*; D012321:DNA-Directed RNA Polymerases / Q000037:antagonists & inhibitors*; D006790:Host-Parasite Interactions; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D012808:Sigma Factor / Q000378:metabolism; D014158:Transcription, Genetic; D014764:Viral Proteins / Q000378:metabolism*; D014974:Xanthomonas / Q000235:genetics / Q000821:virology*
chemical_list: D001426:Bacterial Proteins; D012808:Sigma Factor; D014764:Viral Proteins; D012321:DNA-Directed RNA Polymerases
keywords: RNA polymerase; bacteria; bacteriophage; transcription regulation; σ factor