biostudies-literatureMittermeier MDeutsche ForschungsgemeinschaftNational Cancer InstituteNCI NIH HHSNational Institute of General Medical SciencesNIGMS NIH HHSNIH HHS871-885https://www.ebi.ac.uk/biostudies/studies/S-EPMC9018486biostudies-literatureUnknown117(4)Escherichia coli RfaH abrogates Rho-mediated polarity in lipopolysaccharide core biosynthesis operons, and ΔrfaH cells are hypersensitive to antibiotics, bile salts, and detergents. Selection for rfaH suppressors that restore growth on SDS identified a temperature-sensitive mutant in which 46 C-terminal residues of the RNA polymerase (RNAP) β' subunit are replaced with 23 residues carrying a net positive charge. Based on similarity to rpoC397, which confers a temperature-sensitive phenotype and resistance to bacteriophages, we named this mutant rpoC397*. We show that SDS resistance depends on a single nonpolar residue within the C397* tail, whereas basic residues are dispensable. In line with its mimicry of RfaH, C397* RNAP is resistant to Rho but responds to pause signals, NusA, and NusG Molecular microbiologyA non-native C-terminal extension of the β' subunit compromises RNA polymerase and Rho functions.PMC9018486P30 CA016058R01 GM067153CA0168058433623608S10 OD018056GM067153Gjorgjevikj DArtsimovitch IWang BWahl MCMittermeier MSaid NfalseA non-native C-terminal extension of the β' subunit compromises RNA polymerase and Rho functions.Escherichia coli RfaH abrogates Rho-mediated polarity in lipopolysaccharide core biosynthesis operons, and ΔrfaH cells are hypersensitive to antibiotics, bile salts, and detergents. Selection for rfaH suppressors that restore growth on SDS identified a temperature-sensitive mutant in which 46 C-terminal residues of the RNA polymerase (RNAP) β' subunit are replaced with 23 residues carrying a net positive charge. Based on similarity to rpoC397, which confers a temperature-sensitive phenotype and resistance to bacteriophages, we named this mutant rpoC397*. We show that SDS resistance depends on a single nonpolar residue within the C397* tail, whereas basic residues are dispensable. In line with its mimicry of RfaH, C397* RNAP is resistant to Rho but responds to pause signals, NusA, and NusG 2022-01-01T00:00:00Z2022 Apr2026-05-09T13:46:22.805Z2025-02-18T23:45:04.246ZS-EPMC90184863504909310.1111/mmi.14879