Mutations in the ss subunit of the Bacillus subtilis RNA polymerase that confer both rifampicin resistance and hypersensitivity to NusG.
Mutations conferring resistance to the antibiotic rifampicin (Rif(r)) occur at specific sites within the ss subunit of the prokaryotic RNA polymerase. Rif(r) mutants of Escherichia coli are frequently altered in the elongation and termination of transcription. Rif(r) rpoB mutations were isolated in Bacillus subtilis and their effects on transcription elongation factor NusG and Rho-dependent termination were investigated. RNase protection assay, Northern analysis and the expression of nusG-lacZ fusions in cells with an inducible NusG suggested the B. subtilis nusG gene was autoregulated at the level of transcription. Rif(r) mutations that changed residue Q469 to a basic residue (Q469K and Q469R) enhanced autoregulation of nusG. A mutant expressing a truncated form of NusG, due to a nonsense mutation within the nusG gene, was isolated on the basis of the loss of autoregulation. The mechanism of autoregulation was found to be independent both of transcription termination factor Rho and of the promoter transcribing nusG. Autoregulation required sequences within the 5' coding sequence of the nusG gene or immediately upstream. This is the first evidence from any bacterium that Rif(r) RNA polymerases can display altered transcription regulation by NusG.
Ingham
C J
CJ
School of Biological Sciences, University Park, Nottingham University, Nottingham NG7 2RD, UK1.
Furneaux
P A
PA
School of Biological Sciences, University Park, Nottingham University, Nottingham NG7 2RD, UK1.
D000595:Amino Acid Sequence; D001412:Bacillus subtilis / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D012321:DNA-Directed RNA Polymerases / Q000235:genetics* / Q000378:metabolism; D004352:Drug Resistance, Microbial / Q000235:genetics; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial; D008969:Molecular Sequence Data; D009154:Mutation; D010445:Peptide Elongation Factors / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012293:Rifampin / Q000494:pharmacology*; D000069816:SEC Translocation Channels; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; C070291:NusG protein, E coli; D010445:Peptide Elongation Factors; D011993:Recombinant Fusion Proteins; D000069816:SEC Translocation Channels; C065493:SecE protein, E coli; D014157:Transcription Factors; D012321:DNA-Directed RNA Polymerases; D012293:Rifampin