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The Delta subunit of RNA polymerase is required for virulence of Streptococcus agalactiae.

ABSTRACT: Group B streptococci (GBS) remain the most significant bacterial pathogen causing neonatal sepsis, pneumonia, and meningitis in the United States despite the chemoprophylaxis strategies for preventing infection recommended by the Centers for Disease Control and Prevention. Using signature-tagged transposon mutagenesis to screen for novel virulence factors, we identified the rpoE gene as essential for development of sepsis in a neonatal rat model of GBS infection. An rpoE allelic replacement mutant displayed attenuated virulence in the sepsis model of infection identical to that of the transposon mutant, confirming linkage of the phenotype to the mutation in rpoE. The rpoE mutants also displayed increased sensitivity to killing in whole-blood bactericidal assays, which may explain the attenuated virulence. The mutants were otherwise phenotypically identical to the wild-type strain, including growth rate in plasma, indicating that a growth defect is not responsible for the attenuated virulence. rpoE is found only in gram-positive bacterial species and encodes the delta peptide, a subunit of RNA polymerase. Previous in vitro studies in other bacteria suggest that the delta peptide plays a role in maintaining transcriptional fidelity by blocking RNA polymerase binding at all but the strongest promoters, thereby inhibiting initiation of transcription. Despite the availability of rpoE mutants for several gram-positive bacterial species, a role for the peptide in vivo has not been defined, though it has been postulated that the delta peptide may be important for long-term survival in vitro or during growth phase transitions. Our data represent the first report of a phenotype relevant to virulence for rpoE mutants.

SUBMITTER: Jones AL

PROVIDER: S-EPMC161970 | biostudies-literature | 2003 Jul

REPOSITORIES: biostudies-literature

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The Delta subunit of RNA polymerase is required for virulence of Streptococcus agalactiae.

Jones Amanda L AL Needham Rachel H V RH Rubens Craig E CE

Infection and immunity 20030701 7

Group B streptococci (GBS) remain the most significant bacterial pathogen causing neonatal sepsis, pneumonia, and meningitis in the United States despite the chemoprophylaxis strategies for preventing infection recommended by the Centers for Disease Control and Prevention. Using signature-tagged transposon mutagenesis to screen for novel virulence factors, we identified the rpoE gene as essential for development of sepsis in a neonatal rat model of GBS infection. An rpoE allelic replacement muta ...[more]

PMID: 12819089

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Project description:Transcriptional profiling of S. mutans rpoE knockout mutant comparing to the wild type. The mutation of rpoE cause dramatic changes in phenotypes. The goal is to determine the genes affected by rpoE. The delta subunit of RNA polymerase, RpoE, is wide spread in low G+C Gram-positive bacteria and is thought to play a role in enhancing transcriptional specificity by blocking RNA polymerase binding at weak-promoter sites and stimulating RNA synthesis by accelerating core enzyme recycling. Despite the well-studied biochemical properties of RpoE, a role for this protein in vivo has not been defined in depth. In this study, we show that inactivation of rpoE in the human dental caries pathogen Streptococcus mutans causes impaired growth, and loss of important virulence traits, including biofilm formation, resistance to antibiotics, and tolerance to environmental stresses. Complementation of the mutant with rpoE expressed in trans restored its phenotype to wild type. The luciferase fusion reporter showed that rpoE was highly transcribed throughout growth, and that acid and hydrogen peroxide stresses repressed rpoE expression. Transcriptome profiling of wild type and ΔrpoE cells in the exponential and early stationary phase of growth, under acid and hydrogen peroxide stress and under both stresses combined revealed that genes involved in histidine synthesis, malolactic fermentation, biofilm formation, and antibiotic resistance were down-regulated in the ΔrpoE mutant in all conditions. Moreover, the loss of RpoE resulted in dramatic changes in transport and metabolism of carbohydrates and amino acids. Interestingly, differential expression, mostly up-regulation, of 330 non-coding regions was found. In conclusion, this study demonstrates that RpoE is an important global modulator of gene expression in S. mutans, which is required for optimal growth and environmental adaptation. 5 conditions, mutant vs wild type, biological replicates: 2, technical replicates: 2

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The Delta subunit of RNA polymerase is required for virulence of Streptococcus agalactiae.

Publications

The Delta subunit of RNA polymerase is required for virulence of Streptococcus agalactiae.

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