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A Fluorescence-based Method to Study Bacterial Gene Regulation in Infected Tissues
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A Fluorescence-based Method to Study Bacterial Gene Regulation in Infected Tissues

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Mn2+-dependent regulation of multiple genes in Streptococcus pneumoniae through PsaR and the resultant impact on

Jason W Johnston1, David E Briles, Lisa E Myers

  • 1Department of Microbiology, University of Iowa, BSB 3-401, 51 Newton Road, Iowa City, IA 52242, USA. jason-johnston@uiowa.edu

Infection and Immunity
|January 24, 2006
PubMed

Insights

Manganese (Mn2+) acts as a bacterial signal, with the regulator PsaR controlling virulence genes in Streptococcus pneumoniae. This Mn2+-dependent regulation is crucial for pneumonia but not nasopharyngeal colonization.

Area of Science:

  • Microbiology
  • Bacterial Pathogenesis
  • Molecular Biology

Background:

  • Bacterial pathogens must adapt to changing host environments.
  • Manganese (Mn2+) concentrations vary significantly between mucosal surfaces and internal tissues.
  • This concentration gradient suggests Mn2+ could act as a signal for bacterial adaptation.

Purpose of the Study:

  • To investigate the role of Mn2+ as a signaling molecule in Streptococcus pneumoniae.
  • To identify bacterial regulators and genes responsive to Mn2+.
  • To determine the impact of Mn2+-dependent regulation on bacterial virulence in vivo.

Main Methods:

  • Transcriptional analysis of Streptococcus pneumoniae genes in response to varying Mn2+ concentrations.
  • Gene expression studies using wild-type and mutant strains (e.g., psaR mutant).
  • In vivo mouse models to assess bacterial colonization and virulence (pneumonia and nasopharyngeal carriage).

Main Results:

  • The regulator PsaR directly and indirectly controls the transcription of multiple virulence-associated genes (psaBCA, pcpA, rrgA, rrgB, rrgC, srtBCD, rlrA) in response to Mn2+.
  • PsaR-mediated and PcpA-mediated gene regulation are essential for Streptococcus pneumoniae virulence during pneumonia.
  • Neither PsaR nor PcpA is required for nasopharyngeal colonization.

Conclusions:

  • Manganese (Mn2+) serves as a critical environmental signal for bacteria, modulating virulence factor expression.
  • PsaR is a key regulator mediating Mn2+-dependent gene expression in Streptococcus pneumoniae.
  • Targeted regulation of virulence genes by Mn2+ is vital for establishing infection at specific host sites.

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