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The MicAB two-component signaling system is involved in virulence of Streptococcus pneumoniae

Aras Kadioglu1, Josè Echenique, Sonia Manco

  • 1Department of Microbiology and Immunology, University of Leicester, Leicester LE1 9HN, United Kingdom. ak13@le.ac.uk

Infection and Immunity
|October 24, 2003
PubMed

Insights

The MicAB two-component system in Streptococcus pneumoniae helps bacteria adapt to low oxygen. Mutating this system reduced bacterial virulence and improved growth during oxygen level changes, suggesting its role in infection.

Area of Science:

  • Microbiology
  • Bacterial Pathogenesis
  • Molecular Biology

Background:

  • The MicAB two-component system in Streptococcus pneumoniae regulates gene expression.
  • This system is known to repress competence under limited oxygen conditions.

Purpose of the Study:

  • To investigate the role of the MicAB two-component system in Streptococcus pneumoniae virulence and adaptation to changing oxygen levels during infection.

Main Methods:

  • Generating a micB kinase mutant (micB::km) in virulent Streptococcus pneumoniae strains.
  • Assessing growth kinetics under aerobic to anaerobic transitions.
  • Evaluating bacterial virulence in a mouse intranasal challenge model, measuring symptoms and CFU in lungs and blood.

Main Results:

  • Mutation of the MicB kinase reduced the lag phase of bacterial growth during shifts from aerobic to anaerobic conditions.
  • The micB::km mutation significantly decreased bacterial virulence in mice, evidenced by fewer symptoms and lower CFU counts in lungs and blood.

Conclusions:

  • The MicAB system plays a crucial role in the adaptive response of Streptococcus pneumoniae to fluctuating oxygen levels encountered during infection.
  • MicAB contributes to bacterial virulence, likely by mediating survival and growth under varying oxygen tensions in the host.

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