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Role of Streptococcus pyogenes two-component response regulators in the temporal control of Mga and the Mga-regulated

Deborah A Ribardo1, Thomas J Lambert, Kevin S McIver

  • 1Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, Texas 75235-9048, USA.

Infection and Immunity
|May 25, 2004
PubMed

Insights

Streptococcus pyogenes two-component response regulators (SptR) do not control Mga and emm gene expression. Mutants lacking most SptR genes showed normal virulence gene levels, indicating SptR is not required for temporal control.

Area of Science:

  • Microbiology
  • Bacterial genetics
  • Molecular biology

Background:

  • Streptococcus pyogenes is a significant human pathogen.
  • The Mga virulence regulator controls key S. pyogenes virulence factors, including the emm gene.
  • Two-component response regulators (SptR) are known to regulate gene expression in bacteria.

Purpose of the Study:

  • To investigate the role of Streptococcus pyogenes two-component response regulators (SptR) in the expression of the Mga virulence regulator and the Mga-regulated emm gene.
  • To determine if SptR proteins are necessary for the temporal control of these virulence genes during different growth phases.

Main Methods:

  • Construction and analysis of Streptococcus pyogenes mutants lacking individual or multiple sptR genes (serotypes M6 and M1).
  • Quantification of emm gene transcripts using RT-qPCR.
  • Measurement of Mga protein levels via Western blot analysis.
  • Comparison of gene expression and protein levels between wild-type and mutant strains during exponential and stationary growth phases.

Main Results:

  • Mutants lacking 12 of the 13 identified sptR genes showed comparable levels of emm transcripts to the wild-type strain.
  • Mga protein levels were similar in both wild-type and sptR mutant strains across different growth phases.
  • No significant difference in virulence gene expression or Mga protein levels was observed between wild-type and mutant strains.

Conclusions:

  • Streptococcus pyogenes two-component response regulators (SptR) are not essential for the temporal regulation of Mga and emm gene expression.
  • The identified SptR proteins do not play a critical role in controlling the expression of these key virulence factors during S. pyogenes growth.
  • Alternative regulatory mechanisms likely govern the precise temporal control of S. pyogenes virulence genes.

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