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Identification of pel, a Streptococcus pyogenes locus that affects both surface and secreted proteins

Z Li1, D D Sledjeski, B Kreikemeyer

  • 1Department of Microbiology and Immunology, Medical College of Ohio, Toledo, Ohio 43614, USA.

Journal of Bacteriology
|September 28, 1999
PubMed

Insights

A mutation in Streptococcus pyogenes revealed a new regulatory factor, Pel, controlling multiple virulence factors. This finding sheds light on the coordinated expression of secreted and surface proteins in this pathogen.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Genetics

Background:

  • Streptococcus pyogenes (M49 serotype) is a significant human pathogen.
  • Virulence factors like streptolysin S, cysteine protease, and streptokinase contribute to M49 pathogenesis.
  • Coordinated regulation of these factors is crucial for M49 virulence.

Purpose of the Study:

  • To identify and characterize a novel regulatory factor influencing multiple virulence phenotypes in Streptococcus pyogenes.
  • To investigate the genetic basis for pleiotropic effects on secreted and surface proteins.

Main Methods:

  • Isolation and characterization of a Tn917 insertion mutant in Streptococcus pyogenes.
  • Determination of Tn917 insertion site and sequencing of the pel region.
  • Phage transduction to confirm cotransduction of mutations.
  • Cloning and expression analysis of the pel region.
  • Analysis of gene transcription (emm, speB) and protein secretion.

Main Results:

  • A Tn917 insertion mutant exhibited decreased beta-hemolysis, reduced protease and streptokinase activity, and altered binding of immunoglobulin and fibrinogen.
  • The Tn917 insertion occurred upstream of a gene in the pel region, disrupting a 500-base mRNA transcript.
  • Loss of the pel transcript led to decreased emm and speB gene transcription and reduced streptokinase secretion.
  • Enhanced Pel expression increased emm message levels in wild-type Streptococcus pyogenes.

Conclusions:

  • The pel region harbors a novel global regulatory factor in Streptococcus pyogenes.
  • This factor coordinates the expression of both secreted and surface virulence proteins.
  • Understanding Pel-mediated regulation offers new targets for therapeutic intervention against Streptococcus pyogenes infections.

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