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Characterization of a virulence-associated and cell-wall-located DNase of Streptococcus pyogenes

Tadao Hasegawa1, Masaaki Minami1, Akira Okamoto2

  • 1Department of Bacteriology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan.

Microbiology (Reading, England)
|October 24, 2009
PubMed

Insights

Streptococcus pyogenes produces a cell-wall DNase, SpnA, crucial for virulence. This enzyme, dependent on calcium and magnesium, is present in all examined clinical strains, highlighting its importance in M1 serotype infections.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Biochemistry

Background:

  • Streptococcus pyogenes is a significant human pathogen.
  • Understanding virulence factors is key to combating infections.
  • The role of cell-wall-associated enzymes in S. pyogenes pathogenesis requires further elucidation.

Purpose of the Study:

  • To characterize the function and localization of the Spy0747 protein from Streptococcus pyogenes M1 serotype.
  • To investigate the role of Spy0747 (designated SpnA) in bacterial virulence.
  • To determine the prevalence of the spnA gene in clinical isolates.

Main Methods:

  • Two-dimensional gel electrophoresis and peptide mass mapping to identify proteins.
  • Shotgun proteomic analysis for subcellular localization.
  • Recombinant protein expression and activity assays (DNase activity).
  • Bacterial virulence assays (blood bactericidal assays, mouse infection models).
  • Polymerase Chain Reaction (PCR) for gene detection.

Main Results:

  • The Spy0747 protein was identified and designated SpnA.
  • SpnA was confirmed to be a cell-wall-located DNase with Ca(2+) and Mg(2+) dependency.
  • SpnA is present in both culture supernatant and cell wall fractions.
  • Mice infected with an spnA knockout strain showed reduced virulence compared to the parental strain.
  • The spnA gene was detected in all tested clinical S. pyogenes strains.

Conclusions:

  • SpnA is a significant cell-wall-associated DNase in Streptococcus pyogenes.
  • SpnA plays a critical role in the virulence of S. pyogenes.
  • The enzyme is widely distributed among clinical isolates, suggesting broad importance in pathogenesis.

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