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Pyruvate oxidase of Streptococcus pneumoniae contributes to pneumolysin release

Joseph C Bryant1, Ridge C Dabbs1, Katie L Oswalt1

  • 1Department of Biological Sciences, Mississippi State University, 295 E Lee Blvd., Harned Hall, Rm 219, Mississippi State, MS, 39762, USA.

BMC Microbiology
|November 11, 2016
PubMed
Abstract

Insights

Pyruvate oxidase (SpxB) expression enhances pneumolysin (PLY) release in Streptococcus pneumoniae. This discovery links pneumolysin release to oxygen availability and bacterial metabolism.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Pathogenesis

Background:

  • Streptococcus pneumoniae causes pneumonia and otitis media.
  • Pneumolysin (PLY) and pyruvate oxidase (SpxB) are key virulence factors.
  • Investigating the synergy between PLY and SpxB.

Purpose of the Study:

  • To investigate the relationship between SpxB expression and PLY release.
  • To understand the mechanism by which SpxB influences PLY release.
  • To explore the role of peroxide production in PLY release.

Main Methods:

  • Genetic manipulation of spxB gene in S. pneumoniae.
  • Assessing PLY release via cytotoxicity assays on epithelial and red blood cells.
  • Measuring peroxide production and its correlation with PLY release.
  • Investigating the effect of exogenous H2O2 and catalase.

Main Results:

  • Mutants lacking spxB showed reduced PLY release.
  • Complementation of spxB restored PLY release.
  • Peroxide production correlated significantly with PLY release.
  • H2O2 did not induce PLY release; catalase partially prevented it, suggesting intracellular or strain-dependent effects.
  • SpxB expression predisposed cells to deoxycholate lysis but not cell death or autolysis.

Conclusions:

  • A novel link exists between spxB expression and PLY release.
  • SpxB enhances pneumolysin release.
  • Findings connect PLY toxin liberation to oxygen availability and pneumococcal metabolism.
Keywords:
CytotoxicityMetabolismPneumococcusPneumolysinProtein secretionStreptococcus pneumoniaeToxinVirulence

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