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SCM, a novel M-like protein from Streptococcus canis, binds (mini)-plasminogen with high affinity and facilitates

Marcus Fulde1, Manfred Rohde, Angela Hitzmann

  • 1Department of Medical Microbiology, Helmholtz Centre for Infection Research (HZI), Braunschweig, Germany. Marcus.Fulde@helmholtz-hzi.de

The Biochemical Journal
|January 8, 2011
PubMed

Insights

Streptococcus canis utilizes a novel M-like protein (SCM) to bind human plasminogen, activating it on the bacterial surface. This facilitates fibrinolysis and bacterial invasion through fibrin clots.

Area of Science:

  • Microbiology and Infectious Diseases
  • Molecular Biology
  • Biochemistry

Background:

  • Streptococcus canis is a zoonotic pathogen causing severe invasive diseases in animals and humans.
  • Bacterial pathogens often employ host-derived proteins to facilitate infection and colonization.

Purpose of the Study:

  • To investigate the interaction between Streptococcus canis and human plasminogen.
  • To identify the bacterial receptor responsible for plasminogen binding and activation.
  • To elucidate the role of this interaction in bacterial virulence and fibrinolysis.

Main Methods:

  • Identification of the plasminogen-binding receptor using surface plasmon resonance (SPR) and dot-blot analyses.
  • Heterologous expression of the identified receptor (SCM) on Streptococcus gordonii.
  • Assays for plasminogen activation, fibrinogen degradation, and bacterial transmigration through fibrin clots.

Main Results:

  • A novel M-like protein, SCM, was identified as the plasminogen receptor on S. canis.
  • SCM binds human plasminogen, specifically mini-plasminogen, via its N-terminus.
  • SCM mediates urokinase-dependent plasminogen activation on the bacterial surface, leading to fibrin degradation and bacterial transmigration through fibrin thrombi.

Conclusions:

  • SCM is a novel receptor for human plasminogen on Streptococcus canis.
  • SCM mediates bacterial fibrinolytic activity, enhancing virulence and tissue invasion.
  • This interaction represents a significant virulence mechanism for S. canis.

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