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The fibrinogen-binding M1 protein reduces pharyngeal cell adherence and colonization phenotypes of M1T1 group A

Ericka L Anderson1, Jason N Cole, Joshua Olson

  • 1From the Departments of Pediatrics and.

The Journal of Biological Chemistry
|December 21, 2013
PubMed

Insights

Group A Streptococcus M1 protein binding to fibrinogen reduces bacterial adherence and colonization. However, the protease SpeB counterbalances this effect, enabling invasive disease progression.

Area of Science:

  • Microbiology
  • Pathogenesis
  • Molecular Biology

Background:

  • Group A Streptococcus (GAS) causes various infections, from strep throat to invasive diseases.
  • The GAS M1 protein is a key virulence factor, binding host fibrinogen (Fg) to resist phagocytes and promote inflammation.

Purpose of the Study:

  • To investigate the role of M1-Fg binding in GAS interaction with pharyngeal epithelium.
  • To understand how M1 protein influences GAS adherence and colonization in the pharynx.

Main Methods:

  • Utilized a virulent WT M1T1 GAS strain and an M1-deficient mutant.
  • Assessed GAS adherence to human pharyngeal keratinocytes with and without Fg.
  • Examined the effect of M1 protein cleavage by SpeB on adherence.
  • Employed a mouse model for assessing GAS colonization in nasal-associated lymphoid tissue.

Main Results:

  • M1 protein expression reduced GAS adherence to pharyngeal cells by 2-fold, increasing to 4-fold with Fg.
  • Cleavage of M1 protein by SpeB eliminated Fg binding and reversed the inhibitory effect on adherence.
  • M1 protein expression correlated with a 6-fold decrease in GAS recovery in mouse colonization assays.

Conclusions:

  • GAS M1 protein-Fg binding inhibits pharyngeal cell adherence and colonization, a process counteracted by SpeB.
  • SpeB inactivation during invasive disease allows M1-Fg binding, enhancing pathogen resistance and inflammation.
Keywords:
Bacterial AdhesionBacterial PathogenesisFibrinogenStreptococcus pyogenesVirulence Factors

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