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Generation of a mature streptococcal cysteine proteinase is dependent on cell wall-anchored M1 protein

M Collin1, A Olsén

  • 1Department of Cell and Molecular Biology, Lund University, Sweden.

Molecular Microbiology
|August 10, 2000
PubMed

Insights

Streptococcus pyogenes lacking M protein cannot produce mature cysteine proteinase. M protein is essential for activating this enzyme, a key virulence factor in S. pyogenes infections.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Biochemistry

Background:

  • Streptococcus pyogenes is a significant human pathogen.
  • M protein and streptococcal cysteine proteinase are key virulence factors.
  • The precise interaction between M protein and cysteine proteinase is not fully understood.

Purpose of the Study:

  • To investigate the role of M protein in the maturation of streptococcal cysteine proteinase.
  • To elucidate the mechanism by which M protein influences cysteine proteinase activity.

Main Methods:

  • Generation of a mutant Streptococcus pyogenes strain (MC25) lacking surface M protein.
  • Analysis of cysteine proteinase zymogen and mature forms secreted by wild-type and mutant strains.
  • Conformational analysis of secreted zymogens.

Main Results:

  • The MC25 mutant strain, lacking M protein, failed to produce mature 28 kDa cysteine proteinase.
  • S. pyogenes M1 serotype requires cell wall-anchored M protein for zymogen cleavage.
  • The mutant secreted a 40 kDa zymogen with altered conformation, suggesting M protein facilitates unfolding and active site generation.

Conclusions:

  • Cell wall-anchored M protein is crucial for the unfolding and maturation of streptococcal cysteine proteinase zymogen.
  • M protein's interaction is essential for generating an active cysteine proteinase, suggesting a novel mechanism for virulence factor activation in S. pyogenes.

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