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Characterization of a complement-binding protein, DRS, from strains of Streptococcus pyogenes containing the emm12

Michael Binks1, K S Sriprakash

  • 1Queensland Institute of Medical Research, 300 Herston Road, Herston, Queensland 4006, Australia.

Infection and Immunity
|June 24, 2004
PubMed

Insights

Streptococcus pyogenes secretes a protein variant, DRS, that binds complement proteins C6 and C7. However, DRS does not inhibit complement function or the activity of streptococcal inhibitor of complement (SIC).

Area of Science:

  • Microbiology
  • Immunology
  • Molecular Biology

Background:

  • Streptococcus pyogenes produces streptococcal inhibitor of complement (SIC) and a variant, DRS.
  • SIC interferes with complement-mediated cell lysis by interacting with complement proteins.
  • Some S. pyogenes strains expressing emm12 and emm55 genes secrete DRS.

Purpose of the Study:

  • To investigate the interaction of DRS with complement proteins C6 and C7.
  • To determine the effect of DRS on complement function and SIC activity.

Main Methods:

  • Expressing and secreting DRS from S. pyogenes strains.
  • Using competition enzyme-linked immunosorbent assays to assess binding.
  • Evaluating complement-mediated lysis of sensitized sheep erythrocytes.

Main Results:

  • DRS binds to complement proteins C6 and C7, competing with SIC for binding.
  • Recombinant DRS did not significantly affect complement function.
  • DRS presence did not inhibit SIC activity.

Conclusions:

  • DRS interacts with complement proteins C6 and C7 but lacks inhibitory effects on complement-mediated lysis.
  • DRS does not interfere with the inhibitory function of SIC.

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