Insertional Inactivation of virR in Streptococcus Pyogenes M49 Demonstrates That VirR Functions as a Positive Regulator of ScpA, FcRA, OF, and M Protein

FEMS Microbiol Lett. 1995 Apr 15;128(1):45-51. doi: 10.1111/j.1574-6968.1995.tb07498.x.


Several reports have shown that Streptococcus pyogenes strains which produce opacity factor (OF+) have diverged significantly from OF- serotypes. This study questions whether several surface proteins of an OF+ culture are regulated by the positive regulatory protein VirR, in a manner similar to OF- strains. Interruption of the virR region of an OF+ S. pyogenes (strain CS101, M type 49) was performed using a temperature-sensitive plasmid containing a fragment of virR. Interruption of the virR region produced cultures with undetectable amounts of M49 and ScpA proteins, and reduced the yield of FcRA protein. In addition, mutants had a significant reduction in detectable opacity factor. These results suggest that virR functions as a positive regulator of a variety of surface proteins in OF+ strains.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Antigens, Bacterial*
  • Bacterial Outer Membrane Proteins*
  • Bacterial Proteins / biosynthesis
  • Bacterial Proteins / genetics*
  • Carrier Proteins*
  • Gene Expression Regulation, Bacterial*
  • Genes, Bacterial / physiology*
  • Mutagenesis, Insertional
  • Peptide Hydrolases / biosynthesis
  • Peptide Hydrolases / genetics*
  • Streptococcus pyogenes / genetics*


  • Antigens, Bacterial
  • Bacterial Outer Membrane Proteins
  • Bacterial Proteins
  • Carrier Proteins
  • opacity factor
  • streptococcal M protein
  • Peptide Hydrolases