Identification of a major, CsrRS-regulated secreted protein of Group A streptococcus

Microb Pathog. 2001 Aug;31(2):81-9. doi: 10.1006/mpat.2001.0450.


CsrR/CsrS (CovR/CovS) is a two-component regulator of extracellular virulence factors in Group A streptococcus, but the full range of regulated exoproteins is unknown. Since CsrR represses expression of regulated factors, culture supernates of wild-type and CsrR(-)mutant strains were compared by two-dimensional gel electrophoresis (2DGE) to identify regulated exoproteins. Supernates of DeltacsrRS(-)mutant, but not wild-type, bacteria contained an abundant 23 kDa protein. The N-terminal sequence of this spot corresponded to a putative open reading frame (ORF) in the streptococcal genome. In a mobility shift assay, phosphorylated CsrR bound to a PCR amplicon that included sequences upstream of this ORF. By primer extension analysis, the ORF (designated mspA, for Mucoidy-associated Secreted Protein) was expressed in mid- and late-exponential phase in a DeltacsrRS(-)mutant. The presence of an in-frame deletion in mspA did not affect colony appearance, mucoidy or in vitro growth, and there was no difference between DeltamspA and wild-type strains in a mouse model of skin infection. MspA is co-regulated with other factors required for dermonecrosis (e.g. capsule, streptolysin S and purogenic exotoxin B); however, deletion of this gene does not affect expression of hyaluronic acid capsule or severity of skin infection in mice.

Publication types

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

MeSH terms

  • Animals
  • Bacterial Proteins / chemistry
  • Bacterial Proteins / genetics
  • Bacterial Proteins / isolation & purification*
  • Disease Models, Animal
  • Gene Deletion
  • Male
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism
  • Mice
  • Mice, Hairless
  • Mutation
  • Open Reading Frames
  • Promoter Regions, Genetic
  • Protein Kinases / metabolism*
  • Repressor Proteins / genetics
  • Repressor Proteins / metabolism*
  • Skin Diseases, Infectious / microbiology
  • Streptococcal Infections / microbiology
  • Streptococcus pyogenes / growth & development
  • Streptococcus pyogenes / metabolism*
  • Streptococcus pyogenes / pathogenicity
  • Virulence


  • Bacterial Proteins
  • CsrR protein, Streptococcus pyogenes
  • Membrane Proteins
  • Repressor Proteins
  • Protein Kinases
  • CsrS protein, bacteria