title: Identification of a major, CsrRS-regulated secreted protein of Group A streptococcus.
abstract: 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.
authors.affiliation: Department of Internal Medicine, University of Michigan School of Medicine, Ann Arbor, MI 48109, U.S.A.
authors.forename: A
authors.initials: A
authors.lastname: Heath
authors.forename: A
authors.initials: A
authors.lastname: Miller
authors.forename: V J
authors.initials: VJ
authors.lastname: DiRita
authors.forename: C N
authors.initials: CN
authors.lastname: Engleberg
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification*; D004195:Disease Models, Animal; D017353:Gene Deletion; D008297:Male; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008812:Mice, Hairless; D009154:Mutation; D016366:Open Reading Frames; D011401:Promoter Regions, Genetic; D011494:Protein Kinases / Q000378:metabolism*; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D012874:Skin Diseases, Infectious / Q000382:microbiology; D013290:Streptococcal Infections / Q000382:microbiology; D013297:Streptococcus pyogenes / Q000254:growth & development / Q000378:metabolism* / Q000472:pathogenicity; D014774:Virulence
chemical_list: D001426:Bacterial Proteins; C432143:CsrR protein, Streptococcus pyogenes; D008565:Membrane Proteins; D012097:Repressor Proteins; D011494:Protein Kinases; C432144:CsrS protein, bacteria