Variation in Extracellular Protease Production among Clinical Isolates of Staphylococcus aureus Due to Different Levels of Expression of the Protease Repressor sarA
AUTOR(ES)
Karlsson, Anna
FONTE
American Society for Microbiology
RESUMO
Staphylococcus aureus produces four major extracellular proteases: staphylococcal serine protease (V8 protease; SspA), cysteine protease (SspB), metalloprotease (aureolysin; Aur), and staphopain (Scp). Several in vitro studies have suggested that these enzymes are important virulence factors. Here we analyzed the protease production of 92 S. aureus strains from infected human soft tissue. Twenty-one strains produced variable zones of proteolysis on casein agar plates, while the remaining 71 strains appeared to be protease negative. The major protease genes were present in all protease-positive (n = 5) and protease-negative (n = 12) strains analyzed. Northern blotting showed that transcription of the protease genes was suppressed due to increased sigma factor B (SigB)-dependent expression of the protease repressor SarA. Other SigB-dependent traits such as pigmentation and expression of asp 23 were also increased in protease-negative compared to protease-positive strains. Inactivation of sarA in three protease-negative strains resulted in increased transcription of all protease genes and increased protease production, while overexpression of sarA in a strain producing protease at high levels repressed protease production. Our results suggest that the protease genes are conserved among clinical S. aureus strains and that the level of SigB-dependent expression of the protease repressor sarA determines the level of protease production in each strain.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=128181Documentos Relacionados
- Decreased Amounts of Cell Wall-Associated Protein A and Fibronectin-Binding Proteins in Staphylococcus aureus sarA Mutants due to Up-Regulation of Extracellular Proteases
- Regulation of Staphylococcus aureus Capsular Polysaccharide Expression by agr and sarA
- Characterization of Staphylococcus aureus SarA Binding Sites
- Role of SarA in Virulence Determinant Production and Environmental Signal Transduction in Staphylococcus aureus
- Mutation of sarA in Staphylococcus aureus Limits Biofilm Formation