Phenotypic characterization and virulence of a sae- agr- mutant of Staphylococcus aureus

Can J Microbiol. 1996 Feb;42(2):120-3. doi: 10.1139/m96-019.


A sae::Tn551 agr::tetM double mutant was constructed and characterized. The production of several exoproteins (e.g., beta-hemolysin, DNase, and proteases) by this mutant was determined and found to be lower than the already diminished production of either isogenic single mutant sae- or agr-. The double mutant also showed, like the agr- mutant, null production of alpha- and delta-hemolysins and diminished levels of lipase. The reduced levels of many exoproteins in the double mutant as compared with their already diminished levels in either single mutant suggest that there is an additive or synergistic interaction between the two mutations involved, sae- and agr-. However, inactivation of both loci, sae and agr, had a different effect on the two exoproteins that are up regulated in the agr- mutant; thus, coagulase dropped to levels close to the null levels of the sae- parental strain, while extracellular protein A displayed the high levels characteristic of the agr- single mutant. The virulence of the sae- agr- double mutant, determined by intraperitoneal injection in mice, was found to be significantly diminished as compared with that of the sae+ agr+ parental strain or the sae- agr+ single mutant.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Bacterial Proteins / analysis
  • Bacterial Proteins / biosynthesis*
  • Coagulase / analysis
  • Coagulase / biosynthesis
  • DNA Transposable Elements
  • Deoxyribonucleases / analysis
  • Deoxyribonucleases / biosynthesis
  • Endopeptidases / analysis
  • Endopeptidases / biosynthesis
  • Hemolysin Proteins / analysis
  • Hemolysin Proteins / biosynthesis
  • Lipase / analysis
  • Lipase / biosynthesis
  • Mice
  • Mice, Inbred BALB C
  • Mutagenesis
  • Phenotype
  • Staphylococcus aureus / genetics*
  • Staphylococcus aureus / metabolism
  • Staphylococcus aureus / pathogenicity*
  • Virulence / genetics


  • Bacterial Proteins
  • Coagulase
  • DNA Transposable Elements
  • Hemolysin Proteins
  • Deoxyribonucleases
  • Lipase
  • Endopeptidases