Characterization of a Tn551-mutant of Staphylococcus aureus defective in the production of several exoproteins

Abstract

A Tn551 insertional pleiotropic mutant defective in the production of several exoproteins was isolated from Staphylococcus aureus 196E and characterized. The pleiotropism of the mutant was due to a single insertion of the transposon as evidenced by Southern blot hybridization and by the transfer of its phenotype by transduction to S. aureus ISP479. The mutants showed diminished or null levels of alpha- and beta-hemolysis, DNase, coagulase, and protein A in the supernatants of broth cultures. Production of proteases, lipase, staphylokinase, or enterotoxin A was not modified. The mutants did synthesize the cell-bound form of protein A and also the extracellular form of this protein coded by pRIT11, which lacks the COOH-terminal segment of the molecule. These observations suggest that the sae locus does not involve a positive regulatory gene acting at the transcriptional level. The phenotype of the mutant was different from that of other insertional mutants affecting exoprotein synthesis, such as agr, xpr, or sar. This new mutation has been designated sae (for S. aureus exoprotein expression).

Regulatory organization of the staphylococcal sae locus

“…1a). This shows that the saeP insertion is not significantly polar on saeR and S, confirms that saeR and S are required for a-toxin production as previously reported (Giraudo et al, 1994b), and suggests that saeP is not required. For most of the phenotypic comparisons, we sampled at three time points, starting with a culture density of 50 Klett units, namely t 0 , t 3 and t 6 .…”

“…It was identified on the basis of a Tn551 insertion in saeR (Giraudo et al, 1994a), which profoundly affected the expression of a large set of virulence genes (Giraudo et al, 1997), largely, but not entirely, parallel to the regulatory activities of the agr system (Giraudo et al, 1996). The sae locus contains a classical two-component signalling module (TCS), of which SaeS is the receptor kinase and SaeR the response regulator (Giraudo et al, 1999).…”

Transcriptional profiling of a Staphylococcus aureus clinical isolate and its isogenic agr and sarA mutants reveals global differences in comparison to the laboratory strain RN6390

“…Other regulatory elements that were expressed at different levels in UAMS-1 and RN6390 included saeRS, which also encodes a two-component regulatory system (Giraudo et al, 1994;Novick & Jiang, 2003). Specifically, both genes were expressed at higher levels in UAMS-1 versus RN6390 during post-exponential-phase growth (Table 3).…”

Proteolytic Cleavage of Staphylococcal Exoproteins Analyzed by Two‐Dimensional Gel Electrophoresis

“…aureus secretes a large number of extracellular proteins (exoproteins), which have been shown to contribute to the pathogenic activities or to enhance the virulence of this organism (15,21,25,33). Recently, renewed interest has focused on proteases secreted from S. aureus under the control of agr (accessory gene regulator) and sar (staphylococcal accessory regulator), the main regulators of S. aureus virulence determinant genes (6,7,12,24). The expression of a specific serine glutamyl endopeptidase, V8 protease, was found to be *Address correspondence to Dr. Michio Ohta, Department of Molecular Bacteriology, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, Aichi 466-8550, Japan.…”