CHARACTERIZATION OF A TN551-MUTANT OF STAPHYLOCOCCUS-AUREUS DEFECTIVEIN THE PRODUCTION OF SEVERAL EXOPROTEINS

A Tn551 insertional pleiotropic mutant defective in the production of several exoproteins was isolated from Staphylococcus aureus 196E and c haracterized. The pleiotropism of the mutant was due to a single inser tion 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-hemol ysins, DNase, coagulase, and protein A in the supernatants of broth cu ltures. Production of proteases, lipase, staphylokinase, or enterotoxi n A was not modified. The mutants did synthesize the cell-bound form o f protein A and also the extracellular form of this protein coded by p RIT11, which lacks the COOH-terminal segment of the molecule. These ob servations suggest that the sae locus does not involve a positive regu latory 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).