Effects of Serine Protease-Like F (SPLF) on Alpha-Toxin Expression in Staphylococcus aureus

Pulse, Mark E., Effects of Serine protease-like F (Sp1F) on Alpha-Toxin Expression in Staphylococcus aureus. Master’s of Science (Microbiology). May 2003. Pages-67. Table-5. Figures-9. Transposon mutagenesis (Tn551) was used to generate agr-suppressor mutations in the agr-null Staphylococcus aureus strain RN6911 (Δagr;;tmn). Firty-four suppressor mutants displaying changes in hemolysin, protease, and lipase activities were isolated, and only twenty-six mutants contained Tn551 within their chromosomes. Transposon insertion sites for seven mutants were determined by sequencing amplicons generated by arbitrary-PCR. One of the insertion sites was within the serine protease-like F (spʅF) gene. Alpha-toxin message levels for the spʅF mutant were similar to RN6911. However, alpha-toxin activity in spent media isolated from the spʅF mutant were similar to RN6911. However, alpha-toxin activity in spent media isolated from the spʅF mutant was increased ten-fold as compared to RN6911. Transduction of the spʅf:Tn551 mutation back into the parental strain verified the link between the phenotype and the mutation. Whole cell lysates from Escherichia coli cells containing a plasmid copy of spʅF displayed protease activity on casein. These data suggest that SpʅF may be post-translationally modifying alpha-toxin through proteolysis.