Interactive regulatory pathways control exoproteases production in Staphylococcus aureus

WILL, I.; PELLEGRINO, M.; ODDI, T.; FERRARI, M.; DUCRÓS, E.; RASPANTI, C.; BOGNI, C.

Huerta Grande, Córdoba

Congreso; I Reunión Conjunta de Sociedades de Biología de la República Argentina; 2007

Asociaciones de Biología de Argentina

Staphylococcus aureus is a major pathogen of humans and animals that synthesizes a large number of extracellular proteins that play a role in bacterial virulence. Several global regulatory loci regulate the production of these virulence factors, among which the most relevant are the agr, sar, sae and sigB loci. Two-component signal transduction system, SaeRS, characterized in our laboratory, up regulates the synthesis of several exoproteins at the transcriptional level. S. aureus synthesizes several extracellular proteases. The synthesis of these proteases is positively regulated by agr and negatively regulated by sae, sarA, and sigB. In this study we examined how the interactions between these pathways affect proteases production. Total protease activity from concentrated supernatants of cultures in late stationary phase, measured using azocasein as a substrate, showed a 3- to 4-fold increase with the sae mutant as compared to the wild type strain. This activity increased about two and three fold with sae agr and sae sigB double mutants, respectively, than the sae mutant. These over-expression was visualized in sodium dodecyl sulfate polyacrylamide gels containing 0.1% gelatin. These observations indicate the existence of some type of additive and (or) synergistic effect between the two mutations that further increases the production of exoproteases.