Regulation of virulence factors in Staphylococcus aureus is affected by salicylic acid.

ALVAREZ, LUCIA P.; BARBAGELATA, MARIA SOL; QUIROGA, CECILIA; CHEUNG, AMBROSE L.; SORDELLI, DANIEL O.; BUZZOLA FERNANDA R.

Mar del Plata, Buenos Aires

Congreso; XLIII Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular,; 2007

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular,

The ability of S. aureus to adapt to different environments is due to a global regulatory network comprising the loci mgrA and sae amongst others. These regulators are involved in the control of the expression of several virulence factors such as eap adhesin which is upregulated by sae. Salicylic acid (SAL) negatively affects the expression of bacterial virulence factors. The aim of this work was to study the effect of SAL on mgrA, sae and eap through expression systems including plasmids carrying a reporter gene (green fluorescent protein –gfp) driven by target gene promoters as well as by quantitative real time PCR (qRTPCR). We demonstrated a reduced expression of eap transcript in mgrA mutant through fluorometric assays and RTPCR suggesting that mgrA is a positive regulator of this adhesin. After seven hours of growth, strains treated with SAL showed reduced expression of mgrA, none differences in sae and increased expression of eap as compared with non-treated controls in fluorometric assays. The qRTPCR data shows that SAL down-regulates mgrA while up regulating sae and eap (mean fold change in gene expression by SAL treatment. mgrA: 0.75 ± 0.09; sae: 1.58 ± 0.19; eap: 2.05 ± 0.59). Altogether these results show that SAL does affect sae and mgrA which would alter the expression of several virulence factors driven by these regulators and therefore pathogenesis of S. aureus.