Methylthioadenosine/S-adenosylhomocysteine nucleosidase (Pfs) of Staphylococcus aureus is essential for the virulence independent of LuxS/AI-2 system

Staphylococcus aureus is a major cause of infectious morbidity and mortality in both community and hospital settings. The bacterium continues to cause diverse invasive, life-threatening infections, such as pneumonia, endocarditis, and septicemia. Methylthioadenosine/S-adenosylhomocysteine nucleosidase (Pfs) is predicted to be an important enzyme involved in methylation reactions, polyamine synthesis, vitamin synthesis, and quorum sensing pathways. For the first time, we demonstrate that Pfs is essential for the virulence of S. aureus. The pfs mutant strain, as compared to the isogenic wild type, displayed a decreased production of extracellular proteases, which was correlated with a dramatic decrease in the expression of the sspABC operon and a moderate decrease of aur expression. The mouse model of sepsis and subcutaneous abscesses indicated that the pfs mutant strain displayed highly impaired virulence compared to the isogenic wild type. The decreased virulence of the pfs mutant strain is in correspondence with its decreased proliferation in vivo, indicated with a real-time analysis in the transparent system of zebrafish embryos. These phenotypes of the pfs mutant strain are LuxS/AI-2 independent despite the essential role pfs plays in AI-2 production. Our data suggest that Pfs is a potential novel target for anti-infection therapy.