Cell population density-dependent regulation of gene expression is an important
determinant of bacterial pathogenesis. Staphylococci have two quorum-sensing (QS)
systems. The accessory gene regulator (agr) is genus specific and uses a post-
translationally modified peptide as an autoinducing signal. In the pathogens Staphylococcus
aureus and Staphylococcus epidermidis, agr controls the expression of a series of toxins
and virulence factors and the interaction with the innate immune system. However, the role …