Figure 2.

The agr system of L. monocytogenes. (A) Schematic of agr autoinduction. AgrB and Sps process AgrD into a secreted cyclic autoinducing peptide (AIP). The detection of AIP by the sensor kinase AgrC induces a phosphorylation cascade resulting in the activation of the regulator AgrA. (B) AgrD sequence alignments of Listeria and the four groups of staphylococcal AgrD. Lino: Listeria innocua; Lmon: Listeria monocytogenes; Lwes: Listeria welshimeri; LFin: Listeria monocytogenes Finland; Lgra: Listeria grayi. In brackets, number of genomes available online; identical sequences were observed in these genomes. In bold face and red-boxed, the conserved cystein residue critical for the thiolactone ring.