LuxS is a homodimeric iron-dependent metalloenzyme containing two identical tetrahedral metal-binding sites similar to those found in peptidases and amidases.
[1] Furthermore, LuxS is involved in the synthesis of autoinducer AI-2 (autoinducer-2), which mediates quorum sensing in roughly half of bacterial species.
[2][3] AI-2 is a signalling molecule that is believed to act in cross-species communication by regulating niche-specific genes with diverse functions, such as toxin production, biofilm formation, sporulation, and virulence gene expression, in various bacteria, often in response to population density.
LuxS cleaves S-ribosyl-homocysteine to form L-homocysteine (Hcy) and 4,5-dihydroxy-2,3-pentanedione (DPD), which can then spontaneously cyclisize to active AI-2 (11-15).
[2][3] An unequivocally AI-2 related behavior was found to be restricted primarily to bacteria bearing known AI-2 receptor genes.