Bacterial quorum sensing receptors (QS receptors)

Bacterial quorum sensing (QS) receptors are specialized proteins that detect signaling molecules called autoinducers, allowing bacteria to monitor their population density and coordinate group behaviors (Zhao et al., 2020). In poultry and swine pathogens such as Salmonella enterica, Campylobacter jejuni, and Streptococcus suis, these receptors—including LuxR-type proteins, LuxS/AI-2 systems, and Agr-like systems—regulate the expression of virulence factors and biofilm formation (Ha et al., 2021). By sensing a threshold concentration of signals, these receptors trigger the transition from a commensal or planktonic state to a pathogenic or biofilm-associated state, which is critical for host colonization and disease progression (Zhang et al., 2021). Therapeutic strategies targeting these receptors, known as quorum quenching, aim to disrupt this communication without necessarily killing the bacteria, thereby reducing the selective pressure for antibiotic resistance (Niu et al., 2006). Common inhibitors include phytochemicals like cinnamaldehyde and baicalin, which interfere with signal binding or receptor activation, as well as enzymes like AHL lactonase that degrade the signals themselves (Brackman et al., 2008). These targets are increasingly important in veterinary medicine as alternatives to traditional antibiotics to manage infections like necrotic enteritis and respiratory diseases in livestock.

Other names

Quorum sensing proteinsLuxR-type receptorsLuxS/AI-2 system receptorsAgr system receptorsAutoinducer receptorsTwo-component system histidine kinasesSdiA proteinLuxP/LuxQ complex

Quorum quenching via competitive inhibition of autoinducer binding, enzymatic degradation of signaling molecules (quorum quenching enzymes), or inhibition of signal synthesis.