Autoinducer-2 quorum sensing receptor complex (AI-2 receptor complex)

The Autoinducer-2 (AI-2) quorum sensing receptor complex is a pivotal molecular assembly responsible for detecting and responding to interspecies signaling molecules in a broad spectrum of bacteria. AI-2, synthesized by the LuxS enzyme, serves as a universal language that allows both Gram-negative and Gram-positive bacteria to monitor population density and synchronize collective behaviors. The architecture of the receptor complex is species-dependent; for instance, in Vibrio species, it comprises the periplasmic binding protein LuxP and the sensor kinase LuxQ, whereas in Salmonella and Escherichia coli, the LsrB protein facilitates AI-2 internalization via an ABC transporter. Activation of these receptors triggers signaling cascades that regulate the expression of genes involved in virulence, biofilm formation, and antibiotic resistance. Consequently, the AI-2 receptor complex has emerged as a significant therapeutic target for the development of quorum-quenching agents, such as cinnamaldehyde and brominated furanones, which aim to attenuate bacterial pathogenicity without killing the microbes. This approach potentially reduces the selective pressure for antibiotic resistance and offers a novel strategy for managing complex, multi-species infections and biofilm-related diseases.

Other names

LuxP-LuxQ complexLsrB-LsrACD complexAutoinducer-2 receptorAI-2 receptorLuxPQ two-component systemLsr (LuxS-regulated) system

Competitive or non-competitive inhibition of AI-2 binding to periplasmic receptors (LuxP or LsrB), or modulation of the sensor kinase (LuxQ) activity to disrupt downstream quorum sensing signaling and gene expression.