Table 1 Basic elements of the quorum sensing systems in bacteria
Type | Sensing molecules | Receptor(s) | Special features |
|---|---|---|---|
Autoinducer type 1, LuxR-I type | N-acyl-homoserine lactones | Intracellular Lux-R homologues as transcriptional coactivator | Found in Gram-negative bacteria (Burkholderia, Vibrio, Pseudomonas spp.); might affect human genes |
Autoinducer type 2, LuxS type | Heterocyclic furanosylborate | Two-component membrane receptor-cytoplasmic kinase complex | Widespread in Gram-negative and Gram-positive bacteria; might be a primary metabolic system rather than a communication system |
Autoinducer type 3, epinephrine/norepinephrine signaling system | Catecholamine-like molecules | Two-component membrane-sensor kinase/response regulator (QseBC) | Found in Gram-negative, enteric bacteria enterohemorrhagic Escherichia coli, enteropathogenic E. coli, Shigella, Salmonella spp.; functional role unclear at present |
Cyclic short-peptide systems (AgrC/AgrA, staphylococci; competence stimulating peptide, pneumococci; Enterococcus faecalis regulator, enterococci) | Small cyclic peptides with thiolactone ring | Two-component sensor kinase (AgrC)-response regulator (AgrA) | Gram-positive bacteria, Staphylococcus, Bacillus, Enterococcus, Streptococcus spp. |