title: Variations on a theme: diverse N-acyl homoserine lactone-mediated quorum sensing mechanisms in gram-negative bacteria.
abstract: Many Gram-negative bacteria employ a mechanism of cell-cell communication known as quorum sensing (QS). The role of QS is to enable the cells in a culture to coordinate their gene expression profile with changes in the population cell density. The best characterized mechanisms of QS employ N-acylated homoserine lactones (AHLs) as signalling molecules. These AHLs are made by enzymes known as LuxI homologs, and accumulate in the culture supernatant at a rate proportional to the increase in cell density. Once the AHL concentration exceeds a certain threshold value, these ligands bind to intracellular receptors known as LuxR homologs. The latter are transcriptional regulators, whose activity alters upon binding the AHL ligand, thereby eliciting a change in gene transcription. Over the last five years, it has become increasingly obvious that this is a rather simplistic view of AHL-dependent QS, and that in fact, there is considerable diversity in the way in which LuxI-R homologs operate. The aim of the current review is to describe these variations on the basic theme, and to show how functional genomics is revolutionizing our understanding of QS-controlled regulons.
authors.affiliation: Department of Biochemistry, Building O, Tennis Court Road, Cambridge CB2 1QW, UK.
authors.forename: Debra
authors.initials: D
authors.lastname: Smith
authors.forename: Jin-Hong
authors.initials: JH
authors.lastname: Wang
authors.forename: Jane E
authors.initials: JE
authors.lastname: Swatton
authors.forename: Peter
authors.initials: P
authors.lastname: Davenport
authors.forename: Bianca
authors.initials: B
authors.lastname: Price
authors.forename: Helga
authors.initials: H
authors.lastname: Mikkelsen
authors.forename: Hannah
authors.initials: H
authors.lastname: Stickland
authors.forename: Kahoko
authors.initials: K
authors.lastname: Nishikawa
authors.forename: Noémie
authors.initials: N
authors.lastname: Gardiol
authors.forename: David R
authors.initials: DR
authors.lastname: Spring
authors.forename: Martin
authors.initials: M
authors.lastname: Welch
mesh_terms: D015107:4-Butyrolactone / Q000031:analogs & derivatives* / Q000378:metabolism; D001426:Bacterial Proteins / Q000378:metabolism*; D018441:Biofilms; D015964:Gene Expression Regulation, Bacterial; D006090:Gram-Negative Bacteria / Q000502:physiology*; D008954:Models, Biological; D011156:Population Density; D053038:Quorum Sensing / Q000502:physiology*; D014157:Transcription Factors / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; C085427:LuxI protein, Bacteria; D014157:Transcription Factors; C088386:homoserine lactone; D015107:4-Butyrolactone