Variations on a theme: diverse N-acyl homoserine lactone-mediated quorum sensing mechanisms in gram-negative bacteria.
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.
Smith
Debra
D
Department of Biochemistry, Building O, Tennis Court Road, Cambridge CB2 1QW, UK.
Wang
Jin-Hong
JH
Swatton
Jane E
JE
Davenport
Peter
P
Price
Bianca
B
Mikkelsen
Helga
H
Stickland
Hannah
H
Nishikawa
Kahoko
K
Gardiol
Noémie
N
Spring
David R
DR
Welch
Martin
M
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*
D001426:Bacterial Proteins; C085427:LuxI protein, Bacteria; D014157:Transcription Factors; C088386:homoserine lactone; D015107:4-Butyrolactone