title: Quorum-sensing in Gram-negative bacteria.
abstract: It has become increasingly and widely recognised that bacteria do not exist as solitary cells, but are colonial organisms that exploit elaborate systems of intercellular communication to facilitate their adaptation to changing environmental conditions. The languages by which bacteria communicate take the form of chemical signals, excreted from the cells, which can elicit profound physiological changes. Many types of signalling molecules, which regulate diverse phenotypes across distant genera, have been described. The most common signalling molecules found in Gram-negative bacteria are N-acyl derivatives of homoserine lactone (acyl HSLs). Modulation of the physiological processes controlled by acyl HSLs (and, indeed, many of the non-acyl HSL-mediated systems) occurs in a cell density- and growth phase-dependent manner. Therefore, the term 'quorum-sensing' has been coined to describe this ability of bacteria to monitor cell density before expressing a phenotype. In this paper, we review the current state of research concerning acyl HSL-mediated quorum-sensing. We also describe two non-acyl HSL-based systems utilised by the phytopathogens Ralstonia solanacearum and Xanthomonas campestris.
authors.affiliation: Department of Biochemistry, University of Cambridge, Tennis Court Road, Building O, Downing Site, CB2 1QW, Cambridge, UK.
authors.forename: N A
authors.initials: NA
authors.lastname: Whitehead
authors.forename: A M
authors.initials: AM
authors.lastname: Barnard
authors.forename: H
authors.initials: H
authors.lastname: Slater
authors.forename: N J
authors.initials: NJ
authors.lastname: Simpson
authors.forename: G P
authors.initials: GP
authors.lastname: Salmond
mesh_terms: D015107:4-Butyrolactone / Q000031:analogs & derivatives* / Q000378:metabolism; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism*; D015169:Colony Count, Microbial; D006090:Gram-Negative Bacteria / Q000166:cytology* / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity; D008954:Models, Biological; D008969:Molecular Sequence Data; D012097:Repressor Proteins / Q000737:chemistry / Q000378:metabolism*; D015398:Signal Transduction; D015534:Trans-Activators / Q000737:chemistry / Q000378:metabolism*; D014157:Transcription Factors / Q000737:chemistry / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; C085427:LuxI protein, Bacteria; D012097:Repressor Proteins; D015534:Trans-Activators; D014157:Transcription Factors; C064778:LuxR autoinducer binding proteins; C088386:homoserine lactone; D015107:4-Butyrolactone