Three parallel quorum-sensing systems regulate gene expression in Vibrio harveyi.
In a process called quorum sensing, bacteria communicate using extracellular signal molecules termed autoinducers. Two parallel quorum-sensing systems have been identified in the marine bacterium Vibrio harveyi. System 1 consists of the LuxM-dependent autoinducer HAI-1 and the HAI-1 sensor, LuxN. System 2 consists of the LuxS-dependent autoinducer AI-2 and the AI-2 detector, LuxPQ. The related bacterium, Vibrio cholerae, a human pathogen, possesses System 2 (LuxS, AI-2, and LuxPQ) but does not have obvious homologues of V. harveyi System 1. Rather, System 1 of V. cholerae is made up of the CqsA-dependent autoinducer CAI-1 and a sensor called CqsS. Using a V. cholerae CAI-1 reporter strain we show that many other marine bacteria, including V. harveyi, produce CAI-1 activity. Genetic analysis of V. harveyi reveals cqsA and cqsS, and phenotypic analysis of V. harveyi cqsA and cqsS mutants shows that these functions comprise a third V. harveyi quorum-sensing system that acts in parallel to Systems 1 and 2. Together these communication systems act as a three-way coincidence detector in the regulation of a variety of genes, including those responsible for bioluminescence, type III secretion, and metalloprotease production.
Henke
Jennifer M
JM
Department of Molecular Biology, Princeton University, Princeton, NJ 08544-1014, USA.
Bassler
Bonnie L
BL
D015107:4-Butyrolactone / Q000031:analogs & derivatives / Q000502:physiology*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D006714:Homoserine / Q000031:analogs & derivatives* / Q000235:genetics / Q000378:metabolism*; D007783:Lactones / Q000378:metabolism*; D008163:Luminescent Measurements; D015398:Signal Transduction; D014158:Transcription, Genetic; D014733:Vibrio / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D014734:Vibrio cholerae / Q000235:genetics / Q000254:growth & development / Q000378:metabolism
D001426:Bacterial Proteins; D007783:Lactones; C091088:N-octanoylhomoserine lactone; D006714:Homoserine; D015107:4-Butyrolactone