Regulation of quorum sensing in Vibrio harveyi by LuxO and Sigma-54
Article first published online: 18 JAN 2002
Volume 36, Issue 4, pages 940–954, May 2000
How to Cite
Lilley, B. N. and Bassler, B. L. (2000), Regulation of quorum sensing in Vibrio harveyi by LuxO and Sigma-54. Molecular Microbiology, 36: 940–954. doi: 10.1046/j.1365-2958.2000.01913.x
- Issue published online: 18 JAN 2002
- Article first published online: 18 JAN 2002
- Received 1 February, 2000; revised 2 March, 2000; accepted 6 March, 2000.
The bioluminescent marine bacterium Vibrio harveyi controls light production (lux) by an elaborate quorum-sensing circuit. V. harveyi produces and responds to two different autoinducer signals (AI-1 and AI-2) to modulate the luciferase structural operon (luxCDABEGH) in response to changes in cell-population density. Unlike all other Gram-negative quorum-sensing organisms, V. harveyi regulates quorum sensing using a two-component phosphorylation–dephosphorylation cascade. Each autoinducer is recognized by a cognate hybrid sensor kinase (called LuxN and LuxQ). Both sensors transduce information to a shared phosphorelay protein called LuxU, which in turn conveys the signal to the response regulator protein LuxO. Phospho-LuxO is responsible for repression of luxCDABEGH expression at low cell density. In the present study, we demonstrate that LuxO functions as an activator protein via interaction with the alternative sigma factor, σ54 (encoded by rpoN). Our results suggest that LuxO, together with σ54, activates the expression of a negative regulator of luminescence. We also show that phenotypes other than lux are regulated by LuxO and σ54, demonstrating that in Vibrio harveyi, quorum sensing controls multiple processes.