Difference between revisions of "AHL"

Revision as of 20:52, 19 September 2006

Full name: [N-]acyl-homoserine lactones

These are small signalling molecules which are employed in [http://en.wikipedia.org/wiki/Quorum_sensing "quorum sensing"] systems. They are also known as autoinducers (AIs) and are present in many Gram-negative bacteria.

"Although the target genes regulated by AIs are extremely varied, the basic mechanism of AIs biosynthesis and gene regulation seems to be conserved in different bacteria. The general feature of gene regulation by AIs is cell-density dependence, also known as [http://en.wikipedia.org/wiki/Quorum_sensing "quorum sensing"].

At low cell densities, the AIs are at low concentrations, and, at high cell densities, the AIs can accumulate to a concentration sufficient for activation of related regulatory genes. Because the concentration of AHL's is a key factor in determining virulence gene expression in several pathogenic bacteria, it is possible to develop a strategy for disease control by controlling production of AIs or eliminating AIs produced by pathogenic bacteria." [1]

Acyl-HSL's in different species

"In recent years, AIs have been identified in several Gram-negative bacteria. AIs are involved in the regulation of a range of biological functions, including Ti plasmid conjugal transfer in Agrobacterium tumefaciens, induction of virulence genes in Erwinia carotovora, Erwinia chrysanthemi, Erwinia stewartii, Pseudomonas aeruginosa, Pseudomonas solanacearum, and Xenorhabdus nematophilus, regulation of antibiotic production in Pseudomonas aureofaciens and E. carotovora, regulation of swarming motility in Serratia liquefaciens, and biofilm formation in Pseudomonas fluorescens and P. aeruginosa. Many more bacterial species are known to produce AIs, but the relevant biological functions have not yet been established."[1]

3-oxohexanoyl-homoserine lactone 3OC6HSL

Currently, the most well studied of these AHL molecules is 3-oxohexanoyl-homoserine lactone 3OC6HSL, which binds to the transcriptional activator protein LuxR to alter transcriptional regulation of the Lux operon.

Related Pages

• Featured Parts:Cell-Cell-Signaling - A listing of parts relating to the Lux operon's signalling system

References

1. Dong et al. "AiiA, an enzyme that inactivates the acylhomoserine lactone quorum-sensing signal and attenuates the virulence of Erwinia carotovora" . PNAS 2000. [http://www.pnas.org/cgi/content/full/97/7/3526 link]
2. Collins, C.H. et al. Directed Evolution of V. Fischeri LuxR for increased acyl-HSL's. Molecular Microbiology. 2005. [http://www.blackwell-synergy.com/doi/abs/10.1111/j.1365-2958.2004.04437.x Abstract]