Lactonase

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Structure of an AHL
Structure of an AHL

An enzyme, produced by certain species of bacteria, which targets and inactivates acylated homoserine lactones (AHLs).

Many species of the Proteobacteria genus from the alpha, beta and gamma classes have been shown to produce acylated homoserine lactones (AHLs), which are small hormone-like molecules commonly used as communication signals between bacterial cells in a population to regulate certain gene expression and phenotypic behaviours [1]. This type of gene regulation is known as quorum sensing.

Examples of AHL-producing bacteria include Pseudomonas aeruginosa, an opportunistic pathogen that infects immuno-compromised patients [2], and Erwinia carotovora, a plant pathogen that causes soft rot in a number of crops such as potatoes and carrots [3].

Lactonases are able to interfere with AHL-mediated quorum sensing and some examples of these lactonases are AiiA produced by Bacillus species and AttM produced by Agrobacterium tumefaciens.


Contents

[edit] Mode of Action (Mechanism)

Hydrolysing the lactone bond of AHLs [4].

[edit] Ecology

It is still unclear the ecological effects of lactonase but it has been proposed that since bacteria mostly coexist with other microorganisms in the environment, some bacteria strains could have evolved its feeding strategies and utilize AHLs as their main resource for energy and nitrogen [5].

[edit] Applications

By understanding the mechanisms of these actions and purposes of these communications, it could lead to potential applied roles for these lactonases to control bacterial infections and bring about profound effects on human health and the environment.

[edit] References

  1. ^ Fuqua, C., Winans, S. C. & Greenberg, E. P. (1996) Census and consensus in bacterial ecosystems: the LuxR-LuxI family of quorum-sensing transcriptional regulators. Annu. Rev. Microbiol. 50, 727-751.
  2. ^ Whitehead, N. A., Barnard A. M. L., Slater H., Simpson, N. J. L., and Salmond, G. P. C. (2001) Quorum sensing in Gram-negative bacteria. FEMS Microbiol. Rev. 25, 365-404.
  3. ^ Pirhonen, M., Flegom, D., Heikinheimo, R., and Palva, E. T. (1993) A small diffusible signal molecule is responsible for the global control of virulence and exoenzyme production in the plant pathogen Erwinia carotovora. EMBO J. 12, 2467-2476.
  4. ^ Dong, Y., Wang, L., Xu, J., Zhang, H., Zhang, X. and Zhang, L. (2001) Quencing quorum-sensing-dependent bacterial infection by an N-acyl homoserine lactonase. Nature 411, 813-817.
  5. ^ Leadbetter, J. R. G., Greenberg, E. P. (2000) Metabolism of acyl-homoserine lactone quorum-sensing signals by Variovorax paradoxus. J. Bacteriol. 182, 6921-6926