N-Acyl homoserine lactone

N-Acyl homoserine lactone
General chemical structure of an N-acyl homoserine lactone

N-Acyl homoserine lactones (AHLs or N-AHLs) are a class of signaling molecules involved in bacterial quorum sensing. Quorum sensing is a method of communication between bacteria that enables the coordination of group-based behavior based on population density. They signal changes in gene expression, such as switching between the flagella gene and the gene for pili for the development of a biofilm.

Contents

Quorum sensing

Mechanism

Signaling molecules are produced within the cell and are released into the environment. The resulting concentration of signaling molecules in the environment is dependent upon population density. Once the population density has reached a particular threshold, gene expression can begin. This allows bacteria to coordinate group-based behavior. N-AHLs produced by different bacteria differ in the length of the R-group side-chain. Chain lengths vary from 4 to 18 carbon atoms and in the substitution of a carbonyl at the third carbon.[1] It has also been suggested that N-AHLs alter local surface tension enough to create Marangoni flows which facilitate swarming and colony motility. [2]

Example

One example of the involvement of AHLs in quorum sensing is in the regulation of the bioluminescent protein luciferase in the luminescent bacteria Vibrio fischeri. Similar pathways occur in other luminescent bacteria. In Vibrio fischeri, AHL binds to the protein product of the LuxR gene and activates it. The C-terminal domain of activated LuxR relieves the repression exerted by H-NS nucleoid proteins that bind to the promoters of LuxR, LuxI and the LuxCDABEG operon, as well as to A-T-rich stretches within that operon and other genomic regions. The product of LuxI catalyses the synthesis of AHL. Thus, AHL acts as an autoinducer. Transcription of the LuxCDABEG operon results in luminescence due to the expression of LuxA and LuxB, which form a protein known as a luciferase and the expression of LuxC, D, E, and G, which are involved in the synthesis of the luciferase's substrate, tetradecanal. This is an important feature of quorum sensing, as it makes little sense for one cell to waste the energy producing light, as the resulting light will be so faint that it will be more or less undetectable. Instead, once the bacterial population has reached a specific size, only then does light production commence.

Edman degradation

Homoserine lactone is also a product of the proteolytic reaction of cyanogen bromide (CNBR) with a methionine residue in a protein. This reaction is important for chemical sequencing of proteins, as the Edman degradation process is unable to sequence more than 70 consecutive residues.

History

Homoserine lactones were first discovered at Cornell University[3].

Notes

  1. ^ Kumari, A.; Pasini, P.; Deo, S. K.; Flomenhoft, D.; Shashidhar, S.; Daunert, S. (2006). "Biosensing Systems for the Detection of Bacterial Quorum Signaling Molecules". Analytical Chemistry 78 (22): 7603–7609. doi:10.1021/ac061421n. PMID 17105149. 
  2. ^ Daniels, R.; Reynaert, S.; Hoekstra, H.; Verreth, C; Janssens, J.; Braeken, K.; Fauvart, M.; Beullens, S.; Heusdens, C.; Lambrichts, I.; De Vos, D.E.; Vanderleyden, J.; Vermant J.; Michiels, J. (2006). "Quorum signal molecules as biosurfactants affecting swarming in Rhizobium etli". PNAS 103 (40): 14965–14970. doi:10.1073/pnas.0511037103. http://www.pnas.org/content/103/40/14965.full.pdf. 
  3. ^ Eberhard, A.; Burlingame, A. L.; Eberhard, C.; Kenyon, G. L.; Nealson, K. H.; Oppenheimer, N. J. (1981). "Structural identification of autoinducer of Photobacterium fischeri luciferase". Biochemistry 20 (9): 2444–2449. doi:10.1021/bi00512a013. PMID 7236614. 

Wikimedia Foundation. 2010.

Игры ⚽ Нужно сделать НИР?

Look at other dictionaries:

  • Homoserine lactone — Homosérine lactone Structure des acyl homosérine lactones Les Homosérine lactones sont des composés chimiques qui, sous forme acylée, sont impliqués dans le quorum sensing chez les bactéries. Différentes formes d acyl homosérine lactones sont… …   Wikipédia en Français

  • Homosérine Lactone — Structure des acyl homosérine lactones Les Homosérine lactones sont des composés chimiques qui, sous forme acylée, sont impliqués dans le quorum sensing chez les bactéries. Différentes formes d acyl homosérine lactones sont utilisées par diverses …   Wikipédia en Français

  • Homosérine lactone — Structure des acyl homosérine lactones Les Homosérine lactones sont des composés chimiques qui, sous forme acylée, sont impliqués dans le quorum sensing chez les bactéries. Différentes formes d acyl homosérine lactones sont utilisées par diverses …   Wikipédia en Français

  • Lactonase — 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… …   Wikipedia

  • Hydrolase — Cristal de lysozyme Les hydrolases constituent une classe d enzymes qui catalysent les réactions d hydrolyse de molécules suivant la réaction générale : R R + H2O ⇌ R OH + R H On y trouve par exemple les estérases, qui hydrolysent les …   Wikipédia en Français

  • EC 3.5 — Le groupe EC3.5 rassemble des enzymes appartenant à la famille des hydrolases. Elles ont pour particularité de catalyser des réactions d hydrolyse dans des molécules possédant un carbone et un azote liés par liaison simple, double ou triple. À la …   Wikipédia en Français

  • Pseudomonas amygdali — Taxobox color = lightgrey name = Pseudomonas amygdali regnum = Bacteria phylum = Proteobacteria classis = Gamma Proteobacteria ordo = Pseudomonadales familia = Pseudomonadaceae genus = Pseudomonas species = P. amygdali binomial = Pseudomonas… …   Wikipedia

  • Pseudomonas coronafaciens — Taxobox color = lightgrey name = Pseudomonas coronafaciens image width = 240px image caption = regnum = Bacteria phylum = Proteobacteria classis = Gamma Proteobacteria ordo = Pseudomonadales familia = Pseudomonadaceae genus = Pseudomonas species …   Wikipedia

  • Pseudomonas tomato — Taxobox color = lightgrey name = Pseudomonas tomato regnum = Bacteria phylum = Proteobacteria classis = Gamma Proteobacteria ordo = Pseudomonadales familia = Pseudomonadaceae genus = Pseudomonas species = P. tomato binomial = Pseudomonas tomato… …   Wikipedia

  • Pseudomonas helianthi — Taxobox color = lightgrey name = Pseudomonas helianthi regnum = Bacteria phylum = Proteobacteria classis = Gamma Proteobacteria ordo = Pseudomonadales familia = Pseudomonadaceae genus = Pseudomonas species = P. helianthi binomial = Pseudomonas… …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”