This view shows enzymes only for those organisms listed below, in the list of taxa known to possess the pathway. If an enzyme name is shown in bold, there is experimental evidence for this enzymatic activity.
|Superclasses:||Biosynthesis → Other Biosynthesis → Autoinducer Biosynthesis|
Expected Taxonomic Range: Vibrionales
Cell-cell communication in bacteria is accomplished through the exchange of extracellular signalling molecules called autoinducers. This process, termed quorum sensing, allows bacterial populations to coordinate gene expression as a function of cell density. Many processes benefit from community cooperation, including bioluminescence, virulence factor expression, antibiotic production and biofilm development.
One of the main families of bacterial autoinducers is known as AI-2, for autoinducer 2. AI-2 was first described as an extracellular signal produced by the marine bacterium Vibrio harveyi to control luciferase expression [Bassler94, Surette99]. However, it was eventually found to be produced by a remarkably wide variety of Gram-negative and Gram-positive bacteria, leading to the proposal that AI-2 is a 'universal' signal, which functions in interspecies cell-to-cell communication [Miller01, Rezzonico08].
The precursor of AI-2, (S)-4,5-dihydroxypentan-2,3-dione, is synthesized by the enzyme S-ribosylhomocysteine lyase, in a reaction that is also a step in the S-adenosyl-L-methionine cycle I pathway (SAM cycle). The enzyme converts S-ribosyl-L-homocysteine to L-homocysteine in a reaction that also produces (S)-4,5-dihydroxypentan-2,3-dione. Within the SAM cycle, the main product of the enzyme is the former compound. However, in organisms that produce an AI-2 autoinducer, (S)-4,5-dihydroxypentan-2,3-dione is of major importance as it appears to be the last enzyme-generated precursor for AI-2, and is converted to the functional autoinducer in a series of chemical modifications without the help of any known enzyme.
The exact nature of the chemical transformations depends on the species. In Vibrionales the spontaneous transformations include cyclyzation to (2S,4S)-2-methyl-2,4-dihydroxydihydrofuran-3-one, hydration to (2S,4S)-2-methyl-2,3,3,4-tetrahydroxytetrahydrofuran, and finally, in the presence of free borate ions, complexation with the later to form the active autoinducer, (2S,4S)-2-methyl-2,3,3,4-tetrahydroxytetrahydrofuran-borate [Chen02a, Rezzonico08]. This particular form of the autoinducer appears to be unique to Vibrionales, which detect it using dedicated AI-2 receptors encoded by the luxP and luxQ genes [Bassler94, Reading06].
Other bacteria that produce AI-2 utilize a different form of the autoinducer. In those organisms (S)-4,5-dihydroxypentan-2,3-dione appears to form a different stereoisomer, namely (2R,4S)-2-methyl-2,4-dihydroxydihydrofuran-3-one, which does not complex borate [Miller04] (see autoinducer AI-2 biosynthesis I). The mechanism that controls which stereoisomer is formed is still not understood.
Bassler94: Bassler BL, Wright M, Silverman MR (1994). "Multiple signalling systems controlling expression of luminescence in Vibrio harveyi: sequence and function of genes encoding a second sensory pathway." Mol Microbiol 13(2);273-86. PMID: 7984107
Chen02a: Chen X, Schauder S, Potier N, Van Dorsselaer A, Pelczer I, Bassler BL, Hughson FM (2002). "Structural identification of a bacterial quorum-sensing signal containing boron." Nature 415(6871);545-9. PMID: 11823863
Miller04: Miller ST, Xavier KB, Campagna SR, Taga ME, Semmelhack MF, Bassler BL, Hughson FM (2004). "Salmonella typhimurium recognizes a chemically distinct form of the bacterial quorum-sensing signal AI-2." Mol Cell 15(5);677-87. PMID: 15350213
Surette99: Surette MG, Miller MB, Bassler BL (1999). "Quorum sensing in Escherichia coli, Salmonella typhimurium, and Vibrio harveyi: a new family of genes responsible for autoinducer production." Proc Natl Acad Sci U S A 96(4);1639-44. PMID: 9990077
Allart98: Allart B, Gatel M, Guillerm D, Guillerm G (1998). "The catalytic mechanism of adenosylhomocysteine/methylthioadenosine nucleosidase from Escherichia coli--chemical evidence for a transition state with a substantial oxocarbenium character." Eur J Biochem 256(1);155-62. PMID: 9746359
Capitanio03: Capitanio N, Capitanio G, De Nitto E, Boffoli D, Papa S (2003). "Proton transfer reactions associated with the reaction of the fully reduced, purified cytochrome C oxidase with molecular oxygen and ferricyanide." Biochemistry 42(16);4607-12. PMID: 12705823
Cornell98: Cornell KA, Riscoe MK (1998). "Cloning and expression of Escherichia coli 5'-methylthioadenosine/S-adenosylhomocysteine nucleosidase: identification of the pfs gene product." Biochim Biophys Acta 1396(1);8-14. PMID: 9524204
Della85: Della Ragione F, Porcelli M, Carteni-Farina M, Zappia V, Pegg AE (1985). "Escherichia coli S-adenosylhomocysteine/5'-methylthioadenosine nucleosidase. Purification, substrate specificity and mechanism of action." Biochem J 232(2);335-41. PMID: 3911944
Farrar10: Farrar CE, Siu KK, Howell PL, Jarrett JT (2010). "Biotin synthase exhibits burst kinetics and multiple turnovers in the absence of inhibition by products and product-related biomolecules." Biochemistry 49(46);9985-96. PMID: 20961145
Ferro76: Ferro AJ, Barrett A, Shapiro SK (1976). "Kinetic properties and the effect of substrate analogues on 5'-methylthioadenosine nucleosidase from Escherichia coli." Biochim Biophys Acta 438(2);487-94. PMID: 782530
Gopishetty09: Gopishetty B, Zhu J, Rajan R, Sobczak AJ, Wnuk SF, Bell CE, Pei D (2009). "Probing the catalytic mechanism of S-ribosylhomocysteinase (LuxS) with catalytic intermediates and substrate analogues." J Am Chem Soc 131(3);1243-50. PMID: 19099445
Gutierrez09: Gutierrez JA, Crowder T, Rinaldo-Matthis A, Ho MC, Almo SC, Schramm VL (2009). "Transition state analogs of 5'-methylthioadenosine nucleosidase disrupt quorum sensing." Nat Chem Biol 5(4):251-7. PMID: 19270684
Lee03a: Lee JE, Cornell KA, Riscoe MK, Howell PL (2003). "Structure of Escherichia coli 5'-methylthioadenosine/ S-adenosylhomocysteine nucleosidase inhibitor complexes provide insight into the conformational changes required for substrate binding and catalysis." J Biol Chem 278(10);8761-70. PMID: 12496243
Lee05b: Lee JE, Luong W, Huang DJ, Cornell KA, Riscoe MK, Howell PL (2005). "Mutational analysis of a nucleosidase involved in quorum-sensing autoinducer-2 biosynthesis." Biochemistry 44(33);11049-57. PMID: 16101288
Lewis01: Lewis HA, Furlong EB, Laubert B, Eroshkina GA, Batiyenko Y, Adams JM, Bergseid MG, Marsh CD, Peat TS, Sanderson WE, Sauder JM, Buchanan SG (2001). "A structural genomics approach to the study of quorum sensing: crystal structures of three LuxS orthologs." Structure 9(6);527-37. PMID: 11435117
Schauder01: Schauder S, Shokat K, Surette MG, Bassler BL (2001). "The LuxS family of bacterial autoinducers: biosynthesis of a novel quorum-sensing signal molecule." Mol Microbiol 41(2);463-76. PMID: 11489131
Winzer02: Winzer K, Hardie KR, Burgess N, Doherty N, Kirke D, Holden MT, Linforth R, Cornell KA, Taylor AJ, Hill PJ, Williams P (2002). "LuxS: its role in central metabolism and the in vitro synthesis of 4-hydroxy-5-methyl-3(2H)-furanone." Microbiology 148(Pt 4);909-22. PMID: 11932438
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