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.
Synonyms: D-acetoin biosynthesis I
|Superclasses:||Generation of Precursor Metabolites and Energy → Fermentation → Acetoin Biosynthesis|
Some taxa known to possess this pathway include : Aeromonas hydrophila, Bacillus subtilis, Brevibacillus brevis S1, Corynebacterium glutamicum, Enterobacter aerogenes, Klebsiella pneumoniae, Lactobacillus brevis, Lactobacillus casei, Lactobacillus helveticus, Lactobacillus plantarum, Lactococcus lactis, Lactococcus lactis lactis bv. diacetylactis, Leuconostoc lactis, Leuconostoc mesenteroides cremoris, Oenococcus oeni, Pediococcus pentosaceus, Raoultella terrigena, Saccharomyces cerevisiae, Serratia marcescens
In lactic acid bacteria (LAB), pyruvate (which can be formed in large amounts from citrate) is converted into either lactate, by the enzymes L-lactate dehydrogenase or D-lactate dehydrogenase, or to (S)-2-acetolactate by the enzyme α-acetolactate synthase (α-ALS). The conversion of pyruvate to lactate requires NADH, so under conditions of low NADH, the majority of the pyruvate is converted to 2-acetolactate. The relative activities of α-ALS and α-ALD in specific strains determine the fluxes and concentrations of the different intermediates in these organisms.
2-acetolactate is an unstable intermediate. In the presence of oxygen it can undergo a spontaneous decarboxylation, producing diacetyl. Once diacetyl is formed, it can be converted to acetoin by the activity of the enzyme diacetyl reductase (also known as acetoin dehydrogenase).
There seems to be some confusion concerning the two enzyme activities acetoin reductase and diacetyl reductase. Initially, they were reported to be catalyzed by two different enzymes [Strecker54], and two different EC numbers were issued based on that observation (EC 126.96.36.199 and EC 188.8.131.52). However, later research indicated that at least in Enterobacter aerogenes both activities are catalyzed by the same enzyme, for which the name diacetyl(acetoin) reductase was suggested [Bryn71]. Subsequent work supported that finding [Larsen73, Carballo91, Aungpraphapornc99]. As a matter of fact, the enzyme appears to have a much wider substrate range than orignally believed, and it has been suggested to rename it L-glycol dehydrogenase [Carballo91].
This pathway includes multiple decarboxylation reactions, generating CO2. This CO2 is the source of the "eyes", or holes that certain cheeses, such as Swiss cheese, develop during maturation.
Superpathways: superpathway of (R,R)-butanediol biosynthesis
Aungpraphapornc99: Aungpraphapornchai P, Griffin HG, Gasson MJ (1999). "Cloning, DNA sequence analysis, and deletion of a gene encoding diacetyl-acetoin reductase from Lactococcus lactis." DNA Seq 10(3);163-72. PMID: 10647818
Blomqvist93: Blomqvist K, Nikkola M, Lehtovaara P, Suihko ML, Airaksinen U, Straby KB, Knowles JK, Penttila ME (1993). "Characterization of the genes of the 2,3-butanediol operons from Klebsiella terrigena and Enterobacter aerogenes." J Bacteriol 175(5);1392-404. PMID: 8444801
Bryn71: Bryn K, Hetland O, Stormer FC (1971). "The reduction of diacetyl and acetoin in Aerobacter aerogenes. Evidence for one enzyme catalyzing both reactions." Eur J Biochem 18(1);116-9. PMID: 5540507
Carballo91: Carballo J, Martin R, Bernardo A, Gonzalez J (1991). "Purification, characterization and some properties of diacetyl(acetoin) reductase from Enterobacter aerogenes." Eur J Biochem 198(2);327-32. PMID: 2040298
Gonzalez00: Gonzalez E, Fernandez MR, Larroy C, Sola L, Pericas MA, Pares X, Biosca JA (2000). "Characterization of a (2R,3R)-2,3-butanediol dehydrogenase as the Saccharomyces cerevisiae YAL060W gene product. Disruption and induction of the gene." J Biol Chem 275(46);35876-85. PMID: 10938079
Larsen73: Larsen SH, Johansen L, Stormer FC, Storesund HJ (1973). "Formation of 2,3-pentanediol from 2,3-pentanedione and acetylethylcarbinol by diacetyl(acetoin)reductase from Aerobacter aerogenes. A possible new pathway." FEBS Lett 31(1);39-41. PMID: 4350968
Oppermann94: Oppermann FB, Steinbuchel A (1994). "Identification and molecular characterization of the aco genes encoding the Pelobacter carbinolicus acetoin dehydrogenase enzyme system." J Bacteriol 176(2);469-85. PMID: 8110297
Takusagawa01: Takusagawa Y, Otagiri M, Ui S, Ohtsuki T, Mimura A, Ohkuma M, Kudo T (2001). "Purification and characterization of L-2,3-butanediol dehydrogenase of Brevibacterium saccharolyticum C-1012 expressed in Escherichia coli." Biosci Biotechnol Biochem 65(8);1876-8. PMID: 11577733
Wardwell01: Wardwell SA, Yang YT, Chang HY, San KY, Rudolph FB, Bennett GN (2001). "Expression of the Klebsiella pneumoniae CG21 acetoin reductase gene in Clostridium acetobutylicum ATCC 824." J Ind Microbiol Biotechnol 27(4);220-7. PMID: 11687934
Aymes99: Aymes, F., Monnet, C., Corrieu, G. (1999). "Effect of α-acetolactate decarboxylase inactivation on α-acetolactate and diacetyl production by Lactococcus lactis subsp. lactisdiacetylactis." J. Biosci. Bioeng. 87:87-92. PMID: 16232430
Diderichsen90: Diderichsen B, Wedsted U, Hedegaard L, Jensen BR, Sjoholm C (1990). "Cloning of aldB, which encodes alpha-acetolactate decarboxylase, an exoenzyme from Bacillus brevis." J Bacteriol 172(8);4315-21. PMID: 2198252
Ehsani09: Ehsani M, Fernandez MR, Biosca JA, Julien A, Dequin S (2009). "Engineering of 2,3-butanediol dehydrogenase to reduce acetoin formation by glycerol-overproducing, low-alcohol Saccharomyces cerevisiae." Appl Environ Microbiol 75(10);3196-205. PMID: 19329666
Ehsani09a: Ehsani M, Fernandez MR, Biosca JA, Dequin S (2009). "Reversal of coenzyme specificity of 2,3-butanediol dehydrogenase from Saccharomyces cerevisae and in vivo functional analysis." Biotechnol Bioeng 104(2);381-9. PMID: 19507198
Hill97: Hill CM, Pang SS, Duggleby RG (1997). "Purification of Escherichia coli acetohydroxyacid synthase isoenzyme II and reconstitution of active enzyme from its individual pure subunits." Biochem J 327 ( Pt 3);891-8. PMID: 9581571
LaRossa84: LaRossa RA, Schloss JV (1984). "The sulfonylurea herbicide sulfometuron methyl is an extremely potent and selective inhibitor of acetolactate synthase in Salmonella typhimurium." J Biol Chem 1984;259(14);8753-7. PMID: 6378902
Lu14: Lu J, Brigham CJ, Plassmeier JK, Sinskey AJ (2014). "Characterization and modification of enzymes in the 2-ketoisovalerate biosynthesis pathway of Ralstonia eutropha H16." Appl Microbiol Biotechnol. PMID: 25081555
Marugg94: Marugg JD, Goelling D, Stahl U, Ledeboer AM, Toonen MY, Verhue WM, Verrips CT (1994). "Identification and characterization of the alpha-acetolactate synthase gene from Lactococcus lactis subsp. lactis biovar diacetylactis." Appl Environ Microbiol 60(4);1390-4. PMID: 8017926
OSullivan01: O'Sullivan SM, Condon S, Cogan TM, Sheehan D (2001). "Purification and characterisation of acetolactate decarboxylase from Leuconostoc lactis NCW1." FEMS Microbiol Lett 194(2);245-9. PMID: 11164316
Pang04: Pang SS, Duggleby RG, Schowen RL, Guddat LW (2004). "The crystal structures of Klebsiella pneumoniae acetolactate synthase with enzyme-bound cofactor and with an unusual intermediate." J Biol Chem 279(3);2242-53. PMID: 14557277
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