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:||Degradation/Utilization/Assimilation → Aldehyde Degradation|
|Detoxification → Methylglyoxal Detoxification|
Some taxa known to possess this pathway include : Escherichia coli K-12 substr. MG1655
Expected Taxonomic Range: Bacteria
Methylglyoxal is produced in small amounts during glycolysis (via glycerone phosphate), fatty acid metabolism (via acetone), and protein metabolism (via aminoacetone). Methylglyoxal is highly toxic, most likely as a result of its interaction with protein side chains (see [Kalapos99] for a review). There are several pathways for the detoxification of methylglyoxal, based on different enzymes that are able to convert methylglyoxal to less toxic compounds. These enzymes include glyoxalase enzymes, methylglyoxal reductases, aldose reductases, aldehyde reductases and methylglyoxal dehydrogenases.
About This Pathway
In this pathway, which has been characterized in Escherichia coli K-12, methylglyoxal is reduced to lactaldehyde by the enzyme methylglyoxal reductase [Saikusa87]. (S)-lactaldehyde is then reduced to (S)-lactate which is finally converted to pyruvate and joins the pool of central metobolites [Murata89].
Methylglyoxal reductases have been characterized in bacteria [Saikusa87] and fungi [Murata85, Inoue88a]. Some of the enzymes are NADP-linked, while others are NAD-linked. Two variants of this pathway have been entered in MetaCyc to reflect the different biochemistry of the last enzyme, L-lactate dehydrogenase. The Escherichia coli K-12 enzyme encoded by gene lldD uses an unidentified electron acceptor (see methylglyoxal degradation IV), while the Saccharomyces cerevisiae enzyme uses an an oxidized c-type cytochrome (see methylglyoxal degradation V).
methylglyoxal degradation VI is a similar pathway based on methylglyoxal reductases that are specific for the D form of lactaldehyde.
Superpathways: superpathway of methylglyoxal degradation
Subpathways: L-lactaldehyde degradation (aerobic)
Variants: methylglyoxal degradation I , methylglyoxal degradation II , methylglyoxal degradation III , methylglyoxal degradation V , methylglyoxal degradation VI , methylglyoxal degradation VII , methylglyoxal degradation VIII
Unification Links: EcoCyc:PWY-5459
Inoue88a: Inoue Y, Rhee H, Watanabe K, Murata K, Kimura A (1988). "Metabolism of 2-oxoaldehyde in mold. Purification and characterization of two methylglyoxal reductases from Aspergillus niger." Eur J Biochem 171(1-2);213-8. PMID: 3276516
Murata85: Murata K, Fukuda Y, Simosaka M, Watanabe K, Saikusa T, Kimura A (1985). "Metabolism of 2-oxoaldehyde in yeasts. Purification and characterization of NADPH-dependent methylglyoxal-reducing enzyme from Saccharomyces cerevisiae." Eur J Biochem 151(3);631-6. PMID: 3896793
Saikusa87: Saikusa T, Rhee H, Watanabe K, Murata K, Kimura A (1987). "Metabolism of 2-oxoaldehydes in bacteria: purification and characterization of methylglyoxal reductase from E. coli." Agricultural and Biological Chemistry 51(7): 1893-1899.
Badia91: Badia J, Gimenez R, Baldoma L, Barnes E, Fessner WD, Aguilar J (1991). "L-lyxose metabolism employs the L-rhamnose pathway in mutant cells of Escherichia coli adapted to grow on L-lyxose." J Bacteriol 1991;173(16);5144-50. PMID: 1650346
Baldoma88: Baldoma L, Aguilar J (1988). "Metabolism of L-fucose and L-rhamnose in Escherichia coli: aerobic-anaerobic regulation of L-lactaldehyde dissimilation." J Bacteriol 170(1);416-21. PMID: 3275622
Caballero83: Caballero E, Baldoma L, Ros J, Boronat A, Aguilar J (1983). "Identification of lactaldehyde dehydrogenase and glycolaldehyde dehydrogenase as functions of the same protein in Escherichia coli." J Biol Chem 1983;258(12);7788-92. PMID: 6345530
Cocks74: Cocks GT, Aguilar T, Lin EC (1974). "Evolution of L-1, 2-propanediol catabolism in Escherichia coli by recruitment of enzymes for L-fucose and L-lactate metabolism." J Bacteriol 118(1);83-8. PMID: 4595205
Di07: Di Costanzo L, Gomez GA, Christianson DW (2007). "Crystal structure of lactaldehyde dehydrogenase from Escherichia coli and inferences regarding substrate and cofactor specificity." J Mol Biol 366(2);481-93. PMID: 17173928
DiazMejia09: Diaz-Mejia JJ, Babu M, Emili A (2009). "Computational and experimental approaches to chart the Escherichia coli cell-envelope-associated proteome and interactome." FEMS Microbiol Rev 33(1);66-97. PMID: 19054114
Franchini06: Franchini AG, Egli T (2006). "Global gene expression in Escherichia coli K-12 during short-term and long-term adaptation to glucose-limited continuous culture conditions." Microbiology 152(Pt 7);2111-27. PMID: 16804185
Grochowski06: Grochowski LL, Xu H, White RH (2006). "Identification of lactaldehyde dehydrogenase in Methanocaldococcus jannaschii and its involvement in production of lactate for F420 biosynthesis." J Bacteriol 188(8);2836-44. PMID: 16585745
Hacking76: Hacking AJ, Lin EC (1976). "Disruption of the fucose pathway as a consequence of genetic adaptation to propanediol as a carbon source in Escherichia coli." J Bacteriol 126(3);1166-72. PMID: 181364
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