title: Conversion of methylglyoxal to acetol by Escherichia coli aldo-keto reductases.
abstract: Methylglyoxal (MG) is a toxic metabolite known to accumulate in various cell types. We detected in vivo conversion of MG to acetol in MG-accumulating Escherichia coli cells by use of (1)H nuclear magnetic resonance ((1)H-NMR) spectroscopy. A search for homologs of the mammalian aldo-keto reductases (AKRs), which are known to exhibit activity to MG, revealed nine open reading frames from the E. coli genome. Based on both sequence similarities and preliminary characterization with (1)H-NMR for crude extracts of the corresponding mutant strains, we chose five genes, yafB, yqhE, yeaE, yghZ, and yajO, for further study. Quantitative assessment of the metabolites produced in vitro from the crude extracts of these mutants and biochemical study with purified AKRs indicated that the yafB, yqhE, yeaE, and yghZ genes are involved in the conversion of MG to acetol in the presence of NADPH. When we assessed their in vivo catalytic activities by creating double mutants, all of these genes except for yqhE exhibited further sensitivities to MG in a glyoxalase-deficient strain. The results imply that the glutathione-independent detoxification of MG can occur through multiple pathways, consisting of yafB, yqhE, yeaE, and yghZ genes, leading to the generation of acetol.
authors.affiliation: Department of Life Sciences, Korea Advanced Institute of Science and Technology, Yusong-Ku, Taejon 305-701, Republic of Korea.
authors.forename: Junsang
authors.initials: J
authors.lastname: Ko
authors.forename: Insook
authors.initials: I
authors.lastname: Kim
authors.forename: Seokho
authors.initials: S
authors.lastname: Yoo
authors.forename: Bumchan
authors.initials: B
authors.lastname: Min
authors.forename: Kyungmin
authors.initials: K
authors.lastname: Kim
authors.forename: Chankyu
authors.initials: C
authors.lastname: Park
mesh_terms: D000096:Acetone / Q000031:analogs & derivatives* / Q000378:metabolism; D000429:Alcohol Oxidoreductases / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D000449:Aldehyde Reductase; D000074408:Aldo-Keto Reductases; D004926:Escherichia coli / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D029968:Escherichia coli Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D019906:Nuclear Magnetic Resonance, Biomolecular; D011522:Protons; D011765:Pyruvaldehyde / Q000378:metabolism* / Q000633:toxicity; D013379:Substrate Specificity
chemical_list: D029968:Escherichia coli Proteins; D011522:Protons; D000096:Acetone; D011765:Pyruvaldehyde; C004433:acetol; D000429:Alcohol Oxidoreductases; D000074408:Aldo-Keto Reductases; D000449:Aldehyde Reductase