Conversion of methylglyoxal to acetol by Escherichia coli aldo-keto Reductases
Conversion of methylglyoxal to acetol by Escherichia coli aldo-keto Reductases
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DOI：
10.1128/jb.187.16.5782-5789.2005
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发表时间：
2005-08-01
影响因子：
3.2
通讯作者：
Park, C
中科院分区：
文献类型：
--
作者：
Ko, J;Kim, I;Park, C
甲基乙二醛（MG）是一种毒性代谢产物，已知可在各种细胞类型中蓄积。我们检测体内转换MG乙酰醇在MG积累大肠杆菌细胞中使用H-1核磁共振（H-1-NMR）光谱。对哺乳动物醛酮还原酶（AKR）的同源物进行了搜索，发现了9个来自E. coli基因组。基于序列相似性和相应突变株粗提物的H-1-NMR初步表征，我们选择了5个基因，yafB，yqhE，yeaE，yghZ和yajO，进行进一步研究。从这些突变体的粗提取物和纯化的AKR的生化研究在体外产生的代谢物的定量评估表明，yafB，yqhE，yeaE，和yghZ基因参与的MG转化为丙酮醇在NADPH的存在下。当我们通过创建双突变体来评估它们的体内催化活性时，除了yqhE之外，所有这些基因在glycoprotein酶缺陷菌株中对MG表现出进一步的敏感性。结果表明MG的谷胱甘肽非依赖性解毒可以通过多种途径发生，包括yajB，yqhE，yeaE和yghZ基因，导致丙酮醇的产生。
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 H-1 nuclear magnetic resonance (H-1-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 H-1-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 yajB, yqhE, yeaE, and yghZ genes, leading to the generation of acetol.