MacLean M J, Ness L S, Ferguson G P, Booth I R
Department of Molecular and Cell Biology, Institute of Medical Sciences, University of Aberdeen, Foresterhill, UK.
Mol Microbiol. 1998 Feb;27(3):563-71. doi: 10.1046/j.1365-2958.1998.00701.x.
The glyoxalase I gene (gloA) of Escherichia coli has been cloned and used to create a null mutant. Cells overexpressing glyoxalase I exhibit enhanced tolerance of methylglyoxal (MG) and exhibit elevated rates of detoxification, although the increase is not stoichiometric with the change in enzyme activity. Potassium efflux via KefB is also enhanced in the overexpressing strain. Analysis of the physiology of the mutant has revealed that growth and viability are quite normal, unless the cell is challenged with MG either added exogenously or synthesized by the cells. The mutant strain has a low rate of detoxification of MG, and cells rapidly lose viability when exposed to this electrophile. Activation of KefB and KefC is diminished in the absence of functional glyoxalase I. These data suggest that the glutathione-dependent glyoxalase I is the dominant detoxification pathway for MG in E. coli and that the product of glyoxalase I activity, S-lactoylglutathione, is the activator of KefB and KefC.
大肠杆菌的乙二醛酶I基因（gloA）已被克隆并用于构建一个缺失突变体。过表达乙二醛酶I的细胞对甲基乙二醛（MG）的耐受性增强，解毒速率提高，尽管这种增加与酶活性的变化不成化学计量关系。在过表达菌株中，通过KefB的钾离子外流也增强。对该突变体生理学的分析表明，除非细胞受到外源添加的MG或细胞自身合成的MG的挑战，其生长和活力相当正常。突变菌株对MG的解毒速率较低，当暴露于这种亲电试剂时，细胞会迅速失去活力。在缺乏功能性乙二醛酶I的情况下，KefB和KefC的激活减弱。这些数据表明，依赖谷胱甘肽的乙二醛酶I是大肠杆菌中MG的主要解毒途径，并且乙二醛酶I活性的产物S-乳酰谷胱甘肽是KefB和KefC的激活剂。
