Glutathione-dependent conversion of N-ethylmaleimide to the maleamic acid by Escherichia coli:: an intracellular detoxification process
Glutathione-dependent conversion of N-ethylmaleimide to the maleamic acid by Escherichia coli:: an intracellular detoxification process
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DOI：
10.1128/aem.66.4.1393-1399.2000
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发表时间：
2000-04-01
影响因子：
4.4
通讯作者：
Booth, IR
中科院分区：
文献类型：
--
作者：
McLaggan, D;Rufino, H;Booth, IR
亲电试剂 N-乙基马来酰亚胺 (NEM) 在与细胞质谷胱甘肽反应形成加合物 N-乙基琥珀酰亚胺-S-谷胱甘肽 (ESG) 后，可从大肠杆菌细胞中引发快速 K+ 流出，该加合物是 KefB 和 KefC 谷胱甘肽门控 K+ 流出系统的强激活剂。 ESG 的命运此前尚未被调查过。在本报告中，我们证明 NEM 和 N-苯基马来酰亚胺 (NPM) 可以被大肠杆菌快速解毒。通过形成 NEM 或 NPM 的谷胱甘肽加合物，然后酰亚胺键水解，释放出 N-取代的马来酰胺酸，进行解毒。即使在高浓度下，N-乙基马来酰胺酸对大肠杆菌细胞也没有毒性。谷胱甘肽加合物不会从细胞中释放，这使得谷胱甘肽可以在细胞质中循环利用。解毒不依赖于新的蛋白质合成和NAD(+)依赖性脱氢酶活性，并且完全依赖于谷胱甘肽。低浓度 NEM 解毒的时间过程与 KefB 和 KefC 谷胱甘肽门控 K+ 流出系统的瞬时激活平行。
The electrophile N-ethylmaleimide (NEM) elicits rapid K+ efflux from Escherichia coli cells consequent upon reaction with cytoplasmic glutathione to form an adduct, N-ethylsuccinimido-S-glutathione (ESG) that is a strong activator of the KefB and KefC glutathione-gated K+ efflux systems. The fate of the ESG has not previously been investigated. In this report we demonstrate that NEM and N-phenylmaleimide (NPM) are rapidly detoxified by E. coli. The detoxification occurs through the formation of the glutathione adduct of NEM or NPM, followed by the hydrolysis of the imide bond after which N-substituted maleamic acids are released. N-Ethylmaleamic acid is not toxic to E. coli cells even at high concentrations. The glutathione adducts are not released from cells, and this allows glutathione to be recycled in the cytoplasm. The detoxification is independent of new protein synthesis and NAD(+)-dependent dehydrogenase activity and entirely dependent upon glutathione. The time course of the detoxification of low concentrations of NEM parallels the transient activation of the KefB and KefC glutathione-gated K+ efflux systems.