Tran Q H, Bongaerts J, Vlad D, Unden G
Institut für Mikrobiologie und Weinforschung, Universität Mainz, Germany.
Eur J Biochem. 1997 Feb 15;244(1):155-60. doi: 10.1111/j.1432-1033.1997.00155.x.
In Escherichia coli the expression of the nuo genes encoding the proton pumping NADH dehydrogenase I is stimulated by the presence of fumarate during anaerobic respiration. The regulatory sites required for the induction by fumarate, nitrate and O2 are located at positions around -309, -277, and downstream of -231 bp, respectively, relative to the transcriptional-start site. The fumarate regulator has to be different from the O2 and nitrate regulators ArcA and NarL. For growth by fumarate respiration, the presence of NADH dehydrogenase I was essential, in contrast to aerobic or nitrate respiration which used preferentially NADH dehydrogenase II. The electron transport from NADH to fumarate strongly decreased in a mutant lacking NADH dehydrogenase I. The mutant used acetyl-CoA instead of fumarate to an increased extent as an electron acceptor for NADH, and excreted ethanol. Therefore, NADH dehydrogenase I is essential for NADH-->fumarate respiration, and is able to use menaquinone as an electron acceptor. NADH-->dimethylsulfoxide respiration is also dependent on NADH dehydrogenase I. The consequences for energy conservation by anaerobic respiration with NADH as a donor are discussed.
在大肠杆菌中，编码质子泵NADH脱氢酶I的nuo基因的表达在厌氧呼吸过程中受到富马酸的刺激。相对于转录起始位点，富马酸、硝酸盐和氧气诱导所必需的调控位点分别位于大约-309、-277以及-231 bp下游的位置。富马酸调节因子必定不同于氧气和硝酸盐调节因子ArcA和NarL。与优先使用NADH脱氢酶II的有氧呼吸或硝酸盐呼吸相反，对于通过富马酸呼吸进行生长而言，NADH脱氢酶I的存在至关重要。在缺乏NADH脱氢酶I的突变体中，从NADH到富马酸的电子传递大幅减少。该突变体增加了使用乙酰辅酶A而非富马酸作为NADH电子受体的程度，并分泌乙醇。因此，NADH脱氢酶I对于NADH→富马酸呼吸至关重要，并且能够使用甲萘醌作为电子受体。NADH→二甲基亚砜呼吸也依赖于NADH脱氢酶I。本文讨论了以NADH作为供体进行厌氧呼吸时能量守恒的后果。
