Boonstra J, Downie J A, Konings W N
J Bacteriol. 1978 Dec;136(3):844-53. doi: 10.1128/jb.136.3.844-853.1978.
Escherichia coli K-12, grown under anaerobic conditions with glucose as the sole source of carbon and energy without any terminal electron acceptor added, contains a fumarate reductase system in which electrons are transferred from formate or reduced nicotinamide adenine dinucleotide via menaquinone and cytochromes to fumarate reductase. This fumarate reductase system plays an important role in the metabolic energy supply of E. coli, grown under so-called "glycolytic conditions," as is indicated by the growth yields and maximal growth rates of mutants impaired in electron transfer or adenosine triphosphatase (uncB). In mutants deficient in menaquinone, cytochromes, or fumarate reductase, these values are considerably lower than in mutants deficient in ubiquinone or a functional adenosine triphosphatase. Electron transfer in this fumarate reductase system leads to the generation of a membrane potential, as is indicated by the uptake of the lipophilic cation triphenylmethylphosphonium by membrane vesicles prepared from cytochrome-sufficient and uncB cells. The generation of a proton-motive force by the fumarate reductase system was also demonstrated by the uptake of amino acids under anaerobic conditions in membrane vesicles of cytochrome containing and uncB cells grown under glycolytic conditions. Membrane vesicles of cytochrome-deficient cells failed to accumulate triphenyl-methylphosphonium and amino acids under these conditions, indicating that cytochromes are essential for the generation of a proton-motive force. Using glutamine uptake as an indication of the generation of ATP and proline uptake as an indication of the generation of a proton-motive force, it was demonstrated in whole cells that the proton-motive force is formed by ATP hydrolysis in cytochrome-deficient cells and by electron transfer in the uncB cells. In cytochrome-containing cells it was not possible to distinguish between these two possibilities, but the growth parameters suggest that, under glycolytic conditions, the proton-motive force is generated via electron transfer in the fumarate reductase system rather than via ATP hydrolysis.
大肠杆菌K-12在厌氧条件下生长，以葡萄糖作为唯一的碳源和能源，不添加任何末端电子受体，其含有一种延胡索酸还原酶系统，在该系统中电子从甲酸或还原型烟酰胺腺嘌呤二核苷酸经甲基萘醌和细胞色素传递至延胡索酸还原酶。这种延胡索酸还原酶系统在所谓“糖酵解条件”下生长的大肠杆菌的代谢能量供应中发挥重要作用，这一点由电子传递或三磷酸腺苷酶（uncB）受损的突变体的生长产量和最大生长速率表明。在缺乏甲基萘醌、细胞色素或延胡索酸还原酶的突变体中，这些值显著低于缺乏泛醌或功能性三磷酸腺苷酶的突变体。该延胡索酸还原酶系统中的电子传递导致膜电位的产生，这由从细胞色素充足和uncB细胞制备的膜囊泡对亲脂性阳离子三苯基甲基鏻的摄取表明。延胡索酸还原酶系统产生质子动力也通过在糖酵解条件下生长的含细胞色素和uncB细胞的膜囊泡在厌氧条件下对氨基酸的摄取得到证明。在这些条件下，缺乏细胞色素的细胞的膜囊泡无法积累三苯基甲基鏻和氨基酸，表明细胞色素对于质子动力的产生至关重要。利用谷氨酰胺摄取作为ATP产生的指标，脯氨酸摄取作为质子动力产生的指标，在完整细胞中证明，质子动力在缺乏细胞色素的细胞中由ATP水解形成，在uncB细胞中由电子传递形成。在含细胞色素的细胞中，无法区分这两种可能性，但生长参数表明，在糖酵解条件下，质子动力是通过延胡索酸还原酶系统中的电子传递而非通过ATP水解产生的。
