During fermentation in Escherichia coli succinate is transported via Dcu transporters, encoded dcuA, dcuB, dcuC and dcuD although the role of DcuD protein has not been elucidated yet. It has been shown contribution of Dcu transporters in the N,N’-dicyclohexylcarbodiimide (DCCD) sensitive proton and potassium transport through the cytoplasmic membrane and membrane-associated ATPase activity. Total H^± efflux was decreased ~ 40% while K^± uptake was absent in dcuD mutant. DCCD-sensitive H^± flux was absent in dcuD nevertheless it was increased ~ 3 fold in dcuACB. K^± uptake in dcuACB was stimulated ~ 30% compared to wild type but in DCCD assays K^± ions were effluxed with the rate of 0.15 mmol/min per 10⁹ cells/ml. In dcuACB mutant membrane potential (ΔΨ) was ~ 30 mV higher than in wild type. dcuD gene expression was increased in the dcuACB mutant respect to wild type at pH 7.5 (~120%), suggesting that an increment of DcuD activity compensates the lack of DcuA, DcuC and DcuB carriers. It can be concluded that active DcuD is important for H^± efflux via the F_OF₁-ATPase and K^± uptake at pH 7.5. In addition, DcuA, DcuB and DcuC transporters are crucial for regulating DCCD-sensitive K^± transport and ΔΨ in E. coli.

在大肠杆菌发酵过程中，琥珀酸通过 Dcu 转运蛋白转运，编码dcuA、dcuB、dcuC和dcuD，尽管 DcuD 蛋白的作用尚未阐明。已显示 Dcu 转运蛋白在N,N'-二环己基碳二亚胺 (DCCD) 敏感质子和钾转运通过细胞质膜和膜相关 ATP 酶活性中的贡献。总 H ^±流出减少了约 40%，而dcuD突变体中不存在K ^±吸收。dcuD中不存在DCCD 敏感的 H ^±通量，但在dcuD中增加了~3 倍dcuACB。与野生型相比，dcuACB 中的K ^±吸收被刺激约 30%，但在 DCCD 测定中，K ^±离子以每 10 ^{9 个}细胞/ml 0.15 mmol/min的速率流出。在dcuACB突变体膜电位 (ΔΨ) 中，比野生型高约 30 mV。在 pH 7.5 (~120%) 时，dcuACB突变体中dcuD基因表达相对于野生型增加，表明 DcuD 活性的增加补偿了 DcuA、DcuC 和 DcuB 载体的缺乏。可以得出结论，活性 DcuD 对 H ^±通过 F _O F ₁ -ATPase 和 K ^±流出很重要在 pH 7.5 时吸收。此外，DcuA、DcuB 和 DcuC 转运蛋白对于调节大肠杆菌中DCCD 敏感的 K ^±转运和 ΔΨ至关重要。