Trchunian A A, Vardanian V A, Vasilian A V
Yerevan State University, Armenia.
Biofizika. 1998 May-Jun;43(3):470-4.
It is shown that the uptake of K+ ions by anaerobically grown E. coli bacteria, which perform glycolysis with the production of H2 in exchange for H+ ions, which are extruded from the cells, occurs with a fixed stoichiometry of N,N'-dicyclohexylcarbodiimide-sensitive ion fluxes (2H+/K+). This process is observed in the precursor strain and arcB mutant, and is destroyed in arcA mutant. The K(+)-uptake by the latter mutant, which proceeds with a moderate affinity (KM 2.0 mM) and is triggered by a positive shock, is sensitive to external osmotonicity. The K(+)-uptake by the arcA mutant is also inhibited by N,N'-dicyclohexylcarbodiimide and has a variable stoichiometry of N,N'-dicyclohexylcarbodiimide-sensitive ion fluxes and does not significantly change in the presence of valinomycin and with varying temperature, whereas the intracellular activity of K+ ions is lower. The Arc-system for the control of synthesis of respiratory enzymes in E. coli participates in the regulation of the K(+)-transporting TrkA system, which directly interacts with F0F1 H-ATPasa; this system in the arcA mutant operates independent of F0F1 and interacts with the latter by mediation of the proton gradient.
结果表明，厌氧生长的大肠杆菌吸收K⁺离子的过程中，这些细菌通过糖酵解产生H₂以交换从细胞中排出的H⁺离子，该过程以固定的化学计量比（2H⁺/K⁺）进行对N,N'-二环己基碳二亚胺敏感的离子通量。在前体菌株和arcB突变体中观察到该过程，而在arcA突变体中该过程被破坏。后一种突变体的K⁺吸收以中等亲和力（KM 2.0 mM）进行，并由正向冲击触发，对外部渗透压敏感。arcA突变体的K⁺吸收也受到N,N'-二环己基碳二亚胺的抑制，并且对N,N'-二环己基碳二亚胺敏感的离子通量具有可变的化学计量比，在缬氨霉素存在和温度变化时没有明显变化，而细胞内K⁺离子的活性较低。大肠杆菌中用于控制呼吸酶合成的Arc系统参与了K⁺转运TrkA系统的调节，该系统直接与F₀F₁ H⁻ATP酶相互作用；arcA突变体中的该系统独立于F₀F₁运行，并通过质子梯度的介导与后者相互作用。
