ATP synthesis by the F1Fo ATP synthase of Escherichia coli is obligatorily dependent on the electric potential

FEBS Letters

Kaim, Georg¹  Dimroth, Peter¹ 

[1]Mikrobiologisches Institut, Eidgenössische Technische Hochschule, ETH-Zentrum, Schmelzbergstr. 7, CH-8092 Zürich, Switzerland

关键词: ATP synthesis;    Driving force;    Electric potential;    Succinate diffusion potential;   

DOI  :  10.1016/S0014-5793(98)00969-7

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The H⁺-translocating F₁F_o ATP synthase of Escherichia coli was purified and reconstituted into proteoliposomes. This system catalyzed ATP synthesis when energized by an acid/base transition (pH_in=5.0; pH_out=8.3) with succinate, malonate or maleinate but not with MES as the acidic buffer. Under these experimental conditions an electric potential of 125–130 mV is generated by the diffusion of succinate, probably the monoanionic species, whereas with MES buffer the measured potential was at background level (∼5 mV). ATP was also synthesized at pH 7.2 in the absence of a ΔpH by applying a K⁺/valinomycin diffusion potential. The rate of ATP synthesis increased with the potential in an exponential manner with an inflection point at about 70 mV. We conclude from these results that ΔpH and ΔΨ are kinetically unequivalent driving forces for ATP synthesis by the E. coli ATP synthase and that ΔΨ is a mandatory force for this synthesis. The significance of these findings for the mechanism of ATP synthesis in general is discussed.

【 授权许可】

Unknown