The respiration‐driven active sodium transport system in E. coli does not function with lithium

FEBS Letters

Verkhovskaya, Marina L.¹  Verkhovsky, Michael I.¹  Wikström, Mårten¹ 

[1] Helsinki Bioenergetics Group, Department of Medical Chemistry, Institute of Biomedical Sciences, P.O.B. 8, 00014 University of Helsinki, Helsinki, Finland

关键词: Na+ transport;    Na+/Li+ selectivity;    E. coli;   

DOI  :  10.1016/0014-5793(96)00531-5

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Comparison of respiration-driven active transport of alkali cations from E. coli cells loaded with Na⁺ or Li⁺ showed that Li⁺ could not be expelled from the cells like Na⁺. K⁺ accumulation, which was fast in Na⁺-loaded cells, was strongly inhibited in Li⁺-loaded cells, despite high membrane potential and respiratory rate. When Li⁺-loaded cells were placed into medium containing Na⁺ instead of Li⁺, Li⁺/Na⁺ exchange took place initially, while K⁺ accumulation was delayed. Only after almost all inside Li⁺ was replaced by Na⁺ did active Na⁺ and K⁺ transport commence. These data confirm that it is a distinct active sodium transport system (AST) with Na⁺,K⁺/H⁺ antiporter activity, and not the Na⁺/H⁺ antiporters, that is responsible for active Na⁺ transport in E. coli [Verkhovskaya, M.L., Verkhovsky, M.I. and Wikström, M. (1996) Biochim. Biophys. Acta 1273, 207–216]. In contrast to the Na⁺/H⁺ antiporters, the AST system is inhibited by Li⁺.

【 授权许可】

Unknown