The proton‐pumping NADH:ubiquinone oxidoreductase (complex I) of Aquifex aeolicus

FEBS Letters

Huber, Robert¹  Friedrich, Thorsten²  Scheide, Dierk² 

[1] Universität Regensburg, Lehrstuhl für Mikrobiologie, Universitätsstr. 31, D-93044 Regensburg, Germany;Heinrich-Heine-Universität Düsseldorf, Institut für Biochemie, Universitätsstr. 1, D-40225 Düsseldorf, Germany

关键词: Complex I;    NADH:ubiquinone oxidoreductase;    NADH dehydrogenase;    Extremophile;    Hyperthermophile;    Aquifex aeolicus;   

DOI  :  10.1016/S0014-5793(02)02224-X

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The proton-pumping NADH:ubiquinone oxidoreductase, also called complex I, is the first energy-transducing complex of many respiratory chains. Homologues of complex I are present in the three domains of life. Here, we report the properties of complex I in membranes of the hyperthermophilic bacterium Aquifex aeolicus. The complex reacted with NADH but not with NADPH and F₄₂₀H₂ as electron donors. Short-chain analogues of ubiquinone like decyl-ubiquinone and ubiquinone-2 were suitable electron acceptors. The affinities towards NADH and ubiquinone-2 were comparable to the ones obtained with the Escherichia coli complex I. The reaction was inhibited by piericidin A at the same concentration as in E. coli. The complex showed an unusual pH optimum at pH 9 and a maximal rate at 80°C. We found no evidence for the presence of an alternative, single subunit NADH dehydrogenase in A. aeolicus membranes. The NADH:ferricyanide reductase activity of detergent extracts of A. aeolicus membranes sedimented as a protein with a molecular mass of approximately 550 kDa. From the data we concluded that A. aeolicus contains a NADH:ubiquinone oxidoreductase resembling complex I of mesophilic bacteria.

【 授权许可】

Unknown