A new hypothesis on the simultaneous direct and indirect proton pump mechanisms in NADH-quinone oxidoreductase (complex I)

作者：Ohnishi Tomoko^*; Nakamaru Ogiso Eiko; Ohnishi S Tsuyoshi

来源：FEBS Letters, 2010, 584(19): 4131-4137.

DOI：10.1016/j.febslet.2010.08.039

• NADH-quinone oxidoreductase
• Complex I
• SQ(Nf)-gated &quot
• direct&quot
• proton pump
• Q(Ns)-induced &quot
• indirect&quot
• proton pump
• Conformationally-driven H(+) pump

Recently, Sazanov's group reported the X-ray structure of whole complex I [Nature, 465, 441 (2010)], which presented a strong clue for a "piston-like" structure as a key element in an "indirect" proton pump. We have studied the NuoL subunit which has a high sequence similarity to Na(+)/H(+) antiporters, as do the NuoM and N subunits. We constructed 27 site-directed NuoL mutants. Our data suggest that the H(+)/e stoichiometry seems to have decreased from (4H(+)/2e(-)) in the wild-type to approximately (3H(+)/2e(-)) in NuoL mutants. We propose a revised hypothesis that each of the "direct" and the "indirect" proton pumps transports 2H(+) per 2e(-).

• 出版日期2010-10-8