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

Ohnishi Tomoko | Zendy; Nakamaru-Ogiso Eiko | Zendy; Ohnishi S. Tsuyoshi | Zendy

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

Author(s) -

Ohnishi Tomoko,

Nakamaru-Ogiso Eiko,

Ohnishi S. Tsuyoshi

Publication year - 2010

Publication title -

febs letters

Language(s) - English

Resource type - Journals

SCImago Journal Rank - 1.593

H-Index - 257

eISSN - 1873-3468

pISSN - 0014-5793

DOI - 10.1016/j.febslet.2010.08.039

Subject(s) - antiporters , proton , protein subunit , mutant , oxidoreductase , quinone , chemistry , proton pump , stereochemistry , crystallography , biochemistry , physics , enzyme , atpase , antiporter , quantum mechanics , membrane , gene

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 − .

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