Proton pumping by NADH:ubiquinone oxidoreductase. A redox driven conformational change mechanism?
The modular evolutionary origin of NADH:ubiquinone oxidoreductase (complex I) provides useful insights into its functional organization. Iron-sulfur cluster N2 and the PSST and 49 kDa subunits were identified as key players in ubiquinone reduction and proton pumping. Structural studies indicate that this 'catalytic core' region of complex I is clearly separated from the membrane. Complex I from Escherichia coli and Klebsiella pneumoniae was shown to pump sodium ions rather than protons. These new insights into structure and function of complex I strongly suggest that proton or sodium pumping in complex I is achieved by conformational energy transfer rather than by a directly linked redox pump.
Brandt
Ulrich
U
Universität Frankfurt, Fachbereich Medizin, Institut für Biochemie I, Theodor-Stern-Kai 7, Haus 25B, D-60590 Frankfurt am Main, Germany. brandt@zbc.kgu.de
Kerscher
Stefan
S
Dröse
Stefan
S
Zwicker
Klaus
K
Zickermann
Volker
V
D000595:Amino Acid Sequence; D016227:Benzoquinones / Q000032:analysis; D005075:Biological Evolution; D020134:Catalytic Domain; D042967:Electron Transport Complex I; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000494:pharmacology; D017136:Ion Transport; D008969:Molecular Sequence Data; D009247:NADH, NADPH Oxidoreductases / Q000737:chemistry* / Q000378:metabolism; D010084:Oxidation-Reduction; D011487:Protein Conformation; D021122:Protein Subunits; D017494:Proton Pumps / Q000737:chemistry* / Q000378:metabolism; D011522:Protons; D012964:Sodium / Q000378:metabolism
D016227:Benzoquinones; D004791:Enzyme Inhibitors; D021122:Protein Subunits; D017494:Proton Pumps; D011522:Protons; C025232:semiquinone radicals; D012964:Sodium; D009247:NADH, NADPH Oxidoreductases; D042967:Electron Transport Complex I