Learning from hydrogenases: location of a proton pump and of a second FMN in bovine NADH--ubiquinone oxidoreductase (Complex I).
Hydrogenases have clear evolutionary links to the much more complex NADH-ubiquinone oxidoreductases (Complex I). Certain membrane-bound [NiFe]-hydrogenases presumably pump protons. From a detailed comparison of hydrogenases and Complex I, it is concluded here that the TYKY subunit in these enzymes is a special 2[4Fe-4S] ferredoxin, which functions as the electrical driving unit for a proton pump. The comparison further revealed that the flavodoxin fold from [NiFe]-hydrogenases is presumably conserved in the PSST subunit of Complex I. It is proposed that bovine Complex I and the soluble NAD(+)-reducing hydrogenase from Ralstonia eutropha each contain a second FMN group.
Albracht
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Swammerdam Institute for Life Sciences, Biochemistry, University of Amsterdam, The Netherlands. a31siem@chem.uva.nl
Hedderich
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D000595:Amino Acid Sequence; D000818:Animals; D002417:Cattle; D019281:Dimerization; D042967:Electron Transport Complex I; D005288:Ferredoxins / Q000737:chemistry; D005486:Flavin Mononucleotide / Q000032:analysis*; D006864:Hydrogenase / Q000737:chemistry; D007501:Iron; D008969:Molecular Sequence Data; D009247:NADH, NADPH Oxidoreductases / Q000737:chemistry*; D009532:Nickel; D017494:Proton Pumps / Q000032:analysis*; D016415:Sequence Alignment
D005288:Ferredoxins; D017494:Proton Pumps; D005486:Flavin Mononucleotide; D009532:Nickel; D007501:Iron; D006864:Hydrogenase; D009247:NADH, NADPH Oxidoreductases; D042967:Electron Transport Complex I