Fourier transform infrared spectroscopic study on the conformational reorganization in Escherichia coli complex I due to redox-driven proton translocation.
The proton-pumping NADH:ubiquinone oxidoreductase (complex I) couples the transfer of electrons from NADH to ubiquinone with the translocation of protons across the membrane. Electron transfer is accomplished by flavin mononucleotide (FMN) and a series of iron-sulfur (Fe/S) clusters. A novel mechanism has been proposed wherein the electron transfer reaction induces conformational changes that subsequently lead to the translocation of protons. Redox-induced Fourier transform infrared difference spectra have been obtained, showing strong conformational changes in the amide I region. The amplitude of the signal is pH dependent, as expected for an energy coupling step in the enzymes reaction. Furthermore, pH-dependent protonation events and quinone binding were detected.
Hellwig
Petra
P
Institut für Biophysik, Johann-Wolfgang-Goethe-Universität, Theodor-Stern-Kai 7, Haus 75, 60590 Frankfurt/M., Germany. hellwig@biophysik.uni-frankfurt.de
Stolpe
Stefan
S
Friedrich
Thorsten
T
D000577:Amides / Q000737:chemistry; D016227:Benzoquinones / Q000737:chemistry; D004563:Electrochemistry; D004583:Electrons; D004926:Escherichia coli / Q000378:metabolism*; D029968:Escherichia coli Proteins; D005486:Flavin Mononucleotide / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D009243:NAD / Q000737:chemistry; D010084:Oxidation-Reduction; D011487:Protein Conformation; D021381:Protein Transport; D011522:Protons; D011809:Quinones / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods*; D014157:Transcription Factors / Q000737:chemistry
D000577:Amides; D016227:Benzoquinones; D029968:Escherichia coli Proteins; C499695:IscR protein, E coli; D011522:Protons; D011809:Quinones; D014157:Transcription Factors; D009243:NAD; C004532:quinone; D005486:Flavin Mononucleotide