Nucleotide-induced conformational changes in the Escherichia coli NADH:ubiquinone oxidoreductase (complex I).
The energy-converting NADH:ubiquinone oxidoreductase, also known as respiratory complex I, couples the transfer of electrons from NADH to ubiquinone with the translocation of protons across the membrane. Electron microscopy revealed the two-part structure of the complex consisting of a peripheral and a membrane arm. The peripheral arm contains all known cofactors and the NADH-binding site, whereas the membrane arm has to be involved in proton translocation. Owing to this, a conformation-linked mechanism for redox-driven proton translocation is discussed. By means of electron microscopy, we show that both arms of the Escherichia coli complex I are widened after the addition of NADH but not of NADPH. NADH-induced conformational changes were also detected in solution: ATR-FTIR (attenuated total reflection Fourier-transform infrared) of the soluble NADH dehydrogenase fragment of the complex indicates protein re-arrangements induced by the addition of NADH. EPR spectroscopy of surface mutants of the complex containing a covalently bound spin label at distinct positions demonstrates NADH-dependent conformational changes in both arms of the complex.
Pohl
Thomas
T
Institut für Organische Chemie und Biochemie, Albert-Ludwigs-Universität, Albertstrasse 21, D-79104 Freiburg, Germany.
Schneider
Daniel
D
Hielscher
Ruth
R
Stolpe
Stefan
S
Dörner
Katerina
K
Kohlstädt
Markus
M
Böttcher
Bettina
B
Hellwig
Petra
P
Friedrich
Thorsten
T
D004578:Electron Spin Resonance Spectroscopy; D042967:Electron Transport Complex I / Q000737:chemistry* / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology*; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000378:metabolism; D009243:NAD / Q000378:metabolism; D009711:Nucleotides / Q000378:metabolism*; D010084:Oxidation-Reduction; D011487:Protein Conformation; D011522:Protons; D017550:Spectroscopy, Fourier Transform Infrared
D029968:Escherichia coli Proteins; D009711:Nucleotides; D011522:Protons; D009243:NAD; D042967:Electron Transport Complex I