Cluster N1 of complex I from Yarrowia lipolytica studied by pulsed EPR spectroscopy
- 89 Downloads
After reduction with nicotinamide adenine dinucleotide (NADH), NADH:ubiquinone oxidoreductase (complex I) of the strictly aerobic yeast Yarrowia lipolytica shows clear signals from five different paramagnetic iron–sulfur (FeS) clusters (N1–N5) which can be detected using electron paramagnetic resonance (EPR) spectroscopy. The ligand environment and the assignment of several FeS clusters to specific binding motifs found in several subunits of the complex are still under debate. In order to characterize the hyperfine interaction of the surrounding nuclei with FeS cluster N1, one- and two-dimensional electron spin echo envelope modulation experiments were performed at a temperature of 30 K. At this temperature only cluster N1 contributes to the overall signal in a pulsed EPR experiment. The hyperfine and quadrupole tensors of a nitrogen nucleus and the isotropic and dipolar hyperfine couplings of two sets of protons could be determined by numerical simulation of the one- and two-dimensional spectra. The values obtained are in perfect agreement with a ferredoxin-like binding structure by four cysteine amino acid residues and allow the assignment of the nitrogen couplings to a backbone nitrogen nucleus and the proton couplings to the β-protons of the bound cysteine residues.
KeywordsComplex I Iron–sulfur clusters Ferredoxins Electron spin echo envelope modulation Hyperfine sublevel correlation
This work was supported by the Sonderforschungsbereich SFB 472 “Molecular Bio-energetics.” The authors also want to thank the two anonymous reviewers for their helpful comments and suggestions.
- 4.Weiss H, Friedrich T (1991) Biochim Biophys Acta 23:743–771Google Scholar
- 7.Yagi T, Yano S, Di Bernado S, Matsuno-Yagi A (1998) Biochim Biophys Acta 1354:125–133Google Scholar
- 25.Gemperle C, Aebli G, Schweiger A, Ernst RR (1990) J Magn Reson 88:241–256Google Scholar
- 26.Bowman MK, Massoth RJ (1987) In: Weil JA (ed) Electron magnetic resonance of the solid state. The Canadian Society for Chemistry, Ottawa, pp 99–110Google Scholar