Characterization of a subcomplex of mitochondrial NADH:ubiquinone oxidoreductase (complex I) lacking the flavoprotein part of the N-module |
| |
Authors: | Zickermann Volker Zwicker Klaus Tocilescu Maja A Kerscher Stefan Brandt Ulrich |
| |
Affiliation: | Johann Wolfgang Goethe-Universit?t, Fachbereich Medizin, Molekulare Bioenergetik, Centre of Excellence Frankfurt Macromolecular Complexes, D-60590 Frankfurt am Main, Germany. |
| |
Abstract: | Mitochondrial NADH:ubiquinone oxidoreductase is the largest and most complicated proton pump of the respiratory chain. Here we report the preparation and characterization of a subcomplex of complex I selectively lacking the flavoprotein part of the N-module. Removing the 51-kDa and the 24-kDa subunit resulted in loss of catalytic activity. The redox centers of the subcomplex could be reduced neither by NADH nor NADPH demonstrating that physiological electron input into complex I occurred exclusively via the N-module and that the NADPH binding site in the 39-kDa subunit and further potential nucleotide binding sites are isolated from the electron transfer pathway within the enzyme. Taking advantage of the selective removal of two of the eight iron-sulfur clusters of complex I and providing additional evidence by redox titration and site-directed mutagenesis, we could for the first time unambiguously assign cluster N1 of fungal complex I to mammalian cluster N1b. |
| |
Keywords: | |
本文献已被 PubMed 等数据库收录! |
|