Assembly of the Escherichia coli NADH: ubiquinone oxidoreductase (complex I). Biochim Biophys Acta

Institut für Organische Chemie und Biochemie, Albert-Ludwigs-Universität Freiburg, Albertstr. 21, 79104 Freiburg, Germany.
Biochimica et Biophysica Acta (Impact Factor: 4.66). 07/2008; 1777(7-8):735-9. DOI: 10.1016/j.bbabio.2008.03.003
Source: PubMed


The proton-pumping NADH:ubiquinone oxidoreductase is the first of the respiratory chain complexes in many bacteria and the mitochondria of most eukaryotes. In general, the bacterial complex consists of 14 different subunits. In addition to the homologues of these subunits, the mitochondrial complex contains approximately 31 additional proteins. While it was shown that the mitochondrial complex is assembled from distinct intermediates, nothing is known about the assembly of the bacterial complex. We used Escherichia coli mutants, in which the nuo-genes coding the subunits of complex I were individually disrupted by an insertion of a resistance cartridge to determine whether they are required for the assembly of a functional complex I. No complex I-mediated enzyme activity was detectable in the mutant membranes and it was not possible to extract a structurally intact complex I from the mutant membranes. However, the subunits and the cofactors of the soluble NADH dehydrogenase fragment of the complex were detected in the cytoplasm of some of the nuo-mutants. It is discussed whether this fragment represents an assembly intermediate. In addition, a membrane-bound fragment exhibiting NADH/ferricyanide oxidoreductase activity and containing the iron-sulfur cluster N2 was detected in one mutant.

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Available from: Thorsten Friedrich, Jun 11, 2014
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    • "Most of the individual components of prokaryotic supercomplexes have been previously isolated without reported instability. Furthermore, in E. coli devoid of complexes III and IV, the complex I is a fully stable entity (Schneider et al., 2008). Recently, the Ugalde's group has provided a molecular description of the mitochondrial respirasome assembly allowing to explain the requirements for complex I stability (Moreno-Lastres et al., 2012). "
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    • "This has been a major hurdle in the de fi nition of the molecular steps of, and players in, CI assembly. Together, these facts explain why CI assembly is still poorly de fi ned; however, observations from CI-defective patients, siRNA experiments in mammalian cells (Remacle et al. 2008 ; Schef fl er et al. 2004 ; Schneider et al. 2008 ) , and gene targeting in CI-dependent fungi, such as Neurospora crassa , have contributed to outline a module-based general model of assembly (Vogel et al. 2007 ; Lazarou et al. 2009 ) (Fig. 4.1 ). Accordingly, the earliest stage consists in the formation of an evolutionarily conserved hydrogenase (Q) module composed of subunits NDUFS2, NDUFS3, NDUFS7, and NDUFS8. "
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