Three-dimensional structure of respiratory complex I from Escherichia coli in ice in the presence of nucleotides.

TitleThree-dimensional structure of respiratory complex I from Escherichia coli in ice in the presence of nucleotides.
Publication TypeJournal Article
Year of Publication2008
AuthorsMorgan, DJ, Sazanov, LA
JournalBiochim Biophys Acta
Date Published2008 Jul-Aug
KeywordsCryoelectron Microscopy, Electron Transport Complex I, Escherichia coli, Escherichia coli Proteins, Image Processing, Computer-Assisted, Microscopy, Electron, Models, Molecular, NAD, Protein Conformation

Complex I (NADH:ubiquinone oxidoreductase) is the largest protein complex of bacterial and mitochondrial respiratory chains. The first three-dimensional structure of bacterial complex I in vitrified ice was determined by electron cryo-microscopy and single particle analysis. The structure of the Escherichia coli enzyme incubated with either NAD(+) (as a reference) or NADH was calculated to 35 and 39 A resolution, respectively. The X-ray structure of the peripheral arm of Thermus thermophilus complex I was docked into the reference EM structure. The model obtained indicates that Fe-S cluster N2 is close to the membrane domain interface, allowing for effective electron transfer to membrane-embedded quinone. At the current resolution, the structures in the presence of NAD(+) or NADH are similar. Additionally, side-view class averages were calculated for the negatively stained bovine enzyme. The structures of bovine complex I in the presence of either NAD(+) or NADH also appeared to be similar. These observations indicate that conformational changes upon reduction with NADH, suggested to occur by a range of studies, are smaller than had been thought previously. The model of the entire bacterial complex I could be built from the crystal structures of subcomplexes using the EM envelope described here.

Alternate JournalBiochim. Biophys. Acta
Citation Key10.1016/j.bbabio.2008.03.023
PubMed ID18433710
Grant ListMC_U105674180 / / Medical Research Council / United Kingdom