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


Author(s): Morgan, David J; Sazanov, Leonid A
Article Title: Three-dimensional structure of respiratory complex I from Escherichia coli in ice in the presence of nucleotides
Affiliation
Abstract: 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 Å 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.
Keywords: Electron microscopy; Complex I; Membrane protein structure; NADH:ubiquinone oxidoreductase; Single particle analysis
Journal Title: Biochimica et Biophysica Acta - Bioenergetics
Volume: 1777
Issue 7-8
ISSN: 0005-2728
Publisher: Elsevier  
Date Published: 2008-07-01
Start Page: 711
End Page: 718
Sponsor: This work was supported by the Medical Research Council.
DOI: 10.1016/j.bbabio.2008.03.023
Open access: no