Mamedova, Aygun A ; Holt, Peter J ; Carroll, Joe D ; Sazanov, Leonid AIST Austria
The mechanism coupling electron transfer and proton pumping in respiratory complex I (NADH-ubiquinone oxidoreductase) has not been established, but it has been suggested that it involves conformational changes. Here, the influence of substrates on the conformation of purified complex I from Escherichia coli was studied by cross-linking and electron microscopy. When a zero-length cross-linking reagent was used, the presence of NAD(P)H, in contrast to that of NAD+, prevented the formation of cross-links between the hydrophilic subunits of the complex, including NuoB, NuoI, and NuoCD. Comparisons using different cross-linkers suggested that NuoB, which is likely to coordinate the key iron-sulfur cluster N2, is the most mobile subunit. The presence of NAD(P)H led also to enhanced proteolysis of subunit NuoG. These data indicate that upon NAD(P)H binding, the peripheral arm of the complex adopts a more open conformation, with increased distances between subunits. Single particle analysis showed the nature of this conformational change. The enzyme retains its L-shape in the presence of NADH, but exhibits a significantly more open or expanded structure both in the peripheral arm and, unexpectedly, in the membrane domain also.
Journal of Biological Chemistry
This work was supported by the Medical Research Council and by a Royal Society/North Atlantic Treaty Organization postdoctoral fellowship (to A. A. M.)
23830 - 23836
Mamedova A, Holt P, Carroll J, Sazanov LA. Substrate-induced conformational change in bacterial complex I. Journal of Biological Chemistry. 2004;279(22):23830-23836. doi:10.1074/jbc.M401539200
Mamedova, A., Holt, P., Carroll, J., & Sazanov, L. A. (2004). Substrate-induced conformational change in bacterial complex I. Journal of Biological Chemistry, 279(22), 23830–23836. https://doi.org/10.1074/jbc.M401539200
Mamedova, Aygun, Peter Holt, Joe Carroll, and Leonid A Sazanov. “Substrate-Induced Conformational Change in Bacterial Complex I.” Journal of Biological Chemistry 279, no. 22 (2004): 23830–36. https://doi.org/10.1074/jbc.M401539200.
A. Mamedova, P. Holt, J. Carroll, and L. A. Sazanov, “Substrate-induced conformational change in bacterial complex I,” Journal of Biological Chemistry, vol. 279, no. 22, pp. 23830–23836, 2004.
Mamedova A, Holt P, Carroll J, Sazanov LA. 2004. Substrate-induced conformational change in bacterial complex I. Journal of Biological Chemistry. 279(22), 23830–23836.
Mamedova, Aygun, et al. “Substrate-Induced Conformational Change in Bacterial Complex I.” Journal of Biological Chemistry, vol. 279, no. 22, American Society for Biochemistry and Molecular Biology, 2004, pp. 23830–36, doi:10.1074/jbc.M401539200.