scholarly journals Energetics and Dynamics of Proton-Coupled Electron Transfer in the NADH/FMN Site of Respiratory Complex I

2019 ◽  
Vol 141 (14) ◽  
pp. 5710-5719 ◽  
Author(s):  
Patricia Saura ◽  
Ville R. I. Kaila
Keyword(s):  
Electron Transfer ◽  
Complex I ◽  
Respiratory Complex ◽  
Proton Coupled Electron Transfer ◽  
Respiratory Complex I

scholarly journals Correlating kinetic and structural data on ubiquinone binding and reduction by respiratory complex I

2017 ◽  
Vol 114 (48) ◽  
pp. 12737-12742 ◽  
Author(s):  
Justin G. Fedor ◽  
Andrew J. Y. Jones ◽  
Andrea Di Luca ◽  
Ville R. I. Kaila ◽  
Judy Hirst
Keyword(s):  
Electron Transfer ◽  
Complex I ◽  
Mammalian Cells ◽  
Membrane Surface ◽  
Proton Translocation ◽  
Structural Data ◽  
Nadh:Ubiquinone Oxidoreductase ◽  
Respiratory Complex ◽  
Respiratory Complex I ◽  
Ubiquinone 10

Respiratory complex I (NADH:ubiquinone oxidoreductase), one of the largest membrane-bound enzymes in mammalian cells, powers ATP synthesis by using the energy from electron transfer from NADH to ubiquinone-10 to drive protons across the energy-transducing mitochondrial inner membrane. Ubiquinone-10 is extremely hydrophobic, but in complex I the binding site for its redox-active quinone headgroup is ∼20 Å above the membrane surface. Structural data suggest it accesses the site by a narrow channel, long enough to accommodate almost all of its ∼50-Å isoprenoid chain. However, how ubiquinone/ubiquinol exchange occurs on catalytically relevant timescales, and whether binding/dissociation events are involved in coupling electron transfer to proton translocation, are unknown. Here, we use proteoliposomes containing complex I, together with a quinol oxidase, to determine the kinetics of complex I catalysis with ubiquinones of varying isoprenoid chain length, from 1 to 10 units. We interpret our results using structural data, which show the hydrophobic channel is interrupted by a highly charged region at isoprenoids 4–7. We demonstrate that ubiquinol-10 dissociation is not rate determining and deduce that ubiquinone-10 has both the highest binding affinity and the fastest binding rate. We propose that the charged region and chain directionality assist product dissociation, and that isoprenoid stepping ensures short transit times. These properties of the channel do not benefit the exhange of short-chain quinones, for which product dissociation may become rate limiting. Thus, we discuss how the long channel does not hinder catalysis under physiological conditions and the possible roles of ubiquinone/ubiquinol binding/dissociation in energy conversion.

scholarly journals A Quinol Anion as Catalytic Intermediate Coupling Proton Translocation With Electron Transfer in E. coli Respiratory Complex I

2021 ◽  
Vol 9 ◽  
Author(s):  
Franziska Nuber ◽  
Luca Mérono ◽  
Sabrina Oppermann ◽  
Johannes Schimpf ◽  
Daniel Wohlwend ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Complex I ◽  
Proton Translocation ◽  
Difference Spectrum ◽  
Nadh:Ubiquinone Oxidoreductase ◽  
Protonmotive Force ◽  
Respiratory Complex ◽  
Quinone Reduction ◽  
Vis Spectroscopy ◽  
Respiratory Complex I

Energy-converting NADH:ubiquinone oxidoreductase, respiratory complex I, plays a major role in cellular energy metabolism. It couples NADH oxidation and quinone reduction with the translocation of protons across the membrane, thus contributing to the protonmotive force. Complex I has an overall L-shaped structure with a peripheral arm catalyzing electron transfer and a membrane arm engaged in proton translocation. Although both reactions are arranged spatially separated, they are tightly coupled by a mechanism that is not fully understood. Using redox-difference UV-vis spectroscopy, an unknown redox component was identified in Escherichia coli complex I as reported earlier. A comparison of its spectrum with those obtained for different quinone species indicates features of a quinol anion. The re-oxidation kinetics of the quinol anion intermediate is significantly slower in the D213GH variant that was previously shown to operate with disturbed quinone chemistry. Addition of the quinone-site inhibitor piericidin A led to strongly decreased absorption peaks in the difference spectrum. A hypothesis for a mechanism of proton-coupled electron transfer with the quinol anion as catalytically important intermediate in complex I is discussed.

scholarly journals Energetics and dynamics of long-range electron transfer in respiratory complex I

2018 ◽  
Vol 1859 ◽  
pp. e42
Author(s):  
Michael Röpke ◽  
Ana P. Gamiz-Hernandez ◽  
Alexander Jussupow ◽  
Mikael P. Johansson ◽  
Ville R.I. Kaila
Keyword(s):  
Electron Transfer ◽  
Long Range ◽  
Complex I ◽  
Respiratory Complex ◽  
Respiratory Complex I

scholarly journals Real-time electron transfer in respiratory complex I

2008 ◽  
Vol 105 (10) ◽  
pp. 3763-3767 ◽  
Author(s):  
M. L. Verkhovskaya ◽  
N. Belevich ◽  
L. Euro ◽  
M. Wikstrom ◽  
M. I. Verkhovsky
Keyword(s):  
Electron Transfer ◽  
Real Time ◽  
Complex I ◽  
Respiratory Complex ◽  
Respiratory Complex I
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