scholarly journals Electron tunneling and proton translocation in respiratory complex I

2012 ◽  
Vol 1817 ◽  
pp. S144
Author(s):  
A.A. Stuchebrukhov
Keyword(s):  
Complex I ◽  
Electron Tunneling ◽  
Proton Translocation ◽  
Respiratory Complex ◽  
Respiratory Complex I

The mechanism of proton translocation in respiratory complex I from molecular dynamics

2014 ◽  
Vol 35 (2) ◽  
pp. 170-179 ◽  
Author(s):  
Pengli Tan ◽  
Zhiwei Feng ◽  
Liling Zhang ◽  
Tingjun Hou ◽  
Youyong Li
Keyword(s):  
Molecular Dynamics ◽  
Complex I ◽  
Proton Translocation ◽  
Respiratory Complex ◽  
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 Structure of Escherichia coli respiratory complex I reconstituted into lipid nanodiscs reveals an uncoupled conformation

2021 ◽  
Author(s):  
Rouslan G. Efremov ◽  
Piotr Kolata
Keyword(s):  
Escherichia Coli ◽  
Complex I ◽  
Proton Translocation ◽  
Structural Data ◽  
Coupling Mechanism ◽  
Membrane Domains ◽  
Dynamic Features ◽  
Respiratory Complex ◽  
Respiratory Complex I ◽  
Lipid Nanodiscs

Respiratory complex I is a multi-subunit membrane protein complex that reversibly couples NADH oxidation and ubiquinone reduction with proton translocation against trans-membrane potential. Complex I from Escherichia coli is among the best functionally characterized complexes, but its structure remains unknown, hindering further mechanistic studies to understand the enzyme coupling mechanism. Here we describe the single particle cryoelectron microscopy (cryo-EM) structure of the entire catalytically active E. coli complex I reconstituted into lipid nanodiscs. The structure of this mesophilic bacterial complex I displays highly dynamic connection between the peripheral and membrane domains. The peripheral domain assembly is stabilized by unique terminal extensions and an insertion loop. The membrane domain structure reveals novel dynamic features. Unusual conformation of the conserved interface between the cytoplasmic and membrane domains suggests an uncoupled conformation of the complex. Based on these structural data we suggest a new simple and testable coupling mechanism for the molecular machine.

scholarly journals Structure of Escherichia coli respiratory complex I reconstituted into lipid nanodiscs reveals an uncoupled conformation

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Rouslan G Efremov ◽  
Piotr Kolata
Keyword(s):  
Escherichia Coli ◽  
Complex I ◽  
Proton Translocation ◽  
Structural Data ◽  
Coupling Mechanism ◽  
Membrane Domains ◽  
Dynamic Features ◽  
Respiratory Complex ◽  
Respiratory Complex I ◽  
Lipid Nanodiscs

Respiratory complex I is a multi-subunit membrane protein complex that reversibly couples NADH oxidation and ubiquinone reduction with proton translocation against trans-membrane potential. Complex I from Escherichia coli is among the best functionally characterized complexes, but its structure remains unknown, hindering further mechanistic studies to understand the enzyme coupling mechanism. Here we describe the single particle cryo-electron microscopy (cryo-EM) structure of the entire catalytically active E. coli complex I reconstituted into lipid nanodiscs. The structure of this mesophilic bacterial complex I displays highly dynamic connection between the peripheral and membrane domains. The peripheral domain assembly is stabilized by unique terminal extensions and an insertion loop. The membrane domain structure reveals novel dynamic features. Unusual conformation of the conserved interface between the peripheral and membrane domains suggests an uncoupled conformation of the complex. Considering constraints imposed by the structural data we suggest a new simple hypothetical coupling mechanism for the molecular machine.

scholarly journals Electron tunneling in respiratory complex I

2010 ◽  
Vol 107 (45) ◽  
pp. 19157-19162 ◽  
Author(s):  
T. Hayashi ◽  
A. A. Stuchebrukhov
Keyword(s):  
Complex I ◽  
Electron Tunneling ◽  
Respiratory Complex ◽  
Respiratory Complex I
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