The coupling mechanism of mammalian respiratory complex I

Science ◽  
2020 ◽  
Vol 370 (6516) ◽  
pp. eabc4209 ◽  
Author(s):  
Domen Kampjut ◽  
Leonid A. Sazanov
Keyword(s):  
Conformational Changes ◽  
Complex I ◽  
Electrostatic Interactions ◽  
Proton Translocation ◽  
Proton Pumping ◽  
State Transitions ◽  
Coupling Mechanism ◽  
Cryo Electron Microscopy ◽  
Open Conformation ◽  
Respiratory Complex I

Mitochondrial complex I couples NADH:ubiquinone oxidoreduction to proton pumping by an unknown mechanism. Here, we present cryo–electron microscopy structures of ovine complex I in five different conditions, including turnover, at resolutions up to 2.3 to 2.5 angstroms. Resolved water molecules allowed us to experimentally define the proton translocation pathways. Quinone binds at three positions along the quinone cavity, as does the inhibitor rotenone that also binds within subunit ND4. Dramatic conformational changes around the quinone cavity couple the redox reaction to proton translocation during open-to-closed state transitions of the enzyme. In the induced deactive state, the open conformation is arrested by the ND6 subunit. We propose a detailed molecular coupling mechanism of complex I, which is an unexpected combination of conformational changes and electrostatic interactions.

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 Deactivation blocks proton pathways in the mitochondrial complex I

2021 ◽  
Vol 118 (29) ◽  
pp. e2019498118
Author(s):  
Michael Röpke ◽  
Daniel Riepl ◽  
Patricia Saura ◽  
Andrea Di Luca ◽  
Max E. Mühlbauer ◽  
...  
Keyword(s):  
Proton Transfer ◽  
Conformational Changes ◽  
Complex I ◽  
Large Scale ◽  
Proton Pumping ◽  
Cellular Respiration ◽  
Transmembrane Helices ◽  
Membrane Bound ◽  
Respiratory Complex I ◽  
Microscopy Data

Cellular respiration is powered by membrane-bound redox enzymes that convert chemical energy into an electrochemical proton gradient and drive the energy metabolism. By combining large-scale classical and quantum mechanical simulations with cryo-electron microscopy data, we resolve here molecular details of conformational changes linked to proton pumping in the mammalian complex I. Our data suggest that complex I deactivation blocks water-mediated proton transfer between a membrane-bound quinone site and proton-pumping modules, decoupling the energy-transduction machinery. We identify a putative gating region at the interface between membrane domain subunits ND1 and ND3/ND4L/ND6 that modulates the proton transfer by conformational changes in transmembrane helices and bulky residues. The region is perturbed by mutations linked to human mitochondrial disorders and is suggested to also undergo conformational changes during catalysis of simpler complex I variants that lack the “active”-to-“deactive” transition. Our findings suggest that conformational changes in transmembrane helices modulate the proton transfer dynamics by wetting/dewetting transitions and provide important functional insight into the mammalian respiratory complex I.

A long road towards the structure of respiratory complex I, a giant molecular proton pump

2013 ◽  
Vol 41 (5) ◽  
pp. 1265-1271 ◽  
Author(s):  
Leonid A. Sazanov ◽  
Rozbeh Baradaran ◽  
Rouslan G. Efremov ◽  
John M. Berrisford ◽  
Gurdeep Minhas
Keyword(s):  
Conformational Changes ◽  
Complex I ◽  
Thermus Thermophilus ◽  
Proton Translocation ◽  
Nadh:Ubiquinone Oxidoreductase ◽  
Coupling Mechanism ◽  
Membrane Domains ◽  
Transmembrane Helices ◽  
Inner Mitochondrial Membrane ◽  
Wide Range

Complex I (NADH:ubiquinone oxidoreductase) is central to cellular energy production, being the first and largest enzyme of the respiratory chain in mitochondria. It couples electron transfer from NADH to ubiquinone with proton translocation across the inner mitochondrial membrane and is involved in a wide range of human neurodegenerative disorders. Mammalian complex I is composed of 44 different subunits, whereas the ‘minimal’ bacterial version contains 14 highly conserved ‘core’ subunits. The L-shaped assembly consists of hydrophilic and membrane domains. We have determined all known atomic structures of complex I, starting from the hydrophilic domain of Thermus thermophilus enzyme (eight subunits, nine Fe–S clusters), followed by the membrane domains of the Escherichia coli (six subunits, 55 transmembrane helices) and T. thermophilus (seven subunits, 64 transmembrane helices) enzymes, and finally culminating in a recent crystal structure of the entire intact complex I from T. thermophilus (536 kDa, 16 subunits, nine Fe–S clusters, 64 transmembrane helices). The structure suggests an unusual and unique coupling mechanism via long-range conformational changes. Determination of the structure of the entire complex was possible only through this step-by-step approach, building on from smaller subcomplexes towards the entire assembly. Large membrane proteins are notoriously difficult to crystallize, and so various non-standard and sometimes counterintuitive approaches were employed in order to achieve crystal diffraction to high resolution and solve the structures. These steps, as well as the implications from the final structure, are discussed in the present review.

scholarly journals How cardiolipin modulates the dynamics of respiratory complex I

2019 ◽  
Vol 5 (3) ◽  
pp. eaav1850 ◽  
Author(s):  
Alexander Jussupow ◽  
Andrea Di Luca ◽  
Ville R. I. Kaila
Keyword(s):  
Conformational Changes ◽  
Complex I ◽  
Specific Interaction ◽  
Proton Pumping ◽  
Respiratory Enzymes ◽  
Respiratory Complex ◽  
Respiratory Chains ◽  
Membrane Bound ◽  
Respiratory Complex I ◽  
Structure And Activity

Cardiolipin modulates the activity of membrane-bound respiratory enzymes that catalyze biological energy transduction. The respiratory complex I functions as the primary redox-driven proton pump in mitochondrial and bacterial respiratory chains, and its activity is strongly enhanced by cardiolipin. However, despite recent advances in the structural biology of complex I, cardiolipin-specific interaction mechanisms currently remain unknown. On the basis of millisecond molecular simulations, we suggest that cardiolipin binds to proton-pumping subunits of complex I and induces global conformational changes that modulate the accessibility of the quinone substrate to the enzyme. Our findings provide key information on the coupling between complex I dynamics and activity and suggest how biological membranes modulate the structure and activity of proteins.

Nucleotide-induced conformational changes in the Escherichia coli NADH:ubiquinone oxidoreductase (complex I)

2008 ◽  
Vol 36 (5) ◽  
pp. 971-975 ◽  
Author(s):  
Thomas Pohl ◽  
Daniel Schneider ◽  
Ruth Hielscher ◽  
Stefan Stolpe ◽  
Katerina Dörner ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Escherichia Coli ◽  
Conformational Changes ◽  
Complex I ◽  
Proton Translocation ◽  
Attenuated Total Reflection ◽  
Nadh:Ubiquinone Oxidoreductase ◽  
Respiratory Complex I ◽  
Part Structure ◽  
Energy Converting

The energy-converting NADH:ubiquinone oxidoreductase, also known as respiratory complex I, couples the transfer of electrons from NADH to ubiquinone with the translocation of protons across the membrane. Electron microscopy revealed the two-part structure of the complex consisting of a peripheral and a membrane arm. The peripheral arm contains all known cofactors and the NADH-binding site, whereas the membrane arm has to be involved in proton translocation. Owing to this, a conformation-linked mechanism for redox-driven proton translocation is discussed. By means of electron microscopy, we show that both arms of the Escherichia coli complex I are widened after the addition of NADH but not of NADPH. NADH-induced conformational changes were also detected in solution: ATR-FTIR (attenuated total reflection Fourier-transform infrared) of the soluble NADH dehydrogenase fragment of the complex indicates protein re-arrangements induced by the addition of NADH. EPR spectroscopy of surface mutants of the complex containing a covalently bound spin label at distinct positions demonstrates NADH-dependent conformational changes in both arms of the complex.

scholarly journals Roles of subunit NuoL in the proton pumping coupling mechanism of NADH:ubiquinone oxidoreductase (complex I) fromEscherichia coli

2016 ◽  
Vol 160 (4) ◽  
pp. 205-215 ◽  
Author(s):  
Madhavan Narayanan ◽  
Joseph A. Sakyiama ◽  
Mahmoud M. Elguindy ◽  
Eiko Nakamaru-Ogiso
Keyword(s):  
Complex I ◽  
Proton Pumping ◽  
Nadh:Ubiquinone Oxidoreductase ◽  
Coupling Mechanism ◽  
Fromescherichia Coli

scholarly journals Structure and mechanism of the Mrp complex, an ancient cation/proton antiporter

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Julia Steiner ◽  
Leonid Sazanov
Keyword(s):  
Electron Transfer ◽  
Electrostatic Interactions ◽  
Proton Translocation ◽  
Proton Pumps ◽  
Entire Family ◽  
Surface Charge Distribution ◽  
Large Protein Family ◽  
Anoxybacillus Flavithermus ◽  
Respiratory Complex I ◽  
Ph Adaptation

Multiple resistance and pH adaptation (Mrp) antiporters are multi-subunit Na+ (or K+)/H+ exchangers representing an ancestor of many essential redox-driven proton pumps, such as respiratory complex I. The mechanism of coupling between ion or electron transfer and proton translocation in this large protein family is unknown. Here, we present the structure of the Mrp complex from Anoxybacillus flavithermus solved by cryo-EM at 3.0 Å resolution. It is a dimer of seven-subunit protomers with 50 trans-membrane helices each. Surface charge distribution within each monomer is remarkably asymmetric, revealing probable proton and sodium translocation pathways. On the basis of the structure we propose a mechanism where the coupling between sodium and proton translocation is facilitated by a series of electrostatic interactions between a cation and key charged residues. This mechanism is likely to be applicable to the entire family of redox proton pumps, where electron transfer to substrates replaces cation movements.

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