scholarly journals The respiratory supercomplex from C. glutamicum

2021 ◽  
Author(s):  
Agnes Moe ◽  
Terezia Kovalova ◽  
Sylwia Król ◽  
David J. Yanofsky ◽  
Michael Bott ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Mycobacterium Tuberculosis ◽  
Corynebacterium Glutamicum ◽  
Respiratory Chain ◽  
Proton Translocation ◽  
Atp Synthesis ◽  
Transport Processes ◽  
Positive Bacterium ◽  
Iron Sulfur ◽  
Cytoplasmic Side

Corynebacterium glutamicum is a preferentially aerobic Gram-positive bacterium belonging to the Actinobacteria phylum, which also includes the pathogen Mycobacterium tuberculosis. In the respiratory chain of these bacteria, complexes III (CIII) and IV (CIV) form a CIII2CIV2 supercomplex that catalyzes oxidation of menaquinol and reduction of dioxygen to water. Electron transfer within the CIII2CIV2 supercomplex is linked to transmembrane proton translocation, which maintains an electrochemical proton gradient that drives ATP synthesis and transport processes. We isolated the C. glutamicum supercomplex and used cryo EM to determine its structure at 2.9 Å resolution. The structure shows a central CIII2 dimer flanked by a CIV on each side. One menaquinone is bound in each of the QN and QP sites in each CIII, near the cytoplasmic and periplasmic sides, respectively. In addition, we identified a menaquinone positioned ~14 Å from heme bL on the periplasmic side. A di-heme cyt. cc subunit provides an electronic connection between each CIII monomer and the adjacent CIV. In CIII2, the Rieske iron-sulfur (FeS) proteins are positioned with the iron near heme bL. Multiple subunits interact to form a convoluted sub-structure at the cytoplasmic side of the supercomplex, which defines a novel path that conducts protons into CIV.

scholarly journals Five decades of research on mitochondrial NADH-quinone oxidoreductase (complex I)

2018 ◽  
Vol 399 (11) ◽  
pp. 1249-1264 ◽  
Author(s):  
Tomoko Ohnishi ◽  
S. Tsuyoshi Ohnishi ◽  
John C. Salerno
Keyword(s):  
Electron Transfer ◽  
Respiratory Chain ◽  
Complex I ◽  
Proton Translocation ◽  
Atp Synthesis ◽  
Mitochondrial Respiratory Chain ◽  
Proton Pumping ◽  
Entry Site ◽  
Quinone Oxidoreductase ◽  
Terminal Electron Acceptor

AbstractNADH-quinone oxidoreductase (complex I) is the largest and most complicated enzyme complex of the mitochondrial respiratory chain. It is the entry site into the respiratory chain for most of the reducing equivalents generated during metabolism, coupling electron transfer from NADH to quinone to proton translocation, which in turn drives ATP synthesis. Dysfunction of complex I is associated with neurodegenerative diseases such as Parkinson’s and Alzheimer’s, and it is proposed to be involved in aging. Complex I has one non-covalently bound FMN, eight to 10 iron-sulfur clusters, and protein-associated quinone molecules as electron transport components. Electron paramagnetic resonance (EPR) has previously been the most informative technique, especially in membranein situanalysis. The structure of complex 1 has now been resolved from a number of species, but the mechanisms by which electron transfer is coupled to transmembrane proton pumping remains unresolved. Ubiquinone-10, the terminal electron acceptor of complex I, is detectable by EPR in its one electron reduced, semiquinone (SQ) state. In the aerobic steady state of respiration the semi-ubiquinone anion has been observed and studied in detail. Two distinct protein-associated fast and slow relaxing, SQ signals have been resolved which were designated SQNfand SQNs. This review covers a five decade personal journey through the field leading to a focus on the unresolved questions of the role of the SQ radicals and their possible part in proton pumping.

scholarly journals Structure of mycobacterial CIII2CIV2 respiratory supercomplex bound to the tuberculosis drug candidate telacebec (Q203)

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
David J Yanofsky ◽  
Justin M Di Trani ◽  
Sylwia Krol ◽  
Rana Abdelaziz ◽  
Stephanie A Bueler ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Mycobacterium Tuberculosis ◽  
Mycobacterium Smegmatis ◽  
Atp Synthesis ◽  
Drug Candidate ◽  
Antituberculosis Activity ◽  
Binding Modes ◽  
Electron Cryomicroscopy ◽  
Oxidoreductase Activity ◽  
Electron Transport Chains

The imidazopyridine telacebec, also known as Q203, is one of only a few new classes of compounds in more than fifty years with demonstrated antituberculosis activity in humans. Telacebec inhibits the mycobacterial respiratory supercomplex composed of complexes III and IV (CIII2CIV2). In mycobacterial electron transport chains, CIII2CIV2 replaces canonical CIII and CIV, transferring electrons from the intermediate carrier menaquinol to the final acceptor, molecular oxygen, while simultaneously transferring protons across the inner membrane to power ATP synthesis. We show that telacebec inhibits the menaquinol:oxygen oxidoreductase activity of purified Mycobacterium smegmatis CIII2CIV2 at concentrations similar to those needed to inhibit electron transfer in mycobacterial membranes and Mycobacterium tuberculosis growth in culture. We then used electron cryomicroscopy (cryoEM) to determine structures of CIII2CIV2 both in the presence and absence of telacebec. The structures suggest that telacebec prevents menaquinol oxidation by blocking two different menaquinol binding modes to prevent CIII2CIV2 activity.

scholarly journals Sensitivity to NN'-dicyclohexylcarbodi-imide of proton translocation by mitochondrial NADH:ubiquinone oxidoreductase

1986 ◽  
Vol 237 (3) ◽  
pp. 927-930 ◽  
Author(s):  
P J Honkakoski ◽  
I E Hassinen
Keyword(s):  
Electron Transfer ◽  
Respiratory Chain ◽  
Proton Translocation ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Nadh:Ubiquinone Oxidoreductase ◽  
Proton Extrusion ◽  
Ferricyanide Reduction ◽  
Isolated Rat Liver ◽  
Isolated Rat

Proton extrusion during ferricyanide reduction by NADH-generating substrates or succinate was studied in isolated rat liver mitochondria with the use of optical indicators. NN'-Dicyclohexylcarbodi-imide (DCCD) caused a decrease of 84% in the H+/e- ratio of NADH:cytochrome c reduction, but a decrease of only 49% in that of succinate:cytochrome c reduction, even though electron transfer was decreased equally in both spans. The data indicate that a DCCD-sensitive channel operates in the NADH:ubiquinone oxidoreductase region of the respiratory chain.

scholarly journals Thermodynamic efficiency, reversibility, and degree of coupling in energy conservation by the mitochondrial respiratory chain

2020 ◽  
Vol 3 (1) ◽  
Author(s):  
Mårten Wikström ◽  
Roger Springett
Keyword(s):  
Respiratory Chain ◽  
Proton Translocation ◽  
Atp Synthesis ◽  
Mitochondrial Respiratory Chain ◽  
Point Of View ◽  
Proton Gradient ◽  
Thermodynamic Efficiency ◽  
Inner Mitochondrial Membrane ◽  
Degree Of Coupling ◽  
Mitochondrial Respiratory

AbstractThe protonmotive mitochondrial respiratory chain, comprising complexes I, III and IV, transduces free energy of the electron transfer reactions to an electrochemical proton gradient across the inner mitochondrial membrane. This gradient is used to drive synthesis of ATP and ion and metabolite transport. The efficiency of energy conversion is of interest from a physiological point of view, since the energy transduction mechanisms differ fundamentally between the three complexes. Here, we have chosen actively phosphorylating mitochondria as the focus of analysis. For all three complexes we find that the thermodynamic efficiency is about 80–90% and that the degree of coupling between the redox and proton translocation reactions is very high during active ATP synthesis. However, when net ATP synthesis stops at a high ATP/ADP.Pi ratio, and mitochondria reach “State 4” with an elevated proton gradient, the degree of coupling drops substantially. The mechanistic cause and the physiological implications of this effect are discussed.

scholarly journals Direct assignment of EPR spectra to structurally defined iron-sulfur clusters in complex I by double electron–electron resonance

2010 ◽  
Vol 107 (5) ◽  
pp. 1930-1935 ◽  
Author(s):  
Maxie M. Roessler ◽  
Martin S. King ◽  
Alan J. Robinson ◽  
Fraser A. Armstrong ◽  
Jeffrey Harmer ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Complex I ◽  
Proton Translocation ◽  
Flavin Mononucleotide ◽  
Detailed Knowledge ◽  
Electron Resonance ◽  
Nadh:Quinone Oxidoreductase ◽  
Iron Sulfur ◽  
Double Electron ◽  
Double Electron Electron Resonance

In oxidative phosphorylation, complex I (NADH:quinone oxidoreductase) couples electron transfer to proton translocation across an energy-transducing membrane. Complex I contains a flavin mononucleotide to oxidize NADH, and an unusually long series of iron-sulfur (FeS) clusters, in several subunits, to transfer the electrons to quinone. Understanding coupled electron transfer in complex I requires a detailed knowledge of the properties of individual clusters and of the cluster ensemble, and so it requires the correlation of spectroscopic and structural data: This has proved a challenging task. EPR studies on complex I from Bos taurus have established that EPR signals N1b, N2 and N3 arise, respectively, from the 2Fe cluster in the 75 kDa subunit, and from 4Fe clusters in the PSST and 51 kDa subunits (positions 2, 7, and 1 along the seven-cluster chain extending from the flavin). The other clusters have either evaded detection or definitive signal assignments have not been established. Here, we combine double electron-electron resonance (DEER) spectroscopy on B. taurus complex I with the structure of the hydrophilic domain of Thermus thermophilus complex I. By considering the magnetic moments of the clusters and the orientation selectivity of the DEER experiment explicitly, signal N4 is assigned to the first 4Fe cluster in the TYKY subunit (position 5), and N5 to the all-cysteine ligated 4Fe cluster in the 75 kDa subunit (position 3). The implications of our assignment for the mechanisms of electron transfer and energy transduction by complex I are discussed.

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