scholarly journals A scaffold of accessory subunits links the peripheral arm and the distal proton-pumping module of mitochondrial complex I

2011 ◽  
Vol 437 (2) ◽  
pp. 279-288 ◽  
Author(s):  
Heike Angerer ◽  
Klaus Zwicker ◽  
Zibiernisha Wumaier ◽  
Lucie Sokolova ◽  
Heinrich Heide ◽  
...  
Keyword(s):  
Complex I ◽  
Structural Information ◽  
Proton Pumping ◽  
Nadh:Ubiquinone Oxidoreductase ◽  
Mitochondrial Complex I ◽  
Mitochondrial Complex ◽  
Central Function ◽  
Membrane Protein Complex ◽  
Accessory Subunits ◽  
Insight Into

Mitochondrial NADH:ubiquinone oxidoreductase (complex I) is a very large membrane protein complex with a central function in energy metabolism. Complex I from the aerobic yeast Yarrowia lipolytica comprises 14 central subunits that harbour the bioenergetic core functions and at least 28 accessory subunits. Despite progress in structure determination, the position of individual accessory subunits in the enzyme complex remains largely unknown. Proteomic analysis of subcomplex Iδ revealed that it lacked eleven subunits, including the central subunits ND1 and ND3 forming the interface between the peripheral and the membrane arm in bacterial complex I. This unexpected observation provided insight into the structural organization of the connection between the two major parts of mitochondrial complex I. Combining recent structural information, biochemical evidence on the assignment of individual subunits to the subdomains of complex I and sequence-based predictions for the targeting of subunits to different mitochondrial compartments, we derived a model for the arrangement of the subunits in the membrane arm of mitochondrial complex I.

scholarly journals Paracoccus denitrificans: a genetically tractable model system for studying respiratory complex I

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Owen D. Jarman ◽  
Olivier Biner ◽  
John J. Wright ◽  
Judy Hirst
Keyword(s):  
Complex I ◽  
Paracoccus Denitrificans ◽  
Model System ◽  
Proton Pumping ◽  
Model Systems ◽  
Metabolic Enzyme ◽  
Nadh:Ubiquinone Oxidoreductase ◽  
Mitochondrial Complex I ◽  
Mitochondrial Complex ◽  
Inner Mitochondrial Membrane

AbstractMitochondrial complex I (NADH:ubiquinone oxidoreductase) is a crucial metabolic enzyme that couples the free energy released from NADH oxidation and ubiquinone reduction to the translocation of four protons across the inner mitochondrial membrane, creating the proton motive force for ATP synthesis. The mechanism by which the energy is captured, and the mechanism and pathways of proton pumping, remain elusive despite recent advances in structural knowledge. Progress has been limited by a lack of model systems able to combine functional and structural analyses with targeted mutagenic interrogation throughout the entire complex. Here, we develop and present the α-proteobacterium Paracoccus denitrificans as a suitable bacterial model system for mitochondrial complex I. First, we develop a robust purification protocol to isolate highly active complex I by introducing a His6-tag on the Nqo5 subunit. Then, we optimize the reconstitution of the enzyme into liposomes, demonstrating its proton pumping activity. Finally, we develop a strain of P. denitrificans that is amenable to complex I mutagenesis and create a catalytically inactive variant of the enzyme. Our model provides new opportunities to disentangle the mechanism of complex I by combining mutagenesis in every subunit with established interrogative biophysical measurements on both the soluble and membrane bound enzymes.

scholarly journals Cryo-EM structure of respiratory complex I at work

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Kristian Parey ◽  
Ulrich Brandt ◽  
Hao Xie ◽  
Deryck J Mills ◽  
Karin Siegmund ◽  
...  
Keyword(s):  
Complex I ◽  
Atp Synthesis ◽  
Proton Pumping ◽  
Mitochondrial Complex I ◽  
Mitochondrial Complex ◽  
Membrane Protein Complex ◽  
Change Mechanism ◽  
Steady State Activity ◽  
Respiratory Complex I ◽  
Ubiquinone Binding

Mitochondrial complex I has a key role in cellular energy metabolism, generating a major portion of the proton motive force that drives aerobic ATP synthesis. The hydrophilic arm of the L-shaped ~1 MDa membrane protein complex transfers electrons from NADH to ubiquinone, providing the energy to drive proton pumping at distant sites in the membrane arm. The critical steps of energy conversion are associated with the redox chemistry of ubiquinone. We report the cryo-EM structure of complete mitochondrial complex I from the aerobic yeast Yarrowia lipolytica both in the deactive form and after capturing the enzyme during steady-state activity. The site of ubiquinone binding observed during turnover supports a two-state stabilization change mechanism for complex I.

Why does mitochondrial complex I have so many subunits?

2011 ◽  
Vol 437 (2) ◽  
pp. e1-e3 ◽  
Author(s):  
Judy Hirst
Keyword(s):  
Complex I ◽  
Enzyme Stability ◽  
Energy Transduction ◽  
Proton Pumping ◽  
Mitochondrial Complex I ◽  
Mitochondrial Complex ◽  
Nadh:Quinone Oxidoreductase ◽  
Biochemical Journal ◽  
Accessory Subunits ◽  
New Evidence

The prokaryotic and eukaryotic homologues of complex I (proton-pumping NADH:quinone oxidoreductase) perform the same function in energy transduction, but the eukaryotic enzymes are twice as big as their prokaryotic cousins, and comprise three times as many subunits. Fourteen core subunits are conserved in all complexes I, and are sufficient for catalysis – so why are the eukaryotic enzymes embellished by so many supernumerary or accessory subunits? In this issue of the Biochemical Journal, Angerer et al. have provided new evidence to suggest that the supernumerary subunits are important for enzyme stability. This commentary aims to put this suggestion into context.

scholarly journals Mechanistic insight from the crystal structure of mitochondrial complex I

Science ◽  
2015 ◽  
Vol 347 (6217) ◽  
pp. 44-49 ◽  
Author(s):  
Volker Zickermann ◽  
Christophe Wirth ◽  
Hamid Nasiri ◽  
Karin Siegmund ◽  
Harald Schwalbe ◽  
...  
Keyword(s):  
Complex I ◽  
Protein Complexes ◽  
Active Form ◽  
Mitochondrial Respiratory Chain ◽  
Structural Rearrangement ◽  
Proton Pumping ◽  
Mitochondrial Complex I ◽  
Mitochondrial Complex ◽  
Degenerative Disorders ◽  
Pumping Units

Proton-pumping complex I of the mitochondrial respiratory chain is among the largest and most complicated membrane protein complexes. The enzyme contributes substantially to oxidative energy conversion in eukaryotic cells. Its malfunctions are implicated in many hereditary and degenerative disorders. We report the x-ray structure of mitochondrial complex I at a resolution of 3.6 to 3.9 angstroms, describing in detail the central subunits that execute the bioenergetic function. A continuous axis of basic and acidic residues running centrally through the membrane arm connects the ubiquinone reduction site in the hydrophilic arm to four putative proton-pumping units. The binding position for a substrate analogous inhibitor and blockage of the predicted ubiquinone binding site provide a model for the “deactive” form of the enzyme. The proposed transition into the active form is based on a concerted structural rearrangement at the ubiquinone reduction site, providing support for a two-state stabilization-change mechanism of proton pumping.

scholarly journals Specific features and assembly of the plant mitochondrial complex I revealed by cryo-EM

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Heddy Soufari ◽  
Camila Parrot ◽  
Lauriane Kuhn ◽  
Florent Waltz ◽  
Yaser Hashem
Keyword(s):  
Carbonic Anhydrase ◽  
Complex I ◽  
Mitochondrial Respiratory Chain ◽  
Nadh:Ubiquinone Oxidoreductase ◽  
Mitochondrial Complex I ◽  
Mitochondrial Complex ◽  
Entry Site ◽  
Lipid Complex ◽  
Maturation Factor ◽  
Specific Complex

Abstract Mitochondria are the powerhouses of eukaryotic cells and the site of essential metabolic reactions. Complex I or NADH:ubiquinone oxidoreductase is the main entry site for electrons into the mitochondrial respiratory chain and constitutes the largest of the respiratory complexes. Its structure and composition vary across eukaryote species. However, high resolution structures are available only for one group of eukaryotes, opisthokonts. In plants, only biochemical studies were carried out, already hinting at the peculiar composition of complex I in the green lineage. Here, we report several cryo-electron microscopy structures of the plant mitochondrial complex I. We describe the structure and composition of the plant respiratory complex I, including the ancestral mitochondrial domain composed of the carbonic anhydrase. We show that the carbonic anhydrase is a heterotrimeric complex with only one conserved active site. This domain is crucial for the overall stability of complex I as well as a peculiar lipid complex composed of cardiolipin and phosphatidylinositols. Moreover, we also describe the structure of one of the plant-specific complex I assembly intermediates, lacking the whole PD module, in presence of the maturation factor GLDH. GLDH prevents the binding of the plant specific P1 protein, responsible for the linkage of the PP to the PD module.

Accessory subunits of mitochondrial complex I

2013 ◽  
Vol 41 (5) ◽  
pp. 1272-1279 ◽  
Author(s):  
Katarzyna Kmita ◽  
Volker Zickermann
Keyword(s):  
Molecular Mass ◽  
Complex I ◽  
Proton Translocation ◽  
Present Review ◽  
Mitochondrial Complex I ◽  
Mitochondrial Complex ◽  
Cellular Functions ◽  
Accessory Subunits

Mitochondrial complex I has a molecular mass of almost 1 MDa and comprises more than 40 polypeptides. Fourteen central subunits harbour the bioenergetic core functions. We are only beginning to understand the significance of the numerous accessory subunits. The present review addresses the role of accessory subunits for assembly, stability and regulation of complex I and for cellular functions not directly associated with redox-linked proton translocation.

Sign in / Sign up

Export Citation Format

Share Document