scholarly journals A ferredoxin bridge connects the two arms of plant mitochondrial complex I

2020 ◽  
Author(s):  
Niklas Klusch ◽  
Jennifer Senkler ◽  
Özkan Yildiz ◽  
Werner Kühlbrandt ◽  
Hans-Peter Braun
Keyword(s):  
Arabidopsis Thaliana ◽  
Complex I ◽  
Mitochondrial Membrane ◽  
Mitochondrial Complex I ◽  
Mitochondrial Complex ◽  
Inner Mitochondrial Membrane ◽  
Main Site ◽  
The Matrix ◽  
Quinol Binding ◽  
Complex I Activity

SUMMARYMitochondrial complex I is the main site for electron transfer to the respiratory chain and generates much of the proton gradient across the inner mitochondrial membrane. It is composed of two arms, which form a conserved L-shape. We report the structures of the intact, 47-subunit mitochondrial complex I from Arabidopsis thaliana and from the green alga Polytomella sp. at 3.2 and 3.3 Å resolution. In both, a heterotrimeric γ-carbonic anhydrase domain is attached to the membrane arm on the matrix side. Two states are resolved in A. thaliana complex I, with different angles between the two arms and different conformations of the ND1 loop near the quinol binding site. The angle appears to depend on a bridge domain, which links the peripheral arm to the membrane arm and includes an unusual ferredoxin. We suggest that the bridge domain regulates complex I activity.One sentence summaryThe activity of complex I depends on the angel between its two arms, which, in plants, is adjusted by a protein bridge that includes an unusual ferredoxin.The authors responsible for distribution of materials integral to the findings presented in this article in accordance with the policy described in the Instructions for Authors (www.plantcell.org) are: Hans-Peter Braun ([email protected]) and Werner Kühlbrandt ([email protected]).

scholarly journals A ferredoxin bridge connects the two arms of plant mitochondrial complex I

2021 ◽  
Author(s):  
Niklas Klusch ◽  
Jennifer Senkler ◽  
Özkan Yildiz ◽  
Werner Kühlbrandt ◽  
Hans-Peter Braun
Keyword(s):  
Complex I ◽  
Nadh Dehydrogenase ◽  
Mitochondrial Complex I ◽  
Mitochondrial Complex ◽  
Nadh Dehydrogenase Subunit ◽  
Inner Mitochondrial Membrane ◽  
Main Site ◽  
Membrane Complex ◽  
The Matrix ◽  
Quinol Binding

Abstract Mitochondrial complex I is the main site for electron transfer to the respiratory chain and generates much of the proton gradient across the inner mitochondrial membrane. Complex I is composed of two arms, which form a conserved L-shape. We report the structures of the intact, 47-subunit mitochondrial complex I from Arabidopsis thaliana and the 51-subunit complex I from the green alga Polytomella sp., both at around 2.9 Å resolution. In both complexes, a heterotrimeric γ-carbonic anhydrase domain is attached to the membrane arm on the matrix side. Two states are resolved in A. thaliana complex I, with different angles between the two arms and different conformations of the ND1 (NADH dehydrogenase subunit 1) loop near the quinol binding site. The angle appears to depend on a bridge domain, which links the peripheral arm to the membrane arm and includes an unusual ferredoxin. We propose that the bridge domain participates in regulating the activity of plant 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.

CFM6 is an Essential CRM Protein Required for the Splicing of nad5 Transcript in Arabidopsis Mitochondria

2021 ◽  
Author(s):  
Wei-Chih Lin ◽  
Ya-Huei Chen ◽  
Shin-Yuan Gu ◽  
Hwei-Ling Shen ◽  
Kai-Chau Huang ◽  
...  
Keyword(s):  
Complex I ◽  
Mitochondrial Complex I ◽  
Mitochondrial Complex ◽  
High Accumulation ◽  
Stunted Growth ◽  
Growth Defects ◽  
Group I ◽  
Or Genes ◽  
Complex I Activity ◽  
Intron 4

Abstract Plant CRM domain-containing proteins are capable of binding RNA to facilitate the splicing of group I or II introns in chloroplasts, but their functions in mitochondria are less clear. In the present study, Arabidopsis thaliana CFM6, a protein with a single CRM domain, was expressed in most plant tissues, particularly in flower tissues, and restricted to mitochondria. Mutation of CFM6 causes severe growth defects, including stunted growth, curled leaves, delayed embryogenesis, and pollen development. CFM6 functions specifically in the splicing of group II intron 4 of nad5, which encodes a subunit of mitochondrial complex I, as evidenced by the loss of nad5 intron 4 splicing and high accumulation of its pretranscripts in cfm6 mutants. The phenotypic and splicing defects of cfm6 were rescued in transgenic plants overexpressing 35S::CFM6-YFP. Splicing failure in cfm6 also led to the loss of complex I activity and to its improper assembly. Moreover, dysfunction of complex I induced the expression of proteins or genes involved in alternative respiratory pathways in cfm6. Collectively, CFM6, a previously uncharacterized CRM domain-containing protein, is specifically involved in the cis-splicing of nad5 intron 4 and plays a pivotal role in mitochondrial complex I biogenesis and normal plant growth.

Synthesis and Mitochondrial Complex I Activity of Annonaceous Trans and Cis Solamins Precursors

2004 ◽  
Vol 1 (4) ◽  
pp. 316-322 ◽  
Author(s):  
Julie Defretin ◽  
Christophe Gleye ◽  
Diego Cortes ◽  
Xavier Franck ◽  
Reynald Hocquemiller ◽  
...  
Keyword(s):  
Complex I ◽  
Mitochondrial Complex I ◽  
Mitochondrial Complex ◽  
Complex I Activity
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