scholarly journals Atomic structures of respiratory complex III2, complex IV, and supercomplex III2-IV from vascular plants

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Maria Maldonado ◽  
Fei Guo ◽  
James A Letts
Keyword(s):  
Vascular Plants ◽  
Proton Translocation ◽  
Complex Iii ◽  
Conformational Heterogeneity ◽  
Mitochondrial Matrix ◽  
Mitochondrial Complex ◽  
Complex Iv ◽  
Atomic Structures ◽  
Iron Sulfur ◽  
Heterogeneity Analysis

Mitochondrial complex III (CIII2) and complex IV (CIV), which can associate into a higher-order supercomplex (SC III2+IV), play key roles in respiration. However, structures of these plant complexes remain unknown. We present atomic models of CIII2, CIV, and SC III2+IV from Vigna radiata determined by single-particle cryoEM. The structures reveal plant-specific differences in the MPP domain of CIII2 and define the subunit composition of CIV. Conformational heterogeneity analysis of CIII2 revealed long-range, coordinated movements across the complex, as well as the motion of CIII2’s iron-sulfur head domain. The CIV structure suggests that, in plants, proton translocation does not occur via the H channel. The supercomplex interface differs significantly from that in yeast and bacteria in its interacting subunits, angle of approach and limited interactions in the mitochondrial matrix. These structures challenge long-standing assumptions about the plant complexes and generate new mechanistic hypotheses.

scholarly journals Atomic structures of respiratory complex III2, complex IV and supercomplex III2-IV from vascular plants

2020 ◽  
Author(s):  
María Maldonado ◽  
Fei Guo ◽  
James A. Letts
Keyword(s):  
Vascular Plants ◽  
Proton Translocation ◽  
Complex Iii ◽  
Conformational Heterogeneity ◽  
Mitochondrial Matrix ◽  
Mitochondrial Complex ◽  
Complex Iv ◽  
Atomic Structures ◽  
Iron Sulfur ◽  
Heterogeneity Analysis

Mitochondrial complex III (CIII2) and complex IV (CIV), which can associate into a higher-order supercomplex (SC III2+IV), play key roles in respiration. However, structures of these plant complexes remain unknown. We present atomic models of CIII2, CIV and SC III2+IV from Vigna radiata determined by single-particle cryoEM. The structures reveal plant-specific differences in the MPP domain of CIII2 and define the subunit composition of CIV. Conformational heterogeneity analysis of CIII2 revealed long-range, coordinated movements across the complex, as well as the motion of CIII2’s iron-sulfur head domain. The CIV structure suggests that, in plants, proton translocation does not occur via the H-channel. The supercomplex interface differs significantly from that in yeast and bacteria in its interacting subunits, angle of approach and limited interactions in the mitochondrial matrix. These structures challenge long-standing assumptions about the plant complexes, generate new mechanistic hypotheses and allow for the generation of more selective agricultural inhibitors.

scholarly journals Respiratory chain supercomplexes associate with the cysteine desulfurase complex of the iron–sulfur cluster assembly machinery

2018 ◽  
Vol 29 (7) ◽  
pp. 776-785 ◽  
Author(s):  
Lena Böttinger ◽  
Christoph U. Mårtensson ◽  
Jiyao Song ◽  
Nicole Zufall ◽  
Nils Wiedemann ◽  
...  
Keyword(s):  
Respiratory Chain ◽  
Complex Iii ◽  
Bc1 Complex ◽  
Cytochrome Bc1 Complex ◽  
Respiratory Chain Complexes ◽  
Cysteine Desulfurase ◽  
Complex Iv ◽  
Iron Sulfur Cluster ◽  
Iron Sulfur ◽  
Chain Complexes

Mitochondria are the powerhouses of eukaryotic cells. The activity of the respiratory chain complexes generates a proton gradient across the inner membrane, which is used by the F1FO-ATP synthase to produce ATP for cellular metabolism. In baker’s yeast, Saccharomyces cerevisiae, the cytochrome bc1 complex (complex III) and cytochrome c oxidase (complex IV) associate in respiratory chain supercomplexes. Iron–sulfur clusters (ISC) form reactive centers of respiratory chain complexes. The assembly of ISC occurs in the mitochondrial matrix and is essential for cell viability. The cysteine desulfurase Nfs1 provides sulfur for ISC assembly and forms with partner proteins the ISC-biogenesis desulfurase complex (ISD complex). Here, we report an unexpected interaction of the active ISD complex with the cytochrome bc1 complex and cytochrome c oxidase. The individual deletion of complex III or complex IV blocks the association of the ISD complex with respiratory chain components. We conclude that the ISD complex binds selectively to respiratory chain supercomplexes. We propose that this molecular link contributes to coordination of iron–sulfur cluster formation with respiratory activity.

scholarly journals A defect in the mitochondrial complex III, but not complex IV, triggers early ROS-dependent damage in defined brain regions

2012 ◽  
Vol 21 (23) ◽  
pp. 5066-5077 ◽  
Author(s):  
Francisca Diaz ◽  
Sofia Garcia ◽  
Kyle R. Padgett ◽  
Carlos T. Moraes
Keyword(s):  
Brain Regions ◽  
Complex Iii ◽  
Mitochondrial Complex ◽  
Complex Iv

scholarly journals Differential responses of targeted lung redox enzymes to rat exposure to 60 or 85% oxygen

2011 ◽  
Vol 111 (1) ◽  
pp. 95-107 ◽  
Author(s):  
Zhuohui Gan ◽  
David L. Roerig ◽  
Anne V. Clough ◽  
Said H. Audi
Keyword(s):  
Lung Tissue ◽  
Complex I ◽  
Complex Iii ◽  
Oxygen Species ◽  
Mitochondrial Complex ◽  
Complex Iv ◽  
Arterial Inflow ◽  
Tissue Homogenates ◽  
Species Production ◽  
Complex I Activity

Rat exposure to 60% O2 (hyper-60) or 85% O2 (hyper-85) for 7 days confers susceptibility or tolerance, respectively, of the otherwise lethal effects of exposure to 100% O2. The objective of this study was to determine whether activities of the antioxidant cytosolic enzyme NAD(P)H:quinone oxidoreductase 1 (NQO1) and mitochondrial complex III are differentially altered in hyper-60 and hyper-85 lungs. Duroquinone (DQ), an NQO1 substrate, or its hydroquinone (DQH2), a complex III substrate, was infused into the arterial inflow of isolated, perfused lungs, and the venous efflux rates of DQH2 and DQ were measured. Based on inhibitor effects and kinetic modeling, capacities of NQO1-mediated DQ reduction ( Vmax1) and complex III-mediated DQH2 oxidation ( Vmax2) increased by ∼140 and ∼180% in hyper-85 lungs, respectively, compared with rates in lungs of rats exposed to room air (normoxic). In hyper-60 lungs, Vmax1 increased by ∼80%, with no effect on Vmax2. Additional studies revealed that mitochondrial complex I activity in hyper-60 and hyper-85 lung tissue homogenates was ∼50% lower than in normoxic lung homogenates, whereas mitochondrial complex IV activity was ∼90% higher in only hyper-85 lung tissue homogenates. Thus NQO1 activity increased in both hyper-60 and hyper-85 lungs, whereas complex III activity increased in hyper-85 lungs only. This increase, along with the increase in complex IV activity, may counter the effects the depression in complex I activity might have on tissue mitochondrial function and/or reactive oxygen species production and may be important to the tolerance of 100% O2 observed in hyper-85 rats.

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