Cryo-EM structure and kinetics reveal electron transfer by 2D diffusion of cytochrome c in the yeast III-IV respiratory supercomplex

Energy conversion in aerobic organisms involves an electron current from low-potential donors, such as NADH and succinate, to dioxygen through the membrane-bound respiratory chain. Electron transfer is coupled to transmembrane proton transport, which maintains the electrochemical proton gradient used to produce ATP and drive other cellular processes. Electrons are transferred from respiratory complexes III to IV (CIII and CIV) by water-soluble cytochrome (cyt.) c. In Saccharomyces cerevisiae and some other organisms, these complexes assemble into larger CIII2CIV1/2 supercomplexes, the functional significance of which has remained enigmatic. In this work, we measured the kinetics of the S. cerevisiae supercomplex cyt. c-mediated QH2:O2 oxidoreductase activity under various conditions. The data indicate that the electronic link between CIII and CIV is confined to the surface of the supercomplex. Single-particle electron cryomicroscopy (cryo-EM) structures of the supercomplex with cyt. c show the positively charged cyt. c bound to either CIII or CIV or along a continuum of intermediate positions. Collectively, the structural and kinetic data indicate that cyt. c travels along a negatively charged patch on the supercomplex surface. Thus, rather than enhancing electron transfer rates by decreasing the distance that cyt. c must diffuse in three dimensions, formation of the CIII2CIV1/2 supercomplex facilitates electron transfer by two-dimensional (2D) diffusion of cyt. c. This mechanism enables the CIII2CIV1/2 supercomplex to increase QH2:O2 oxidoreductase activity and suggests a possible regulatory role for supercomplex formation in the respiratory chain.

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Cryo-EM structure and kinetics reveal electron transfer by 2D diffusion of cytochrome c in the yeast III-IV respiratory supercomplex

10.1101/2020.11.27.401935 ◽

2020 ◽

Author(s):

Agnes Moe ◽

Justin Di Trani ◽

John L. Rubinstein ◽

Peter Brzezinski

Keyword(s):

Electron Transfer ◽

Respiratory Chain ◽

Supramolecular Assembly ◽

Kinetic Studies ◽

Water Soluble ◽

Complex Iii ◽

Surface Patch ◽

Cellular Respiration ◽

Oxidoreductase Activity ◽

Membrane Bound

AbstractEnergy conversion in aerobic organisms involves an electron current from low-potential donors, such as NADH and succinate, to dioxygen through the membrane-bound respiratory chain. Electron transfer is coupled to transmembrane proton transport that maintains the electrochemical proton gradient used to produce ATP and drive other cellular processes. Electrons are transferred between respiratory complexes III and IV (CIII and CIV) by water-soluble cyt. c. In S. cerevisiae and some other organisms, these complexes assemble into larger CIII2CIV1/2 supercomplexes, the functional significance of which has remained enigmatic. In this work, we measured the kinetics of the S. cerevisiae supercomplex’s cyt.c-mediated QH2:O2 oxidoreductase activity under various conditions. The data indicate that the electronic link between CIII and CIV is confined to the surface of the supercomplex. Cryo-EM structures of the supercomplex with cyt. c reveal distinct states where the positively-charged cyt. c is bound either to CIII or CIV, or resides at intermediate positions. Collectively, the structural and kinetic data indicate that cyt. c travels along a negatively-charged surface patch of the supercomplex. Thus, rather than enhancing electron-transfer rates by decreasing the distance cyt. c must diffuse in 3D, formation of the CIII2CIV1/2 supercomplex facilitates electron transfer by 2D diffusion of cyt. c. This mechanism enables the CIII2CIV1/2 supercomplex to increase QH2:O2 oxidoreductase activity and suggests a possible regulatory role for supercomplex formation in the respiratory chain.Significance StatementIn the last steps of food oxidation in living organisms, electrons are transferred to oxygen through the membrane-bound respiratory chain. This electron transfer is mediated by mobile carriers such as membrane-bound quinone and water-soluble cyt. c. The latter transfers electrons from respiratory complex III to IV. In yeast these complexes assemble into III2IV1/2 supercomplexes, but their role has remained enigmatic. This study establishes a functional role for this supramolecular assembly in the mitochondrial membrane. We used cryo-EM and kinetic studies to show that cyt. c shuttles electrons by sliding along the surface of III2IV1/2 (2D diffusion). The structural arrangement into III2IV1/2 supercomplexes suggests a mechanism to regulate cellular respiration.

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The NADH dehydrogenase of the respiratory chain of Escherichia coli. II. Kinetics of the purified enzyme and the effects of antibodies elicited against it on membrane-bound and free enzyme.

Journal of Biological Chemistry ◽

10.1016/s0021-9258(17)33040-5 ◽

1976 ◽

Vol 251 (19) ◽

pp. 5921-5928

Author(s):

G F Dancey ◽

B M Shapiro

Keyword(s):

Escherichia Coli ◽

Respiratory Chain ◽

Nadh Dehydrogenase ◽

Free Enzyme ◽

Membrane Bound ◽

Kinetics Of

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How to Control the Rate of Heterogeneous Electron Transfer Across the Rim of M6L12 and M12L24 Nanospheres

10.26434/chemrxiv.11855469.v1 ◽

2020 ◽

Author(s):

Riccardo Zaffaroni ◽

Eduard.O. Bobylev ◽

Plessius, Raoul ◽

Jarl Ivar van der Vlugt ◽

Joost reek

Keyword(s):

Electron Transfer ◽

Active Species ◽

Transition Metal Catalysts ◽

Supramolecular Assemblies ◽

Fine Tuning ◽

Transfer Rates ◽

Heterogeneous Electron Transfer ◽

Redox Active ◽

Kinetics Of ◽

Fine Tune

Catalysis in confined spaces, such as provided by supramolecular cages, is quickly gaining momentum. It allows for second coordination sphere strategies to control the selectivity and activity of transition metal catalysts, beyond the classical methods like fine-tuning the steric and electronic properties of the coordinating ligands. Only a few electrocatalytic reactions within cages have been reported, and there is no information regarding the electron transfer kinetics and thermodynamics of redox-active species encapsulated into supramolecular assemblies. This contribution revolves around the preparation of M6L12 and larger M12L24 (M= Pd or Pt) nanospheres functionalized with different numbers of redox-active probes encapsulated within their cavity, either in a covalent fashion via different types of linkers (flexible, rigid and conjugated or rigid and non-conjugated) or by supramolecular hydrogen bonding interactions. The redox-probes can be addressed by electrochemical electron transfer across the rim of nanospheres and the thermodynamics and kinetics of this process are described. Our study identifies that the linker type and the number of redox probes within the cage are useful handles to fine-tune the electron transfer rates, paving the way for the encapsulation of electro-active catalysts and electrocatalytic applications of such supramolecular assemblies.

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Kinetics of Electron Transfer through the Respiratory Chain

Biophysical Journal ◽

10.1016/s0006-3495(02)73945-3 ◽

2002 ◽

Vol 83 (4) ◽

pp. 1797-1808 ◽

Cited By ~ 70

Author(s):

Qusheng Jin ◽

Craig M. Bethke

Keyword(s):

Electron Transfer ◽

Respiratory Chain ◽

Kinetics Of

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How to Control the Rate of Heterogeneous Electron Transfer Across the Rim of M6L12 and M12L24 Nanospheres

10.26434/chemrxiv.11855469 ◽

2020 ◽

Author(s):

Riccardo Zaffaroni ◽

Eduard.O. Bobylev ◽

Plessius, Raoul ◽

Jarl Ivar van der Vlugt ◽

Joost reek

Keyword(s):

Electron Transfer ◽

Active Species ◽

Transition Metal Catalysts ◽

Supramolecular Assemblies ◽

Fine Tuning ◽

Transfer Rates ◽

Heterogeneous Electron Transfer ◽

Redox Active ◽

Kinetics Of ◽

Fine Tune

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Photochemical reactions in organized assemblies. 40. Amylose and carboxymethylamylose inclusion complexes with photoreactive molecules

Canadian Journal of Chemistry ◽

10.1139/v85-223 ◽

1985 ◽

Vol 63 (6) ◽

pp. 1315-1319 ◽

Cited By ~ 9

Author(s):

Brian R. Suddaby ◽

Raymond N. Dominey ◽

Y. Hui ◽

David G. Whitten

Keyword(s):

Electron Transfer ◽

Photochemical Reactions ◽

Water Soluble ◽

Enhanced Fluorescence ◽

Transfer Rates ◽

Back Electron Transfer ◽

Organized Assemblies ◽

Stilbene Derivatives ◽

Polypyridine Complexes ◽

Ruthenium Polypyridine

This paper focuses on a study of unimolecular and bimolecular photoreactions occurring with reactants which can be incorporated into the linear polysugars amylose and carboxymethylamylose. Hydrophobic and surfactant trans (E) stilbene derivatives form complexes in which the stilbene chromophore shows enhanced fluorescence and reduced trans → cis isomerization efficiencies. The reactivity of the excited surfactant–stilbene singlet towards the quencher iodide ion has been compared in water/dimethylsulfoxide in the presence and absence of amylose under conditions where complex formation is nearly complete. Some relatively hydrophobic viologen dications have also been found to form complexes with the water soluble carboxymethylamylose. Although the dications complex relatively weakly, the partially reduced monocations complex more strongly. This results in selective retardation of back electron transfer rates when the viologens are used as electron transfer quencher-oxidants for certain luminescent ruthenium polypyridine complexes.

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Kinetics of some electron-transfer reactions in biological Photosystems II. Study of intramolecular electron-transfer rates between ferredoxin-NADP reductase, NADP. radical and oxidized ferredoxin

Biochimica et Biophysica Acta (BBA) - Bioenergetics ◽

10.1016/0005-2728(82)90142-6 ◽

1982 ◽

Vol 680 (3) ◽

pp. 297-303 ◽

Cited By ~ 10

Author(s):

Richard Maskiewicz ◽

Benon H.J. Bielski

Keyword(s):

Electron Transfer ◽

Transfer Reactions ◽

Intramolecular Electron Transfer ◽

Electron Transfer Reactions ◽

Transfer Rates ◽

Kinetics Of

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Inhibition of Membrane-Bound Methane Monooxygenase and Ammonia Monooxygenase by Diphenyliodonium: Implications for Electron Transfer

Journal of Bacteriology ◽

10.1128/jb.186.4.928-937.2004 ◽

2004 ◽

Vol 186 (4) ◽

pp. 928-937 ◽

Cited By ~ 37

Author(s):

Andrew K. Shiemke ◽

Daniel J. Arp ◽

Luis A. Sayavedra-Soto

Keyword(s):

Electron Transfer ◽

Methane Monooxygenase ◽

Methylococcus Capsulatus ◽

Ammonia Monooxygenase ◽

Oxidoreductase Activity ◽

Nadh:Quinone Oxidoreductase ◽

Membrane Bound ◽

Quinone Pool

ABSTRACT Diphenyliodonium (DPI) is known to irreversibly inactivate flavoproteins. We have found that DPI inhibits both membrane-bound methane monooxygenase (pMMO) from Methylococcus capsulatus and ammonia monooxygenase (AMO) of Nitrosomonas europaea. The effect of DPI on NADH-dependent pMMO activity in vitro is ascribed to inactivation of NDH-2, a flavoprotein which we proposed catalyzes reduction of the quinone pool by NADH. DPI is a potent inhibitor of type 2 NADH:quinone oxidoreductase (NDH-2), with 50% inhibition occurring at ≈5 μM. Inhibition of NDH-2 is irreversible and requires NADH. Inhibition of NADH-dependent pMMO activity by DPI in vitro is concomitant with inhibition of NDH-2, consistent with our proposal that NDH-2 mediates reduction of pMMO. Unexpectedly, DPI also inhibits pMMO activity driven by exogenous hydroquinols, but with ≈100 μM DPI required to achieve 50% inhibition. Similar concentrations of DPI are required to inhibit formate-, formaldehyde-, and hydroquinol-driven pMMO activities in whole cells. The pMMO activity in DPI-treated cells greatly exceeds the activity of NDH-2 or pMMO in membranes isolated from those cells, suggesting that electron transfer from formate to pMMO in vivo can occur independent of NADH and NDH-2. AMO activity, which is known to be independent of NADH, is affected by DPI in a manner analogous to pMMO in vivo: ≈100 μM is required for 50% inhibition regardless of the nature of the reducing agent. DPI does not affect hydroxylamine oxidoreductase activity and does not require AMO turnover to exert its inhibitory effect. Implications of these data for the electron transfer pathway from the quinone pool to pMMO and AMO are discussed.

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