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Clarifying the supercomplex: the higher-order organization of the mitochondrial electron transport chain

Nature Structural & Molecular Biology volume 24, pages 800–808 (2017)Cite this article

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Abstract

The oxidative phosphorylation electron transport chain (OXPHOS-ETC) of the inner mitochondrial membrane is composed of five large protein complexes, named CI–CV. These complexes convert energy from the food we eat into ATP, a small molecule used to power a multitude of essential reactions throughout the cell. OXPHOS-ETC complexes are organized into supercomplexes (SCs) of defined stoichiometry: CI forms a supercomplex with CIII2 and CIV (SC I+III2+IV, known as the respirasome), as well as with CIII2 alone (SC I+III2). CIII2 forms a supercomplex with CIV (SC III2+IV) and CV forms dimers (CV2). Recent cryo-EM studies have revealed the structures of SC I+III2+IV and SC I+III2. Furthermore, recent work has shed light on the assembly and function of the SCs. Here we review and compare these recent studies and discuss how they have advanced our understanding of mitochondrial electron transport.

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Figure 1: The complexes of the mitochondrial OXPHOS-ETC.
Figure 2: The supercomplexes of the mitochondrial OXPHOS-ETC.
Figure 3: Two possible paths for the assembly of respirasomes.
Figure 4: Interaction sites within the tight respirasome.
Figure 5: The four major pivots of the respirasome.
Figure 6: Asymmetric electron flow through CIII2 may reduce ROS production.

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Acknowledgements

This work was supported in part by European Union's 2020 Research and Innovation Program under grant 701309.

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    James A Letts & Leonid A Sazanov

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Letts, J., Sazanov, L. Clarifying the supercomplex: the higher-order organization of the mitochondrial electron transport chain. Nat Struct Mol Biol 24, 800–808 (2017). https://doi.org/10.1038/nsmb.3460

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