Structures of respiratory supercomplex I+III2 reveal functional and conformational crosstalk

J.A. Letts, K. Fiedorczuk, G. Degliesposti, M. Skehel, L.A. Sazanov, Molecular Cell 75 (2019) 1131–1146.e6.

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Journal Article | Published | English

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Abstract
The mitochondrial electron transport chain complexes are organized into supercomplexes (SCs) of defined stoichiometry, which have been proposed to regulate electron flux via substrate channeling. We demonstrate that CoQ trapping in the isolated SC I+III2 limits complex (C)I turnover, arguing against channeling. The SC structure, resolved at up to 3.8 Å in four distinct states, suggests that CoQ oxidation may be rate limiting because of unequal access of CoQ to the active sites of CIII2. CI shows a transition between “closed” and “open” conformations, accompanied by the striking rotation of a key transmembrane helix. Furthermore, the state of CI affects the conformational flexibility within CIII2, demonstrating crosstalk between the enzymes. CoQ was identified at only three of the four binding sites in CIII2, suggesting that interaction with CI disrupts CIII2 symmetry in a functionally relevant manner. Together, these observations indicate a more nuanced functional role for the SCs.
Publishing Year
Date Published
2019-09-19
Journal Title
Molecular Cell
Volume
75
Issue
6
Page
1131-1146.e6
ISSN
IST-REx-ID

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Letts JA, Fiedorczuk K, Degliesposti G, Skehel M, Sazanov LA. Structures of respiratory supercomplex I+III2 reveal functional and conformational crosstalk. Molecular Cell. 2019;75(6):1131-1146.e6. doi:10.1016/j.molcel.2019.07.022
Letts, J. A., Fiedorczuk, K., Degliesposti, G., Skehel, M., & Sazanov, L. A. (2019). Structures of respiratory supercomplex I+III2 reveal functional and conformational crosstalk. Molecular Cell, 75(6), 1131–1146.e6. https://doi.org/10.1016/j.molcel.2019.07.022
Letts, James A, Karol Fiedorczuk, Gianluca Degliesposti, Mark Skehel, and Leonid A Sazanov. “Structures of Respiratory Supercomplex I+III2 Reveal Functional and Conformational Crosstalk.” Molecular Cell 75, no. 6 (2019): 1131–1146.e6. https://doi.org/10.1016/j.molcel.2019.07.022.
J. A. Letts, K. Fiedorczuk, G. Degliesposti, M. Skehel, and L. A. Sazanov, “Structures of respiratory supercomplex I+III2 reveal functional and conformational crosstalk,” Molecular Cell, vol. 75, no. 6, p. 1131–1146.e6, 2019.
Letts JA, Fiedorczuk K, Degliesposti G, Skehel M, Sazanov LA. 2019. Structures of respiratory supercomplex I+III2 reveal functional and conformational crosstalk. Molecular Cell. 75(6), 1131–1146.e6.
Letts, James A., et al. “Structures of Respiratory Supercomplex I+III2 Reveal Functional and Conformational Crosstalk.” Molecular Cell, vol. 75, no. 6, Cell Press, 2019, p. 1131–1146.e6, doi:10.1016/j.molcel.2019.07.022.
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