A modular mechanism determines the proton-pumping stoichiometry of respiratory complex I
- 1University of Cambridge
Abstract
Respiratory complex I, a crucial metabolic enzyme, uses the reducing potential of NADH to pump protons across energy-transducing membranes, but its mechanism of catalysis remains unknown. Here, guided by detailed structural information, we combine targeted mutagenesis and biophysical analyses to define the proton-pumping pathways in the three antiporter-like (proton-pumping) subunits of complex I from Paracoccus denitrificans and Escherichia coli. In Pd-CI, a four-proton pump, one of the three proton-uptake pathways is inactive, reconciling the four-proton/three-subunit mismatch. In Ec-CI two pathways are inactive - and Ec-CI pumps only two protons. We define the structural determinants for redox-coupled proton uptake, establish a mechanistic framework for proton pumping, and reveal how the proton-pumping stoichiometry has been adapted to deliver efficient energy conservation in diverse bioenergetic environments.
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BibTeX
@misc{waddell2026modular,
title = {{A modular mechanism determines the proton-pumping stoichiometry of respiratory complex I}},
author = {R. A. Waddell and H. L. Messent and M. M. Costa-Lima and J. J. Wright and J. H. Salisbury and J. Hirst},
howpublished = {bioRxiv},
year = {2026},
month = oct,
doi = {10.64898/2026.10.08.757549},
url = {https://www.biorxiv.org/content/10.64898/2026.10.08.757549v1},
note = {CC BY},
}
RIS
TY - UNPB
TI - A modular mechanism determines the proton-pumping stoichiometry of respiratory complex I
AU - R. A. Waddell
AU - H. L. Messent
AU - M. M. Costa-Lima
AU - J. J. Wright
AU - J. H. Salisbury
AU - J. Hirst
PY - 2026
DA - 2026/10/08
PB - bioRxiv
DO - 10.64898/2026.10.08.757549
UR - https://www.biorxiv.org/content/10.64898/2026.10.08.757549v1
AB - Respiratory complex I, a crucial metabolic enzyme, uses the reducing potential of NADH to pump protons across energy-transducing membranes, but its mechanism of catalysis remains unknown. Here, guided by detailed structural information, we combine targeted mutagenesis and biophysical analyses to define the proton-pumping pathways in the three antiporter-like (proton-pumping) subunits of complex I from Paracoccus denitrificans and Escherichia coli. In Pd-CI, a four-proton pump, one of the three proton-uptake pathways is inactive, reconciling the four-proton/three-subunit mismatch. In Ec-CI two pathways are inactive - and Ec-CI pumps only two protons. We define the structural determinants for redox-coupled proton uptake, establish a mechanistic framework for proton pumping, and reveal how the proton-pumping stoichiometry has been adapted to deliver efficient energy conservation in diverse bioenergetic environments.
ER -