%0 Journal Article %A Richardson, KH %A Wright, JJ %A Simenas, M %A Thiemann, J %A Esteves, AM %A McGuire, G %A Myers, WK %A Morton, JJL %A Hippler, M %A Nowaczyk, MM %A Hanke, GT %A Roessler, MM %D 2021 %F discovery:10135179 %I NATURE PORTFOLIO %J Nature Communications %K Science & Technology, Multidisciplinary Sciences, Science & Technology - Other Topics, NADH-UBIQUINONE OXIDOREDUCTASE, IRON-SULFUR CLUSTERS, PHOTOSYSTEM-I, EPR-SPECTRA, SUPEROXIDE-PRODUCTION, GENE ORGANIZATION, CHLOROPLAST NDH, 4FE-4S CLUSTER, SUBUNIT, FLOW %N 1 %T Functional basis of electron transport within photosynthetic complex I %U https://discovery.ucl.ac.uk/id/eprint/10135179/ %V 12 %X Photosynthesis and respiration rely upon a proton gradient to produce ATP. In photosynthesis, the Respiratory Complex I homologue, Photosynthetic Complex I (PS-CI) is proposed to couple ferredoxin oxidation and plastoquinone reduction to proton pumping across thylakoid membranes. However, little is known about the PS-CI molecular mechanism and attempts to understand its function have previously been frustrated by its large size and high lability. Here, we overcome these challenges by pushing the limits in sample size and spectroscopic sensitivity, to determine arguably the most important property of any electron transport enzyme – the reduction potentials of its cofactors, in this case the iron-sulphur clusters of PS-CI (N0, N1 and N2), and unambiguously assign them to the structure using double electron-electron resonance. We have thus determined the bioenergetics of the electron transfer relay and provide insight into the mechanism of PS-CI, laying the foundations for understanding of how this important bioenergetic complex functions. %Z This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/ licenses/by/4.0/.