Mayneord, G.E., Vasilev, C. orcid.org/0000-0002-0536-882X, Malone, L.A. orcid.org/0000-0002-7625-7545 et al. (3 more authors) (2019) Single-molecule study of redox control involved in establishing the spinach plastocyanin-cytochrome b6f electron transfer complex. Biochimica et Biophysica Acta (BBA) - Bioenergetics, 1860 (7). pp. 591-599. ISSN 0005-2728
Abstract
Small diffusible redox proteins play a ubiquitous role in bioenergetic systems, facilitating electron transfer (ET) between membrane bound complexes. Sustaining high ET turnover rates requires that the association between extrinsic and membrane-bound partners is highly specific, yet also sufficiently weak to promote rapid post-ET separation. In oxygenic photosynthesis the small soluble electron carrier protein plastocyanin (Pc) shuttles electrons between the membrane integral cytochrome b6f (cytb6f) and photosystem I (PSI) complexes. Here we use peak-force quantitative nanomechanical mapping (PF-QNM) atomic force microscopy (AFM) to quantify the dynamic forces involved in transient interactions between cognate ET partners. An AFM probe functionalised with Pc molecules is brought into contact with cytb6f complexes, immobilised on a planar silicon surface. PF-QNM interrogates the unbinding force of the cytb6f-Pc interactions at the single molecule level with picoNewton force resolution and on a time scale comparable to the ET time in vivo (ca. 120 μs). Using this approach, we show that although the unbinding force remains unchanged the interaction frequency increases over five-fold when Pc and cytb6f are in opposite redox states, so complementary charges on the cytb6f and Pc cofactors likely contribute to the electrostatic forces that initiate formation of the ET complex. These results suggest that formation of the docking interface is under redox state control, which lowers the probability of unproductive encounters between Pc and cytb6f molecules in the same redox state, ensuring the efficiency and directionality of this central reaction in the ‘Z-scheme’ of photosynthetic ET.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2019 Elsevier. This is an author produced version of a paper subsequently published in BBA - Bioenergetics. Uploaded in accordance with the publisher's self-archiving policy. Article available under the terms of the CC-BY-NC-ND licence (https://creativecommons.org/licenses/by-nc-nd/4.0/). |
Keywords: | Photosynthesis; Electron transfer; cytochrome b6f; Plastocyanin; Atomic force microscopy |
Dates: |
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Institution: | The University of Sheffield |
Academic Units: | The University of Sheffield > Faculty of Science (Sheffield) > School of Biosciences (Sheffield) > Department of Molecular Biology and Biotechnology (Sheffield) |
Depositing User: | Symplectic Sheffield |
Date Deposited: | 25 Sep 2019 13:45 |
Last Modified: | 24 Jun 2020 00:39 |
Status: | Published |
Publisher: | Elsevier |
Refereed: | Yes |
Identification Number: | 10.1016/j.bbabio.2019.06.013 |
Related URLs: | |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:151341 |
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