Proctor, M.S., Malone, L.A., Farmer, D.A. et al. (8 more authors) (2022) Cryo-EM structures of the Synechocystis sp. PCC 6803 cytochrome b6f complex with and without the regulatory PetP subunit. Biochemical Journal, 479 (13). pp. 1487-1503. ISSN 0264-6021
Abstract
In oxygenic photosynthesis, the cytochrome b6f (cytb6f) complex links the linear electron transfer (LET) reactions occurring at photosystems I and II and generates a transmembrane proton gradient via the Q-cycle. In addition to this central role in LET, cytb6f also participates in a range of processes including cyclic electron transfer (CET), state transitions and photosynthetic control. Many of the regulatory roles of cytb6f are facilitated by auxiliary proteins that differ depending upon the species, yet because of their weak and transient nature the structural details of these interactions remain unknown. An apparent key player in the regulatory balance between LET and CET in cyanobacteria is PetP, a ~10 kDa protein that is also found in red algae but not in green algae and plants. Here, we used cryogenic electron microscopy to determine the structure of the Synechocystis sp. PCC 6803 cytb6f complex in the presence and absence of PetP. Our structures show that PetP interacts with the cytoplasmic side of cytb6f, displacing the C-terminus of the PetG subunit and shielding the C-terminus of cytochrome b6, which binds the heme cn molecule that is suggested to mediate CET. The structures also highlight key differences in the mode of plastoquinone binding between cyanobacterial and plant cytb6f complexes, which we suggest may reflect the unique combination of photosynthetic and respiratory electron transfer in cyanobacterial thylakoid membranes. The structure of cytb6f from a model cyanobacterial species amenable to genetic engineering will enhance future site-directed mutagenesis studies of structure-function relationships in this crucial ET complex.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2022 The Author(s). This is an open access article published by Portland Press Limited on behalf of the Biochemical Society and distributed under the Creative Commons Attribution License 4.0 (https://creativecommons.org/licenses/by/4.0/). |
Keywords: | cytochrome b6f; Synechocystis; cyanobacteria; photosynthesis; PetP; cryo-EM |
Dates: |
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Institution: | The University of Sheffield |
Academic Units: | The University of Sheffield > Faculty of Science (Sheffield) > School of Biosciences (Sheffield) |
Funding Information: | Funder Grant number DIAMOND LIGHT SOURCE LTD UNSPECIFIED BIOTECHNOLOGY AND BIOLOGICAL SCIENCES RESEARCH COUNCIL BB/V006630/1 ROYAL SOCIETY URF\R1\191548 |
Depositing User: | Symplectic Sheffield |
Date Deposited: | 30 Jun 2022 10:36 |
Last Modified: | 24 Jun 2024 14:35 |
Status: | Published |
Publisher: | Portland Press Ltd. |
Refereed: | Yes |
Identification Number: | 10.1042/bcj20220124 |
Related URLs: | |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:188585 |