Huang, X. orcid.org/0000-0003-1674-0065, Vasilev, C. orcid.org/0000-0002-0536-882X, Swainsbury, D.J.K. orcid.org/0000-0002-0754-0363 et al. (1 more author) (2024) Excitation energy transfer in proteoliposomes reconstituted with LH2 and RC-LH1 complexes from Rhodobacter sphaeroides. Bioscience Reports, 44 (2). BSR20231302. ISSN 0144-8463
Abstract
Light-harvesting 2 (LH2) and reaction-centre light-harvesting 1 (RC-LH1) complexes purified from the photosynthetic bacterium Rhodobacter (Rba.) sphaeroides were reconstituted into proteoliposomes either separately, or together at three different LH2:RC-LH1 ratios, for excitation energy transfer studies. Atomic force microscopy (AFM) was used to investigate the distribution and association of the complexes within the proteoliposome membranes. Absorption and fluorescence emission spectra were similar for LH2 complexes in detergent and liposomes, indicating that reconstitution retains the structural and optical properties of the LH2 complexes. Analysis of fluorescence emission shows that when LH2 forms an extensive series of contacts with other such complexes, fluorescence is quenched by 52.6 ± 1.4%. In mixed proteoliposomes, specific excitation of carotenoids in LH2 donor complexes resulted in emission of fluorescence from acceptor RC-LH1 complexes engineered to assemble with no carotenoids. Extents of energy transfer were measured by fluorescence lifetime microscopy; the 0.72 ± 0.08 ns lifetime in LH2-only membranes decreases to 0.43 ± 0.04 ns with a ratio of 2:1 LH2 to RC-LH1, and to 0.35 ± 0.05 ns for a 1:1 ratio, corresponding to energy transfer efficiencies of 40 ± 14% and 51 ± 18%, respectively. No further improvement is seen with a 0.5:1 LH2 to RC-LH1 ratio. Thus, LH2 and RC-LH1 complexes perform their light harvesting and energy transfer roles when reconstituted into proteoliposomes, providing a way to integrate native, non-native, engineered and de novo designed light-harvesting complexes into functional photosynthetic systems.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2024 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 (http://creativecommons.org/licenses/by/4.0/). |
Keywords: | LH2; Light harvesting; RC-LH1; Rhodobacter sphaeroides; photosynthesis; Rhodobacter sphaeroides; Cytoplasm; Photosynthesis; Energy Transfer; Bacterial Proteins; Proteolipids |
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 BIOTECHNOLOGY AND BIOLOGICAL SCIENCES RESEARCH COUNCIL BB/M000265/1 US DEPARTMENT OF ENERGY DE-SC0001035 EUROPEAN COMMISSION - HORIZON 2020 854126 |
Depositing User: | Symplectic Sheffield |
Date Deposited: | 27 Feb 2024 11:39 |
Last Modified: | 27 Feb 2024 11:39 |
Status: | Published |
Publisher: | Portland Press Ltd. |
Refereed: | Yes |
Identification Number: | 10.1042/bsr20231302 |
Related URLs: | |
Sustainable Development Goals: | |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:209635 |