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ToolsHuang, Xia, Vasilev, Cvetelin, Swainsbury, David J. K. and Hunter, C. Neil (2024) Excitation energy transfer in proteoliposomes reconstituted with LH2 and RC-LH1 complexes from Rhodobacter sphaeroides. Bioscience Reports, 44 (2). ISSN 0144-8463
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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.
| Item Type: | Article |
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| Additional Information: | Funding Information: This work was supported as part of the Photosynthetic Antenna Research Center (PARC), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award Number DE-SC0001035. PARC supported the AFM, spectral imaging and fluorescence lifetime studies, provided a doctoral studentship for X.H., supported C.V. and provided partial support for C.N.H., C.N.H. and D.J.K.S. acknowledge financial support from the Biotechnology and Biological Sciences Research Council (BBSRC UK), award number BB/M000265/1, and European Research Council Synergy Award 854126. D.J.K.S. also acknowledges new-investigator start-up finding from the University of East Anglia. X.H. also acknowledges support from the Natural Science Foundation of Shandong [grant number ZR2021MC192] and XJTLU Research Development Funding [grant number RDF-21-02-003]. |
| Faculty \ School: | Faculty of Science > School of Biological Sciences |
| UEA Research Groups: | Faculty of Science > Research Groups > Molecular Microbiology |
| Related URLs: | |
| Depositing User: | LivePure Connector |
| Date Deposited: | 12 Sep 2024 11:30 |
| Last Modified: | 25 Sep 2024 18:09 |
| URI: | https://ueaeprints.uea.ac.uk/id/eprint/96733 |
| DOI: | 10.1042/BSR20231302 |
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