Carotenoid to bacteriochlorophyll energy transfer in the RC–LH1–PufX complex from Rhodobacter sphaeroides containing the extended conjugation keto-carotenoid diketospirilloxanthin

Šlouf, Václav, Keşan, Gürkan, Litvín, Radek, Swainsbury, David J.K., Martin, Elizabeth C., Hunter, C. Neil and Polívka, Tomáš (2018) Carotenoid to bacteriochlorophyll energy transfer in the RC–LH1–PufX complex from Rhodobacter sphaeroides containing the extended conjugation keto-carotenoid diketospirilloxanthin. Photosynthesis Research, 135 (1-3). pp. 33-43. ISSN 0166-8595

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Abstract

RC–LH1–PufX complexes from a genetically modified strain of Rhodobacter sphaeroides that accumulates carotenoids with very long conjugation were studied by ultrafast transient absorption spectroscopy. The complexes predominantly bind the carotenoid diketospirilloxanthin, constituting about 75% of the total carotenoids, which has 13 conjugated C=C bonds, and the conjugation is further extended to two terminal keto groups. Excitation of diketospirilloxanthin in the RC–LH1–PufX complex demonstrates fully functional energy transfer from diketospirilloxanthin to BChl a in the LH1 antenna. As for other purple bacterial LH complexes having carotenoids with long conjugation, the main energy transfer route is via the S2–Qx pathway. However, in contrast to LH2 complexes binding diketospirilloxanthin, in RC–LH1–PufX we observe an additional, minor energy transfer pathway associated with the S1 state of diketospirilloxanthin. By comparing the spectral properties of the S1 state of diketospirilloxanthin in solution, in LH2, and in RC–LH1–PufX, we propose that the carotenoid-binding site in RC–LH1–PufX activates the ICT state of diketospirilloxanthin, resulting in the opening of a minor S1/ICT-mediated energy transfer channel.

Item Type: Article
Additional Information: Funding Information: The research in Czech Republic was supported by the grant P501/12/G055 from the Czech Science Foundation. D.J.K.S., E.C.M., and C.N.H. gratefully acknowledge financial support from the Biotechnology and Biological Sciences Research Council (BBSRC UK), award number BB/M000265/1. CNH was also supported by an Advanced Award 338895 from the European Research Council. This work was also 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-SC 0001035. The role of PARC role was to provide partial support for CNH. Publisher Copyright: © 2017, Springer Science+Business Media Dordrecht.
Uncontrolled Keywords: carotenoids,energy transfer,intramolecular charge transfer state,light-harvesting,purple bacteria,ultrafast spectroscopy,biochemistry,plant science,cell biology ,/dk/atira/pure/subjectarea/asjc/1300/1303
Faculty \ School: Faculty of Science > School of Biological Sciences
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Depositing User: LivePure Connector
Date Deposited: 17 Aug 2022 12:31
Last Modified: 01 Oct 2022 07:42
URI: https://ueaeprints.uea.ac.uk/id/eprint/87364
DOI: 10.1007/s11120-017-0397-4

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