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Dewa T, Kimoto K, Kasagi G, Harada H, Sumino A, Kondo M. Functional Coupling of Biohybrid Photosynthetic Antennae and Reaction Center Complexes: Quantitative Comparison with Native Antennae. J Phys Chem B 2023; 127:10315-10325. [PMID: 38015096 DOI: 10.1021/acs.jpcb.3c04922] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2023]
Abstract
Light-harvesting (LH) complexes in photosynthetic organisms absorb photons within limited wavelength ranges over a broad solar spectrum. Extension of the LH wavelength has been realized by attaching artificial fluorophores to LH complexes (biohybrid LH complexes) for complementing the limited-wavelength regions. However, how efficiently such fluorophores in biohybrid LH complexes function to drive the photocatalytic reaction center (RC) has not been quantitatively evaluated, specifically in comparison with native LH antenna complexes. In this study, we prepared various biohybrid LH1-RC complexes (from Rhodopseudomonas palustris), to quantitatively evaluate the LH activity of the attached external chromophores through a photocurrent generation reaction by LH1-RC on an electrode. For a direct comparison of the LH activity among the LH chromophores that were examined, we introduced the k1 term, which represents the extent of the functional coupling of LH and the photochemical reactions in the RC. We determined that the hydrophobic fluorophore ATTO647N attached to LH1 possesses the highest LH activity among the examined hydrophilic fluorophores such as Alexa647, and its activity is comparable to that of native LH1(-RC). The LH activity of LH2 (from Rhodoblastus acidophilus strain 10050) and its biohybrid LH2s were examined for the comprehensive assessment of their LH activity.
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Affiliation(s)
- Takehisa Dewa
- Department of Life Science and Applied Chemistry, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya, Aichi 466-8555, Japan
| | - Komei Kimoto
- Department of Life Science and Applied Chemistry, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya, Aichi 466-8555, Japan
| | - Genki Kasagi
- Department of Life Science and Applied Chemistry, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya, Aichi 466-8555, Japan
| | - Hiromi Harada
- Department of Life Science and Applied Chemistry, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya, Aichi 466-8555, Japan
| | - Ayumi Sumino
- Department of Life Science and Applied Chemistry, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya, Aichi 466-8555, Japan
| | - Masaharu Kondo
- Department of Life Science and Applied Chemistry, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya, Aichi 466-8555, Japan
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Hancock AM, Swainsbury DJK, Meredith SA, Morigaki K, Hunter CN, Adams PG. Enhancing the spectral range of plant and bacterial light-harvesting pigment-protein complexes with various synthetic chromophores incorporated into lipid vesicles. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY. B, BIOLOGY 2022; 237:112585. [PMID: 36334507 DOI: 10.1016/j.jphotobiol.2022.112585] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Revised: 09/16/2022] [Accepted: 10/11/2022] [Indexed: 11/06/2022]
Abstract
The Light-Harvesting (LH) pigment-protein complexes found in photosynthetic organisms have the role of absorbing solar energy with high efficiency and transferring it to reaction centre complexes. LH complexes contain a suite of pigments that each absorb light at specific wavelengths, however, the natural combinations of pigments within any one protein complex do not cover the full range of solar radiation. Here, we provide an in-depth comparison of the relative effectiveness of five different organic "dye" molecules (Texas Red, ATTO, Cy7, DiI, DiR) for enhancing the absorption range of two different LH membrane protein complexes (the major LHCII from plants and LH2 from purple phototrophic bacteria). Proteoliposomes were self-assembled from defined mixtures of lipids, proteins and dye molecules and their optical properties were quantified by absorption and fluorescence spectroscopy. Both lipid-linked dyes and alternative lipophilic dyes were found to be effective excitation energy donors to LH protein complexes, without the need for direct chemical or generic modification of the proteins. The Förster theory parameters (e.g., spectral overlap) were compared between each donor-acceptor combination and found to be good predictors of an effective dye-protein combination. At the highest dye-to-protein ratios tested (over 20:1), the effective absorption strength integrated over the full spectral range was increased to ∼180% of its natural level for both LH complexes. Lipophilic dyes could be inserted into pre-formed membranes although their effectiveness was found to depend upon favourable physicochemical interactions. Finally, we demonstrated that these dyes can also be effective at increasing the spectral range of surface-supported models of photosynthetic membranes, using fluorescence microscopy. The results of this work provide insight into the utility of self-assembled lipid membranes and the great flexibility of LH complexes for interacting with different dyes.
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Affiliation(s)
- Ashley M Hancock
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK; Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK
| | - David J K Swainsbury
- School of Biosciences, University of Sheffield, Sheffield S10 2TN, UK; School of Biological Sciences, University of East Anglia, Norwich NR4 7TJ, UK
| | - Sophie A Meredith
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK; Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK
| | - Kenichi Morigaki
- Graduate School of Agricultural Science and Biosignal Research Center, Kobe University, Rokkodaicho 1-1, Nada, Kobe 657-8501, Japan
| | - C Neil Hunter
- School of Biosciences, University of Sheffield, Sheffield S10 2TN, UK
| | - Peter G Adams
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK; Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK.
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