Hitchcock, A. orcid.org/0000-0001-6572-434X, Swainsbury, D.J.K. orcid.org/0000-0002-0754-0363 and Hunter, C.N. orcid.org/0000-0003-2533-9783 (2023) Photosynthesis in the near infrared: the γ subunit of Blastochloris viridis LH1 red-shifts absorption beyond 1000 nm. Biochemical Journal, 480 (6). pp. 455-460. ISSN 0264-6021
Abstract
The reaction centre (RC) in purple phototrophic bacteria is encircled by the primary light-harvesting complex 1 (LH1) antenna, forming the RC–LH1 ‘core’ complex. The Qy absorption maximum of LH1 complexes ranges from ∼875–960 nm in bacteriochlorophyll (BChl) a-utilising organisms, to 1018 nm in the BChl b-containing complex from Blastochloris (Blc.) viridis. The red-shifted absorption of the Blc. viridis LH1 was predicted to be due in part to the presence of the γ subunit unique to Blastochloris spp., which binds to the exterior of the complex and is proposed to increase packing and excitonic coupling of the BChl pigments. The study by Namoon et al. provides experimental evidence for the red-shifting role of the γ subunit and an evolutionary rationale for its incorporation into LH1. The authors show that cells producing RC–LH1 lacking the γ subunit absorb maximally at 972 nm, 46 nm to the blue of the wild-type organism. Wavelengths in the 900–1000 nm region of the solar spectrum transmit poorly through water, thus γ shifts absorption of LH1 to a region where photons have lower energy but are more abundant. Complementation of the mutant with a divergent copy of LH1γ resulted in an intermediate red shift, revealing the possibility of tuning LH1 absorption using engineered variants of this subunit. These findings provide new insights into photosynthesis in the lowest energy phototrophs and how the absorption properties of light-harvesting complexes are modified by the recruitment of additional subunits.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2023 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 (CC BY) (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. |
Keywords: | Light-Harvesting Protein Complexes; Photosynthesis; Hyphomicrobiaceae; Proteobacteria; Bacterial Proteins |
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 EUROPEAN COMMISSION - HORIZON 2020 854126 |
Depositing User: | Symplectic Sheffield |
Date Deposited: | 24 Apr 2023 13:42 |
Last Modified: | 24 Apr 2023 13:42 |
Published Version: | http://dx.doi.org/10.1042/bcj20220585 |
Status: | Published |
Publisher: | Portland Press Ltd. |
Refereed: | Yes |
Identification Number: | 10.1042/bcj20220585 |
Related URLs: | |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:198395 |