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ToolsHitchcock, Andrew, Swainsbury, David J.K. and Hunter, C. Neil (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
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Abstract
This is a commentary on: The role of the γ subunit in the photosystem of the lowest-energy phototrophs (https://doi.org/10.1042/BCJ20220508). 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.
| Item Type: | Article |
|---|---|
| Additional Information: | Funding Information: A.H. is funded by a Royal Society University Research Fellowship (award number URF\R1\191548). D.J.K.S. acknowledges new investigator start-up funding from the University of East Anglia. C.N.H. is supported by Synergy Award 854126 from the European Research Council. Publisher Copyright: © 2023 The Author(s). |
| Uncontrolled Keywords: | bioenergetics,microbiology,photosynthesis,structural biology,molecular biology,biochemistry,cell biology ,/dk/atira/pure/subjectarea/asjc/1300/1312 |
| Faculty \ School: | Faculty of Science > School of Biological Sciences |
| Related URLs: | |
| Depositing User: | LivePure Connector |
| Date Deposited: | 08 Aug 2024 14:30 |
| Last Modified: | 01 Nov 2024 12:30 |
| URI: | https://ueaeprints.uea.ac.uk/id/eprint/96189 |
| DOI: | 10.1042/BCJ20220585 |
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