Synthesis of C8-Vinyl Chlorophylls d and f Impairs Far-Red Light Photoacclimation and Growth Under Far-Red Light

Chaudhary, Afeefa K, Fuchs, Lorenz K ORCID: 0000-0002-3092-4234, Pawlak, Krzysztof, Dykes, Gregory F ORCID: 0000-0002-0626-9487, Goodacre, Royston ORCID: 0000-0002-6286-8775, Nurnberg, Dennis J and Canniffe, Daniel P ORCID: 0000-0002-5022-0437 (2025) Synthesis of C8-Vinyl Chlorophylls d and f Impairs Far-Red Light Photoacclimation and Growth Under Far-Red Light PHYSIOLOGIA PLANTARUM, 177 (6). e70647-. ISSN 0031-9317, 1399-3054

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Abstract

The inducible biosynthesis of chlorophylls d and f enables a subset of specialised cyanobacteria to perform oxygenic photosynthesis under far-red light—in the absence of visible wavelengths—via a process termed far-red light photoacclimation. These pigments, like the more common chlorophylls a and b, typically carry an ethyl substituent at the C8 position of the macrocycle, formed by reduction of a vinyl group by an 8-vinyl reductase enzyme. Here, we disrupted the gene encoding BciB, an 8-vinyl reductase found in the majority of cyanobacteria, in Chroococcidiopsis thermalis PCC 7203, a model organism for studying far-red light photoacclimation. Disruption of bciB results in the synthesis of 8-vinyl chlorophyll a when cells are grown in white light; upon switching to far-red light, 8-vinyl forms of chlorophylls d and f, which have not been detected in nature, are synthesised in this strain. The bciB mutant exhibits sensitivity to high irradiance under both light regimes. Pigment analysis and whole-cell absorption and fluorescence spectroscopy reveal decreased synthesis of far-red absorbing chlorophylls, reduced photosystem assembly and an impaired acclimation to far-red light, and transmission electron microscopy demonstrates altered thylakoid membrane morphology in the mutant when compared to the wild type. These results demonstrate the importance of 8-vinyl group reduction for acclimation to far-red light.

Item Type:	Article
Uncontrolled Keywords:	chlorophyll, far-red light, photosynthesis
Divisions:	Faculty of Health & Life Sciences Faculty of Science & Engineering Faculty of Science & Engineering > Faculty of Science & Engineering Faculty of Science & Engineering > Materials Innovation Factory Faculty of Health & Life Sciences > Inst. Systems, Molec & Integrative Biology Faculty of Health & Life Sciences > Inst. Systems, Molec & Integrative Biology > Inst. Systems, Molec & Integrative Biology (T&R Staff) Faculty of Health & Life Sciences > Tech, Infrastructure & Env Directorate Faculty of Health & Life Sciences > Tech, Infrastructure & Env Directorate > Liverpool Shared Research Facilities Faculty of Health & Life Sciences > Inst. Systems, Molec & Integrative Biology > Biochemistry, Cell and Systems Biology
Depositing User:	Symplectic Admin
Date Deposited:	03 Dec 2025 13:08
Last Modified:	23 May 2026 10:44
DOI:	10.1111/ppl.70647
Open Access URL:	https://doi.org/10.1111/ppl.70647
Related Websites:	Author Publisher
URI:	https://livrepository.liverpool.ac.uk/id/eprint/3195816
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