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Allophycocyanin A is a carbon dioxide receptor in the cyanobacterial phycobilisome

Guillen-Garcia, A.; Gibson, S.; Jordan, C.; Ramaswamy, V.; Linthwaite, V.; Bromley, E.H.C.; Brown, A.P.; Hodgson, D.; Blower, T.; Verlet, J.; Degiacomi, M.; Palsson, L-O.; Cann, M.J.

Allophycocyanin A is a carbon dioxide receptor in the cyanobacterial phycobilisome Thumbnail


C. Jordan

V. Ramaswamy

V. Linthwaite


Light harvesting is fundamental for production of ATP and reducing equivalents for CO2 fixation during photosynthesis. However, electronic energy transfer (EET) through a photosystem can harm the photosynthetic apparatus when not balanced with CO2. Here, we show that CO2 binding to the light-harvesting complex modulates EET in photosynthetic cyanobacteria. More specifically, CO2 binding to the allophycocyanin alpha subunit of the light-harvesting complex regulates EET and its fluorescence quantum yield in the cyanobacterium Synechocystis sp. PCC 6803. CO2 binding decreases the inter-chromophore distance in the allophycocyanin trimer. The result is enhanced EET in vitro and in live cells. Our work identifies a direct target for CO2 in the cyanobacterial light-harvesting apparatus and provides insights into photosynthesis regulation.


Guillen-Garcia, A., Gibson, S., Jordan, C., Ramaswamy, V., Linthwaite, V., Bromley, E., …Cann, M. (2022). Allophycocyanin A is a carbon dioxide receptor in the cyanobacterial phycobilisome. Nature Communications, 13, Article 5289.

Journal Article Type Article
Acceptance Date Aug 24, 2022
Online Publication Date Sep 8, 2022
Publication Date 2022
Deposit Date Feb 28, 2022
Publicly Available Date Sep 9, 2022
Journal Nature Communications
Publisher Nature Research
Peer Reviewed Peer Reviewed
Volume 13
Article Number 5289
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