Sohail, S.H. orcid.org/0000-0003-2640-1745, Sohoni, S., Ting, P.-C. et al. (7 more authors) (2025) Functional connectivity of red chlorophylls in cyanobacterial photosystem I revealed by fluence-dependent transient absorption. The Journal of Physical Chemistry B. ISSN 1520-6106
Abstract
External stressors modulate the oligomerization state of photosystem I (PSI) in cyanobacteria. The number of red chlorophylls (Chls), pigments lower in energy than the P700 reaction center, depends on the oligomerization state of PSI. Here, we use ultrafast transient absorption spectroscopy to interrogate the effective connectivity of the red Chls in excitonic energy pathways in trimeric PSI in native thylakoid membranes of the model cyanobacterium Synechocystis sp. PCC 6803, including emergent dynamics, as red Chls increase in number and proximity. Fluence-dependent dynamics indicate singlet-singlet annihilation within energetically connected red Chl sites in the PSI antenna but not within bulk Chl sites on the picosecond time scale. These data support picosecond energy transfer between energetically connected red Chl sites as the physical basis of singlet-singlet annihilation. The time scale of this energy transfer is faster than predicted by Förster resonance energy transfer calculations, raising questions about the physical mechanism of the process. Our results indicate distinct strategies to steer excitations through the PSI antenna; the red Chls present a shallow reservoir that direct excitations away from P700, extending the time to trapping by the reaction center.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2025 The Authors. Published by American Chemical Society. This publication is licensed under CC-BY 4.0. (https://creativecommons.org/licenses/by/4.0/) |
Keywords: | Dyes and pigments; Energy; Energy transfer; Monomers; Quantum mechanics |
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 ROYAL SOCIETY URF\R1\191548 |
Depositing User: | Symplectic Sheffield |
Date Deposited: | 21 Mar 2025 15:11 |
Last Modified: | 21 Mar 2025 15:11 |
Status: | Published online |
Publisher: | American Chemical Society (ACS) |
Refereed: | Yes |
Identification Number: | 10.1021/acs.jpcb.5c00198 |
Related URLs: | |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:224687 |