Huokko, Tuomas and Sporre, Emil and Koch, Bradley and Patil, Priyanka Pradeep and Wey, Laura and Nikkanen, Lauri and Napaumpaiporn, Pornpan and Virtanen, Olli and Hubácek, Michal and Kulik, Natalia and Komenda, Josef and Hudson, Elton and Vass, Imre and Allahverdiyeva, Yagut (2026) Differences in photosystem II activity and carbon allocation during photomixotrophic growth in distinct wild‐type strains of Synechocystis sp. PCC 6803. PLANT JOURNAL, 125 (2). No. e70683. ISSN 0960-7412
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Abstract
The regulation of photosynthetic electron transport during photomixotrophic growth in cyanobacteria remains incompletely understood. In this study, we characterized four wild‐type strains (WT 1–4) of Synechocystis sp. PCC 6803 and observed distinct strain‐specific differences in photosystem II (PSII) function under photomixotrophic conditions. Specifically, WT 1 and WT 2 exhibited near‐complete inhibition of electron transfer from Q A − to Q B following approximately 3 days of glucose supplementation, possibly mediated by binding of the small PSII‐associated protein, Psb28‐2, and resulting in a metabolic shift toward photoheterotrophy. Observed electron transport blockage was associated with changes in the abundances of various photosynthetic proteins. However, the structural integrity of both Photosystems appeared to be largely preserved. Such stabilization may be driven by a transient downregulation of linear electron transport to prevent overreduction of the electron transport chain under photomixotrophy. In contrast, WT 3 and WT 4 maintained photomixotrophic growth throughout the experiment but exhibited slower growth rates than WT 1 and WT 2. Although glucose uptake was slower in WT 1 and WT 2, both strains accumulated more glycogen than WT 3 and WT 4, suggesting divergent regulation of carbon allocation and storage metabolism. Together, these findings highlight the capacity of cyanobacterial strains to deploy distinct metabolic strategies to optimize photosynthetic function, carbon assimilation, and energy storage under photomixotrophic conditions.
| Item Type: | Article |
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| Additional Information: | Funding Agency and Grant Number: Novo Nordisk [NNF20OC0064371, NNF22OCOO79717]; Jane ja Aatos Erkon Sti; Turku Collegium for Science, Medicine and Technology Funding text: We thank Dr. Taina Tyystjarvi for her valuable assistance and discussions, and Dr. Juha Kurkela for helping with submitting sequencing results to the NCBI database. We thank Dr. Pablo Ortega-Martinez for providing the method to determine intracellular glycogen concentrations. Also, Sandeesha Kodru is acknowledged for the initial testing of electron transport in WTs 3 and 4 under PA and PM conditions. All physiological experiments were conducted using the PHOTOSYN infrastructure at the University of Turku. This work was supported by the NovoNordisk Foundation "PhotoCat" project (NNF20OC0064371 to YA), the Turku Collegium for Science, Medicine and Technology (to TH), and by the Jane and Aatos Erkko Foundation 'PhotoFactory' project (to YA). LW salary was covered by Novo Nordisk Foundation Photo-e-microbes project (NNF22OCOO79717 to LTW). Open access publishing facilitated by Turun yliopisto, as part of the Wiley - FinELib agreement. |
| Uncontrolled Keywords: | hotomixotrophy, PSII, photosynthetic electron transport, carbon allocation, Synechocystis sp. PCC 6803 |
| Subjects: | Q Science / természettudomány > QH Natural history / természetrajz > QH301 Biology / biológia |
| SWORD Depositor: | MTMT SWORD |
| Depositing User: | MTMT SWORD |
| Date Deposited: | 05 Oct 2026 14:32 |
| Last Modified: | 05 Oct 2026 14:32 |
| URI: | https://real.mtak.hu/id/eprint/248332 |
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