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 QA - to QB 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.

Department of Protein Science Science for Life Laboratory KTH Royal Institute of Technology Stockholm Sweden

Doctoral School of Biology Faculty of Science and Informatics University of Szeged Szeged Hungary

Institute of Microbiology Centre Algatech Třeboň Czech Republic

Institute of Plant Biology HUN REN Biological Research Center of HAS Szeged Hungary

Molecular Plant Biology Department of Life Technologies University of Turku Turku Finland

University of Helsinki Helsinki Finland

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Antonacci, A. , Lambreva, M.D. , Margonelli, A. , Sobolev, A.P. , Pastorelli, S. , Bertalan, I. et al. (2018) Photosystem‐II D1 protein mutants of PubMed PMC

Beckmann, K. , Messinger, J. , Badger, M.R. , Wydrzynski, T. & Hillier, W. (2009) On‐line mass spectrometry: membrane inlet sampling. Photosynthesis Research, 102, 511–522. PubMed PMC

Bečková, M. , Gardian, Z. , Yu, J. , Konik, P. , Nixon, P.J. & Komenda, J. (2017) Association of Psb28 and Psb27 proteins with PSII‐PSI Supercomplexes upon exposure of PubMed

Boehm, M. , Yu, J. , Reisinger, V. , Beckova, M. , Eichacker, L.A. , Schlodder, E. et al. (2012) Subunit composition of CP43‐less photosystem II complexes of PubMed PMC

Brinkert, K. , De Causmaecker, S. , Krieger‐Liszkay, A. , Fantuzzi, A. & Rutherford, A.W. (2016) Bicarbonate‐induced redox tuning in photosystem II for regulation and protection. Proceedings of the National Academy of Sciences of the United States of America, 113, 12144–12149. PubMed PMC

Burnap, R.L. , Hagemann, M. & Kaplan, A. (2015) Regulation of CO PubMed PMC

Cano, M. , Holland, S.C. , Artier, J. , Burnap, R.L. , Ghirardi, M. , Morgan, J.A. et al. (2018) Glycogen synthesis and metabolite overflow contribute to energy balancing in cyanobacteria. Cell Reports, 23, 667–672. PubMed

Cantrell, M. , Cano, M. , Sebesta, J. , Paddock, T. , Xiong, W. , Chou, K.J. et al. (2023) Manipulation of glycogen and sucrose synthesis increases photosynthetic productivity in cyanobacteria. Frontiers in Microbiology, 14, 1124274. PubMed PMC

Cardona, T. , Sedoud, A. , Cox, N. & Rutherford, A.W. (2012) Charge separation in photosystem II: a comparative and evolutionary overview. Biochimica et Biophysica Acta, Bioenergetics, 1817, 26–43. PubMed

Chu, H.A. , Nguyen, A.P. & Debus, R.J. (1994) Site‐directed photosystem II mutants with perturbed oxygen‐evolving properties. 1. Instability or inefficient assembly of the manganese cluster in vivo. Biochemistry, 33, 6137–6149. PubMed

Cingolani, P. , Platts, A. , Wang, L.L. , Coon, M. , Nguyen, T. , Wang, L. et al. (2012) A program for annotating and predicting the effects of single nucleotide polymorphisms, SnpEff. Fly (Austin), 6, 80–92. PubMed PMC

Conway, J.R. , Lex, A. & Gehlenborg, N. (2017) UpSetR: an R package for the visualization of intersecting sets and their properties. Bioinformatics, 33, 2938–2940. PubMed PMC

De Porcellinis, A.J. , Klähn, S. , Rosgaard, L. , Kirsch, R. , Gutekunst, K. , Georg, J. et al. (2016) The non‐coding RNA Ncr0700/PmgR1 is required for photomixotrophic growth and the regulation of glycogen accumulation in the cyanobacterium PubMed

Deák, Z. , Sass, L. , Kiss, É. & Vass, I. (2014) Characterization of wave phenomena in the relaxation of flash‐induced chlorophyll fluorescence yield in cyanobacteria. Biochimica et Biophysica Acta, 1837, 1522–1532. PubMed

Díaz‐Troya, S. , Roldán, M. , Mallén‐Ponce, M.J. , Ortega‐Martínez, P. & Florencio, F.J. (2020) Lethality caused by ADP‐glucose accumulation is suppressed by salt‐induced carbon flux redirection in cyanobacteria. Journal of Experimental Botany, 71, 2005–2017. PubMed PMC

Ermakova, M. , Huokko, T. , Richaud, P. , Bersanini, L. , Howe, C.J. , Lea‐Smith, D.J. et al. (2016) Distinguishing the roles of thylakoid respiratory terminal oxidases in the cyanobacterium PubMed PMC

Fantuzzi, A. , Allgower, F. , Baker, H. , McGuire, G. , Teh, W.K. , Gamiz‐Hernandez, A.P. et al. (2022) Bicarbonate‐controlled reduction of oxygen by the QA semiquinone in photosystem II in membranes. Proceedings of the National Academy of Sciences of the United States of America, 119, e2116063119. PubMed PMC

Field, C.B. , Behrenfeld, M.J. , Randerson, J.T. & Falkowski, P. (1998) Primary production of the biosphere: Integrating terrestrial and oceanic components. Science, 281, 237–240. PubMed

Forsman, J.A. , Vass, I. & Eaton‐Rye, J.J. (2019) D1:Glu244 and D1:Tyr246 of the bicarbonate‐binding environment of photosystem II moderate high light susceptibility and electron transfer through the quinone‐Fe‐acceptor complex. Biochimica et Biophysica Acta, 1860, 148054. PubMed

Gómez‐García, M.R. , Losada, M. & Serrano, A. (2003) Concurrent transcriptional activation of ppa and ppx genes by phosphate deprivation in the cyanobacterium PubMed

Graan, T. & Ort, D.R. (1986) Detection of oxygen‐evolving photosystem II centers inactive in plastoquinone reduction. Biochimica et Biophysica Acta, Bioenergetics, 852, 320–330.

Gründel, M. , Scheunemann, R. , Lockau, W. & Zilliges, Y. (2012) Impaired glycogen synthesis causes metabolic overflow reactions and affects stress responses in the cyanobacterium PubMed

Gurrieri, L. , Fermani, S. , Zaffagnini, M. , Sparla, F. & Trost, P. (2021) Calvin–Benson cycle regulation is getting complex. Trends in Plant Science, 26, 898–912. PubMed

Haimovich‐Dayan, M. , Kahlon, S. , Hihara, Y. , Hagemann, M. , Ogawa, T. , Ohad, I. et al. (2011) Cross‐talk between photomixotrophic growth and CO(2)‐concentrating mechanism in PubMed

Hihara, Y. , Sonoike, K. & Ikeuchi, M. (1998) A novel gene, pmgA, specifically regulates photosystem stoichiometry in the cyanobacterium PubMed PMC

Huokko, T. , Muth‐Pawlak, D. , Battchikova, N. , Allahverdiyeva, Y. & Aro, E.M. (2017) Role of type 2 NAD(P)H dehydrogenase NdbC in redox regulation of carbon allocation in PubMed PMC

Iglesias, A.A. , Kakefuda, G. & Preiss, J. (1991) Regulatory and structural properties of the cyanobacterial ADPglucose Pyrophosphorylases. Plant Physiology, 97, 1187–1195. PubMed PMC

Johnson, G.N. , Rutherford, A.W. & Krieger, A. (1995) A change in the midpoint potential of the quinone QA in photosystem II associated with photoactivation of oxygen evolution. Biochimica et Biophysica Acta, 1229, 202–207.

Kamada, S. , Nakajima, Y. & Shen, J.R. (2023) Structural insights into the action mechanisms of artificial electron acceptors in photosystem II. The Journal of Biological Chemistry, 299, 104839. PubMed PMC

Kämäräinen, J. , Huokko, T. , Kreula, S. , Jones, P.R. , Aro, E.M. & Kallio, P. (2017) Pyridine nucleotide transhydrogenase PntAB is essential for optimal growth and photosynthetic integrity under low‐light mixotrophic conditions in PubMed

Kaneko, T. , Sato, S. , Kotani, H. , Tanaka, A. , Asamizu, E. , Nakamura, Y. et al. (1996) Sequence analysis of the genome of the unicellular cyanobacterium PubMed

Koskinen, S. , Kurkela, J. , Linhartová, M. & Tyystjärvi, T. (2023) The genome sequence of PubMed PMC

Lee, K. , Doello, S. , Hagemann, M. & Forchhammer, K. (2024) Deciphering the tight metabolite‐level regulation of glucose‐1‐phosphate adenylyltransferase (GlgC) for glycogen synthesis in cyanobacteria. The FEBS Journal, 292, 759–775. PubMed PMC

Lee, S. , Ryu, J.Y. , Soo, Y.K. , Jeon, J.H. , Ji, Y.S. , Cho, H.T. et al. (2007) Transcriptional regulation of the respiratory genes in the cyanobacterium PubMed PMC

Li, H. (2011) A statistical framework for SNP calling, mutation discovery, association mapping and population genetical parameter estimation from sequencing data. Bioinformatics, 27, 2987. PubMed PMC

Li, H. & Durbin, R. (2009) Fast and accurate short read alignment with Burrows–Wheeler transform. Bioinformatics, 25, 1754–1760. PubMed PMC

Livingston, A.K. , Cruz, J.A. , Kohzuma, K. , Dhingra, A. & Kramer, D.M. (2012) An Arabidopsis mutant with high cyclic electron flow around photosystem I (hcef) involving the NADPH dehydrogenase complex. Plant Cell, 22, 221–233. PubMed PMC

Lucius, S. , Theune, M. , Arrivault, S. , Hildebrandt, S. , Mullineaux, C.W. , Gutekunst, K. et al. (2022) CP12 fine‐tunes the Calvin‐Benson cycle and carbohydrate metabolism in cyanobacteria. Frontiers in Plant Science, 13, 1028794. PubMed PMC

Matson, M.M. & Atsumi, S. (2018) Photomixotrophic chemical production in cyanobacteria. Current Opinion in Biotechnology, 50, 65–71. PubMed

Meng, E. , Goddard, T. , Pettersen, E. , Couch, G. , Pearson, Z. , Morris, J. et al. (2023) UCSF ChimeraX: tools for structure building and analysis. Protein Science, 32, e4792. PubMed PMC

Milou Schuurmans, R. , Merijn Schuurmans, J. , Bekker, M. , Kromkamp, J.C. , Matthijs, H.C.P. & Hellingwerf, K.J. (2014) The redox potential of the plastoquinone Pool of the cyanobacterium PubMed PMC

Müh, F. , Glöckner, C. , Hellmich, J. & Zouni, A. (2012) Light‐induced quinone reduction in photosystem II. Biochimica et Biophysica Acta, 1817, 44–65. PubMed

Mullineaux, C.W. (2014) Co‐existence of photosynthetic and respiratory activities in cyanobacterial thylakoid membranes. Biochimica et Biophysica Acta, 1837, 503–511. PubMed

Mulo, P. , Laakso, S. , Mäenpää, P. & Aro, E.M. (1998) Stepwise photoinhibition of photosystem II. Studies with PubMed PMC

Mulo, P. , Tyystjärvi, T. , Tyystjärvi, E. , Govindjee, Mäenpää, P. & Aro, E.M. (1997) Mutagenesis of the D‐E loop of photosystem II reaction centre protein D1. Function and assembly of photosystem II. Plant Molecular Biology, 33, 1059–1071. PubMed

Muñoz‐Marín, M.d.C. , López‐Lozano, A. , Moreno‐Cabezuelo, J.Á. , Díez, J. & García‐Fernández, J.M. (2024) Mixotrophy in cyanobacteria. Current Opinion in Microbiology, 78, 102432. PubMed

Muth‐Pawlak, D. , Kreula, S. , Gollan, P.J. , Huokko, T. , Allahverdiyeva, Y. & Aro, E.M. (2022) Patterning of the autotrophic, mixotrophic, and heterotrophic proteomes of oxygen‐evolving cyanobacterium PubMed PMC

Nagy, V. , Vidal‐Meireles, A. , Podmaniczki, A. , Szentmihályi, K. , Rákhely, G. , Zsigmond, L. et al. (2018) The mechanism of photosystem‐II inactivation during sulphur deprivation‐induced H PubMed

Nakajima, T. , Kajihata, S. , Yoshikawa, K. , Matsuda, F. , Furusawa, C. , Hirasawa, T. et al. (2014) Integrated metabolic flux and omics analysis of PubMed

Nikkanen, L. , Solymosi, D. , Jokel, M. & Allahverdiyeva, Y. (2021) Regulatory electron transport pathways of photosynthesis in cyanobacteria and microalgae: recent advances and biotechnological prospects. Physiologia Plantarum, 173, 514–525. PubMed

Nowaczyk, M.M. , Hebeler, R. , Schlodder, E. , Meyer, H.E. , Warscheid, B. & Rögner, M. (2006) Psb27, a cyanobacterial lipoprotein, is involved in the repair cycle of photosystem II. Plant Cell, 18, 3121–3131. PubMed PMC

Ortega‐Martínez, P. , Nikkanen, L. , Wey, L.T. , Florencio, F.J. , Allahverdiyeva, Y. & Díaz‐Troya, S. (2024) Glycogen synthesis prevents metabolic imbalance and disruption of photosynthetic electron transport from photosystem II during transition to photomixotrophy in PubMed

Ortega‐Martínez, P. , Roldán, M. , Díaz‐Troya, S. & Florencio, F.J. (2023) Stress response requires an efficient connection between glycogen and central carbon metabolism by phosphoglucomutases in cyanobacteria. Journal of Experimental Botany, 74, 1532–1550. PubMed PMC

Price, S. , Kuzhiumparambil, U. , Pernice, M. & Ralph, P.J. (2020) Cyanobacterial polyhydroxybutyrate for sustainable bioplastic production: critical review and perspectives. Journal of Environmental Chemical Engineering, 8, 104007.

Regel, R.E. , Ivleva, N.B. , Zer, H. , Meurer, J. , Shestakov, S.V. , Herrmann, R.G. et al. (2001) Deregulation of electron flow within photosystem II in the absence of the PsbJ protein. Journal of Biological Chemistry, 276, 41473–41478. PubMed

Roach, T. , Seloud, A. & Krieger‐Liszkay, A. (2013) Acetate in mixotrophic growth medium affects photosystem II in PubMed

Sakuragi, Y. , Maeda, H. , DellaPenna, D. & Bryant, D.A. (2006) α‐Tocopherol plays a role in photosynthesis and macronutrient homeostasis of the cyanobacterium PubMed PMC

Satoh, K. , Oh‐hashi, M. , Kashino, Y. & Koike, H. (1995) Satoh_1995. Plant and Cell Physiology, 36, 597–605.

Schulze, D. , Kohlstedt, M. , Becker, J. , Cahoreau, E. , Peyriga, L. , Makowka, A. et al. (2022) GC/MS‐based 13C metabolic flux analysis resolves the parallel and cyclic photomixotrophic metabolism of PubMed PMC

Sebesta, J. , Cantrell, M. , Schaedig, E. , Hou, H.J.M. , Pastore, C. , Chou, K.J. et al. (2024) Polyphosphate kinase deletion increases laboratory productivity in cyanobacteria. Frontiers in Plant Science, 15, 1342496. PubMed PMC

Shevela, D. , Eaton‐Rye, J.J. , Shen, J.R. & Govindjee. (2012) Photosystem II and the unique role of bicarbonate: a historical perspective. Biochimica et Biophysica Acta, Bioenergetics, 1817, 1134–1151. PubMed

Solymosi, D. , Nikkanen, L. , Muth‐Pawlak, D. , Fitzpatrick, D. , Vasudevan, R. , Howe, C.J. et al. (2020) Cytochrome c M decreases photosynthesis under Photomixotrophy in PubMed PMC

Suchard, M.A. , Lemey, P. , Baele, G. , Ayres, D.L. , Drummond, A.J. & Rambaut, A. (2018) Bayesian phylogenetic and phylodynamic data integration using BEAST 1.10. Virus Evolution, 4, vey016. PubMed PMC

Sun, Z. , Zhao, X. , Li, G. , Yang, J. , Chen, Y. , Xia, M. et al. (2023) Metabolic flexibility during a trophic transition reveals the phenotypic plasticity of greater duckweed ( PubMed

Takahashi, H. , Uchimiya, H. & Hihara, Y. (2008) Difference in metabolite levels between photoautotrophic and photomixotrophic cultures of PubMed PMC

Vass, I. , Kirilovsky, D. & Etienne, A.L. (1999) UV‐B radiation‐induced donor‐ and acceptor‐side modifications of photosystem II in the cyanobacterium PubMed

Volgusheva, A. , Kruse, O. , Styring, S. & Mamedov, F. (2016) Changes in the photosystem II complex associated with hydrogen formation in sulfur deprived

Volgusheva, A. , Styring, S. & Mamedov, F. (2013) Increased photosystem II stability promotes H PubMed PMC

Waterhouse, A.M. , Procter, J.B. , Martin, D.M.A. , Clamp, M. & Barton, G.J. (2009) Jalview version 2‐a multiple sequence alignment editor and analysis workbench. Bioinformatics, 25, 1189–1191. PubMed PMC

Watzer, B. & Forchhammer, K. (2018) Cyanophycin synthesis optimizes nitrogen utilization in the unicellular cyanobacterium PubMed PMC

Wedel, N. , Soll, J. & Paap, B.K. (1997) CP12 provides a new mode of light regulation of Calvin cycle activity in higher plants. Proceedings of the National Academy of Sciences of the United States of America, 94, 10479–10484. PubMed PMC

Wilken, S. , Schuurmans, J.M. & Matthijs, H.C.P. (2014) Do mixotrophs grow as photoheterotrophs? Photophysiological acclimation of the chrysophyte Ochromonas danica after feeding. New Phytologist, 204, 882–889. PubMed

Williams, J.G.K. (1988) Construction of specific mutations in photosystem II photosynthetic reaction center by genetic engineering methods in Synechocystis 6803. Methods in Enzymology, 167, 766–778.

Xiao, Y. , Huang, G. , You, X. , Zhu, Q. , Wang, W. , Kuang, T. et al. (2021) Structural insights into cyanobacterial photosystem II intermediates associated with Psb28 and Tsl0063. Nature Plants, 7, 1132–1142. PubMed

Yoshikawa, K. , Hirasawa, T. , Ogawa, K. , Hidaka, Y. , Nakajima, T. , Furusawa, C. et al. (2013) Integrated transcriptomic and metabolomic analysis of the central metabolism of PubMed

You, L. , Berla, B. , He, L. , Pakrasi, H.B. & Tang, Y.J. (2014) 13C‐MFA delineates the photomixotrophic metabolism of PubMed

Zabret, J. , Bohn, S. , Schuller, S.K. , Arnolds, O. , Möller, M. , Meier‐Credo, J. et al. (2021) Structural insights into photosystem II assembly. Nature Plants, 7, 524–538. PubMed PMC

Zavřel, T. , Očenášová, P. & Červený, J. (2017) Phenotypic characterization of PubMed PMC

Zhang, P. , Allahverdiyeva, Y. , Eisenhut, M. & Aro, E.M. (2009) Flavodiiron proteins in oxygenic photosynthetic organisms: photoprotection of photosystem II by Flv2 and Flv4 in PubMed PMC

Zhang, P. , Battchikova, N. , Jansen, T. , Appel, J. , Ogawa, T. & Aro, E.M. (2004) Expression and functional roles of the two distinct NDH‐1 complexes and the carbon acquisition complex NdhD3/NdhF3/CupA/Sll1735 in PubMed PMC

Zilliges, Y. & Dau, H. (2016) Unexpected capacity for organic carbon assimilation by Thermosynechococcus elongatus, a crucial photosynthetic model organism. FEBS Letters, 590, 962–970. PubMed