Photosystem I-independent oxygenic photosynthesis in cyanobacteria

Ludwiczak, Marta; Dann, Marcel; Figueroa-Gonzalez, Theo; Abdel-Salam, Eslam M.; Chen, Weiyang; Schwenkert, Serena; Lehmann, Martin; Zhivkovikj, Milena; Noureddine, Maysoon; Linhartová, Markéta; Gupta, Sadanand; Komenda, Josef; Guljamov, Arthur; Viola, Stefania; Liu, Feng; Leister, Dario (2026): Photosystem I-independent oxygenic photosynthesis in cyanobacteria. Nature Communications, 17: 6081. ISSN 2041-1723

Abstract

Oxygenic photosynthesis generates ATP and NADPH via linear electron flow from water to NADP + , a process thought to require photosystem I (PSI) for reductant formation. Here we demonstrate that oxygenic photosynthesis can operate without PSI in the cyanobacterium Synechocystis sp. PCC 6803. Using genetic engineering and adaptive laboratory evolution, we obtained PSI-deficient lineages capable of photoautotrophic growth, inorganic carbon fixation, and light-driven oxygen evolution. PSI-independent photoautotrophy arose from co-mutations in at least two proteins, including the translation elongation factor G (FusA), and required a functional NDH-1 complex. We propose that the light-driven electron transport in the evolved strains is reorganised in two branches: one involving terminal oxidases to generate proton motive force, and a second in which reverse NDH-1 activity exploits this gradient to produce reductant. These findings uncover unexpected plasticity in the thylakoid electron transport network and prompt a reassessment of the canonical requirement for PSI in oxygenic photosynthesis.

• Dokumententyp: Artikel (LMU)
• Organisationseinheit (Fakultäten): 19 Biologie
• DFG-Fachsystematik der Wissenschaftsbereiche: Lebenswissenschaften
• DFG: Gefördert durch die Deutsche Forschungsgemeinschaft (DFG) - 252961272
• DFG: Gefördert durch die Deutsche Forschungsgemeinschaft (DFG) - 390776260
• DFG: Gefördert durch die Deutsche Forschungsgemeinschaft (DFG) - 491502892