2026/07/10 by Marta Ludwiczak, Marcel Dann, Theo Figueroa-Gonzalez +13 · 1 voice
Biochemistry, Genetics and Molecular Biology · Energy · #Photosynthetic Processes and Mechanisms #Mitochondrial Function and Pathology #Metalloenzymes and iron-sulfur proteins
paper · pdf · doi:10.1038/s41467-026-74903-2
openalex publication_date 2026/07/10 · openalex created_date 2026/07/11 · openalex updated_date 2026/07/27
, 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.