2026-07-10 ミュンヘン大学（LMU）
＜関連情報＞
- https://www.lmu.de/en/newsroom/news-overview/news/discovery-oxygenic-photosynthesis-is-possible-with-only-one-photosystem-35e80a22.html
- https://www.nature.com/articles/s41467-026-74903-2
シアノバクテリアにおける光化学系I非依存性酸素発生型光合成 Photosystem I-independent oxygenic photosynthesis in cyanobacteria
Marta Ludwiczak,Marcel Dann,Theo Figueroa-Gonzalez,Eslam M. Abdel-Salam,Weiyang Chen,Serena Schwenkert,Martin Lehmann,Milena Zhivkovikj,Maysoon Noureddine,Markéta Linhartová,Sadanand Gupta,Josef Komenda,Arthur Guljamov,Stefania Viola,Feng Liu & Dario Leister
Nature Communications Published:10 July 2026
DOI:https://doi.org/10.1038/s41467-026-74903-2
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.
