Cyclic electron transport around photosystem I (PSI) is essential for the protection of the photosynthetic apparatus in plants under diverse light conditions. This process is primarily mediated by Proton Gradient Regulation 5 protein/Proton Gradient Regulation 5-like photosynthetic phenotype 1 protein (PGR5/PGRL1) and NADH dehydrogenase-like complex (NDH). In angiosperms, NDH interacts with two PSI complexes through distinct monomeric antennae, LHCA5 and LHCA6, which is crucial for its higher stability under variable light conditions. This interaction represents an advanced evolutionary stage and offers limited insight into the origin of the PSI-NDH supercomplex in evolutionarily older organisms. In contrast, the moss Physcomitrium patens (Pp), which retains the lhca5 gene but lacks the lhca6, offers a glimpse into an earlier evolutionary stage of the PSI-NDH supercomplex. Here we present structural evidence of the Pp PSI-NDH supercomplex formation by single particle electron microscopy, demonstrating the unique ability of Pp to bind a single PSI in two different configurations. One configuration closely resembles the angiosperm model, whereas the other exhibits a novel PSI orientation, rotated clockwise. This structural flexibility in Pp is presumably enabled by the variable incorporation of LHCA5 within PSI and is indicative of an early evolutionary adaptation that allowed for greater diversity at the PSI-NDH interface. Our findings suggest that this variability was reduced as the structural complexity of the NDH complex increased in vascular plants, primarily angiosperms. This study not only clarifies the evolutionary development of PSI-NDH supercomplexes but also highlights the dynamic nature of the adaptive mechanisms of plant photosynthesis.

• Klíčová slova
• LHCA5, PSI‐NDH supercomplex, Physcomitrium patens, cyclic electron transport, single particle analysis, transmission electron microscopy,
• MeSH
• fotosyntéza MeSH
• fotosystém I - proteinový komplex * metabolismus   genetika   MeSH
• mechy * genetika   metabolismus   MeSH
• NADH-dehydrogenasa metabolismus   genetika   MeSH
• rostlinné proteiny * metabolismus   genetika   MeSH
• světlosběrné proteinové komplexy metabolismus   genetika   chemie   MeSH
• transport elektronů MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• fotosystém I - proteinový komplex * MeSH
• NADH-dehydrogenasa MeSH
• rostlinné proteiny * MeSH
• světlosběrné proteinové komplexy MeSH