Structure of the red-shifted Fittonia albivenis photosystem I

• Published in: Nature communications 2024-07, Vol.15 (1), p.6325-14, Article 6325
• Main Authors: Li, Xiuxiu, Huang, Guoqiang, Zhu, Lixia, Hao, Chenyang, Sui, Sen-Fang, Qin, Xiaochun
• Format: Article
• Language: English
• Subjects: 101/28; 631/449/1734/2075; 631/449/1734/2077; 631/45/535/1258; 82/83; Amino Acid Sequence; Amino acids; Antennas; Binding sites; Chlorophyll; Chlorophyll - chemistry; Chlorophyll - metabolism; Chloroplasts; Cryoelectron Microscopy; Electron microscopy; Emission; Emissions; Energy; Energy harvesting; Humanities and Social Sciences; Life sciences; Light; Light-Harvesting Protein Complexes - chemistry; Light-Harvesting Protein Complexes - metabolism; Microscopy; Models, Molecular; multidisciplinary; Ornamental plants; Photochemistry; Photosynthesis; Photosystem I; Photosystem I Protein Complex - chemistry; Photosystem I Protein Complex - metabolism; Photosystem I Protein Complex - ultrastructure; Pigments; Plant Proteins - chemistry; Plant Proteins - metabolism; Prokaryotes; Proteins; Science; Science (multidisciplinary); Structural members
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-024-50655-9

Photosystem I (PSI) from Fittonia albivenis , an Acanthaceae ornamental plant, is notable among green plants for its red-shifted emission spectrum. Here, we solved the structure of a PSI–light harvesting complex I (LHCI) supercomplex from F. albivenis at 2.46-Å resolution using cryo-electron microscopy. The supercomplex contains a core complex of 14 subunits and an LHCI belt with four antenna subunits (Lhca1–4) similar to previously reported angiosperm PSI–LHCI structures; however, Lhca3 differs in three regions surrounding a dimer of low-energy chlorophylls (Chls) termed red Chls, which absorb far-red beyond visible light. The unique amino acid sequences within these regions are exclusively shared by plants with strongly red-shifted fluorescence emission, suggesting candidate structural elements for regulating the energy state of red Chls. These results provide a structural basis for unraveling the mechanisms of light harvest and transfer in PSI–LHCI of under canopy plants and for designing Lhc to harness longer-wavelength light in the far-red spectral range. Fittonia albivenis is shade-adapted ornamental plant that can efficiently use far-red light for photosynthesis. Here the authors describe the structure of the red-shifted F. albivenis photosystem I to give insights into how plants can use far-red light to drive photochemistry.