Structure of the far-red light utilizing photosystem I of Acaryochloris marina

• Published in: Nature communications Vol. 12; no. 1; p. 2333
• Main Authors: Hamaguchi, Tasuku, Kawakami, Keisuke, Shinzawa-Itoh, Kyoko, Inoue-Kashino, Natsuko, Itoh, Shigeru, Ifuku, Kentaro, Yamashita, Eiki, Maeda, Kou, Yonekura, Koji, Kashino, Yasuhiro
• Format: Journal Article
• Language: English
• Published: England Nature Publishing Group 20.04.2021; Nature Publishing Group UK; Nature Portfolio
• Subjects: Acaryochloris marina; Bacterial Proteins - chemistry; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Chlorophyll; Chlorophyll - chemistry; Chlorophyll - metabolism; Cryoelectron Microscopy; Cyanobacteria; Cyanobacteria - chemistry; Cyanobacteria - genetics; Cyanobacteria - metabolism; Dimers; Electron microscopy; Electron Transport; Light; Models, Molecular; Oxygen - metabolism; Phaeophytin; Photochemical reactions; Photochemicals; Photosynthesis; Photosystem I; Photosystem I Protein Complex - chemistry; Photosystem I Protein Complex - genetics; Photosystem I Protein Complex - metabolism; Pigments; Protein Structure, Quaternary; Protein Subunits; Reaction centers; Static Electricity
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-021-22502-8

Acaryochloris marina is one of the cyanobacterial species that can use far-red light to drive photochemical reactions for oxygenic photosynthesis. Here, we report the structure of A. marina photosystem I (PSI) reaction center, determined by cryo-electron microscopy at 2.58 Å resolution. The structure reveals an arrangement of electron carriers and light-harvesting pigments distinct from other type I reaction centers. The paired chlorophyll, or special pair (also referred to as P740 in this case), is a dimer of chlorophyll d and its epimer chlorophyll d'. The primary electron acceptor is pheophytin a, a metal-less chlorin. We show the architecture of this PSI reaction center is composed of 11 subunits and we identify key components that help explain how the low energy yield from far-red light is efficiently utilized for driving oxygenic photosynthesis.