9SE6

Structure of Photosystem I from Chlamydomonas reinhardtii at 1.83 A resolution

9SE6 の概要

• エントリーDOI: 10.2210/pdb9se6/pdb
• 関連するPDBエントリー: 9se7
• EMDBエントリー: 54803
• 分子名称: Light-harvesting chlorophyll-a/b protein of photosystem I, type III, Photosystem I reaction center subunit II, chloroplastic, Photosystem I reaction center subunit IV, chloroplastic, ... (32 entities in total)
• 機能のキーワード: photosystem i, chlamydomonas reinhardtii, cryoem, photosynthesis
• 由来する生物種: Chlamydomonas reinhardtii; 詳細
• タンパク質・核酸の鎖数: 19
• 化学式量合計: 697983.49

構造登録者

Mahapatra, G.P.,Schuller, J.M. (登録日: 2025-08-15, 公開日: 2026-04-01, 最終更新日: 2026-04-08)

主引用文献

Ogawa, Y.,Mahapatra, G.P.,Milrad, Y.,Schimpf, M.,Kurisu, G.,Hippler, M.,Schuller, J.M.
Cryo-EM structure of Chlamydomonas reinhardtii Photosystem I complexed with cytochrome c 6 .
Nat Commun, 2026

PubMed Abstract: Photosynthetic electron transfer relies on small soluble carriers that shuttle electrons between the cytochrome b₆f complex and Photosystem I (PSI). While copper-containing plastocyanin (Pc) serves this role in plants, the heme protein cytochrome c₆ (Cyt c₆) is also employed in algae and cyanobacteria. Here, we present a cryo-electron microscopy structure of a Cyt c₆:PSI complex from Chlamydomonas reinhardtii. We observe that the heme group of Cyt c₆ is positioned ~11 Å away from P700, stabilized by extensive contacts involving a N-terminal helix-loop-helix motif of PSAF, characteristic of eukaryotic PSI. Notably, the algal Cyt c₆ also retains an arginine residue (R66) which is crucial for cyanobacterial donor:PSI reactions. Our structure reveals the previously uncharacterized interactions involving this residue; it can form a putative electrostatic contact with PsaB-D623 while also contributing to a tri-planar π(cation)-π interactions with adjacent residues. Our findings provide a structural framework for understanding the mechanism and evolution of donor:PSI interactions.

PubMed: 41896549
DOI: 10.1038/s41467-026-70944-9

実験手法

ELECTRON MICROSCOPY (1.83 Å)