2026-03-09 中国科学院（CAS）
＜関連情報＞
- https://english.cas.cn/newsroom/research-news/202603/t20260306_1151835.shtml
- https://www.science.org/doi/10.1126/sciadv.aea5561
ミドリムシの光化学系I超複合体におけるジアジノキサンチン-クロロフィルa/b結合タンパク質の構造基盤 Structural basis of diadinoxanthin-Chl a/b–binding proteins in the photosystem I supercomplex of Euglena gracilis
Tianyu Bai, Zhiyuan Mao, Dapeng Sun, Yang Tang, […] , and Lirong Tian
Science Advances Published:6 Mar 2026
Abstract
Euglena gracilis is a phototrophic flagellate that has evolved through secondary endosymbiotic events and belongs to green-lineage organisms. We report a unique structure of photosystem I-light harvesting complex I (PSI-LHCI) supercomplex from E. gracilis at a 2.23-angstrom resolution by cryo–electron microscopy. The supercomplex is composed of 8 core subunits and 16 LHCIs and exhibits distinctive structural features compared to its counterparts in green algae and plants. The LHCI subunits encircle the core complex, forming a two-layered arrangement that comprises six pairs of tightly packed heterodimers. Specifically, the 16 LHCIs consist of 4 diadinoxanthin-chlorophyll (Chl) a/b–binding antennae (Lhcbm) and 12 diadinoxanthin-Chl a–binding antennae (Lhca), and they exhibit characteristic pigment compositions combining features of green- and red-lineage organisms. These findings provide a robust structural foundation for elucidating the mechanisms of light harvesting and energy transfer as well as insights into the evolutionary changes of green-lineage PSI-LHCI.
