Structural highlights
Publication Abstract from PubMedEuglena 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. Structural basis of diadinoxanthin-Chl a/b-binding proteins in the photosystem I supercomplex of Euglena gracilis.,Bai T, Mao Z, Sun D, Tang Y, Lu Z, Ma F, Ma B, Chen J, Wang W, Li Y, Liu S, Yang Y, Wang Y, Tian L Sci Adv. 2026 Mar 6;12(10):eaea5561. doi: 10.1126/sciadv.aea5561. Epub 2026 Mar , 6. PMID:41790873[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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