9VFJ

PSI-LHCI of Euglena gracilis strain Z

This is a non-PDB format compatible entry.

Summary for 9VFJ

• Entry DOI: 10.2210/pdb9vfj/pdb
• EMDB information: 65026
• Descriptor: Photosystem I P700 chlorophyll a apoprotein A1, LHCI-2, LHCI-3, ... (29 entities in total)
• Functional Keywords: photosystem i, electron transport, photosynthesis
• Biological source: Euglena gracilis; More
• Total number of polymer chains: 21
• Total formula weight: 1551344.28

Authors

Kato, K.,Nakajima, Y.,Shen, J.R.,Nagao, R. (deposition date: 2025-06-11, release date: 2025-10-08, Last modification date: 2025-11-12)

Primary citation

Kato, K.,Nakajima, Y.,Sakamoto, R.,Kumazawa, M.,Ifuku, K.,Ishikawa, T.,Shen, J.R.,Takabayashi, A.,Nagao, R.
Structural insights into the divergent evolution of a photosystem I supercomplex in Euglena gracilis.
Sci Adv, 11:eaea6241-eaea6241, 2025

PubMed Abstract: Photosystem I (PSI) forms supercomplexes with light-harvesting complexes (LHCs) to perform oxygenic photosynthesis. Here, we report a 2.82-angstrom cryo-electron microscopy structure of the PSI-LHCI supercomplex from , a eukaryotic alga with secondary green alga-derived plastids. The structure reveals a PSI monomer core with eight subunits and 13 asymmetrically arranged LHCI proteins. LHCIs bind diadinoxanthin, which is one of the carotenoids typically associated with red-lineage LHCs and is not present in the canonical LHCI belt found in green-lineage PSI-LHCI structures. Phylogenetic analysis shows that the LHCIs originated from LHCII-related clades rather than from the green-lineage LHCI group and that the nuclear-encoded PSI subunit PsaD likely originated from cyanobacteria via horizontal gene transfer. These observations indicate a mosaic origin of the PSI-LHCI. Our findings uncover a noncanonical light-harvesting architecture and highlight the structural and evolutionary plasticity of photosynthetic systems, illustrating how endosymbiotic acquisition and lineage-specific adaptation shape divergent light-harvesting strategies.

PubMed: 41171917
DOI: 10.1126/sciadv.aea6241

Experimental method

ELECTRON MICROSCOPY (2.83 Å)