9E0J

Structure and evolution of Photosystem I in the early-branching cyanobacterium Anthocerotibacter panamensis

Summary for 9E0J

• Entry DOI: 10.2210/pdb9e0j/pdb
• EMDB information: 47359
• Descriptor: Photosystem I P700 chlorophyll a apoprotein A1, Photosystem I reaction center subunit XI, CHLOROPHYLL A ISOMER, ... (20 entities in total)
• Functional Keywords: photosystem i, evolution, thylakoid-free, chlorophyll, cyanobacteria, photosynthesis
• Biological source: Anthocerotibacter panamensis; More
• Total number of polymer chains: 30
• Total formula weight: 1039560.22

Authors

Gisriel, C.J.,Ho, M. (deposition date: 2024-10-18, release date: 2025-05-07, Last modification date: 2025-05-28)

Primary citation

Jiang, H.W.,Gisriel, C.J.,Cardona, T.,Flesher, D.A.,Brudvig, G.W.,Ho, M.Y.
Structure and evolution of photosystem I in the early-branching cyanobacterium Anthocerotibacter panamensis.
Proc.Natl.Acad.Sci.USA, 122:e2427090122-e2427090122, 2025

PubMed Abstract: Thylakoid-free cyanobacteria are thought to preserve ancestral traits of early-evolving organisms capable of oxygenic photosynthesis. However, and until recently, photosynthesis studies in thylakoid-free cyanobacteria were only possible in the model strain , limiting our understanding of photosynthesis evolution. Here, we report the isolation, biochemical characterization, cryo-EM structure, and phylogenetic analysis of photosystem I (PSI) from a recently discovered thylakoid-free cyanobacterium, , a distant relative of the genus . We find that PSI exhibits a distinct carotenoid composition and has one conserved low-energy chlorophyll site, which was lost in . Furthermore, PSI in thylakoid-free cyanobacteria has changed at the sequence level to a degree comparable to that of other strains, yet its subunit composition and oligomeric form might be identical to that of the most recent common ancestor of cyanobacteria. This study therefore provides a glimpse into the ancient evolution of photosynthesis.

PubMed: 40366692
DOI: 10.1073/pnas.2427090122

Experimental method

ELECTRON MICROSCOPY (2.4 Å)