7S3D

Structure of photosystem I with bound ferredoxin from Synechococcus sp. PCC 7335 acclimated to far-red light

Summary for 7S3D

• Entry DOI: 10.2210/pdb7s3d/pdb
• EMDB information: 24821
• Descriptor: Photosystem I P700 chlorophyll a apoprotein A1, PSI subunit V, PsaM, ... (25 entities in total)
• Functional Keywords: photosystem i, far-red light photoacclimation, chlorophyll f, ferredoxin, psaf, psaj, photosynthesis
• Biological source: Synechococcus sp. PCC 7335; More
• Total number of polymer chains: 36
• Total formula weight: 1147334.57

Authors

Gisriel, C.J.,Flesher, D.A.,Shen, G.,Wang, J.,Ho, M.,Brudvig, G.W.,Bryant, D.A. (deposition date: 2021-09-05, release date: 2021-11-24, Last modification date: 2024-06-05)

Primary citation

Gisriel, C.J.,Flesher, D.A.,Shen, G.,Wang, J.,Ho, M.Y.,Brudvig, G.W.,Bryant, D.A.
Structure of a photosystem I-ferredoxin complex from a marine cyanobacterium provides insights into far-red light photoacclimation.
J.Biol.Chem., 298:101408-101408, 2021

PubMed Abstract: Far-red light photoacclimation exhibited by some cyanobacteria allows these organisms to use the far-red region of the solar spectrum (700-800 nm) for photosynthesis. Part of this process includes the replacement of six photosystem I (PSI) subunits with isoforms that confer the binding of chlorophyll (Chl) f molecules that absorb far-red light (FRL). However, the exact sites at which Chl f molecules are bound are still challenging to determine. To aid in the identification of Chl f-binding sites, we solved the cryo-EM structure of PSI from far-red light-acclimated cells of the cyanobacterium Synechococcus sp. PCC 7335. We identified six sites that bind Chl f with high specificity and three additional sites that are likely to bind Chl f at lower specificity. All of these binding sites are in the core-antenna regions of PSI, and Chl f was not observed among the electron transfer cofactors. This structural analysis also reveals both conserved and nonconserved Chl f-binding sites, the latter of which exemplify the diversity in FRL-PSI among species. We found that the FRL-PSI structure also contains a bound soluble ferredoxin, PetF1, at low occupancy, which suggests that ferredoxin binds less transiently than expected according to the canonical view of ferredoxin-binding to facilitate electron transfer. We suggest that this may result from structural changes in FRL-PSI that occur specifically during FRL photoacclimation.

PubMed: 34793839
DOI: 10.1016/j.jbc.2021.101408

Experimental method

ELECTRON MICROSCOPY (2.91 Å)