7WZN

PSI-LHCI from Chlamydomonas reinhardtii with bound ferredoxin

Summary for 7WZN

• Entry DOI: 10.2210/pdb7wzn/pdb
• EMDB information: 32907
• Descriptor: Photosystem I P700 chlorophyll a apoprotein A1, Chlorophyll a-b binding protein, chloroplastic, Ferredoxin, chloroplastic, ... (22 entities in total)
• Functional Keywords: membrane supercomplex, light harvesting, electron transport, green algae, photosynthesis
• Biological source: Chlamydomonas reinhardtii; More
• Total number of polymer chains: 16
• Total formula weight: 651127.43

Authors

Kurisu, G.,Gerle, C.,Mitsuoka, K.,Kawamoto, A.,Tanaka, H. (deposition date: 2022-02-18, release date: 2023-02-22, Last modification date: 2024-06-26)

Primary citation

Gerle, C.,Misumi, Y.,Kawamoto, A.,Tanaka, H.,Kubota-Kawai, H.,Tokutsu, R.,Kim, E.,Chorev, D.,Abe, K.,Robinson, C.V.,Mitsuoka, K.,Minagawa, J.,Kurisu, G.
Three structures of PSI-LHCI from Chlamydomonas reinhardtii suggest a resting state re-activated by ferredoxin.
Biochim Biophys Acta Bioenerg, 1864:148986-148986, 2023

PubMed Abstract: Photosystem I (PSI) from the green alga Chlamydomonas reinhardtii, with various numbers of membrane bound antenna complexes (LHCI), has been described in great detail. In contrast, structural characterization of soluble binding partners is less advanced. Here, we used X-ray crystallography and single particle cryo-EM to investigate three structures of the PSI-LHCI supercomplex from Chlamydomonas reinhardtii. An X-ray structure demonstrates the absence of six chlorophylls from the luminal side of the LHCI belts, suggesting these pigments were either physically absent or less stably associated with the complex, potentially influencing excitation transfer significantly. CryoEM revealed extra densities on luminal and stromal sides of the supercomplex, situated in the vicinity of the electron transfer sites. These densities disappeared after the binding of oxidized ferredoxin to PSI-LHCI. Based on these structures, we propose the existence of a PSI-LHCI resting state with a reduced active chlorophyll content, electron donors docked in waiting positions and regulatory binding partners positioned at the electron acceptor site. The resting state PSI-LHCI supercomplex would be recruited to its active form by the availability of oxidized ferredoxin.

PubMed: 37270022
DOI: 10.1016/j.bbabio.2023.148986

Experimental method

ELECTRON MICROSCOPY (4.9 Å)