5OY0

Structure of synechocystis photosystem I trimer at 2.5A resolution

Summary for 5OY0

• Entry DOI: 10.2210/pdb5oy0/pdb
• Descriptor: Photosystem I P700 chlorophyll a apoprotein A1, Photosystem I reaction center subunit XI, Photosystem I reaction center subunit XII, ... (38 entities in total)
• Functional Keywords: photosystem i, reaction center, photosynthesis, cyanobacteria, electron transfer chain, synechocystis
• Biological source: Synechocystis sp. PCC 6803; More
• Total number of polymer chains: 33
• Total formula weight: 1087722.77

Authors

Nelson, N.,Malavath, T.,Caspy, I. (deposition date: 2017-09-07, release date: 2018-02-21, Last modification date: 2019-11-20)

Primary citation

Malavath, T.,Caspy, I.,Netzer-El, S.Y.,Klaiman, D.,Nelson, N.
Structure and function of wild-type and subunit-depleted photosystem I in Synechocystis.
Biochim. Biophys. Acta, 1859:645-654, 2018

PubMed Abstract: The ability of photosynthetic organisms to use the sun's light as a sole source of energy sustains life on our planet. Photosystems I (PSI) and II (PSII) are large, multi-subunit, pigment-protein complexes that enable photosynthesis, but this intriguing process remains to be explained fully. Currently, crystal structures of these complexes are available for thermophilic prokaryotic cyanobacteria. The mega-Dalton trimeric PSI complex from thermophilic cyanobacterium, Thermosynechococcus elongatus, was solved at 2.5 Å resolution with X-ray crystallography. That structure revealed the positions of 12 protein subunits (PsaA-F, PsaI-M, and PsaX) and 127 cofactors. Although mesophilic organisms perform most of the world's photosynthesis, no well-resolved trimeric structure of a mesophilic organism exists. Our research model for a mesophilic cyanobacterium was Synechocystis sp. PCC6803. This study aimed to obtain well-resolved crystal structures of [1] a monomeric PSI with all subunits, [2] a trimeric PSI with a reduced number of subunits, and [3] the full, trimeric wild-type PSI complex. We only partially succeeded with the first two structures, but we successfully produced the trimeric PSI structure at 2.5 Å resolution. This structure was comparable to that of the thermophilic species, but we provided more detail. The PSI trimeric supercomplex consisted of 33 protein subunits, 72 carotenoids, 285 chlorophyll a molecules, 51 lipids, 9 iron-sulfur clusters, 6 plastoquinones, 6 putative calcium ions, and over 870 water molecules. This study showed that the structure of the PSI in Synechocystis sp. PCC6803 differed from previously described PSI structures. These findings have broadened our understanding of PSI structure.

PubMed: 29414678
DOI: 10.1016/j.bbabio.2018.02.002

Experimental method

X-RAY DIFFRACTION (2.501 Å)