View source for 8eqm


==Structure of a dimeric photosystem II complex acclimated to far-red light==
<StructureSection load='8eqm' size='340' side='right'caption='[[8eqm]], [[Resolution|resolution]] 2.60&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[8eqm]] is a 20 chain structure with sequence from [https://en.wikipedia.org/wiki/Synechococcus_sp._PCC_7335 Synechococcus sp. PCC 7335]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=8EQM OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=8EQM FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">Electron Microscopy, [[Resolution|Resolution]] 2.6&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=BCR:BETA-CAROTENE'>BCR</scene>, <scene name='pdbligand=BCT:BICARBONATE+ION'>BCT</scene>, <scene name='pdbligand=CL:CHLORIDE+ION'>CL</scene>, <scene name='pdbligand=CLA:CHLOROPHYLL+A'>CLA</scene>, <scene name='pdbligand=DGD:DIGALACTOSYL+DIACYL+GLYCEROL+(DGDG)'>DGD</scene>, <scene name='pdbligand=F6C:[methyl+9-ethenyl-14-ethyl-8-formyl-4,13,18-trimethyl-20-oxo-3-{3-oxo-3-[(3,7,11,15-tetramethylhexadec-2-en-1-yl)oxy]propyl}-3,4,23,25-tetradehydro-24,26-dihydrophorbine-21-carboxylatato(2-)-kappa~4~N~23~,N~24~,N~25~,N~26~]magnesium'>F6C</scene>, <scene name='pdbligand=FE2:FE+(II)+ION'>FE2</scene>, <scene name='pdbligand=HEM:PROTOPORPHYRIN+IX+CONTAINING+FE'>HEM</scene>, <scene name='pdbligand=LHG:1,2-DIPALMITOYL-PHOSPHATIDYL-GLYCEROLE'>LHG</scene>, <scene name='pdbligand=LMG:1,2-DISTEAROYL-MONOGALACTOSYL-DIGLYCERIDE'>LMG</scene>, <scene name='pdbligand=LMT:DODECYL-BETA-D-MALTOSIDE'>LMT</scene>, <scene name='pdbligand=PHO:PHEOPHYTIN+A'>PHO</scene>, <scene name='pdbligand=PL9:2,3-DIMETHYL-5-(3,7,11,15,19,23,27,31,35-NONAMETHYL-2,6,10,14,18,22,26,30,34-HEXATRIACONTANONAENYL-2,5-CYCLOHEXADIENE-1,4-DIONE-2,3-DIMETHYL-5-SOLANESYL-1,4-BENZOQUINONE'>PL9</scene>, <scene name='pdbligand=RRX:(3R)-BETA,BETA-CAROTEN-3-OL'>RRX</scene>, <scene name='pdbligand=SQD:1,2-DI-O-ACYL-3-O-[6-DEOXY-6-SULFO-ALPHA-D-GLUCOPYRANOSYL]-SN-GLYCEROL'>SQD</scene></td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=8eqm FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=8eqm OCA], [https://pdbe.org/8eqm PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=8eqm RCSB], [https://www.ebi.ac.uk/pdbsum/8eqm PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=8eqm ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/B4WKH9_SYNS7 B4WKH9_SYNS7] Photosystem II (PSII) is a light-driven water:plastoquinone oxidoreductase that uses light energy to abstract electrons from H(2)O, generating O(2) and a proton gradient subsequently used for ATP formation. It consists of a core antenna complex that captures photons, and an electron transfer chain that converts photonic excitation into a charge separation. The D1/D2 (PsbA/PsbD) reaction center heterodimer binds P680, the primary electron donor of PSII as well as several subsequent electron acceptors.[ARBA:ARBA00037683]
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== Publication Abstract from PubMed ==
Photosystem II (PSII) is the water-splitting enzyme central to oxygenic photosynthesis. To drive water oxidation, light is harvested by accessory pigments, mostly chlorophyll (Chl) a molecules, which absorb visible light (400-700 nm). Some cyanobacteria facultatively acclimate to shaded environments by altering their photosynthetic machinery to additionally absorb far-red light (FRL, 700-800 nm), a process termed far-red light photoacclimation or FaRLiP. During far-red light photoacclimation, FRL-PSII is assembled with FRL-specific isoforms of the subunits PsbA, PsbB, PsbC, PsbD, and PsbH, and some Chl-binding sites contain Chls d or f instead of the usual Chl a. The structure of an apo-FRL-PSII monomer lacking the FRL-specific PsbH subunit has previously been determined, but visualization of the dimeric complex has remained elusive. Here, we report the cryo-EM structure of a dimeric FRL-PSII complex. The site assignments for Chls d and f are consistent with those assigned in the previous apo-FRL-PSII monomeric structure. All sites that bind Chl d or Chl f at high occupancy exhibit a FRL-specific interaction of the formyl moiety of the Chl d or Chl f with the protein environment, which in some cases involves a phenylalanine sidechain. The structure retains the FRL-specific PsbH2 subunit, which appears to alter the energetic landscape of FRL-PSII, redirecting energy transfer from the phycobiliprotein complex to a Chl f molecule bound by PsbB2 that acts as a bridge for energy transfer to the electron transfer chain. Collectively, these observations extend our previous understanding of the structure-function relationship that allows PSII to function using lower energy FRL.

Structure of a dimeric photosystem II complex from a cyanobacterium acclimated to far-red light.,Gisriel CJ, Shen G, Flesher DA, Kurashov V, Golbeck JH, Brudvig GW, Amin M, Bryant DA J Biol Chem. 2023 Jan;299(1):102815. doi: 10.1016/j.jbc.2022.102815. Epub 2022 , Dec 20. PMID:36549647<ref>PMID:36549647</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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<div class="pdbe-citations 8eqm" style="background-color:#fffaf0;"></div>

==See Also==
*[[Photosystem II 3D structures|Photosystem II 3D structures]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Large Structures]]
[[Category: Synechococcus sp. PCC 7335]]
[[Category: Amin M]]
[[Category: Brudvig GW]]
[[Category: Bryant DA]]
[[Category: Flesher DA]]
[[Category: Gisriel CJ]]
[[Category: Golbeck JH]]
[[Category: Kurashov V]]
[[Category: Shen G]]