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The | ==Cryo-EM structure of the RC-LH core comples from Halorhodospira halochloris== | ||
<StructureSection load='8k5o' size='340' side='right'caption='[[8k5o]], [[Resolution|resolution]] 2.42Å' scene=''> | |||
== Structural highlights == | |||
<table><tr><td colspan='2'>[[8k5o]] is a 55 chain structure with sequence from [https://en.wikipedia.org/wiki/Halorhodospira_halochloris Halorhodospira halochloris]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=8K5O OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=8K5O 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]] 2.42Å</td></tr> | |||
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=BGL:B-2-OCTYLGLUCOSIDE'>BGL</scene>, <scene name='pdbligand=CDL:CARDIOLIPIN'>CDL</scene>, <scene name='pdbligand=FE:FE+(III)+ION'>FE</scene>, <scene name='pdbligand=HEC:HEME+C'>HEC</scene>, <scene name='pdbligand=LHG:1,2-DIPALMITOYL-PHOSPHATIDYL-GLYCEROLE'>LHG</scene>, <scene name='pdbligand=LYC:LYCOPENE'>LYC</scene>, <scene name='pdbligand=MQ8:MENAQUINONE+8'>MQ8</scene>, <scene name='pdbligand=PEF:DI-PALMITOYL-3-SN-PHOSPHATIDYLETHANOLAMINE'>PEF</scene>, <scene name='pdbligand=PGV:(1R)-2-{[{[(2S)-2,3-DIHYDROXYPROPYL]OXY}(HYDROXY)PHOSPHORYL]OXY}-1-[(PALMITOYLOXY)METHYL]ETHYL+(11E)-OCTADEC-11-ENOATE'>PGV</scene>, <scene name='pdbligand=UQ8:UBIQUINONE-8'>UQ8</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=8k5o FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=8k5o OCA], [https://pdbe.org/8k5o PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=8k5o RCSB], [https://www.ebi.ac.uk/pdbsum/8k5o PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=8k5o ProSAT]</span></td></tr> | |||
</table> | |||
== Function == | |||
[https://www.uniprot.org/uniprot/A0A0X8X829_HALHR A0A0X8X829_HALHR] The reaction center of purple bacteria contains a tightly bound cytochrome molecule which re-reduces the photo oxidized primary electron donor.[ARBA:ARBA00003196][PIRNR:PIRNR000017] | |||
<div style="background-color:#fffaf0;"> | |||
== Publication Abstract from PubMed == | |||
Halorhodospira (Hlr.) halochloris is a triply extremophilic phototrophic purple sulfur bacterium, as it is thermophilic, alkaliphilic, and extremely halophilic. The light-harvesting-reaction center (LH1-RC) core complex of this bacterium displays an LH1-Q(y) transition at 1,016 nm, which is the lowest-energy wavelength absorption among all known phototrophs. Here we report the cryo-EM structure of the LH1-RC at 2.42 A resolution. The LH1 complex forms a tricyclic ring structure composed of 16 alphabetagamma-polypeptides and one alphabeta-heterodimer around the RC. From the cryo-EM density map, two previously unrecognized integral membrane proteins, referred to as protein G and protein Q, were identified. Both of these proteins are single transmembrane-spanning helices located between the LH1 ring and the RC L-subunit and are absent from the LH1-RC complexes of all other purple bacteria of which the structures have been determined so far. Besides bacteriochlorophyll b molecules (B1020) located on the periplasmic side of the Hlr. halochloris membrane, there are also two arrays of bacteriochlorophyll b molecules (B800 and B820) located on the cytoplasmic side. Only a single copy of a carotenoid (lycopene) was resolved in the Hlr. halochloris LH1-alpha3beta3 and this was positioned within the complex. The potential quinone channel should be the space between the LH1-alpha3beta3 that accommodates the single lycopene but does not contain a gamma-polypeptide, B800 and B820. Our results provide a structural explanation for the unusual Q(y) red shift and carotenoid absorption in the Hlr. halochloris spectrum and reveal new insights into photosynthetic mechanisms employed by a species that thrives under the harshest conditions of any phototrophic microorganism known. | |||
Structural insights into the unusual core photocomplex from a triply extremophilic purple bacterium, Halorhodospira halochloris.,Qi CH, Wang GL, Wang FF, Wang J, Wang XP, Zou MJ, Ma F, Madigan MT, Kimura Y, Wang-Otomo ZY, Yu LJ J Integr Plant Biol. 2024 Feb 27. doi: 10.1111/jipb.13628. PMID:38411333<ref>PMID:38411333</ref> | |||
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.<br> | |||
[[Category: | </div> | ||
<div class="pdbe-citations 8k5o" style="background-color:#fffaf0;"></div> | |||
== References == | |||
<references/> | |||
__TOC__ | |||
</StructureSection> | |||
[[Category: Halorhodospira halochloris]] | |||
[[Category: Large Structures]] | |||
[[Category: Qi C-H]] | |||
[[Category: Wang G-L]] | |||
[[Category: Yu L-J]] | |||
Latest revision as of 15:06, 30 October 2024
Cryo-EM structure of the RC-LH core comples from Halorhodospira halochlorisCryo-EM structure of the RC-LH core comples from Halorhodospira halochloris
Structural highlights
FunctionA0A0X8X829_HALHR The reaction center of purple bacteria contains a tightly bound cytochrome molecule which re-reduces the photo oxidized primary electron donor.[ARBA:ARBA00003196][PIRNR:PIRNR000017] Publication Abstract from PubMedHalorhodospira (Hlr.) halochloris is a triply extremophilic phototrophic purple sulfur bacterium, as it is thermophilic, alkaliphilic, and extremely halophilic. The light-harvesting-reaction center (LH1-RC) core complex of this bacterium displays an LH1-Q(y) transition at 1,016 nm, which is the lowest-energy wavelength absorption among all known phototrophs. Here we report the cryo-EM structure of the LH1-RC at 2.42 A resolution. The LH1 complex forms a tricyclic ring structure composed of 16 alphabetagamma-polypeptides and one alphabeta-heterodimer around the RC. From the cryo-EM density map, two previously unrecognized integral membrane proteins, referred to as protein G and protein Q, were identified. Both of these proteins are single transmembrane-spanning helices located between the LH1 ring and the RC L-subunit and are absent from the LH1-RC complexes of all other purple bacteria of which the structures have been determined so far. Besides bacteriochlorophyll b molecules (B1020) located on the periplasmic side of the Hlr. halochloris membrane, there are also two arrays of bacteriochlorophyll b molecules (B800 and B820) located on the cytoplasmic side. Only a single copy of a carotenoid (lycopene) was resolved in the Hlr. halochloris LH1-alpha3beta3 and this was positioned within the complex. The potential quinone channel should be the space between the LH1-alpha3beta3 that accommodates the single lycopene but does not contain a gamma-polypeptide, B800 and B820. Our results provide a structural explanation for the unusual Q(y) red shift and carotenoid absorption in the Hlr. halochloris spectrum and reveal new insights into photosynthetic mechanisms employed by a species that thrives under the harshest conditions of any phototrophic microorganism known. Structural insights into the unusual core photocomplex from a triply extremophilic purple bacterium, Halorhodospira halochloris.,Qi CH, Wang GL, Wang FF, Wang J, Wang XP, Zou MJ, Ma F, Madigan MT, Kimura Y, Wang-Otomo ZY, Yu LJ J Integr Plant Biol. 2024 Feb 27. doi: 10.1111/jipb.13628. PMID:38411333[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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