View source for 8ypb


==Cryo-EM structure of the LH1 complex from Allochromatium tepidum==
<StructureSection load='8ypb' size='340' side='right'caption='[[8ypb]], [[Resolution|resolution]] 2.45&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[8ypb]] is a 28 chain structure with sequence from [https://en.wikipedia.org/wiki/Allochromatium_tepidum Allochromatium tepidum]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=8YPB OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=8YPB 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]] 2.45&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=CA:CALCIUM+ION'>CA</scene>, <scene name='pdbligand=CRT:SPIRILLOXANTHIN'>CRT</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=8ypb FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=8ypb OCA], [https://pdbe.org/8ypb PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=8ypb RCSB], [https://www.ebi.ac.uk/pdbsum/8ypb PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=8ypb ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/O82943_ALLVI O82943_ALLVI] Antenna complexes are light-harvesting systems, which transfer the excitation energy to the reaction centers.[ARBA:ARBA00002455]
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== Publication Abstract from PubMed ==
The genome of the mildly thermophilic hot spring purple sulfur bacterium, Allochromatium (Alc.) tepidum, contains a multigene pufBA family that encodes a series of alpha- and beta-polypeptides, collectively forming a heterogeneous light-harvesting 1 (LH1) complex. The Alc. tepidum LH1, therefore, offers a unique model for studying an intermediate phenotype between phototrophic thermophilic and mesophilic bacteria, particularly regarding their LH1 Qy transition and moderately enhanced thermal stability. Of the 16 alpha-polypeptides in the Alc. tepidum LH1, six alpha1 bind Ca(2+) to connect with beta1- or beta3-polypeptides in specific Ca(2+)-binding sites. Here, we use the purple bacterium Rhodospirillum rubrum strain H2 as a host to express Ca(2+)-bound and Ca(2+)-free Alc. tepidum LH1-only complexes composed of alpha- and beta-polypeptides that either contain or lack the calcium-binding motif WxxDxI; purified preparations of each complex were then used to test how Ca(2+) affects their thermostability and spectral features. The cryo-EM structures of both complexes were closed circular rings consisting of 14 alphabeta-polypeptides. The Q(y) absorption maximum of Ca(2+)-bound LH1 (alpha1/beta1 and alpha1/beta3) was at 894 nm, while that of Ca(2+)-free (alpha2/beta1) was at 888 nm, indicating that Ca(2+) imparts a Q(y) transition of 6 nm. Crucially for the ecological success of Alc. tepidum, Ca(2+)-bound LH1 complexes were more thermostable than Ca(2+)-free complexes, indicating that calcium plays at least two major roles in photosynthesis by Alc. tepidum-improving photocomplex stability and modifying its spectrum.

Probing the Dual Role of Ca(2+) in the Allochromatium tepidum LH1-RC Complex by Constructing and Analyzing Ca(2+)-Bound and Ca(2+)-Free LH1 Complexes.,Zou MJ, Sun S, Wang GL, Yan YH, Ji W, Wang-Otomo ZY, Madigan MT, Yu LJ Biomolecules. 2025 Jan 14;15(1):124. doi: 10.3390/biom15010124. PMID:39858518<ref>PMID:39858518</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 8ypb" style="background-color:#fffaf0;"></div>
== References ==
<references/>
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</StructureSection>
[[Category: Allochromatium tepidum]]
[[Category: Large Structures]]
[[Category: Sun S]]
[[Category: Wang G-L]]
[[Category: Yu L-J]]