View source for 2z55


==Bacterioruberin in the trimeric structure of archaerhodopsin-2==
<StructureSection load='2z55' size='340' side='right'caption='[[2z55]], [[Resolution|resolution]] 2.50&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[2z55]] is a 4 chain structure with sequence from [https://en.wikipedia.org/wiki/Halobacterium_sp._AUS-2 Halobacterium sp. AUS-2]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2Z55 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=2Z55 FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 2.5&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=22B:BACTERIORUBERIN'>22B</scene>, <scene name='pdbligand=GAL:BETA-D-GALACTOSE'>GAL</scene>, <scene name='pdbligand=GLC:ALPHA-D-GLUCOSE'>GLC</scene>, <scene name='pdbligand=L2P:2,3-DI-PHYTANYL-GLYCEROL'>L2P</scene>, <scene name='pdbligand=MAN:ALPHA-D-MANNOSE'>MAN</scene>, <scene name='pdbligand=RET:RETINAL'>RET</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=2z55 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=2z55 OCA], [https://pdbe.org/2z55 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=2z55 RCSB], [https://www.ebi.ac.uk/pdbsum/2z55 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=2z55 ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/BACR2_HALS2 BACR2_HALS2] 
== Evolutionary Conservation ==
[[Image:Consurf_key_small.gif|200px|right]]
Check<jmol>
  <jmolCheckbox>
    <scriptWhenChecked>; select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/z5/2z55_consurf.spt"</scriptWhenChecked>
    <scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview03.spt</scriptWhenUnchecked>
    <text>to colour the structure by Evolutionary Conservation</text>
  </jmolCheckbox>
</jmol>, as determined by [http://consurfdb.tau.ac.il/ ConSurfDB]. You may read the [[Conservation%2C_Evolutionary|explanation]] of the method and the full data available from [http://bental.tau.ac.il/new_ConSurfDB/main_output.php?pdb_ID=2z55 ConSurf].
<div style="clear:both"></div>
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
Archaerhodopsin-2 (aR2), a retinal protein-carotenoid complex found in the claret membrane of Halorubrum sp. aus-2, functions as a light-driven proton pump. In this study, the membrane fusion method was utilized to prepare trigonal P321 crystals (a=b=98.2 A, c=56.2 A) and hexagonal P6(3) crystals (a=b=108.8 A, c=220.7 A). The trigonal crystal is made up of stacked membranes in which the aR2 trimers are arranged on a honeycomb lattice. Similar membranous structures are found in the hexagonal crystal, but four membrane layers with different orientations are contained in the unit cell. In these crystals, the carotenoid bacterioruberin [5,32-bis(2-hydroxypropan-2-yl)-2,8,12,16,21,25,29,35-octamethylhexatriaco nta-6,8,10,12,14,16,18,20,22,24,26,28,30-tridecaene-2,35-diol] binds to crevices between the subunits of the trimer. Its polyene chain is inclined from the membrane normal by an angle of about 20 degrees and, on the cytoplasmic side, it is surrounded by helices AB and DE of neighbouring subunits. This peculiar binding mode suggests that bacterioruberin plays a striking structural role for the trimerization of aR2. When compared with the aR2 structure in another crystal form containing no bacterioruberin, the proton release channel takes a more closed conformation in the P321 or P6(3) crystal; i.e., the native conformation of protein is stabilized in the trimeric protein-bacterioruberin complex. Interestingly, most residues participating in the trimerization are not conserved in bacteriorhodopsin, a homologous protein capable of forming a trimeric structure in the absence of bacterioruberin. Despite a large alteration in the amino acid sequence, the shape of the intratrimer hydrophobic space filled by lipids is highly conserved between aR2 and bacteriorhodopsin. Since a transmembrane helix facing this space undergoes a large conformational change during the proton pumping cycle, it is feasible that trimerization is an important strategy to capture special lipid components that are relevant to the protein activity.

Structural role of bacterioruberin in the trimeric structure of archaerhodopsin-2.,Yoshimura K, Kouyama T J Mol Biol. 2008 Feb 1;375(5):1267-81. Epub 2007 Nov 22. PMID:18082767<ref>PMID:18082767</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 2z55" style="background-color:#fffaf0;"></div>

==See Also==
*[[Bacteriorhodopsin 3D structures|Bacteriorhodopsin 3D structures]]
*[[Rhodopsin 3D structures|Rhodopsin 3D structures]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Halobacterium sp. AUS-2]]
[[Category: Large Structures]]
[[Category: Kouyama T]]
[[Category: Yoshimura K]]