View source for 3rgm


==Crystal structure of spin-labeled BtuB T156R1==
<StructureSection load='3rgm' size='340' side='right'caption='[[3rgm]], [[Resolution|resolution]] 2.60&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[3rgm]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Escherichia_coli_K-12 Escherichia coli K-12]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=3RGM OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=3RGM 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]] 2.6&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=C8E:(HYDROXYETHYLOXY)TRI(ETHYLOXY)OCTANE'>C8E</scene>, <scene name='pdbligand=MG:MAGNESIUM+ION'>MG</scene>, <scene name='pdbligand=MTN:S-[(1-OXYL-2,2,5,5-TETRAMETHYL-2,5-DIHYDRO-1H-PYRROL-3-YL)METHYL]+METHANESULFONOTHIOATE'>MTN</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=3rgm FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=3rgm OCA], [https://pdbe.org/3rgm PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=3rgm RCSB], [https://www.ebi.ac.uk/pdbsum/3rgm PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=3rgm ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/BTUB_ECOLI BTUB_ECOLI] Involved in the active translocation of vitamin B12 (cyanocobalamin) across the outer membrane to the periplasmic space. It derives its energy for transport by interacting with the trans-periplasmic membrane protein TonB. Is also a receptor for bacteriophages BF23 and C1, and for A and E colicins.[HAMAP-Rule:MF_01531]
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== Publication Abstract from PubMed ==
In this work, electron paramagnetic resonance (EPR) spectroscopy and X-ray crystallography were used to examine the origins of EPR line shapes from spin-labels at the protein-lipid interface on the beta-barrel membrane protein BtuB. Two atomic-resolution structures were obtained for the methanethiosulfonate spin-label derivatized to cysteines on the membrane-facing surface of BtuB. At one of these sites, position 156, the label side chain resides in a pocket formed by neighboring residues; however, it extends from the protein surface and yields a single-component EPR spectrum in the crystal that results primarily from fast rotation about the fourth and fifth bonds linking the spin-label to the protein backbone. In lipid bilayers, site 156 yields a multicomponent spectrum resulting from different rotameric states of the labeled side chain. Moreover, changes in the lipid environment, such as variations in bilayer thickness, modulate the EPR spectrum by modulating label rotamer populations. At a second site, position 371, the labeled side chain interacts with a pocket on the protein surface, leading to a highly immobilized single-component EPR spectrum that is not sensitive to hydrocarbon thickness. This spectrum is similar to that seen at other sites that are deep in the hydrocarbon, such as position 170. This work indicates that the rotameric states of spin-labels on exposed hydrocarbon sites are sensitive to the environment at the protein-hydrocarbon interface, and that this environment may modulate weak interactions between the labeled side chain and the protein surface. In the case of BtuB, lipid acyl chain packing is not symmetric around the beta-barrel, and EPR spectra from labeled hydrocarbon-facing sites in BtuB may reflect this asymmetry. In addition to facilitating the interpretation of EPR spectra of membrane proteins, these results have important implications for the use of long-range distance restraints in protein structure refinement that are obtained from spin-labels.

Molecular Origin of Electron Paramagnetic Resonance Line Shapes on beta-Barrel Membrane Proteins: The Local Solvation Environment Modulates Spin-Label Configuration.,Freed DM, Khan AK, Horanyi PS, Cafiso DS Biochemistry. 2011 Oct 18;50(41):8792-803. Epub 2011 Sep 22. PMID:21894979<ref>PMID:21894979</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 3rgm" style="background-color:#fffaf0;"></div>

==See Also==
*[[BtuB 3D structures|BtuB 3D structures]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Escherichia coli K-12]]
[[Category: Large Structures]]
[[Category: Cafiso DS]]
[[Category: Freed DM]]
[[Category: Horanyi PS]]
[[Category: Wiener MC]]