View source for 7cvs


==Crystal structure of the C85A/L194A mutant CLC-ec1 with Fab fragment==
<StructureSection load='7cvs' size='340' side='right'caption='[[7cvs]], [[Resolution|resolution]] 3.01&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[7cvs]] is a 6 chain structure with sequence from [https://en.wikipedia.org/wiki/Escherichia_coli_MS_198-1 Escherichia coli MS 198-1] and [https://en.wikipedia.org/wiki/Mus_musculus Mus musculus]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=7CVS OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=7CVS 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]] 3.01&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=CL:CHLORIDE+ION'>CL</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=7cvs FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=7cvs OCA], [https://pdbe.org/7cvs PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=7cvs RCSB], [https://www.ebi.ac.uk/pdbsum/7cvs PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=7cvs ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/CLCA_ECOLI CLCA_ECOLI] Proton-coupled chloride transporter. Functions as antiport system and exchanges two chloride ions for 1 proton. Probably acts as an electrical shunt for an outwardly-directed proton pump that is linked to amino acid decarboxylation, as part of the extreme acid resistance (XAR) response.<ref>PMID:12384697</ref> <ref>PMID:14985752</ref> <ref>PMID:16341087</ref> <ref>PMID:16905147</ref> <ref>PMID:18678918</ref> 
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
CLC-ec1 is a Cl(-)/H(+) antiporter that forms stable homodimers in lipid bilayers, with a free energy of -10.9 kcal/mol in 2:1 POPE/POPG lipid bilayers. The dimerization interface is formed by four transmembrane helices: H, I, P and Q, that are lined by non-polar side-chains that come in close contact, yet it is unclear as to whether their interactions drive dimerization. To investigate whether non-polar side-chains are required for dimer assembly, we designed a series of constructs where side-chain packing in the dimer state is significantly reduced by making 4-5 alanine substitutions along each helix (H-ala, I-ala, P-ala, Q-ala). All constructs are functional and three purify as stable dimers in detergent micelles despite the removal of significant side-chain interactions. On the other hand, H-ala shows the unique behavior of purifying as a mixture of monomers and dimers, followed by a rapid and complete conversion to monomers. In lipid bilayers, all four constructs are monomeric as examined by single-molecule photobleaching analysis. Further study of the H-helix shows that the single mutation L194A is sufficient to yield monomeric CLC-ec1 in detergent micelles and lipid bilayers. X-ray crystal structures of L194A reveal the protein re-assembles to form dimers, with a structure that is identical to wild-type. Altogether, these results demonstrate that non-polar membrane embedded side-chains play an important role in defining dimer stability, but the stoichiometry is highly contextual to the solvent environment. Furthermore, we discovered that L194 is a molecular hot-spot for defining dimerization of CLC-ec1.

Altering CLC stoichiometry by reducing non-polar side-chains at the dimerization interface.,Mersch K, Ozturk TN, Park K, Lim HH, Robertson JL J Mol Biol. 2021 Apr 16;433(8):166886. doi: 10.1016/j.jmb.2021.166886. Epub 2021 , Feb 20. PMID:33617898<ref>PMID:33617898</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 7cvs" style="background-color:#fffaf0;"></div>

==See Also==
*[[Antibody 3D structures|Antibody 3D structures]]
*[[Ion channels 3D structures|Ion channels 3D structures]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Escherichia coli MS 198-1]]
[[Category: Large Structures]]
[[Category: Mus musculus]]
[[Category: Lim H-H]]
[[Category: Mersch K]]
[[Category: Park K]]
[[Category: Robertson J]]