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[[Image:2i68.gif|left|200px]]<br /><applet load="2i68" size="350" color="white" frame="true" align="right" spinBox="true"
caption="2i68" />
'''Cryo-EM based theoretical model structure of transmembrane domain of the multidrug-resistance antiporter from E. coli EmrE'''<br />


==Overview==
==Cryo-EM based theoretical model structure of transmembrane domain of the multidrug-resistance antiporter from E. coli EmrE==
Small multidrug resistance (SMR) transporters contribute to bacterial resistance by coupling the efflux of a wide range of toxic aromatic cations, some of which are commonly used as antibiotics and antiseptics, to proton influx. EmrE is a prototypical small multidrug resistance transporter comprising four transmembrane segments (M1-M4) that forms dimers. It was suggested recently that EmrE molecules in the dimer have different topologies, i.e. monomers have opposite orientations with respect to the membrane plane. A 3-D structure of EmrE acquired by electron cryo-microscopy (cryo-EM) at 7.5 Angstroms resolution in the membrane plane showed that parts of the structure are related by quasi-symmetry. We used this symmetry relationship, combined with sequence conservation data, to assign the transmembrane segments in EmrE to the densities seen in the cryo-EM structure. A C alpha model of the transmembrane region was constructed by considering the evolutionary conservation pattern of each helix. The model is validated by much of the biochemical data on EmrE with most of the positions that were identified as affecting substrate translocation being located around the substrate-binding cavity. A suggested mechanism for proton-coupled substrate translocation in small multidrug resistance antiporters provides a mechanistic rationale to the experimentally observed inverted topology.
<StructureSection load='2i68' size='340' side='right'caption='[[2i68]], [[Resolution|resolution]] 7.50&Aring;' scene=''>
 
== Structural highlights ==
==About this Structure==
<table><tr><td colspan='2'>[[2i68]] is a 2 chain structure with sequence from [https://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2I68 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=2I68 FirstGlance]. <br>
2I68 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2I68 OCA].  
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">Electron crystallography, [[Resolution|Resolution]] 7.5&#8491;</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=2i68 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=2i68 OCA], [https://pdbe.org/2i68 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=2i68 RCSB], [https://www.ebi.ac.uk/pdbsum/2i68 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=2i68 ProSAT]</span></td></tr>
==Reference==
</table>
Quasi-symmetry in the cryo-EM structure of EmrE provides the key to modeling its transmembrane domain., Fleishman SJ, Harrington SE, Enosh A, Halperin D, Tate CG, Ben-Tal N, J Mol Biol. 2006 Nov 17;364(1):54-67. Epub 2006 Aug 30. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=17005200 17005200]
== Function ==
[https://www.uniprot.org/uniprot/EMRE_ECOLI EMRE_ECOLI] Multidrug transporter that expels positively charged hydrophobic drugs across the inner membrane of E.coli., thereby conferring resistance to a wide range of toxic compounds. The drug efflux is coupled to an influx of protons. Is involved in the resistance of E.coli cells to methyl viologen, ethidium bromide and acriflavine. Is also able to transport tetraphenylphosphonium (TPP(+)) and benzalkonium.<ref>PMID:7896833</ref> <ref>PMID:10681497</ref> <ref>PMID:15371426</ref>
== 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/i6/2i68_consurf.spt"</scriptWhenChecked>
    <scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview01.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=2i68 ConSurf].
<div style="clear:both"></div>
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Escherichia coli]]
[[Category: Escherichia coli]]
[[Category: Single protein]]
[[Category: Large Structures]]
[[Category: Ben-Tal, N.]]
[[Category: Ben-Tal N]]
[[Category: Enosh, A.]]
[[Category: Enosh A]]
[[Category: Fleishman, S J.]]
[[Category: Fleishman SJ]]
[[Category: Halperin, D.]]
[[Category: Halperin D]]
[[Category: Harrington, S E.]]
[[Category: Harrington SE]]
[[Category: Tate, C G.]]
[[Category: Tate CG]]
[[Category: dual topology]]
[[Category: homodimer]]
[[Category: small-multidrug resistance]]
[[Category: transmembrane protein]]
[[Category: transporter]]
 
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 17:49:30 2008''

Latest revision as of 16:52, 13 March 2024

Cryo-EM based theoretical model structure of transmembrane domain of the multidrug-resistance antiporter from E. coli EmrECryo-EM based theoretical model structure of transmembrane domain of the multidrug-resistance antiporter from E. coli EmrE

Structural highlights

2i68 is a 2 chain structure with sequence from Escherichia coli. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Method:Electron crystallography, Resolution 7.5Å
Resources:FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT

Function

EMRE_ECOLI Multidrug transporter that expels positively charged hydrophobic drugs across the inner membrane of E.coli., thereby conferring resistance to a wide range of toxic compounds. The drug efflux is coupled to an influx of protons. Is involved in the resistance of E.coli cells to methyl viologen, ethidium bromide and acriflavine. Is also able to transport tetraphenylphosphonium (TPP(+)) and benzalkonium.[1] [2] [3]

Evolutionary Conservation

Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf.

References

  1. ↑ Yerushalmi H, Lebendiker M, Schuldiner S. EmrE, an Escherichia coli 12-kDa multidrug transporter, exchanges toxic cations and H+ and is soluble in organic solvents. J Biol Chem. 1995 Mar 24;270(12):6856-63. PMID:7896833
  2. ↑ Yerushalmi H, Schuldiner S. An essential glutamyl residue in EmrE, a multidrug antiporter from Escherichia coli. J Biol Chem. 2000 Feb 25;275(8):5264-9. PMID:10681497
  3. ↑ Rotem D, Schuldiner S. EmrE, a multidrug transporter from Escherichia coli, transports monovalent and divalent substrates with the same stoichiometry. J Biol Chem. 2004 Nov 19;279(47):48787-93. Epub 2004 Sep 15. PMID:15371426 doi:10.1074/jbc.M408187200

2i68, resolution 7.50Å

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