2i68: Difference between revisions
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{{STRUCTURE_2i68| PDB=2i68 | SCENE= }} | |||
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'''Cryo-EM based theoretical model structure of transmembrane domain of the multidrug-resistance antiporter from E. coli EmrE''' | '''Cryo-EM based theoretical model structure of transmembrane domain of the multidrug-resistance antiporter from E. coli EmrE''' | ||
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[[Category: Harrington, S E.]] | [[Category: Harrington, S E.]] | ||
[[Category: Tate, C G.]] | [[Category: Tate, C G.]] | ||
[[Category: | [[Category: Dual topology]] | ||
[[Category: | [[Category: Homodimer]] | ||
[[Category: | [[Category: Small-multidrug resistance]] | ||
[[Category: | [[Category: Transmembrane protein]] | ||
[[Category: | [[Category: Transporter]] | ||
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun May 4 07:07:33 2008'' | |||
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Revision as of 07:07, 4 May 2008
Cryo-EM based theoretical model structure of transmembrane domain of the multidrug-resistance antiporter from E. coli EmrE
OverviewOverview
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.
About this StructureAbout this Structure
2I68 is a Single protein structure of sequence from Escherichia coli. Full crystallographic information is available from OCA.
ReferenceReference
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:17005200 Page seeded by OCA on Sun May 4 07:07:33 2008