Organization of reconstituted lipoprotein MexA onto supported lipid membrane |
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Authors: | Sylvain Trépout Jean-Christophe Taveau Stéphane Mornet Houssain Benabdelhak Arnaud Ducruix Olivier Lambert |
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Institution: | (1) Laboratoire d’Imagerie Moléculaire et Nano-Bio-Technologie, UMR 5248 CBMN, CNRS, Université Bordeaux 1, ENITAB, IECB, 2 rue Robert Escarpit, 33607 Pessac, France;(2) Laboratoire de Cristallographie et RMN Biologiques, UMR 8015 CNRS, Faculté de Pharmacie, Université Paris Descartes, 4 avenue de l’observatoire, 75270 Paris Cedex 06, France;(3) Present address: European Commission Joint Research Centre Institute for Health and Consumer Protection, Via E. Fermi 1, TP 203, 21020 Ispra, Italy |
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Abstract: | MexA, a periplasmic component of OprM-MexA-MexB tripartite multidrug efflux pump from Pseudomonas aeruginosa, is natively anchored via its fatty acid in the bacteria inner membrane protruding into the periplasm. We used supported
lipid bilayer (SLB) to attach the protein to a single leaflet mimicking its perisplamic orientation. For that purpose, we
studied the solubilization of DOPC lipid bilayer supported on silica surface with β-octyl glucoside (βOG). First we showed
that SLBs resist to βOG concentrations that usually solubilize liposomes. Native form of MexA was directly inserted in the
outer leaflet at (βOG concentrations in a range of 20–25 mM). Second, observations by cryo-electron microscopy (cryoEM) revealed
a dense protein layer attached to the surface corresponding to a 13-nm layer of MexA proteins. Analysis of protein densities
allows proposing a schematic organization of native MexA inserted in lipid membrane. This structural organization provides
further insights with respect to the partially solved structure of the soluble form.
Presented at the joint biannual meeting of the SFB-GEIMM-GRIP, Anglet France, 14–19 October, 2006. |
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Keywords: | Membrane protein Multidrug resistance Cryo-electron microscopy Membrane protein on solid support SLB QCM-D |
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