title: A tethered bilayer assembled on top of immobilized calmodulin to mimic cellular compartmentalization.
abstract: BACKGROUND
  Biomimetic membrane models tethered on solid supports are important tools for membrane protein biochemistry and biotechnology. The supported membrane systems described up to now are composed of a lipid bilayer tethered or not to a surface separating two compartments: a "trans" side, one to a few nanometer thick, located between the supporting surface and the membrane; and a "cis" side, above the synthetic membrane, exposed to the bulk medium. We describe here a novel biomimetic design composed of a tethered bilayer membrane that is assembled over a surface derivatized with a specific intracellular protein marker. This multilayered biomimetic assembly exhibits the fundamental characteristics of an authentic biological membrane in creating a continuous yet fluid phospholipidic barrier between two distinct compartments: a "cis" side corresponding to the extracellular milieu and a "trans" side marked by a key cytosolic signaling protein, calmodulin.
  
  
  RESULTS
  We established and validated the experimental conditions to construct a multilayered structure consisting in a planar tethered bilayer assembled over a surface derivatized with calmodulin. We demonstrated the following: (i) the grafted calmodulin molecules (in trans side) were fully functional in binding and activating a calmodulin-dependent enzyme, the adenylate cyclase from Bordetella pertussis; and (ii) the assembled bilayer formed a continuous, protein-impermeable boundary that fully separated the underlying calmodulin (trans side) from the above medium (cis side).
  
  
  CONCLUSIONS
  The simplicity and robustness of the tethered bilayer structure described here should facilitate the elaboration of biomimetic membrane models incorporating membrane embedded proteins and key cytoplasmic constituents. Such biomimetic structures will also be an attractive tool to study translocation across biological membranes of proteins or other macromolecules.
authors.affiliation: UMR 6022 CNRS, Université de Technologie de Compiègne, Compiègne, France.
authors.forename: Claire
authors.initials: C
authors.lastname: Rossi
authors.forename: Samah
authors.initials: S
authors.lastname: Doumiati
authors.forename: Clarine
authors.initials: C
authors.lastname: Lazzarelli
authors.forename: Marilyne
authors.initials: M
authors.lastname: Davi
authors.forename: Fetta
authors.initials: F
authors.lastname: Meddar
authors.forename: Daniel
authors.initials: D
authors.lastname: Ladant
authors.forename: Joël
authors.initials: J
authors.lastname: Chopineau
mesh_terms: D000262:Adenylyl Cyclases / Q000378:metabolism; D002147:Calmodulin / Q000378:metabolism*; D002451:Cell Compartmentation; D005453:Fluorescence; D008051:Lipid Bilayers; D008567:Membranes, Artificial; D018716:Molecular Mimicry; D011485:Protein Binding; D020349:Surface Plasmon Resonance
chemical_list: D002147:Calmodulin; D008051:Lipid Bilayers; D008567:Membranes, Artificial; D000262:Adenylyl Cyclases