title: High fluidity and soft elasticity of the inner membrane of Escherichia coli revealed by the surface rheology of model Langmuir monolayers.
abstract: We have studied the equilibrium and linear mechanical properties of model membranes of Escherichia coli built up as Langmuir monolayers of a native lipid extract using surface thermodynamics, fluorescence microscopy, and surface rheology measurements. The experimental study has been carried out at different temperatures across the physiological operative range 15-37 degrees C. Lipid phase coexistence has been revealed over a broad pressure range by fluorescence microscopy. The presence of ordered domains has been invoked to explain the emergence of shear elasticity accompanying the hydrostatic compression elasticity typical of fluid monolayers. The surface rheology measurements point out the soft character of E. coli membranes; i.e., upon deformation they react as a near-ideal compliant body with minimal energy dissipation, thus optimizing the effectiveness of external stresses in producing membrane deformations. These mechanical features appear to be independent of temperature, suggesting the existence of a passive thermoregulation mechanism.
authors.affiliation: Departamento de Química Física I, Universidad Complutense de Madrid, 28040 Madrid, Spain.
authors.forename: Ivan
authors.initials: I
authors.lastname: López-Montero
authors.forename: Laura R
authors.initials: LR
authors.lastname: Arriaga
authors.forename: Francisco
authors.initials: F
authors.lastname: Monroy
authors.forename: Germán
authors.initials: G
authors.lastname: Rivas
authors.forename: Pedro
authors.initials: P
authors.lastname: Tarazona
authors.forename: Marisela
authors.initials: M
authors.lastname: Vélez
mesh_terms: D002462:Cell Membrane / Q000737:chemistry*; D004548:Elasticity; D004926:Escherichia coli / Q000737:chemistry* / Q000166:cytology; D008567:Membranes, Artificial; D008856:Microscopy, Fluorescence; D008954:Models, Biological; D011312:Pressure; D012212:Rheology; D013499:Surface Properties; D013696:Temperature; D014783:Viscosity
chemical_list: D008567:Membranes, Artificial