title: Alterations of wheat root plasma membrane lipid composition induced by copper stress result in changed physicochemical properties of plasma membrane lipid vesicles.
abstract: A response when wheat is grown in excess copper is an altered lipid composition of the root plasma membrane (PM). With detailed characterisation of the root PM lipid composition of the copper-treated plants as a basis, in the present study, model systems were used to gain a wider understanding about membrane behaviour, and the impact of a changed lipid composition.PMs from root cells of plants grown in excess copper (50 microM Cu(2+)) and control (0.3 microM Cu(2+)) were isolated using the two-phase partitioning method. Membrane vesicles were prepared of total lipids extracts from the isolated PMs, and also reference vesicles of phosphatidylcholine (PC). In a series of tests, the vesicle permeability for glucose and for protons was analysed. The vesicles show that copper stress reduced the permeability for glucose of the lipid bilayer barrier. When vesicles from stressed plants were modified by addition of lipids to resemble vesicles from control plants, the permeability for glucose was very similar to that of vesicles from control plants. The permeability for protons did not change upon stress. Electron paramagnetic resonance (EPR) of the lipid vesicles spin probed with n-doxylstearic acid (nDSA) was used to explore the lipid rotational freedom at different depth of the bilayer. The EPR measurements supported the permeability data, indicating that the copper stress resulted in more tightly packed bilayers of the PMs with reduced acyl chain motion.
authors.affiliation: Department of Plant Physiology, Botanical Institute, Göteborg University, Box 461, Carl Skottbergs gata 22, S-405 30, Göteborg, Sweden.
authors.forename: Anna H
authors.initials: AH
authors.lastname: Berglund
authors.forename: Mike F
authors.initials: MF
authors.lastname: Quartacci
authors.forename: Lucia
authors.initials: L
authors.lastname: Calucci
authors.forename: Flavia
authors.initials: F
authors.lastname: Navari-Izzo
authors.forename: Calogero
authors.initials: C
authors.lastname: Pinzino
authors.forename: Conny
authors.initials: C
authors.lastname: Liljenberg
mesh_terms: D002462:Cell Membrane / Q000737:chemistry*; D002463:Cell Membrane Permeability; D003300:Copper; D019327:Copper Sulfate; D004578:Electron Spin Resonance Spectroscopy; D008563:Membrane Lipids / Q000737:chemistry* / Q000378:metabolism; D018384:Oxidative Stress; D018517:Plant Roots / Q000737:chemistry; D013113:Spin Labels; D014908:Triticum
chemical_list: D008563:Membrane Lipids; D013113:Spin Labels; D003300:Copper; D019327:Copper Sulfate