title: Insights into the role of specific lipids in the formation and delivery of lipid microdomains to the plasma membrane of plant cells.
abstract: The existence of sphingolipid- and sterol-enriched microdomains, known as lipid rafts, in the plasma membrane (PM) of eukaryotic cells is well documented. To obtain more insight into the lipid molecular species required for the formation of microdomains in plants, we have isolated detergent (Triton X-100)-resistant membranes (DRMs) from the PM of Arabidopsis (Arabidopsis thaliana) and leek (Allium porrum) seedlings as well as from Arabidopsis cell cultures. Here, we show that all DRM preparations are enriched in sterols, sterylglucosides, and glucosylceramides (GluCer) and depleted in glycerophospholipids. The GluCer of DRMs from leek seedlings contain hydroxypalmitic acid. We investigated the role of sterols in DRM formation along the secretory pathway in leek seedlings. We present evidence for the presence of DRMs in both the PM and the Golgi apparatus but not in the endoplasmic reticulum. In leek seedlings treated with fenpropimorph, a sterol biosynthesis inhibitor, the usual Delta(5)-sterols are replaced by 9beta,19-cyclopropylsterols. In these plants, sterols and hydroxypalmitic acid-containing GluCer do not reach the PM, and most DRMs are recovered from the Golgi apparatus, indicating that Delta(5)-sterols and GluCer play a crucial role in lipid microdomain formation and delivery to the PM. In addition, DRM formation in Arabidopsis cells is shown to depend on the unsaturation degree of fatty acyl chains as evidenced by the dramatic decrease in the amount of DRMs prepared from the Arabidopsis mutants, fad2 and Fad3+, affected in their fatty acid desaturases.
authors.affiliation: Laboratoire de Biogenèse Membranaire, Unité Mixte de Recherche 5200-Centre National de la Recherche Scientifique-Université Victor Segalen Bordeaux 2, BP 33076 Bordeaux cedex, France.
authors.forename: Maryse
authors.initials: M
authors.lastname: Laloi
authors.forename: Anne-Marie
authors.initials: AM
authors.lastname: Perret
authors.forename: Laurent
authors.initials: L
authors.lastname: Chatre
authors.forename: Su
authors.initials: S
authors.lastname: Melser
authors.forename: Catherine
authors.initials: C
authors.lastname: Cantrel
authors.forename: Marie-Noëlle
authors.initials: MN
authors.lastname: Vaultier
authors.forename: Alain
authors.initials: A
authors.lastname: Zachowski
authors.forename: Katell
authors.initials: K
authors.lastname: Bathany
authors.forename: Jean-Marie
authors.initials: JM
authors.lastname: Schmitter
authors.forename: Myriam
authors.initials: M
authors.lastname: Vallet
authors.forename: René
authors.initials: R
authors.lastname: Lessire
authors.forename: Marie-Andrée
authors.initials: MA
authors.lastname: Hartmann
authors.forename: Patrick
authors.initials: P
authors.lastname: Moreau
mesh_terms: D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D001692:Biological Transport / Q000502:physiology; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism*; D002478:Cells, Cultured; D008563:Membrane Lipids / Q000378:metabolism / Q000502:physiology*; D021962:Membrane Microdomains / Q000378:metabolism*; D008861:Microsomes / Q000378:metabolism; D009025:Morpholines / Q000494:pharmacology; D009154:Mutation; D019697:Onions / Q000187:drug effects / Q000378:metabolism*; D010743:Phospholipids / Q000378:metabolism; D036226:Seedlings / Q000187:drug effects / Q000378:metabolism; D013251:Steroid Isomerases / Q000037:antagonists & inhibitors; D013261:Sterols / Q000378:metabolism; D013347:Subcellular Fractions
chemical_list: D008563:Membrane Lipids; D009025:Morpholines; D010743:Phospholipids; D013261:Sterols; C050435:fenpropimorph; D013251:Steroid Isomerases; C039925:cycloeucalenol-obtusifol isomerase