Affiliation:
1. 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 (M.L., A.M.P., L.C., S.M., M.V., R.L., P.M.); Laboratoire de Physiologie Cellulaire et Moléculaire des Plantes, Unité Mixte de Recherche 2846-Centre National de la Recherche Scientifique, Université Pierre et M
Abstract
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 Δ5-sterols are replaced by 9β,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 Δ5-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.
Publisher
Oxford University Press (OUP)
Subject
Plant Science,Genetics,Physiology
Cited by
151 articles.
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