Insights into the role of specific lipids in the formation and delivery of lipid microdomains to the plasma membrane of plant cells.
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.
Laloi
Maryse
M
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.
Perret
Anne-Marie
AM
Chatre
Laurent
L
Melser
Su
S
Cantrel
Catherine
C
Vaultier
Marie-Noëlle
MN
Zachowski
Alain
A
Bathany
Katell
K
Schmitter
Jean-Marie
JM
Vallet
Myriam
M
Lessire
René
R
Hartmann
Marie-Andrée
MA
Moreau
Patrick
P
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
D008563:Membrane Lipids; D009025:Morpholines; D010743:Phospholipids; D013261:Sterols; C050435:fenpropimorph; D013251:Steroid Isomerases; C039925:cycloeucalenol-obtusifol isomerase