title: Glucosylceramide biosynthesis is involved in Golgi morphology and protein secretion in plant cells.
abstract: Lipids have an established role as structural components of membranes or as signalling molecules, but their role as molecular actors in protein secretion is less clear. The complex sphingolipid glucosylceramide (GlcCer) is enriched in the plasma membrane and lipid microdomains of plant cells, but compared to animal and yeast cells, little is known about the role of GlcCer in plant physiology. We have investigated the influence of GlcCer biosynthesis by glucosylceramide synthase (GCS) on the efficiency of protein transport through the plant secretory pathway and on the maintenance of normal Golgi structure. We determined that GlcCer is synthesized at the beginning of the plant secretory pathway [mainly endoplasmic reticulum (ER)] and that D,L-threo-1-phenyl-2-decanoyl amino-3-morpholino-propanol (PDMP) is a potent inhibitor of plant GCS activity in vitro and in vivo. By an in vivo confocal microscopy approach in tobacco leaves infiltrated with PDMP, we showed that the decrease in GlcCer biosynthesis disturbed the transport of soluble and membrane secretory proteins to the cell surface, as these proteins were partly retained intracellularly in the ER and/or Golgi. Electron microscopic observations of Arabidopsis thaliana root cells after high-pressure freezing and freeze substitution evidenced strong morphological changes in the Golgi bodies, pointing to a link between decreased protein secretion and perturbations of Golgi structure following inhibition of GlcCer biosynthesis in plant cells.
authors.affiliation: Université V. Segalen Bordeaux 2, Laboratoire de Biogenèse Membranaire, CNRS UMR 5200, 146, rue Léo Saignat, 33076 Bordeaux Cedex, France.
authors.forename: Su
authors.initials: S
authors.lastname: Melser
authors.forename: Brigitte
authors.initials: B
authors.lastname: Batailler
authors.forename: Martine
authors.initials: M
authors.lastname: Peypelut
authors.forename: Christel
authors.initials: C
authors.lastname: Poujol
authors.forename: Yannick
authors.initials: Y
authors.lastname: Bellec
authors.forename: Valérie
authors.initials: V
authors.lastname: Wattelet-Boyer
authors.forename: Lilly
authors.initials: L
authors.lastname: Maneta-Peyret
authors.forename: Jean-Denis
authors.initials: JD
authors.lastname: Faure
authors.forename: Patrick
authors.initials: P
authors.lastname: Moreau
mesh_terms: D017360:Arabidopsis / Q000378:metabolism* / Q000648:ultrastructure; D029681:Arabidopsis Proteins / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000378:metabolism / Q000648:ultrastructure; D005963:Glucosylceramides / Q000037:antagonists & inhibitors / Q000096:biosynthesis*; D005964:Glucosyltransferases / Q000032:analysis / Q000378:metabolism*; D006056:Golgi Apparatus / Q000378:metabolism* / Q000648:ultrastructure; D009025:Morpholines / Q000378:metabolism; D021381:Protein Transport / Q000502:physiology; D014026:Nicotiana / Q000378:metabolism / Q000648:ultrastructure
chemical_list: D029681:Arabidopsis Proteins; D005963:Glucosylceramides; D009025:Morpholines; C033110:RV 538; D005964:Glucosyltransferases; C023246:ceramide glucosyltransferase