Glucosylceramide biosynthesis is involved in Golgi morphology and protein secretion in plant cells

Su Melser (1, 2) , Brigitte Batailler (3) , Martine Peypelut (3) , Christel Poujol (4) , Yannick Bellec (5) , Valérie Wattelet-Boyer (1, 2) , Lilly Maneta-Peyret (1, 2) , Jean Denis Faure (5) , Patrick Moreau (6, 2)

1 LBM - Laboratoire de biogenèse membranaire
2 Université Bordeaux Segalen - Bordeaux 2
3 GD2P - Génomique, développement et pouvoir pathogène
4 BIC - Bordeaux Imaging Center
5 IJPB - Institut Jean-Pierre Bourgin
6 EPHYSE - Écologie fonctionnelle et physique de l'environnement

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.

Mots clés: glucosylceramide; golgi bodies; plant cells; protein transport; secretion; arabidopsis metabolism; arabidopsis ultrastructure; arabidopsis proteins metabolism; endoplasmic reticulum; ultrastructure; glucosylceramides antagonists and inhibitors; glucosylceramides biosynthesis; glucosyltransferases analysis; glucosyltransferases metabolism; golgi apparatus metabolism; golgi apparatus ultrastructure; morpholines metabolism; protein transport physiology; tobacco metabolism; tobacco ultrastructure; métabolisme du tabac; ultrastructure du tabac

Domaines: Sciences du Vivant [q-bio]

Su Melser, Brigitte Batailler, Martine Peypelut, Christel Poujol, Yannick Bellec, et al.. Glucosylceramide biosynthesis is involved in Golgi morphology and protein secretion in plant cells. Traffic, 2010, 11 (4), pp.479-490. ⟨10.1111/j.1600-0854.2009.01030.x⟩. ⟨hal-01203898⟩