title: Cell wall polysaccharide synthases are located in detergent-resistant membrane microdomains in oomycetes.
abstract: The pathways responsible for cell wall polysaccharide biosynthesis are vital in eukaryotic microorganisms. The corresponding synthases are potential targets of inhibitors such as fungicides. Despite their fundamental and economical importance, most polysaccharide synthases are not well characterized, and their molecular mechanisms are poorly understood. With the example of Saprolegnia monoica as a model organism, we show that chitin and (1-->3)-beta-d-glucan synthases are located in detergent-resistant membrane microdomains (DRMs) in oomycetes, a phylum that comprises some of the most devastating microorganisms in the agriculture and aquaculture industries. Interestingly, no cellulose synthase activity was detected in the DRMs. The purified DRMs exhibited similar biochemical features as lipid rafts from animal, plant, and yeast cells, although they contained some species-specific lipids. This report sheds light on the lipid environment of the (1-->3)-beta-d-glucan and chitin synthases, as well as on the sterol biosynthetic pathways in oomycetes. The results presented here are consistent with a function of lipid rafts in cell polarization and as platforms for sorting specific sets of proteins targeted to the plasma membrane, such as carbohydrate synthases. The involvement of DRMs in the biosynthesis of major cell wall polysaccharides in eukaryotic microorganisms suggests a function of lipid rafts in hyphal morphogenesis and tip growth.
authors.affiliation: UMR CNRS 5246-Organisation et Dynamique des Membranes Biologiques, Université Lyon 1, 43 Boulevard du 11 Novembre 1918, 69622 Villeurbanne Cedex, France.
authors.forename: Anne
authors.initials: A
authors.lastname: Briolay
authors.forename: Jamel
authors.initials: J
authors.lastname: Bouzenzana
authors.forename: Michel
authors.initials: M
authors.lastname: Guichardant
authors.forename: Christian
authors.initials: C
authors.lastname: Deshayes
authors.forename: Nicolas
authors.initials: N
authors.lastname: Sindt
authors.forename: Laurence
authors.initials: L
authors.lastname: Bessueille
authors.forename: Vincent
authors.initials: V
authors.lastname: Bulone
mesh_terms: D020418:Algal Proteins / Q000032:analysis*; D002687:Chitin Synthase / Q000032:analysis*; D005964:Glucosyltransferases / Q000032:analysis*; D021962:Membrane Microdomains / Q000737:chemistry*; D044762:Saprolegnia / Q000737:chemistry* / Q000201:enzymology*
chemical_list: D020418:Algal Proteins; C036655:1,3-alpha-D-glucan synthase; D005964:Glucosyltransferases; C478648:cellulose synthase; D002687:Chitin Synthase