Glucosylceramide Synthases, a Gene Family Responsible for the Biosynthesis of Glucosphingolipids in Animals, Plants, and Fungi

Abstract

Glucosylceramides are membrane lipids in most eukaryotic organisms and in a few bacteria. The physiological functions of these glycolipids have only been documented in mammalian cells, whereas very little information is available of their roles in plants, fungi, and bacteria. In an attempt to establish appropriate experimental systems to study glucosylceramide functions in these organisms, we performed a systematic functional analysis of a glycosyltransferase gene family with members of animal, plant, fungal, and bacterial origin. Deletion of such putative glycosyltransferase genes in Candida albicans and Pichia pastoris resulted in the complete loss of glucosylceramides. When the corresponding knock-out strains were used as host cells for homologous or heterologous expression of candidate glycosyltransferase genes, five novel glucosylceramide synthase (UDP-glucose:ceramide glucosyltransferase) genes were identified from the plant Gossypium arboreum (cotton), the nematode Caenorhabditis elegans, and the fungi Magnaporthe grisea, Candida albicans, and P. pastoris. The glycosyltransferase gene expressions led to the biosynthesis of different molecular species of glucosylceramides that contained either C18 or very long chain fatty acids. The latter are usually channeled exclusively into inositol-containing sphingolipids known from Saccharomyces cerevisiae and other yeasts. Implications for the biosynthesis, transport, and function of sphingolipids will be discussed.

Compatibility of conventional agrochemicals used in rice crops with the entomopathogenic fungus Metarhizium anisopliae

“…The compound 2,4-D acts by inhibiting the enzyme acetyl-CoA carboxylase, and as a result, prevents the biosynthesis of fatty acids and glucosylceramides, which are components of membrane lipids of animals, plants, and fungi (Leipelt et al, 2001). It remains unclear how the insecticide cypermethrin or other cypermethrin-based insecticides act on fungi.…”

Defensins from Insects and Plants Interact with Fungal Glucosylceramides

“…SYTOX Green was obtained from Molecular Probes (Eugene, OR). Yeast strains used in this study are S. cerevisiae strain BY4741 (Invitrogen), P. pastoris strain GS115 (Invitrogen) and the corresponding P. pastoris gcs-deletion strain (13), C. albicans strain SC5314 CAI4 (23) and the corresponding C. albicans gcs-deletion strain (13).…”

“…Are Resistant to RsAFP2-To investigate a possible role of GlcCer in RsAFP2-mediated growth inhibition, mutants of P. pastoris and C. albicans which are completely devoid of GlcCer were used (13). The gcs-deletion mutants and their corresponding parental strains were tested for sensitivity to growth inhibition by RsAFP2.…”

“…There is growing evidence that fungi maintain two separate pools of ceramides to be used for the synthesis of different sphingolipids (13)(14)(15). Ceramide backbones with very long chain C 24 and C 26 fatty acids bound to the sphingobase 4-hydroxysphinganine are directed to the synthesis of the inositolphosphoryl-containing sphingolipids (Fig.…”

Comprehensive Dissection of Spatiotemporal Metabolic Shifts in Primary, Secondary, and Lipid Metabolism during Developmental Senescence in Arabidopsis

“…3C), suggesting that the specific accumulation of these lipids was senescence dependent and, hence, provides a diagnostic marker. Reports that ceramide induces programmed cell death in Arabidopsis (Leipelt et al, 2001;Liang et al, 2003) and that lysolipids can activate phospholipase A, which generates fatty acids recognized as second messengers in the senescence process (Paul et al, 1998), support the importance of a rapid increase of these lipids in the yellowing regions for mediating the progression from senescence to cell death. Similar to the changes in ceramides and lysolipids, plastoquinone and ubiquinone also showed a senescence-dependent increase ( Figs.…”