Structural and functional aspects of fungal glycosphingolipids

Abstract

ABSTRACT: During the last decade, significant progress has been made on the field of biosynthesis and structural elucidation of fungal glycosphingolipids (GSLs), molecules composed of a hydrophobic ceramide moiety linked to one or more sugars. Ceramide monohexosides (CMHs) from several fungal species were characterized in detail, all of them presenting a ceramide moiety containing 9-methyl-4,8-sphingadienine in amidic linkage to 2-hydroxyoctadecanoic or 2-hydroxyhexadecanoic acids, and a carbohydrate portion consisting of one residue of glucose or galactose. CMHs seem to be associated with growth or differentiation of fungal species such as Pseudallescheria boydii, Candida albicans. Cryptococcus neoformans, Aspergillus nidulans, A. fumigatus , and Schizophyllum commune . A ceramide dihexoside (CDH) was recently described in Magnaporthe grisea . This glycolipid presented phytosphingosine as the long chain base, and this observation revealed the existence of alternative pathways of ceramide glycosylation in fungal cells. Glycoinositolphosphoryl ceramides (GIPCs), a class of acidic glycosphingolipids expressed by plants and certain parasitic organisms, but not in higher animals, were also identified in fungi, representing potential targets for the development of antifungal agents. The structural characterization of GIPCs, CMHs and, more recently, CDHs from fungal cells allows therefore the design of experimental models for studies involving biosynthesis and function of these molecules.