Abstract
Ceramides and glycosylceramides, including desaturated long-chain bases, are present in most fungi as well as animals and plants. However, as the budding yeast Saccharomyces cerevisiae is not capable of desaturating long-chain bases, little is known about the physiological roles of these compounds in fungi. To investigate the necessity of desaturation of long-chain backbones in ceramides and glucosylceramides in fungal cells, we have identified and characterized a sphingolipid Δ8-desaturase (SLD) gene from the pathogenic yeast Candida albicans. Gene disruption of the C. albicans SLD homologue led to the accumulation of (E)-sphing-4-enine, a main substrate for the SLD enzyme. Introducing the Candida SLD gene homologue into these mutant cells resulted in the recovery of synthesis of (4E, 8E)-sphinga-4,8-dienine and this gene homologue was therefore identified as a Ca-SLD gene. Additionally, the sld disruptant of C. albicans had a decreased hyphal growth rate compared with the wild-type strain. These results suggest that Δ8-desaturation of long-chain bases in ceramides plays a role in the morphogenesis of C. albicans.