Dimorphism-associated Variations in the Lipid Composition of Candida albicans

Abstract

Yeast and mycelial forms of Candida albicans ATCC 10231, growing together in 12 h and in 96 h cultures, were separated and their lipids were extracted and characterized. The total lipid content of the yeast forms was always lower than that of the mycelial forms. In 12 h cultures the lipids from the two morphological forms consisted mainly of polar compounds, viz, phospholipids and glycolipids. In 96 h cultures both the yeast and mycelial forms accumulated substantial amounts of apolar compounds, mainly steryl esters and triacylglycerols. The mycelial forms were more active than the yeast forms in this respect. Major differences in the lipid composition between the two morphological forms involved the contents of sterols and complex lipids that contain sterols. As a rule, the yeast lipids contained much larger proportions of free sterols than the mycelial lipids. However, the mycelial lipids contained several times more sterols than the yeast forms but bound as steryl glycosides, esterified steryl glycosides and steryl esters. Steryl glycosides and esterified steryl glycosides occurred in yeast lipids only in traces, if at all. The major steryl glycoside in the mycelial forms was unequivocally identified as cholesteryl mannoside. At both phases of growth the apolar and polar lipid fractions from the mycelial forms contained higher levels of polyunsaturated fatty acids (18:2 and 18:3) but lower levels of oleic acid (18:1) than the corresponding fractions from the yeast forms. The lipid content and composition of 12 h and 96 h yeast and mycelial forms of C. albicans KCCC 14172, a clinical isolate, were almost identical with those of C. albicans ATCC 10231.

Paracoccidioides brasiliensis by ajoene is associated with blockade of phosphatidylcholine biosynthesis

“…Therefore, their proposed role in P. brasiliensis dimorphism (Manocha, 1980) is questioned. These results contrast with those found in C. albicans whose M form contains significantly higher levels of PC, PS and PI, and lower levels of PE, compared to the Y form (Goyal & Khuller, 1994 (Ghannoum et al, 1986;Mishra et al, 1992;Goyal & Khuller, 1994), the ratio of unsaturated to saturated fatty acids (UFA/SFA) was higher in the M form of P. brasiliensis ( Table 2). The higher levels of SFA in the Y form are probably required to maintain normal basic permeability properties of the plasma membranes at its relatively high growth temperature (Goyal & Khuller, 1994).…”

Cloning and Functional Expression of UGT Genes Encoding Sterol Glucosyltransferases from Saccharomyces cerevisiae, Candida albicans, Pichia pastoris, and Dictyostelium discoideum

“…Lipid analyses of other yeasts and fungi showed that some of them contain significantly larger amounts of sterol glycosides than Saccharomyces and that an increase in its synthesis was induced under stress conditions. 6 In this context, it should be mentioned that insertional mutagenesis experiments with the rice blast fungus Magnaporthe grisea and a subsequent screening procedure revealed mutants with reduced pathogenicity (74). One of these mutants identifies the gene PTH8 (GenBank TM accession number AF027983), the partial sequence of which shows striking similarity to the sterol glucosyltransferases from yeasts.…”

“…In contrast to S. cerevisiae, significant amounts of SG were occasionally found in other fungi such as C. bogoriensis (4) and Phytium sylvaticum (5), whereas sterol mannosides were detected in the human pathogen Candida albicans (6,7).…”

Construction and functional analysis of fatty acid desaturase gene disruptants in Candida albicans

“…However, the pathogenic roles of morphological changes remain to be elucidated, because both morphological forms are found in infected tissues and because the molecular mechanisms of the dimorphic transition have not yet been understood clearly. Interestingly, the level of UFAs tended to be higher in the mycelial form than in the yeast form (Sadamori, 1987;Yano et al, 1982;Ghannoum et al, 1986). There is immense interest in studying lipid pathways for several reasons: there are a limited number of effective and safe systemic antifungal drugs, lipids play an important role in pathogenicity and morphogenesis, and lipids provide potential targets for a novel class of antifungals.…”