Differences in the acid-labile component of Candida albicans mannan from hydrophobic and hydrophilic yeast cells

Abstract

Cell surface hydrophobicity of the opportunistic fungal pathogen Candida albicans has been linked to the level of cell wall protein glycosylation. Previous work demonstrated that outer chain mannosylation, rather than overall glycosylation, correlated with cell surface hydrophobicity. These studies further suggested that the phosphodiester-linked, acid-labile beta-1,2-mannan was the correlating element. The present work tests this hypothesis and extends the previous results. The composition of bulk mannan from hydrophobic and hydrophilic yeast cells, and the acid-labile mannan from both cell types are compared. Compositional analysis shows that the protein, hexose, and phosphorus content of bulk mannan is similar between the two phenotypes. Electrophoretic separation of acid-released and fluorophore-labeled mannan shows that the acid-labile oligomannosides from hydrophobic cells are longer and potentially in greater abundance than those from hydrophilic cells. These results suggest that regulation of a single step in cell wall protein outer chain mannosylation affects the cell surface ultrastructure and phenotype of C.albicans.

Candida albicansCell Wall Proteins

“…These studies implicated the protein recognized by MAb and perhaps the hydrophobic properties in the adherence of ligands and cells. The acid-released fraction of mannan from hydrophobic cells was longer and more abundant than that from hydrophilic cells (236), and hydrophobicity was independent of serotype A or B (235).…”

Comparison of the Hydrophobic Properties of Candida albicans and Candida dubliniensis

“…Jabra-Rizk et al recently reported that the surface fibrils of C. dubliniensis do not vary in architecture between cells grown at 25 and 37°C and that the fibrils resemble those seen on hydrophobic C. albicans cells (27,36). The mannosylation modification that appears primarily responsible for the change in the C. albicans N-glycan chain involves the acid labile ␤-1,2-oligomannoside group (41,42). Here we report that C. dubliniensis differs from C. albicans in its ability to express CSH and in its CSH-related glycoprotein components.…”

“…Cell wall glycans of C. albicans LGH1095 and C. dubliniensis CD36 were isolated and separated into mannan and glucan fractions as described previously (41,42). Briefly, cells are grown to stationary phase (26 h; third transfer) and washed and the cell pellet is dried.…”

“…The tubes were cooled to room temperature, and the solutions were neutralized with 1 N NaOH. The samples were transferred to 15-ml Corex tubes, and the acid-stable mannoprotein component was precipitated by the addition of 3 volumes of cold ethanol (42). Precipitation was extended by incubation at Ϫ20°C overnight.…”

“…The basis of these studies is our observation that CSH of C. albicans is due to the direct contribution of multiple surface proteins and the indirect contribution of surface protein N-mannosylation groups (26,27,31,41,42). One such protein, CAgp38, has been recently demonstrated to contribute strongly to attachment of hydrophobic cells to vascular endothelial cells when the yeast cells are exposed to physiologic shear by bulk flow (Glee et al, submitted for publication).…”