HYDROPHOBIC CELL-WALL PROTEIN GLYCOSYLATION BY THE PATHOGENIC FUNGUS CANDIDA-ALBICANS

Cell surface hydrophobicity influences adhesion and virulence of the o pportunistic fungal pathogen Candida albicans. Previous studies have s hown that cell surface hydrophobicity is due to specific proteins that are exposed on hydrophobic cells but are masked by long fibrils on hy drophilic cells. This observation suggests that hydrophobic cell wall proteins may contain little or no mannosylation. In the present study, the glycosylation levels of three hydrophobic cell wall proteins (mol ecular mass range between 36 and 40 kDa) derived from yeast cells were examined. One hydrophilic protein (90 kDa) was also tested. Various e ndoglycosidases (endoglycosidase F-N-glycosidase F, O-glycosidase, bet a-mannosidase, N-glycosidase F), an exoglycosidase (alpha-mannosidase) , and trifluoromethane sulfonic acid were used to deglycosylate the pr oteins. Ah four proteins were reactive to the lectin concanavalin A, d emonstrating that they were mannoproteins. However, gel electrophoresi s of the control and treated proteins revealed that mannosyl groups of hydrophobic proteins were less than 2 kDa in size, while the mannosyl group of the hydrophilic protein had a molecular mass of approximatel y 20 kDa. These results suggest that unlike many hydrophilic proteins, hydrophobic proteins may have low levels of glycosylation. Changes in glycosylation may determine exposure of hydrophobic protein regions a t the cell surface.