CELL-WALL PROTEIN MANNOSYLATION DETERMINES CANDIDA-ALBICANS CELL-SURFACE HYDROPHOBICITY

Cell surface hydrophobicity (CSH) has been shown to be an important fa ctor in the ability of the opportunistic pathogenic yeast Candida albi cans to adhere to surfaces. Hydrophobic cells adhere more readily to h ost tissue, and are more resistant to phagocytic killing, than hydroph ilic cells. Consequently, CSH plays an important role in the pathogeni city of C. albicans. Previous work suggested a relationship between CS H and cell wall protein glycosylation. The present work tests the hypo thesis that changes in outer chain mannosylation, rather than complete loss of oligosaccharide groups, are sufficient to modulate CSH. These studies compared wild-type cells to a variant that has altered mannos ylation and is hydrophobic under conditions in which wild-type cells a re hydrophilic. Composition analysis of cell surface digests showed th at the glycosylation of wild-type cell surface proteins was much more extensive than that seen in the variant. Antibodies which recognize th e acid-labile and acid-stable portions of C. albicans mannan showed no t only differences between wild-type and variant cells but also differ ences between wild-type hydrophilic and wild-type hydrophobic cells. T he results suggest that exposure of surface hydrophobic regions on C. albicans may be related to the abundance of phosphodiester-linked, aci d-labile mannosyl groups rather than the complete loss of outer chain mannosylation on cell wall proteins.