Abstract
The yeast plasma membrane proton pumping ATPase (H+-ATPase) was investigated as a potential molecular target for antifungal drug therapy by examining the inhibitory effects of the sulfhydryl-reactive reagent omeprazole on cell growth, glucose-induced medium acidification and H+-ATPase activity. Omeprazole inhibits the growth of Saccharomyces cerevisiae and the human pathogenic yeast Candida albicans in a pH dependent manner. Omeprazole action is closely correlated with inhibition of the H+-ATPase and is fungicidal. Glucose-dependent medium acidification is correspondingly blocked by omeprazole and appears to require the H+-ATPase to proceed through its reaction cycle. A strong correlation is observed between inhibition of medium acidification and H+-ATPase activity in plasma membranes isolated from treated cells. The inhibitory properties of omeprazole are blocked by pre-treatment of activated drug with β-mercaptoethanol, which is consistent with the expected formation of a sulfhydryl-reactive sulfenamide derivative. Mutagenesis of the three putative membrane sector cysteine residues (C148S, C312S, C867A) in the S. cerevisiae H+-ATPase suggests that covalent modification of the conserved C148 residue may be important for inhibition of ATPase activity and cell growth. Other mutations (M128C and G158D/G156C) mapping near C148 support the importance of this region by modulating omeprazole inhibition of the H+-ATPase. These findings suggest that the plasma membrane H+-ATPase may serve as an important molecular target for antifungal intervention.
Original language | English |
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Pages (from-to) | 81-90 |
Number of pages | 10 |
Journal | Biochimica et Biophysica Acta - Biomembranes |
Volume | 1239 |
Issue number | 1 |
DOIs | |
State | Published - 4 Oct 1995 |
Externally published | Yes |
Keywords
- (Yeast)
- ATPase, H-
- Drug targeting
- Omeprazole
- Plasma membrane