The mutation T315A in Candida albicans sterol 14alpha-demethylase causes reduced enzyme activity and fluconazole resistance through reduced affinity.
J Biol Chem
; 272(9): 5682-8, 1997 Feb 28.
Article
em En
| MEDLINE
| ID: mdl-9038178
ABSTRACT
Sterol 14alpha-demethylase (P45051) is the target for azole antifungal compounds, and resistance to these drugs and agrochemicals is of significant practical importance. We undertook site-directed mutagenesis of the Candida albicans P45051 heterologously expressed in Saccharomyces cerevisiae to probe a model structure for the enzyme. The change T315A reduced enzyme activity 2-fold as predicted for the removal of the residue that formed a hydrogen bond with the 3-OH of the sterol substrate and helped to locate it in the active site. This alteration perturbed the heme environment, causing an altered reduced carbon monoxide difference spectrum with a maximum at 445 nm. The changes also reduced the affinity of the enzyme for the azole antifungals ketoconazole and fluconazole and after expression induced by galactose caused 4-5-fold azole resistance in transformants of S. cerevisiae. This is the first example of a single base change in the target enzyme conferring resistance to azoles through reduced azole affinity.
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Base de dados:
MEDLINE
Assunto principal:
Oxirredutases
/
Candida albicans
/
Fluconazol
/
Sistema Enzimático do Citocromo P-450
/
Antifúngicos
Idioma:
En
Ano de publicação:
1997
Tipo de documento:
Article