MOLECULAR ANALYSIS OF CYP51 FROM FLUCONAZOLE-RESISTANT CANDIDA-ALBICANS STRAINS

The target enzyme for fluconazole is sterol 14 alpha-demethylase, a cy tochrome P450 encoded by cyp51. One mechanism of fluconazole resistanc e likely to occur in Candida albicans is through an altered target sit e. To test this hypothesis DNA sequencing of the cyp51 coding sequence from 19 fluconazole-resistant and 19 fluconazole-sensitive C. albican s was undertaken. A number of point mutations were identified in the r esistant isolates which were not present in the sensitive ones: F105L (five), E266D (five), K287R (one), G448G (one), G450E (one), G464S (th ree) and V488I (one). These alterations are discussed in the light of a molecular model of the enzyme regarding potential roles in resistanc e. It was also demonstrated that sequence-specific primers can be empl oyed to identify polymorphisms which may be associated with resistance ; diagnostic tests for resistant strains will prove of value in combat ing this serious clinical problem.