OBJECTIVES: Functional characterization of the erg1 mutant of ergosterol biosynthesis of Candida albicans. METHODS: We disrupted the ERG1 gene of C. albicans, which encodes squalene epoxidase (EC 1.14.99.7). Since the disruption of both alleles of ERG1 was lethal, the second allele of a heterozygous disruptant was placed under the control of a regulable promoter, MET3p, which is repressed by methionine and cysteine. RESULTS: The reverse-phase HPLC analysis of sterol, extracted from the conditional mutant strain, showed a total lack of ergosterol and instead accumulation of squalene. This imbalance in sterol composition led to defects in growth and increased susceptibilities to drugs including fluconazole, ketoconazole, cycloheximide, nystatin, amphotericin B and terbinafine. Reduced drug efflux activity of the erg1 mutant was associated with poor surface localization of Cdr1p, suggesting that enhanced passive diffusion and reduced efflux mediated by the ABC (ATP binding cassette) transporter Cdr1p increases drug susceptibility. Additionally, conditional erg1 mutant strains were unable to form hyphae in various media. CONCLUSIONS: Taken together, our results demonstrate that the absence of ergosterol, which is one of the constituents of membrane microdomains (rafts), has a direct effect on drug susceptibility and morphogenesis of C. albicans.
OBJECTIVES: Functional characterization of the erg1 mutant of ergosterol biosynthesis of Candida albicans. METHODS: We disrupted the ERG1 gene of C. albicans, which encodes squalene epoxidase (EC 1.14.99.7). Since the disruption of both alleles of ERG1 was lethal, the second allele of a heterozygous disruptant was placed under the control of a regulable promoter, MET3p, which is repressed by methionine and cysteine. RESULTS: The reverse-phase HPLC analysis of sterol, extracted from the conditional mutant strain, showed a total lack of ergosterol and instead accumulation of squalene. This imbalance in sterol composition led to defects in growth and increased susceptibilities to drugs including fluconazole, ketoconazole, cycloheximide, nystatin, amphotericin B and terbinafine. Reduced drug efflux activity of the erg1 mutant was associated with poor surface localization of Cdr1p, suggesting that enhanced passive diffusion and reduced efflux mediated by the ABC (ATP binding cassette) transporter Cdr1p increases drug susceptibility. Additionally, conditional erg1 mutant strains were unable to form hyphae in various media. CONCLUSIONS: Taken together, our results demonstrate that the absence of ergosterol, which is one of the constituents of membrane microdomains (rafts), has a direct effect on drug susceptibility and morphogenesis of C. albicans.
Authors: Prasanna D Khot; Peter A Suci; R Lance Miller; Raoul D Nelson; Bonnie J Tyler Journal: Antimicrob Agents Chemother Date: 2006-09-11 Impact factor: 5.191
Authors: Mengping Liu; Matthew D Healy; Brian A Dougherty; Kim M Esposito; Trina C Maurice; Charles E Mazzucco; Robert E Bruccoleri; Daniel B Davison; Marybeth Frosco; John F Barrett; Ying-Kai Wang Journal: Eukaryot Cell Date: 2006-04
Authors: Thomas Lettner; Ute Zeidler; Mario Gimona; Michael Hauser; Michael Breitenbach; Arnold Bito Journal: PLoS One Date: 2010-08-05 Impact factor: 3.240
Authors: Michael D Lafleur; Lingmei Sun; Ida Lister; John Keating; Andre Nantel; Lisa Long; Mahmoud Ghannoum; Jeffrey North; Richard E Lee; Ken Coleman; Thomas Dahl; Kim Lewis Journal: Antimicrob Agents Chemother Date: 2013-05-20 Impact factor: 5.191