Sterol 14α-Demethylase: Target of the Azole Antifungal Agents

Kelly, S. L.; Quail, Michael A.; Rowe, Jeremy; Kelly, Diane

doi:10.1007/978-1-4899-6729-9_9

Cited by 8 publications

(2 citation statements)

References 72 publications

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“…1). Terbinafine (TBF) is an allylamine that inhibits ergosterol biosynthesis in fungi and Leishmania by targeting squalene epoxidase (29 -31), and itraconazole (ITZ) is an azole that inhibits a subsequent step, the P450-dependent lanosterol C 14 -demethylase (31)(32)(33).…”

Section: A Test Of Overexpression/selection: Mtx Resistance-methotrexmentioning

confidence: 99%

Isolation of Genes Mediating Resistance to Inhibitors of Nucleoside and Ergosterol Metabolism in Leishmania by Overexpression/Selection

Cotrim¹,

Garrity²,

Beverley³

1999

Journal of Biological Chemistry

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We tested a general method for the identification of drug resistance loci in the trypanosomatid protozoan parasite Leishmania major. Genomic libraries in a multicopy episomal cosmid vector were transfected into susceptible parasites, and drug selections of these transfectant libraries yielded parasites bearing cosmids mediating resistance. Tests with two antifolates led to the recovery of cosmids encoding DHFR-TS or PTR1, two known resistance genes. Overexpression/selection using the toxic nucleoside tubercidin similarly yielded the TOR (toxic nucleoside resistance) locus, as well as a new locus (TUB2) conferring collateral hypersensitivity to allopurinol. Leishmania synthesize ergosterol rather than cholesterol, making this pathway attractive as a chemotherapeutic target. Overexpression/selection using the sterol synthesis inhibitors terbinafine (TBF, targeting squalene epoxidase) and itraconazole (ITZ, targeting lanosterol C 14 -demethylase) yielded nine new resistance loci. Several conferred resistance to both drugs; several were drug-specific, and two TBF-resistant cosmids induced hypersensitivity to ITZ. One TBFresistant cosmid encoded squalene synthase (SQS1), which is located upstream of the sites of TBF and ITZ action in the ergosterol biosynthetic pathway. This suggests that resistance to "downstream" inhibitors can be mediated by increased expression of ergosterol biosynthetic intermediates. Our studies establish the feasibility of overexpression/selection in parasites and suggest that many Leishmania drug resistance loci are amenable to identification in this manner.

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Section: A Test Of Overexpression/selection: Mtx Resistance-methotrexmentioning

confidence: 99%

Isolation of Genes Mediating Resistance to Inhibitors of Nucleoside and Ergosterol Metabolism in Leishmania by Overexpression/Selection

Cotrim¹,

Garrity²,

Beverley³

1999

Journal of Biological Chemistry

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“…Azole anti-fungal compounds are used widely in medicine and agriculture and are known to act as cytochrome P450 (P450) inhibitors (for review, see [1]). The predominant P450 of vegetatively growing yeast cells is responsible for sterol 14ademethylation as part of the pathway for ergosterol biosynthesis [2].…”

Section: Introductionmentioning

confidence: 99%

Studies on azole-induced cell death in Saccharomyces cerevisiae

Kelly

1994

FEMS Microbiology Letters

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The Saccharomyces cerevisiae strain XL16-5B exhibited a fungicidal response to treatment with ketoconazole. Cell death became apparent during prolonged treatment over 72 h following an initial period over 24 h where viable cells were found and limited cell division occurred. Sterol analysis showed some differences between XL16-5B and the strain XY729-5a, which had a fungistatic response to ketoconazole. In particular, the level of ergosterol was higher in XL16-5B and remained high during treatment.

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