Inhibitors of CYP51 As Antifungal Agents and Resistance to Azole Antifungals

Kelly, Steven L.; Lamb, David C.; Kelly, Diane

doi:10.1007/978-1-4615-4855-3_11

Cited by 3 publications

(3 citation statements)

References 52 publications

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“…Resistance to azole antifungal compounds has been shown to be attributed to one or a combination of the following mechanisms: (i) reduced accumulation of the compound within the fungal cell, (ii) alteration of the ergosterol biosynthetic pathway to prevent formation of fungistatic sterols, and (iii) alteration in the target enzyme resulting in reduced affinity for the azole antifungal compound (6). In the present study we have proved at the biochemical level that the resistance mechanism resulting from the substitution R467K in CYP51 is due to reduced affinity for the drug.…”

Section: Discussionmentioning

confidence: 99%

“…We have been interested in elucidating the molecular mechanisms of azole antifungal resistance in C. albicans and other fungi. Previously, our work has shown that alteration of the ergosterol biosynthetic pathway by a defect in sterol ⌬ 5,6 -desaturase (responsible for the conversion of ergosta-7,22-dienol to ergosterol) results in resistance to azole antifungals in Saccharomyces cerevisiae, as indicated by Mendelian genetic segregation. Defects in sterol ⌬ 5,6 -desaturation were also found in azole-resistant C. albicans isolated from the clinic and in Ustilago maydis (3, 19; S. L. Kelly, D. C. Lamb, D. E. Kelly, J. Loeffler, and H. Einsele, Letter, Lancet 348:1523-1524).…”

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confidence: 98%

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The R467K Amino Acid Substitution in Candida albicans Sterol 14α-Demethylase Causes Drug Resistance through Reduced Affinity

Lamb

Kelly

White

et al. 2000

Antimicrob Agents Chemother

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116

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The cytochrome P450 sterol 14␣-demethylase (CYP51) of Candida albicans is involved in an essential step of ergosterol biosynthesis and is the target for azole antifungal compounds. We have undertaken site-directed mutation of C. albicans CYP51 to produce a recombinant mutant protein with the amino acid substitution R467K corresponding to a mutation observed clinically. This alteration perturbed the heme environment causing an altered reduced-carbon monoxide difference spectrum with a maximum at 452 nm and reduced the affinity of the enzyme for fluconazole, as shown by ligand binding studies. The specific activity of CYP51(R467K) for the release of formic acid from 3␤-[32-3 H]hydroxylanost-7-en-32-ol was 70 pmol/nmol of P450/min for microsomal protein compared to 240 pmol/nmol of P450/min for microsomal fractions expressing wild-type CYP51. Furthermore, inhibition of activity by fluconazole revealed a 7.5-fold-greater azole resistance of the recombinant protein than that of the wild type. This study demonstrates that resistance observed clinically can result from the altered azole affinity of the fungal CYP51 enzyme.

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 98%

The R467K Amino Acid Substitution in Candida albicans Sterol 14α-Demethylase Causes Drug Resistance through Reduced Affinity

Lamb

Kelly

White

et al. 2000

Antimicrob Agents Chemother

Self Cite

116

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“…Interestingly, quite a number of laboratory-based studies reported better performance of other azoles (itraconazole, voriconazole, posaconazole, and isavuconazole) including the new class of tetrazole compound, VT-1129, against cryptococcal species [10,[12][13][14][15][16][17][18][19][20][21]. Azole compounds exert their anti-fungal activity by inhibiting the enzyme cytochrome P450 monooxygenase (CYP/P450) CYP51 involved in the synthesis of fungal membrane ergosterol [22,23]. CYP51, also known as sterol 14α-demethylase, is highly conserved across the phyla and stimulates a key enzymatic reaction that involves stereoselective three-step oxidative removal of the 14α-methyl group from the sterol [24].…”

Section: Introductionmentioning

confidence: 99%

In Silico Structural Modeling and Analysis of Interactions of Tremellomycetes Cytochrome P450 Monooxygenases CYP51s with Substrates and Azoles

Akapo

Macnar

Krys

et al. 2021

IJMS

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Cytochrome P450 monooxygenase CYP51 (sterol 14α-demethylase) is a well-known target of the azole drug fluconazole for treating cryptococcosis, a life-threatening fungal infection in immune-compromised patients in poor countries. Studies indicate that mutations in CYP51 confer fluconazole resistance on cryptococcal species. Despite the importance of CYP51 in these species, few studies on the structural analysis of CYP51 and its interactions with different azole drugs have been reported. We therefore performed in silico structural analysis of 11 CYP51s from cryptococcal species and other Tremellomycetes. Interactions of 11 CYP51s with nine ligands (three substrates and six azoles) performed by Rosetta docking using 10,000 combinations for each of the CYP51-ligand complex (11 CYP51s × 9 ligands = 99 complexes) and hierarchical agglomerative clustering were used for selecting the complexes. A web application for visualization of CYP51s’ interactions with ligands was developed (http://bioshell.pl/azoledocking/). The study results indicated that Tremellomycetes CYP51s have a high preference for itraconazole, corroborating the in vitro effectiveness of itraconazole compared to fluconazole. Amino acids interacting with different ligands were found to be conserved across CYP51s, indicating that the procedure employed in this study is accurate and can be automated for studying P450-ligand interactions to cater for the growing number of P450s.

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The Diversity and Importance of Microbial Cytochromes P450

Kelly

Jackson

et al.

Cytochrome P450

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Inhibitors of CYP51 As Antifungal Agents and Resistance to Azole Antifungals

Cited by 3 publications

References 52 publications

The R467K Amino Acid Substitution in Candida albicans Sterol 14α-Demethylase Causes Drug Resistance through Reduced Affinity

The R467K Amino Acid Substitution in Candida albicans Sterol 14α-Demethylase Causes Drug Resistance through Reduced Affinity

In Silico Structural Modeling and Analysis of Interactions of Tremellomycetes Cytochrome P450 Monooxygenases CYP51s with Substrates and Azoles

The Diversity and Importance of Microbial Cytochromes P450

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