Contribution of clinically derived mutations in the gene encoding the zinc cluster transcription factor Mrr2 to fluconazole antifungal resistance and CDR1 expression in Candida albicans

Andrew T. Nishimoto, Qing Zhang, Brandon Hazlett, Joachim Morschhäuser, Phillip Rogers

Research output: Contribution to journalArticle

Abstract

Mutations in genes encoding zinc cluster transcription factors (ZCFs) such as TAC1, MRR1, and UPC2 play a key role in Candida albicans azole antifungal resistance. Artificial activation of the ZCF Mrr2 has shown increased expression of the gene encoding the Cdr1 efflux pump and resistance to fluconazole. Amino acid substitutions in Mrr2 have recently been reported to contribute to fluconazole resistance in clinical isolates. In the present study, 57 C. albicans clinical isolates with elevated fluconazole MICs were examined for mutations in MRR2 and expression of CDR1. Mutations in MRR2 resulting in 15 amino acid substitutions were uniquely identified among resistant isolates, including 4 substitutions (S466L, A468G, S469T, T470N) previously reported to reduce fluconazole susceptibility. Three additional, novel amino acid substitutions (R45Q, A459T, V486M) were also discovered in fluconazole-resistant isolates. When introduced into a fluconazole-susceptible background, no change in fluconazole MIC or CDR1 expression was observed for any of the mutations found in this collection. However, introduction of an allele leading to artificial activation of Mrr2 increased resistance to fluconazole as well as CDR1 expression. Moreover, Mrr2 amino acid changes reported previously to have the strongest effect on fluconazole susceptibility and CDR1 expression also exhibited no differences in fluconazole susceptibility or CDR1 expression relative to the parent strain. While all known fluconazole resistance mechanisms are represented within this collection of clinical isolates and contribute to fluconazole resistance to different extents, mutations in MRR2 do not appear to alter CDR1 expression or contribute to resistance in any of these isolates.

Original languageEnglish (US)
Article numbere00078-19
JournalAntimicrobial Agents and Chemotherapy
DOIs
StatePublished - May 1 2019

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Fluconazole
Candida albicans
Zinc
Transcription Factors
Mutation
Genes
Amino Acid Substitution
Azoles
Alleles

All Science Journal Classification (ASJC) codes

  • Pharmacology
  • Pharmacology (medical)
  • Infectious Diseases

Cite this

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title = "Contribution of clinically derived mutations in the gene encoding the zinc cluster transcription factor Mrr2 to fluconazole antifungal resistance and CDR1 expression in Candida albicans",
abstract = "Mutations in genes encoding zinc cluster transcription factors (ZCFs) such as TAC1, MRR1, and UPC2 play a key role in Candida albicans azole antifungal resistance. Artificial activation of the ZCF Mrr2 has shown increased expression of the gene encoding the Cdr1 efflux pump and resistance to fluconazole. Amino acid substitutions in Mrr2 have recently been reported to contribute to fluconazole resistance in clinical isolates. In the present study, 57 C. albicans clinical isolates with elevated fluconazole MICs were examined for mutations in MRR2 and expression of CDR1. Mutations in MRR2 resulting in 15 amino acid substitutions were uniquely identified among resistant isolates, including 4 substitutions (S466L, A468G, S469T, T470N) previously reported to reduce fluconazole susceptibility. Three additional, novel amino acid substitutions (R45Q, A459T, V486M) were also discovered in fluconazole-resistant isolates. When introduced into a fluconazole-susceptible background, no change in fluconazole MIC or CDR1 expression was observed for any of the mutations found in this collection. However, introduction of an allele leading to artificial activation of Mrr2 increased resistance to fluconazole as well as CDR1 expression. Moreover, Mrr2 amino acid changes reported previously to have the strongest effect on fluconazole susceptibility and CDR1 expression also exhibited no differences in fluconazole susceptibility or CDR1 expression relative to the parent strain. While all known fluconazole resistance mechanisms are represented within this collection of clinical isolates and contribute to fluconazole resistance to different extents, mutations in MRR2 do not appear to alter CDR1 expression or contribute to resistance in any of these isolates.",
author = "Nishimoto, {Andrew T.} and Qing Zhang and Brandon Hazlett and Joachim Morschh{\"a}user and Phillip Rogers",
year = "2019",
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T1 - Contribution of clinically derived mutations in the gene encoding the zinc cluster transcription factor Mrr2 to fluconazole antifungal resistance and CDR1 expression in Candida albicans

AU - Nishimoto, Andrew T.

AU - Zhang, Qing

AU - Hazlett, Brandon

AU - Morschhäuser, Joachim

AU - Rogers, Phillip

PY - 2019/5/1

Y1 - 2019/5/1

N2 - Mutations in genes encoding zinc cluster transcription factors (ZCFs) such as TAC1, MRR1, and UPC2 play a key role in Candida albicans azole antifungal resistance. Artificial activation of the ZCF Mrr2 has shown increased expression of the gene encoding the Cdr1 efflux pump and resistance to fluconazole. Amino acid substitutions in Mrr2 have recently been reported to contribute to fluconazole resistance in clinical isolates. In the present study, 57 C. albicans clinical isolates with elevated fluconazole MICs were examined for mutations in MRR2 and expression of CDR1. Mutations in MRR2 resulting in 15 amino acid substitutions were uniquely identified among resistant isolates, including 4 substitutions (S466L, A468G, S469T, T470N) previously reported to reduce fluconazole susceptibility. Three additional, novel amino acid substitutions (R45Q, A459T, V486M) were also discovered in fluconazole-resistant isolates. When introduced into a fluconazole-susceptible background, no change in fluconazole MIC or CDR1 expression was observed for any of the mutations found in this collection. However, introduction of an allele leading to artificial activation of Mrr2 increased resistance to fluconazole as well as CDR1 expression. Moreover, Mrr2 amino acid changes reported previously to have the strongest effect on fluconazole susceptibility and CDR1 expression also exhibited no differences in fluconazole susceptibility or CDR1 expression relative to the parent strain. While all known fluconazole resistance mechanisms are represented within this collection of clinical isolates and contribute to fluconazole resistance to different extents, mutations in MRR2 do not appear to alter CDR1 expression or contribute to resistance in any of these isolates.

AB - Mutations in genes encoding zinc cluster transcription factors (ZCFs) such as TAC1, MRR1, and UPC2 play a key role in Candida albicans azole antifungal resistance. Artificial activation of the ZCF Mrr2 has shown increased expression of the gene encoding the Cdr1 efflux pump and resistance to fluconazole. Amino acid substitutions in Mrr2 have recently been reported to contribute to fluconazole resistance in clinical isolates. In the present study, 57 C. albicans clinical isolates with elevated fluconazole MICs were examined for mutations in MRR2 and expression of CDR1. Mutations in MRR2 resulting in 15 amino acid substitutions were uniquely identified among resistant isolates, including 4 substitutions (S466L, A468G, S469T, T470N) previously reported to reduce fluconazole susceptibility. Three additional, novel amino acid substitutions (R45Q, A459T, V486M) were also discovered in fluconazole-resistant isolates. When introduced into a fluconazole-susceptible background, no change in fluconazole MIC or CDR1 expression was observed for any of the mutations found in this collection. However, introduction of an allele leading to artificial activation of Mrr2 increased resistance to fluconazole as well as CDR1 expression. Moreover, Mrr2 amino acid changes reported previously to have the strongest effect on fluconazole susceptibility and CDR1 expression also exhibited no differences in fluconazole susceptibility or CDR1 expression relative to the parent strain. While all known fluconazole resistance mechanisms are represented within this collection of clinical isolates and contribute to fluconazole resistance to different extents, mutations in MRR2 do not appear to alter CDR1 expression or contribute to resistance in any of these isolates.

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