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An acquired mechanism of antifungal drug resistance simultaneously enables Candida albicans to escape from intrinsic host defenses

Please always quote using this URN: urn:nbn:de:bvb:20-opus-158883
  • The opportunistic fungal pathogen Candida albicans frequently produces genetically altered variants to adapt to environmental changes and new host niches in the course of its life-long association with the human host. Gain-of-function mutations in zinc cluster transcription factors, which result in the constitutive upregulation of their target genes, are a common cause of acquired resistance to the widely used antifungal drug fluconazole, especially during long-term therapy of oropharyngeal candidiasis. In this study, we investigated if C.The opportunistic fungal pathogen Candida albicans frequently produces genetically altered variants to adapt to environmental changes and new host niches in the course of its life-long association with the human host. Gain-of-function mutations in zinc cluster transcription factors, which result in the constitutive upregulation of their target genes, are a common cause of acquired resistance to the widely used antifungal drug fluconazole, especially during long-term therapy of oropharyngeal candidiasis. In this study, we investigated if C. albicans also can develop resistance to the antimicrobial peptide histatin 5, which is secreted in the saliva of humans to protect the oral mucosa from pathogenic microbes. As histatin 5 has been shown to be transported out of C. albicans cells by the Flu1 efflux pump, we screened a library of C. albicans strains that contain artificially activated forms of all zinc cluster transcription factors of this fungus for increased FLU1 expression. We found that a hyperactive Mrr1, which confers fluconazole resistance by upregulating the multidrug efflux pump MDR1 and other genes, also causes FLU1 overexpression. Similarly to the artificially activated Mrr1, naturally occurring gain-of-function mutations in this transcription factor also caused FLU1 upregulation and increased histatin 5 resistance. Surprisingly, however, Mrr1-mediated histatin 5 resistance was mainly caused by the upregulation of MDR1 instead of FLU1, revealing a previously unrecognized function of the Mdr1 efflux pump. Fluconazole-resistant clinical C. albicans isolates with different Mrr1 gain-of-function mutations were less efficiently killed by histatin 5, and this phenotype was reverted when MRR1 was deleted. Therefore, antimycotic therapy can promote the evolution of strains that, as a consequence of drug resistance mutations, simultaneously have acquired increased resistance against an innate host defense mechanism and are thereby better adapted to certain host niches.show moreshow less

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Metadaten
Author: Irene A. I. Hampe, Justin Friedman, Mira Edgerton, Joachim Morschhäuser
URN:urn:nbn:de:bvb:20-opus-158883
Document Type:Journal article
Faculties:Medizinische Fakultät / Institut für Molekulare Infektionsbiologie
Language:English
Parent Title (English):PLoS Pathogens
Year of Completion:2017
Volume:13
Issue:9
Pagenumber:e1006655
Source:PLoS Pathogens 13(9): e1006655 (2017). DOI: 10.1371/journal.ppat.1006655
DOI:https://doi.org/10.1371/journal.ppat.1006655
Dewey Decimal Classification:5 Naturwissenschaften und Mathematik / 57 Biowissenschaften; Biologie / 570 Biowissenschaften; Biologie
Tag:Candida albicans; antifungals; antimicrobial resistance; hyperexpression techniques; mutation; point mutation; transcription factors; transcriptional control
Release Date:2018/03/27
Collections:Open-Access-Publikationsfonds / Förderzeitraum 2017
Licence (German):License LogoCC BY: Creative-Commons-Lizenz: Namensnennung 4.0 International