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Contributions of both ATP-Binding Cassette Transporter and Cyp51A Proteins Are Essential for Azole Resistance in Aspergillus fumigatus. Antimicrob Agents Chemother 2017; 61:AAC.02748-16. [PMID: 28264842 DOI: 10.1128/aac.02748-16] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2016] [Accepted: 02/27/2017] [Indexed: 01/30/2023] Open
Abstract
While azole drugs targeting the biosynthesis of ergosterol are effective antifungal agents, their extensive use has led to the development of resistant organisms. Infections involving azole-resistant forms of the filamentous fungus Aspergillus fumigatus are often associated with genetic changes in the cyp51A gene encoding the lanosterol α14 demethylase target enzyme. Both a sequence duplication in the cyp51A promoter (TR34) and a substitution mutation in the coding sequence (L98H) are required for the full expression of azole resistance. A mechanism commonly observed in pathogenic yeast such as Candida albicans involves gain-of-function mutations in transcriptional regulatory proteins that induce expression of genes encoding ATP-binding cassette (ABC) transporters. We and others have found that an ABC transporter protein called Cdr1B (here referred to as AbcG1) is required for wild-type azole resistance in A. fumigatus Here, we test the genetic relationship between the TR34 L98H allele of cyp51A and an abcG1 null mutation. Loss of AbcG1 from a TR34 L98H cyp51A-containing strain caused a large decrease in the azole resistance of the resulting double-mutant strain. We also generated antibodies that enabled the detection of both the wild-type and L98H forms of the Cyp51A protein. The introduction of the L98H lesion into the cyp51A gene led to a decreased production of immunoreactive enzyme, suggesting that this mutant protein is unstable. Our data confirm the importance of AbcG1 function during azole resistance even in a strongly drug-resistant background.
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Hagiwara D, Miura D, Shimizu K, Paul S, Ohba A, Gonoi T, Watanabe A, Kamei K, Shintani T, Moye-Rowley WS, Kawamoto S, Gomi K. A Novel Zn2-Cys6 Transcription Factor AtrR Plays a Key Role in an Azole Resistance Mechanism of Aspergillus fumigatus by Co-regulating cyp51A and cdr1B Expressions. PLoS Pathog 2017; 13:e1006096. [PMID: 28052140 PMCID: PMC5215518 DOI: 10.1371/journal.ppat.1006096] [Citation(s) in RCA: 96] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Accepted: 11/28/2016] [Indexed: 02/08/2023] Open
Abstract
Successful treatment of aspergillosis caused by Aspergillus fumigatus is threatened by an increasing incidence of drug resistance. This situation is further complicated by the finding that strains resistant to azoles, the major antifungal drugs for aspergillosis, have been widely disseminated across the globe. To elucidate mechanisms underlying azole resistance, we identified a novel transcription factor that is required for normal azole resistance in Aspergillus fungi including A. fumigatus, Aspergillus oryzae, and Aspergillus nidulans. This fungal-specific Zn2-Cys6 type transcription factor AtrR was found to regulate expression of the genes related to ergosterol biosynthesis, including cyp51A that encodes a target protein of azoles. The atrR deletion mutant showed impaired growth under hypoxic conditions and attenuation of virulence in murine infection model for aspergillosis. These results were similar to the phenotypes for a mutant strain lacking SrbA that is also a direct regulator for the cyp51A gene. Notably, AtrR was responsible for the expression of cdr1B that encodes an ABC transporter related to azole resistance, whereas SrbA was not involved in the regulation. Chromatin immunoprecipitation assays indicated that AtrR directly bound both the cyp51A and cdr1B promoters. In the clinically isolated itraconazole resistant strain that harbors a mutant Cyp51A (G54E), deletion of the atrR gene resulted in a hypersensitivity to the azole drugs. Together, our results revealed that AtrR plays a pivotal role in a novel azole resistance mechanism by co-regulating the drug target (Cyp51A) and putative drug efflux pump (Cdr1B).
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Affiliation(s)
- Daisuke Hagiwara
- Medical Mycology Research Center, Chiba University, Chiba, Japan
- * E-mail: (DH); (KG)
| | - Daisuke Miura
- Department of Bioindustrial Informatics and Genomics, Graduate School of Agricultural Science, Tohoku University, Sendai, Japan
| | - Kiminori Shimizu
- Medical Mycology Research Center, Chiba University, Chiba, Japan
| | - Sanjoy Paul
- Department of Molecular Physiology and Biophysics, Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America
| | - Ayumi Ohba
- Department of Bioindustrial Informatics and Genomics, Graduate School of Agricultural Science, Tohoku University, Sendai, Japan
| | - Tohru Gonoi
- Medical Mycology Research Center, Chiba University, Chiba, Japan
| | - Akira Watanabe
- Medical Mycology Research Center, Chiba University, Chiba, Japan
| | - Katsuhiko Kamei
- Medical Mycology Research Center, Chiba University, Chiba, Japan
| | - Takahiro Shintani
- Department of Bioindustrial Informatics and Genomics, Graduate School of Agricultural Science, Tohoku University, Sendai, Japan
| | - W. Scott Moye-Rowley
- Department of Molecular Physiology and Biophysics, Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America
| | - Susumu Kawamoto
- Medical Mycology Research Center, Chiba University, Chiba, Japan
| | - Katsuya Gomi
- Department of Bioindustrial Informatics and Genomics, Graduate School of Agricultural Science, Tohoku University, Sendai, Japan
- * E-mail: (DH); (KG)
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Hagiwara D, Watanabe A, Kamei K, Goldman GH. Epidemiological and Genomic Landscape of Azole Resistance Mechanisms in Aspergillus Fungi. Front Microbiol 2016; 7:1382. [PMID: 27708619 PMCID: PMC5030247 DOI: 10.3389/fmicb.2016.01382] [Citation(s) in RCA: 113] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Accepted: 08/22/2016] [Indexed: 11/13/2022] Open
Abstract
Invasive aspergillosis is a life-threatening mycosis caused by the pathogenic fungus Aspergillus. The predominant causal species is Aspergillus fumigatus, and azole drugs are the treatment of choice. Azole drugs approved for clinical use include itraconazole, voriconazole, posaconazole, and the recently added isavuconazole. However, epidemiological research has indicated that the prevalence of azole-resistant A. fumigatus isolates has increased significantly over the last decade. What is worse is that azole-resistant strains are likely to have emerged not only in response to long-term drug treatment but also because of exposure to azole fungicides in the environment. Resistance mechanisms include amino acid substitutions in the target Cyp51A protein, tandem repeat sequence insertions at the cyp51A promoter, and overexpression of the ABC transporter Cdr1B. Environmental azole-resistant strains harboring the association of a tandem repeat sequence and punctual mutation of the Cyp51A gene (TR34/L98H and TR46/Y121F/T289A) have become widely disseminated across the world within a short time period. The epidemiological data also suggests that the number of Aspergillus spp. other than A. fumigatus isolated has risen. Some non-fumigatus species intrinsically show low susceptibility to azole drugs, imposing the need for accurate identification, and drug susceptibility testing in most clinical cases. Currently, our knowledge of azole resistance mechanisms in non-fumigatus Aspergillus species such as A. flavus, A. niger, A. tubingensis, A. terreus, A. fischeri, A. lentulus, A. udagawae, and A. calidoustus is limited. In this review, we present recent advances in our understanding of azole resistance mechanisms particularly in A. fumigatus. We then provide an overview of the genome sequences of non-fumigatus species, focusing on the proteins related to azole resistance mechanisms.
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Affiliation(s)
| | - Akira Watanabe
- Medical Mycology Research Center, Chiba University Chiba, Japan
| | - Katsuhiko Kamei
- Medical Mycology Research Center, Chiba University Chiba, Japan
| | - Gustavo H Goldman
- Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo Ribeirão Preto, Brazil
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Yeast ABC transporters in lipid trafficking. Fungal Genet Biol 2016; 93:25-34. [DOI: 10.1016/j.fgb.2016.05.008] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Revised: 05/28/2016] [Accepted: 05/31/2016] [Indexed: 12/31/2022]
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55
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Antoniêto ACC, de Paula RG, Castro LDS, Silva-Rocha R, Persinoti GF, Silva RN. Trichoderma reesei CRE1-mediated Carbon Catabolite Repression in Re-sponse to Sophorose Through RNA Sequencing Analysis. Curr Genomics 2016; 17:119-31. [PMID: 27226768 PMCID: PMC4864841 DOI: 10.2174/1389202917666151116212901] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2015] [Revised: 05/28/2015] [Accepted: 06/15/2015] [Indexed: 01/10/2023] Open
Abstract
Carbon catabolite repression (CCR) mediated by CRE1 in Trichoderma reesei emerged as a mechanism by which the fungus could adapt to new environments. In the presence of readily available carbon sources such as glucose, the fungus activates this mechanism and inhibits the production of cellulolytic complex enzymes to avoid unnecessary energy expenditure. CCR has been well described for the growth of T. reesei in cellulose and glucose, however, little is known about this process when the carbon source is sophorose, one of the most potent inducers of cellulase production. Thus, we performed high-throughput RNA sequencing to better understand CCR during cellulase formation in the presence of sophorose, by comparing the mutant ∆cre1 with its parental strain, QM9414. Of the 9129 genes present in the genome of T. reesei, 184 were upregulated and 344 downregulated in the mutant strain ∆cre1 compared to QM9414. Genes belonging to the CAZy database, and those encoding transcription factors and transporters are among the gene classes that were repressed by CRE1 in the presence of sophorose; most were possible indirectly regulated by CRE1. We also observed that CRE1 activity is carbon-dependent. A recent study from our group showed that in cellulose, CRE1 repress different groups of genes when compared to sophorose. CCR differences between these carbon sources may be due to the release of cellodextrins in the cellulose polymer, resulting in different targets of CRE1 in both carbon sources. These results contribute to a better understanding of CRE1-mediated CCR in T. reesei when glucose comes from a potent inducer of cellulase production such as sophorose, which could prove useful in improving cellulase production by the biotechnology sector.
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Affiliation(s)
- Amanda Cristina Campos Antoniêto
- Department of Biochemistry and Immunology, Ribeirão Preto Medical School, University of São Paulo 14049-900, Ribeirão Preto, SP, Brazil
| | - Renato Graciano de Paula
- Department of Biochemistry and Immunology, Ribeirão Preto Medical School, University of São Paulo 14049-900, Ribeirão Preto, SP, Brazil
| | - Lílian Dos Santos Castro
- Department of Biochemistry and Immunology, Ribeirão Preto Medical School, University of São Paulo 14049-900, Ribeirão Preto, SP, Brazil
| | - Rafael Silva-Rocha
- Department of Cell and Molecular Biology and Pathogenic Bioagents, Ribeirão Preto Medical School, University of São Paulo 14049-900, Ribeirão Preto, SP, Brazil
| | - Gabriela Felix Persinoti
- Laboratório Nacional de Ciência e Tecnologia do Bioetanol (CTBE), Centro Nacional, de Pesquisa em Energia e Materiais (CNPEM), Campinas, São Paulo, Brazil
| | - Roberto Nascimento Silva
- Department of Biochemistry and Immunology, Ribeirão Preto Medical School, University of São Paulo 14049-900, Ribeirão Preto, SP, Brazil
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Zhu C, Ai L, Wang L, Yin P, Liu C, Li S, Zeng H. De novo Transcriptome Analysis of Rhizoctonia solani AG1 IA Strain Early Invasion in Zoysia japonica Root. Front Microbiol 2016; 7:708. [PMID: 27242730 PMCID: PMC4870862 DOI: 10.3389/fmicb.2016.00708] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Accepted: 04/28/2016] [Indexed: 12/28/2022] Open
Abstract
Zoysia japonica brown spot was caused by necrotrophic fungus Rhizoctonia solani invasion, which led to severe financial loss in city lawn and golf ground maintenance. However, little was known about the molecular mechanism of R. solani pathogenicity in Z. japonica. In this study we examined early stage interaction between R. solani AG1 IA strain and Z. japonica cultivar “Zenith” root by cell ultra-structure analysis, pathogenesis-related proteins assay and transcriptome analysis to explore molecular clues for AG1 IA strain pathogenicity in Z. japonica. No obvious cell structure damage was found in infected roots and most pathogenesis-related protein activities showedg a downward trend especially in 36 h post inoculation, which exhibits AG1 IA strain stealthy invasion characteristic. According to Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) database classification, most DEGs in infected “Zenith” roots dynamically changed especially in three aspects, signal transduction, gene translation, and protein synthesis. Total 3422 unigenes of “Zenith” root were predicted into 14 kinds of resistance (R) gene class. Potential fungal resistance related unigenes of “Zenith” root were involved in ligin biosynthesis, phytoalexin synthesis, oxidative burst, wax biosynthesis, while two down-regulated unigenes encoding leucine-rich repeat receptor protein kinase and subtilisin-like protease might be important for host-derived signal perception to AG1 IA strain invasion. According to Pathogen Host Interaction (PHI) database annotation, 1508 unigenes of AG1 IA strain were predicted and classified into 37 known pathogen species, in addition, unigenes encoding virulence, signaling, host stress tolerance, and potential effector were also predicted. This research uncovered transcriptional profiling during the early phase interaction between R. solani AG1 IA strain and Z. japonica, and will greatly help identify key pathogenicity of AG1 IA strain.
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Affiliation(s)
- Chen Zhu
- Biochemistry and Molecular Biology Department, College of Biological Sciences and Technology, Beijing Forestry University Beijing, China
| | - Lin Ai
- Ecology Department, College of Forestry, Beijing Forestry University Beijing, China
| | - Li Wang
- Silviculture Forestry Department, College of Forestry, Beijing Forestry University Beijing, China
| | - Pingping Yin
- Turfgrass Management Department, College of Forestry, Beijing Forestry University Beijing, China
| | - Chenglan Liu
- Turfgrass Management Department, College of Forestry, Beijing Forestry University Beijing, China
| | - Shanshan Li
- Turfgrass Management Department, College of Forestry, Beijing Forestry University Beijing, China
| | - Huiming Zeng
- Turfgrass Management Department, College of Forestry, Beijing Forestry University Beijing, China
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57
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Pleiotropic effects of the vacuolar ABC transporter MLT1 of Candida albicans on cell function and virulence. Biochem J 2016; 473:1537-52. [PMID: 27026051 PMCID: PMC4888455 DOI: 10.1042/bcj20160024] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Accepted: 03/29/2016] [Indexed: 01/14/2023]
Abstract
Among the several mechanisms that contribute to MDR (multidrug resistance), the overexpression of drug-efflux pumps belonging to the ABC (ATP-binding cassette) superfamily is the most frequent cause of resistance to antifungal agents. The multidrug transporter proteins Cdr1p and Cdr2p of the ABCG subfamily are major players in the development of MDR in Candida albicans. Because several genes coding for ABC proteins exist in the genome of C. albicans, but only Cdr1p and Cdr2p have established roles in MDR, it is implicit that the other members of the ABC family also have alternative physiological roles. The present study focuses on an ABC transporter of C. albicans, Mlt1p, which is localized in the vacuolar membrane and specifically transports PC (phosphatidylcholine) into the vacuolar lumen. Transcriptional profiling of the mlt1∆/∆ mutant revealed a down-regulation of the genes involved in endocytosis, oxidoreductase activity, virulence and hyphal development. High-throughput MS-based lipidome analysis revealed that the Mlt1p levels affect lipid homoeostasis and thus lead to a plethora of physiological perturbations. These include a delay in endocytosis, inefficient sequestering of reactive oxygen species (ROS), defects in hyphal development and attenuated virulence. The present study is an emerging example where new and unconventional roles of an ABC transporter are being identified.
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58
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Meneau I, Coste AT, Sanglard D. Identification ofAspergillus fumigatusmultidrug transporter genes and their potential involvement in antifungal resistance. Med Mycol 2016; 54:616-27. [DOI: 10.1093/mmy/myw005] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Accepted: 01/13/2016] [Indexed: 01/11/2023] Open
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59
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Dos Santos Castro L, de Paula RG, Antoniêto ACC, Persinoti GF, Silva-Rocha R, Silva RN. Understanding the Role of the Master Regulator XYR1 in Trichoderma reesei by Global Transcriptional Analysis. Front Microbiol 2016; 7:175. [PMID: 26909077 PMCID: PMC4754417 DOI: 10.3389/fmicb.2016.00175] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2015] [Accepted: 02/01/2016] [Indexed: 11/13/2022] Open
Abstract
We defined the role of the transcriptional factor—XYR1—in the filamentous fungus Trichoderma reesei during cellulosic material degradation. In this regard, we performed a global transcriptome analysis using RNA-Seq of the Δxyr1 mutant strain of T. reesei compared with the parental strain QM9414 grown in the presence of cellulose, sophorose, and glucose as sole carbon sources. We found that 5885 genes were expressed differentially under the three tested carbon sources. Of these, 322 genes were upregulated in the presence of cellulose, while 367 and 188 were upregulated in sophorose and glucose, respectively. With respect to genes under the direct regulation of XYR1, 30 and 33 are exclusive to cellulose and sophorose, respectively. The most modulated genes in the Δxyr1 belong to Carbohydrate-Active Enzymes (CAZymes), transcription factors, and transporters families. Moreover, we highlight the downregulation of transporters belonging to the MFS and ABC transporter families. Of these, MFS members were mostly downregulated in the presence of cellulose. In sophorose and glucose, the expression of these transporters was mainly upregulated. Our results revealed that MFS and ABC transporters could be new players in cellulose degradation and their role was shown to be carbon source-dependent. Our findings contribute to a better understanding of the regulatory mechanisms of XYR1 to control cellulase gene expression in T. reesei in the presence of cellulosic material, thereby potentially enhancing its application in several biotechnology fields.
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Affiliation(s)
- Lilian Dos Santos Castro
- Molecular Biotechnology Laboratory, Department of Biochemistry and Immunology, Ribeirão Preto Medical School, University of São Paulo Ribeirão Preto, Brazil
| | - Renato G de Paula
- Molecular Biotechnology Laboratory, Department of Biochemistry and Immunology, Ribeirão Preto Medical School, University of São Paulo Ribeirão Preto, Brazil
| | - Amanda C C Antoniêto
- Molecular Biotechnology Laboratory, Department of Biochemistry and Immunology, Ribeirão Preto Medical School, University of São Paulo Ribeirão Preto, Brazil
| | - Gabriela F Persinoti
- Laboratório Nacional de Ciência e Tecnologia do Bioetanol, Centro Nacional de Pesquisa em Energia e Materiais Campinas, Brazil
| | - Rafael Silva-Rocha
- Systems and Synthetic Biology Laboratory, Department of Cell and Molecular Biology, Ribeirão Preto Medical School, University of São Paulo Ribeirão Preto, Brazil
| | - Roberto N Silva
- Molecular Biotechnology Laboratory, Department of Biochemistry and Immunology, Ribeirão Preto Medical School, University of São Paulo Ribeirão Preto, Brazil
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60
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Transcription factor ADS-4 regulates adaptive responses and resistance to antifungal azole stress. Antimicrob Agents Chemother 2015; 59:5396-404. [PMID: 26100701 DOI: 10.1128/aac.00542-15] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Accepted: 06/13/2015] [Indexed: 11/20/2022] Open
Abstract
Azoles are commonly used as antifungal drugs or pesticides to control fungal infections in medicine and agriculture. Fungi adapt to azole stress by rapidly activating the transcription of a number of genes, and transcriptional increases in some azole-responsive genes can elevate azole resistance. The regulatory mechanisms that control transcriptional responses to azole stress in filamentous fungi are not well understood. This study identified a bZIP transcription factor, ADS-4 (antifungal drug sensitive-4), as a new regulator of adaptive responses and resistance to antifungal azoles. Transcription of ads-4 in Neurospora crassa cells increased when they were subjected to ketoconazole treatment, whereas the deletion of ads-4 resulted in hypersensitivity to ketoconazole and fluconazole. In contrast, the overexpression of ads-4 increased resistance to fluconazole and ketoconazole in N. crassa. Transcriptome sequencing (RNA-seq) analysis, followed by quantitative reverse transcription (qRT)-PCR confirmation, showed that ADS-4 positively regulated the transcriptional responses of at least six genes to ketoconazole stress in N. crassa. The gene products of four ADS-4-regulated genes are known contributors to azole resistance, including the major efflux pump CDR4 (Pdr5p ortholog), an ABC multidrug transporter (NcAbcB), sterol C-22 desaturase (ERG5), and a lipid transporter (NcRTA2) that is involved in calcineurin-mediated azole resistance. Deletion of the ads-4-homologous gene Afads-4 in Aspergillus fumigatus caused hypersensitivity to itraconazole and ketoconazole, which suggested that ADS-4 is a functionally conserved regulator of adaptive responses to azoles. This study provides important information on a new azole resistance factor that could be targeted by a new range of antifungal pesticides and drugs.
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61
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The molecular mechanism of azole resistance in Aspergillus fumigatus: from bedside to bench and back. J Microbiol 2015; 53:91-9. [PMID: 25626363 DOI: 10.1007/s12275-015-5014-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Accepted: 01/13/2015] [Indexed: 10/24/2022]
Abstract
The growing use of immunosuppressive therapies has resulted in a dramatic increased incidence of invasive fungal infections (IFIs) caused by Aspergillus fumigatus, a common pathogen, and is also associated with a high mortality rate. Azoles are the primary guideline-recommended therapy agents for first-line treatment and prevention of IFIs. However, increased azole usage in medicinal and agricultural settings has caused azole-resistant isolates to repeatedly emerge in the environment, resulting in a significant threat to human health. In this review, we present and summarize current research on the resistance mechanisms of azoles in A. fumigatus as well as efficient susceptibility testing methods. Moreover, we analyze and discuss the putative clinical (bedside) indication of these findings from bench work.
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Moye-Rowley WS. Multiple mechanisms contribute to the development of clinically significant azole resistance in Aspergillus fumigatus. Front Microbiol 2015; 6:70. [PMID: 25713565 PMCID: PMC4322724 DOI: 10.3389/fmicb.2015.00070] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2014] [Accepted: 01/20/2015] [Indexed: 01/30/2023] Open
Abstract
Infections caused by the filamentous fungus Aspergillus fumigatus are a significant clinical issue and represent the second most-common form of fungal infection. Azole drugs are effective against this pathogen but resistant isolates are being found more frequently. Infections associated with azole resistant A. fumigatus have a significantly increased mortality making understanding drug resistance in this organism a priority. The target of azole drugs is the lanosterol α-14 demethylase enzyme encoded by the cyp51A gene in A. fumigatus. Mutations in cyp51A have been described that give rise to azole resistance and been argued to be the primary, if not sole, contributor to azole resistance. Here, I discuss recent developments that indicate multiple mechanisms, including increased expression of ATP-binding cassette (ABC) transporter proteins, contribute to azole resistance. ABC transporters are well-established determinants of drug resistance in other fungal pathogens and seem likely to play a similar role in A. fumigatus.
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Affiliation(s)
- W S Moye-Rowley
- Department of Molecular Physiology and Biophysics, Carver College of Medicine, University of Iowa Iowa City, IA, USA
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63
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Novel role of a family of major facilitator transporters in biofilm development and virulence of Candida albicans. Biochem J 2014; 460:223-35. [PMID: 24621232 DOI: 10.1042/bj20140010] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The QDR (quinidine drug resistance) family of genes encodes transporters belonging to the MFS (major facilitator superfamily) of proteins. We show that QDR transporters, which are localized to the plasma membrane, do not play a role in drug transport. Hence, null mutants of QDR1, QDR2 and QDR3 display no alterations in susceptibility to azoles, polyenes, echinocandins, polyamines or quinolines, or to cell wall inhibitors and many other stresses. However, the deletion of QDR genes, individually or collectively, led to defects in biofilm architecture and thickness. Interestingly, QDR-lacking strains also displayed attenuated virulence, but the strongest effect was observed with qdr2∆, qdr3∆ and in qdr1/2/3∆ strains. Notably, the attenuated virulence and biofilm defects could be reversed upon reintegration of QDR genes. Transcripts profiling confirmed differential expression of many biofilm and virulence-related genes in the deletion strains as compared with wild-type Candida albicans cells. Furthermore, lipidomic analysis of QDR-deletion mutants suggests massive remodelling of lipids, which may affect cell signalling, leading to the defect in biofilm development and attenuation of virulence. In summary, the results of the present study show that QDR paralogues encoding MFS antiporters do not display conserved functional linkage as drug transporters and perform functions that significantly affect the virulence of C. albicans.
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64
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Dubey MK, Jensen DF, Karlsson M. An ATP-binding cassette pleiotropic drug transporter protein is required for xenobiotic tolerance and antagonism in the fungal biocontrol agent Clonostachys rosea. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2014; 27:725-732. [PMID: 24654977 DOI: 10.1094/mpmi-12-13-0365-r] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
ATP-binding cassette (ABC) transporters mediate active efflux of natural and synthetic toxicants and are considered to be important for drug tolerance in microorganisms. In biological control agents (BCA), ABC transporters can play important roles in antagonism by providing protection against toxins derived from the fungal prey and by mediating the secretion of endogenous toxins. In the present study, we generated deletion and complementation strains of the ABC transporter abcG5 in the fungal BCA Clonostachys rosea to study its role in xenobiotic tolerance and antagonism. Gene expression analysis shows induced expression of abcG5 in the presence of the Fusarium mycotoxin zearalenone (ZEA), secreted metabolites of F. graminearum, and different classes of fungicides. Phenotypic analysis of abcG5 deletion and complementation strains showed that the deletion strains were more sensitive towards F. graminearum culture filtrates, ZEA, and iprodione- and mefenoxam-based fungicides, thus suggesting the involvement of abcG5 in cell protection. The ΔabcG5 strains displayed reduced antagonism towards F. graminearum in a plate confrontation assay. Furthermore, the ΔabcG5 strains failed to protect barley seedlings from F. graminearium foot rot disease. These data show that the abcG5 ABC transporter is important for xenobiotic tolerance and biocontrol traits in C. rosea.
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65
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Chung D, Thammahong A, Shepardson KM, Blosser SJ, Cramer RA. Endoplasmic reticulum localized PerA is required for cell wall integrity, azole drug resistance, and virulence in Aspergillus fumigatus. Mol Microbiol 2014; 92:1279-98. [PMID: 24779420 DOI: 10.1111/mmi.12626] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/24/2014] [Indexed: 11/29/2022]
Abstract
GPI-anchoring is a universal and critical post-translational protein modification in eukaryotes. In fungi, many cell wall proteins are GPI-anchored, and disruption of GPI-anchored proteins impairs cell wall integrity. After being synthesized and attached to target proteins, GPI anchors undergo modification on lipid moieties. In spite of its importance for GPI-anchored protein functions, our current knowledge of GPI lipid remodelling in pathogenic fungi is limited. In this study, we characterized the role of a putative GPI lipid remodelling protein, designated PerA, in the human pathogenic fungus Aspergillus fumigatus. PerA localizes to the endoplasmic reticulum and loss of PerA leads to striking defects in cell wall integrity. A perA null mutant has decreased conidia production, increased susceptibility to triazole antifungal drugs, and is avirulent in a murine model of invasive pulmonary aspergillosis. Interestingly, loss of PerA increases exposure of β-glucan and chitin content on the hyphal cell surface, but diminished TNF production by bone marrow-derived macrophages relative to wild type. Given the structural specificity of fungal GPI-anchors, which is different from humans, understanding GPI lipid remodelling and PerA function in A. fumigatus is a promising research direction to uncover a new fungal specific antifungal drug target.
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Affiliation(s)
- Dawoon Chung
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, NH, USA
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Medrano FJ, de Souza CS, Romero A, Balan A. Structure determination of a sugar-binding protein from the phytopathogenic bacterium Xanthomonas citri. Acta Crystallogr F Struct Biol Commun 2014; 70:564-71. [PMID: 24817711 PMCID: PMC4014320 DOI: 10.1107/s2053230x14006578] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2014] [Accepted: 03/25/2014] [Indexed: 02/05/2023] Open
Abstract
The uptake of maltose and related sugars in Gram-negative bacteria is mediated by an ABC transporter encompassing a periplasmic component (the maltose-binding protein or MalE), a pore-forming membrane protein (MalF and MalG) and a membrane-associated ATPase (MalK). In the present study, the structure determination of the apo form of the putative maltose/trehalose-binding protein (Xac-MalE) from the citrus pathogen Xanthomonas citri in space group P6522 is described. The crystals contained two protein molecules in the asymmetric unit and diffracted to 2.8 Å resolution. Xac-MalE conserves the structural and functional features of sugar-binding proteins and a ligand-binding pocket with similar characteristics to eight different orthologues, including the residues for maltose and trehalose interaction. This is the first structure of a sugar-binding protein from a phytopathogenic bacterium, which is highly conserved in all species from the Xanthomonas genus.
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Affiliation(s)
- Francisco Javier Medrano
- Department of Chemical and Physical Biology, Centro de Investigaciones Biologicas (CSIC), Madrid, Spain
| | - Cristiane Santos de Souza
- Departamento de Microbiologia, Instituto de Ciências Biomédicas II, Universidade de São Paulo, Cidade Universitária, SP, Brazil
| | - Antonio Romero
- Department of Chemical and Physical Biology, Centro de Investigaciones Biologicas (CSIC), Madrid, Spain
| | - Andrea Balan
- Departamento de Microbiologia, Instituto de Ciências Biomédicas II, Universidade de São Paulo, Cidade Universitária, SP, Brazil
- Laboratório Nacional de Biociências (LNBio), Centro de Pesquisas em Energia e Materiais (CNPEM), Campinas, SP, Brazil
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Paul S, Moye-Rowley WS. Multidrug resistance in fungi: regulation of transporter-encoding gene expression. Front Physiol 2014; 5:143. [PMID: 24795641 PMCID: PMC3997011 DOI: 10.3389/fphys.2014.00143] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2014] [Accepted: 03/25/2014] [Indexed: 11/24/2022] Open
Abstract
A critical risk to the continued success of antifungal chemotherapy is the acquisition of resistance; a risk exacerbated by the few classes of effective antifungal drugs. Predictably, as the use of these drugs increases in the clinic, more resistant organisms can be isolated from patients. A particularly problematic form of drug resistance that routinely emerges in the major fungal pathogens is known as multidrug resistance. Multidrug resistance refers to the simultaneous acquisition of tolerance to a range of drugs via a limited or even single genetic change. This review will focus on recent progress in understanding pathways of multidrug resistance in fungi including those of most medical relevance. Analyses of multidrug resistance in Saccharomyces cerevisiae have provided the most detailed outline of multidrug resistance in a eukaryotic microorganism. Multidrug resistant isolates of S. cerevisiae typically result from changes in the activity of a pair of related transcription factors that in turn elicit overproduction of several target genes. Chief among these is the ATP-binding cassette (ABC)-encoding gene PDR5. Interestingly, in the medically important Candida species, very similar pathways are involved in acquisition of multidrug resistance. In both C. albicans and C. glabrata, changes in the activity of transcriptional activator proteins elicits overproduction of a protein closely related to S. cerevisiae Pdr5 called Cdr1. The major filamentous fungal pathogen, Aspergillus fumigatus, was previously thought to acquire resistance to azole compounds (the principal antifungal drug class) via alterations in the azole drug target-encoding gene cyp51A. More recent data indicate that pathways in addition to changes in the cyp51A gene are important determinants in A. fumigatus azole resistance. We will discuss findings that suggest azole resistance in A. fumigatus and Candida species may share more mechanistic similarities than previously thought.
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Affiliation(s)
- Sanjoy Paul
- Department of Molecular Physiology and Biophysics, Carver College of Medicine, University of Iowa Iowa City, IA, USA
| | - W Scott Moye-Rowley
- Department of Molecular Physiology and Biophysics, Carver College of Medicine, University of Iowa Iowa City, IA, USA
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