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Jado JC, Dow M, Carolino K, Klie A, Fonseca GJ, Ideker T, Carter H, Winzeler EA. In vitro evolution and whole genome analysis to study chemotherapy drug resistance in haploid human cells. Sci Rep 2024; 14:13989. [PMID: 38886371 PMCID: PMC11183241 DOI: 10.1038/s41598-024-63943-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2024] [Accepted: 06/03/2024] [Indexed: 06/20/2024] Open
Abstract
In vitro evolution and whole genome analysis has proven to be a powerful method for studying the mechanism of action of small molecules in many haploid microbes but has generally not been applied to human cell lines in part because their diploid state complicates the identification of variants that confer drug resistance. To determine if haploid human cells could be used in MOA studies, we evolved resistance to five different anticancer drugs (doxorubicin, gemcitabine, etoposide, topotecan, and paclitaxel) using a near-haploid cell line (HAP1) and then analyzed the genomes of the drug resistant clones, developing a bioinformatic pipeline that involved filtering for high frequency alleles predicted to change protein sequence, or alleles which appeared in the same gene for multiple independent selections with the same compound. Applying the filter to sequences from 28 drug resistant clones identified a set of 21 genes which was strongly enriched for known resistance genes or known drug targets (TOP1, TOP2A, DCK, WDR33, SLCO3A1). In addition, some lines carried structural variants that encompassed additional known resistance genes (ABCB1, WWOX and RRM1). Gene expression knockdown and knockout experiments of 10 validation targets showed a high degree of specificity and accuracy in our calls and demonstrates that the same drug resistance mechanisms found in diverse clinical samples can be evolved, discovered and studied in an isogenic background.
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Affiliation(s)
- Juan Carlos Jado
- Division of Host-Microbe Systems & Therapeutics, Department of Pediatrics, University of California, San Diego, Gilman Dr., La Jolla, CA, 92093, USA
- Department of Medicine, Division of Medical Genetics, University of California San Diego, La Jolla, CA, 92093, USA
| | - Michelle Dow
- Department of Medicine, Division of Medical Genetics, University of California San Diego, La Jolla, CA, 92093, USA
- Bioinformatics and Systems Biology Graduate Program, University of California San Diego, La Jolla, CA, 92093, USA
- Health Science, Department of Biomedical Informatics, School of Medicine, University of California San Diego, La Jolla, CA, 92093, USA
| | - Krypton Carolino
- Division of Biological Sciences, University of California San Diego, La Jolla, CA, 92093, USA
| | - Adam Klie
- Department of Medicine, Division of Medical Genetics, University of California San Diego, La Jolla, CA, 92093, USA
- Bioinformatics and Systems Biology Graduate Program, University of California San Diego, La Jolla, CA, 92093, USA
| | - Gregory J Fonseca
- Department of Medicine, Meakins-Christie Laboratories, McGill University Health Centre, 1001 Decaire Blvd, Montreal, QC, H4A 3J1, Canada
| | - Trey Ideker
- Department of Medicine, Division of Medical Genetics, University of California San Diego, La Jolla, CA, 92093, USA.
- Moores Cancer Center, University of California San Diego, La Jolla, CA, 92093, USA.
| | - Hannah Carter
- Department of Medicine, Division of Medical Genetics, University of California San Diego, La Jolla, CA, 92093, USA.
- Moores Cancer Center, University of California San Diego, La Jolla, CA, 92093, USA.
| | - Elizabeth A Winzeler
- Division of Host-Microbe Systems & Therapeutics, Department of Pediatrics, University of California, San Diego, Gilman Dr., La Jolla, CA, 92093, USA.
- Department of Medicine, Division of Medical Genetics, University of California San Diego, La Jolla, CA, 92093, USA.
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Gnaien M, Maufrais C, Rebai Y, Kallel A, Ma L, Hamouda S, Khalsi F, Meftah K, Smaoui H, Khemiri M, Hadj Fredj S, Bachellier-Bassi S, Najjar I, Messaoud T, Boussetta K, Kallel K, Mardassi H, d’Enfert C, Bougnoux ME, Znaidi S. A gain-of-function mutation in zinc cluster transcription factor Rob1 drives Candida albicans adaptive growth in the cystic fibrosis lung environment. PLoS Pathog 2024; 20:e1012154. [PMID: 38603707 PMCID: PMC11037546 DOI: 10.1371/journal.ppat.1012154] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Revised: 04/23/2024] [Accepted: 03/26/2024] [Indexed: 04/13/2024] Open
Abstract
Candida albicans chronically colonizes the respiratory tract of patients with Cystic Fibrosis (CF). It competes with CF-associated pathogens (e.g. Pseudomonas aeruginosa) and contributes to disease severity. We hypothesize that C. albicans undergoes specific adaptation mechanisms that explain its persistence in the CF lung environment. To identify the underlying genetic and phenotypic determinants, we serially recovered 146 C. albicans clinical isolates over a period of 30 months from the sputum of 25 antifungal-naive CF patients. Multilocus sequence typing analyses revealed that most patients were individually colonized with genetically close strains, facilitating comparative analyses between serial isolates. We strikingly observed differential ability to filament and form monospecies and dual-species biofilms with P. aeruginosa among 18 serial isolates sharing the same diploid sequence type, recovered within one year from a pediatric patient. Whole genome sequencing revealed that their genomes were highly heterozygous and similar to each other, displaying a highly clonal subpopulation structure. Data mining identified 34 non-synonymous heterozygous SNPs in 19 open reading frames differentiating the hyperfilamentous and strong biofilm-former strains from the remaining isolates. Among these, we detected a glycine-to-glutamate substitution at position 299 (G299E) in the deduced amino acid sequence of the zinc cluster transcription factor ROB1 (ROB1G299E), encoding a major regulator of filamentous growth and biofilm formation. Introduction of the G299E heterozygous mutation in a co-isolated weak biofilm-former CF strain was sufficient to confer hyperfilamentous growth, increased expression of hyphal-specific genes, increased monospecies biofilm formation and increased survival in dual-species biofilms formed with P. aeruginosa, indicating that ROB1G299E is a gain-of-function mutation. Disruption of ROB1 in a hyperfilamentous isolate carrying the ROB1G299E allele abolished hyperfilamentation and biofilm formation. Our study links a single heterozygous mutation to the ability of C. albicans to better survive during the interaction with other CF-associated microbes and illuminates how adaptive traits emerge in microbial pathogens to persistently colonize and/or infect the CF-patient airways.
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Affiliation(s)
- Mayssa Gnaien
- Institut Pasteur de Tunis, University of Tunis El Manar, Laboratoire de Microbiologie Moléculaire, Vaccinologie et Développement Biotechnologique (LR16IPT01), Tunis, Tunisia
| | - Corinne Maufrais
- Institut Pasteur, Université Paris Cité, INRAE USC2019A, Département Mycologie, Unité Biologie et Pathogénicité Fongiques, Paris, France
- Institut Pasteur, Université Paris Cité, Bioinformatics and Biostatistics Hub, F-75015 Paris, France
| | - Yasmine Rebai
- Institut Pasteur de Tunis, University of Tunis El Manar, Laboratoire de Microbiologie Moléculaire, Vaccinologie et Développement Biotechnologique (LR16IPT01), Tunis, Tunisia
| | - Aicha Kallel
- Institut Pasteur de Tunis, University of Tunis El Manar, Laboratoire de Microbiologie Moléculaire, Vaccinologie et Développement Biotechnologique (LR16IPT01), Tunis, Tunisia
- Hôpital La Rabta, Laboratoire de Parasitologie et de Mycologie, UR17SP03, Tunis, Tunisia
| | - Laurence Ma
- Institut Pasteur, Université Paris Cité, Biomics core facility, Centre de Ressources et Recherche Technologique (C2RT), Paris, France
| | - Samia Hamouda
- Hôpital d’Enfants Béchir Hamza de Tunis, Tunis, Tunisia
| | - Fatma Khalsi
- Hôpital d’Enfants Béchir Hamza de Tunis, Tunis, Tunisia
| | | | - Hanen Smaoui
- Hôpital d’Enfants Béchir Hamza de Tunis, Tunis, Tunisia
| | - Monia Khemiri
- Hôpital d’Enfants Béchir Hamza de Tunis, Tunis, Tunisia
| | | | - Sophie Bachellier-Bassi
- Institut Pasteur, Université Paris Cité, INRAE USC2019A, Département Mycologie, Unité Biologie et Pathogénicité Fongiques, Paris, France
| | - Imène Najjar
- Institut Pasteur, Université Paris Cité, Biomics core facility, Centre de Ressources et Recherche Technologique (C2RT), Paris, France
| | | | | | - Kalthoum Kallel
- Hôpital La Rabta, Laboratoire de Parasitologie et de Mycologie, UR17SP03, Tunis, Tunisia
| | - Helmi Mardassi
- Institut Pasteur de Tunis, University of Tunis El Manar, Laboratoire de Microbiologie Moléculaire, Vaccinologie et Développement Biotechnologique (LR16IPT01), Tunis, Tunisia
| | - Christophe d’Enfert
- Institut Pasteur, Université Paris Cité, INRAE USC2019A, Département Mycologie, Unité Biologie et Pathogénicité Fongiques, Paris, France
| | - Marie-Elisabeth Bougnoux
- Institut Pasteur, Université Paris Cité, INRAE USC2019A, Département Mycologie, Unité Biologie et Pathogénicité Fongiques, Paris, France
| | - Sadri Znaidi
- Institut Pasteur de Tunis, University of Tunis El Manar, Laboratoire de Microbiologie Moléculaire, Vaccinologie et Développement Biotechnologique (LR16IPT01), Tunis, Tunisia
- Institut Pasteur, Université Paris Cité, INRAE USC2019A, Département Mycologie, Unité Biologie et Pathogénicité Fongiques, Paris, France
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Choi JW, Song NE, Hong SP, Rhee YK, Hong HD, Cho CW. Engineering Bacillus subtilis J46 for efficient utilization of galactose through adaptive laboratory evolution. AMB Express 2024; 14:14. [PMID: 38282124 PMCID: PMC10822834 DOI: 10.1186/s13568-024-01666-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2023] [Accepted: 01/08/2024] [Indexed: 01/30/2024] Open
Abstract
Efficient utilization of galactose by microorganisms can lead to the production of valuable bio-products and improved metabolic processes. While Bacillus subtilis has inherent pathways for galactose metabolism, there is potential for enhancement via evolutionary strategies. This study aimed to boost galactose utilization in B. subtilis using adaptive laboratory evolution (ALE) and to elucidate the genetic and metabolic changes underlying the observed enhancements. The strains of B. subtilis underwent multiple rounds of adaptive laboratory evolution (approximately 5000 generations) in an environment that favored the use of galactose. This process resulted in an enhanced specific growth rate of 0.319 ± 0.005 h-1, a significant increase from the 0.03 ± 0.008 h-1 observed in the wild-type strains. Upon selecting the evolved strain BSGA14, a comprehensive whole-genome sequencing revealed the presence of 63 single nucleotide polymorphisms (SNPs). Two of them, located in the coding sequences of the genes araR and glcR, were found to be the advantageous mutations after reverse engineering. The strain with these two accumulated mutations, BSGALE4, exhibited similar specific growth rate on galactose to the evolved strain BSGA14 (0.296 ± 0.01 h-1). Furthermore, evolved strain showed higher productivity of protease and β-galactosidase in mock soybean biomass medium. ALE proved to be a potent tool for enhancing galactose metabolism in B. subtilis. The findings offer valuable insights into the potential of evolutionary strategies in microbial engineering and pave the way for industrial applications harnessing enhanced galactose conversion.
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Affiliation(s)
- Jae Woong Choi
- Research Group of Traditional Food, Korea Food Research Institute, 245, Nongsaengmyeong-ro, Iseo-myeon, Wanju-gun, 55365, Republic of Korea
| | - Nho-Eul Song
- Research Group of Traditional Food, Korea Food Research Institute, 245, Nongsaengmyeong-ro, Iseo-myeon, Wanju-gun, 55365, Republic of Korea
| | - Sang-Pil Hong
- Research Group of Traditional Food, Korea Food Research Institute, 245, Nongsaengmyeong-ro, Iseo-myeon, Wanju-gun, 55365, Republic of Korea
| | - Young Kyoung Rhee
- Research Group of Traditional Food, Korea Food Research Institute, 245, Nongsaengmyeong-ro, Iseo-myeon, Wanju-gun, 55365, Republic of Korea
| | - Hee-Do Hong
- Research Group of Traditional Food, Korea Food Research Institute, 245, Nongsaengmyeong-ro, Iseo-myeon, Wanju-gun, 55365, Republic of Korea
| | - Chang-Won Cho
- Research Group of Traditional Food, Korea Food Research Institute, 245, Nongsaengmyeong-ro, Iseo-myeon, Wanju-gun, 55365, Republic of Korea.
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Osset-Trénor P, Pascual-Ahuir A, Proft M. Fungal Drug Response and Antimicrobial Resistance. J Fungi (Basel) 2023; 9:jof9050565. [PMID: 37233275 DOI: 10.3390/jof9050565] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Revised: 04/27/2023] [Accepted: 05/12/2023] [Indexed: 05/27/2023] Open
Abstract
Antifungal resistance is a growing concern as it poses a significant threat to public health. Fungal infections are a significant cause of morbidity and mortality, especially in immunocompromised individuals. The limited number of antifungal agents and the emergence of resistance have led to a critical need to understand the mechanisms of antifungal drug resistance. This review provides an overview of the importance of antifungal resistance, the classes of antifungal agents, and their mode of action. It highlights the molecular mechanisms of antifungal drug resistance, including alterations in drug modification, activation, and availability. In addition, the review discusses the response to drugs via the regulation of multidrug efflux systems and antifungal drug-target interactions. We emphasize the importance of understanding the molecular mechanisms of antifungal drug resistance to develop effective strategies to combat the emergence of resistance and highlight the need for continued research to identify new targets for antifungal drug development and explore alternative therapeutic options to overcome resistance. Overall, an understanding of antifungal drug resistance and its mechanisms will be indispensable for the field of antifungal drug development and clinical management of fungal infections.
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Affiliation(s)
- Paloma Osset-Trénor
- Department of Biotechnology, Instituto de Biología Molecular y Celular de Plantas IBMCP, Universidad Politécnica de Valencia, 46022 Valencia, Spain
| | - Amparo Pascual-Ahuir
- Department of Biotechnology, Instituto de Biología Molecular y Celular de Plantas IBMCP, Universidad Politécnica de Valencia, 46022 Valencia, Spain
| | - Markus Proft
- Department of Molecular and Cellular Pathology and Therapy, Instituto de Biomedicina de Valencia IBV-CSIC, Consejo Superior de Investigaciones Científicas CSIC, 46010 Valencia, Spain
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Zhao W, Wang X, Yang B, Wang Y, Li Z, Bao X. Unravel the regulatory mechanism of Yrr1p phosphorylation in response to vanillin stress in Saccharomyces cerevisiae. Microb Cell Fact 2023; 22:48. [PMID: 36899374 PMCID: PMC10007725 DOI: 10.1186/s12934-023-02056-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2022] [Accepted: 03/06/2023] [Indexed: 03/12/2023] Open
Abstract
Improving the resistance of Saccharomyces cerevisiae to vanillin, derived from lignin, will benefit the design of robust cell factories for lignocellulosic biorefining. The transcription factor Yrr1p mediates S. cerevisiae resistance to various compounds. In this study, eleven predicted phosphorylation sites were mutated, among which 4 mutants of Yrr1p, Y134A/E and T185A/E could improve vanillin resistance. Both dephosphorylated and phosphorylated mutations at Yrr1p 134 and 185 gathered in the nucleus regardless of the presence or absence of vanillin. However, the phosphorylated mutant Yrr1p inhibited target gene expression, while dephosphorylated mutants promoted expression. Transcriptomic analysis showed that the dephosphorylated Yrr1p T185 mutant, under vanillin stress, upregulated ribosome biogenesis and rRNA processing. These results demonstrate the mechanism by which Yrr1p phosphorylation regulates the expression of target genes. The identification of key phosphorylation sites in Yrr1p offers novel targets for the rational construction of Yrr1p mutants to improve resistance to other compounds.
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Affiliation(s)
- Weiquan Zhao
- State Key Laboratory of Biobased Material and Green Papermaking, School of Bioengineering, Qilu University of Technology Shandong Academy of Sciences, Jinan, 250353, China
| | - Xinning Wang
- State Key Laboratory of Biobased Material and Green Papermaking, School of Bioengineering, Qilu University of Technology Shandong Academy of Sciences, Jinan, 250353, China. .,The Second Hospital of Shandong University, Shandong University Library, Jinan, 250100, China.
| | - Bolun Yang
- State Key Laboratory of Biobased Material and Green Papermaking, School of Bioengineering, Qilu University of Technology Shandong Academy of Sciences, Jinan, 250353, China
| | - Ying Wang
- State Key Laboratory of Biobased Material and Green Papermaking, School of Bioengineering, Qilu University of Technology Shandong Academy of Sciences, Jinan, 250353, China
| | - Zailu Li
- State Key Laboratory of Biobased Material and Green Papermaking, School of Bioengineering, Qilu University of Technology Shandong Academy of Sciences, Jinan, 250353, China
| | - Xiaoming Bao
- State Key Laboratory of Biobased Material and Green Papermaking, School of Bioengineering, Qilu University of Technology Shandong Academy of Sciences, Jinan, 250353, China.
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Istvan ES, Guerra F, Abraham M, Huang KS, Rocamora F, Zhao H, Xu L, Pasaje C, Kumpornsin K, Luth MR, Cui H, Yang T, Diaz SP, Gomez-Lorenzo MG, Qahash T, Mittal N, Ottilie S, Niles J, Lee MCS, Llinas M, Kato N, Okombo J, Fidock DA, Schimmel P, Gamo FJ, Goldberg DE, Winzeler EA. Cytoplasmic isoleucyl tRNA synthetase as an attractive multistage antimalarial drug target. Sci Transl Med 2023; 15:eadc9249. [PMID: 36888694 PMCID: PMC10286833 DOI: 10.1126/scitranslmed.adc9249] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Accepted: 02/17/2023] [Indexed: 03/10/2023]
Abstract
Development of antimalarial compounds into clinical candidates remains costly and arduous without detailed knowledge of the target. As resistance increases and treatment options at various stages of disease are limited, it is critical to identify multistage drug targets that are readily interrogated in biochemical assays. Whole-genome sequencing of 18 parasite clones evolved using thienopyrimidine compounds with submicromolar, rapid-killing, pan-life cycle antiparasitic activity showed that all had acquired mutations in the P. falciparum cytoplasmic isoleucyl tRNA synthetase (cIRS). Engineering two of the mutations into drug-naïve parasites recapitulated the resistance phenotype, and parasites with conditional knockdowns of cIRS became hypersensitive to two thienopyrimidines. Purified recombinant P. vivax cIRS inhibition, cross-resistance, and biochemical assays indicated a noncompetitive, allosteric binding site that is distinct from that of known cIRS inhibitors mupirocin and reveromycin A. Our data show that Plasmodium cIRS is an important chemically and genetically validated target for next-generation medicines for malaria.
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Affiliation(s)
- Eva S. Istvan
- Departments of Medicine and Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63130, USA
| | - Francisco Guerra
- Department of Pediatrics, School of Medicine, University of California, San Diego, La Jolla, California 92093, USA
| | - Matthew Abraham
- Department of Pediatrics, School of Medicine, University of California, San Diego, La Jolla, California 92093, USA
| | | | - Frances Rocamora
- Department of Pediatrics, School of Medicine, University of California, San Diego, La Jolla, California 92093, USA
| | | | - Lan Xu
- The Global Health Drug Discovery Institute, Tsinghua University 30 Shuangqing Rd, Haidian District, Beijing, China
| | - Charisse Pasaje
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | | | - Madeline R. Luth
- Department of Pediatrics, School of Medicine, University of California, San Diego, La Jolla, California 92093, USA
| | - Haissi Cui
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Tuo Yang
- Department of Pediatrics, School of Medicine, University of California, San Diego, La Jolla, California 92093, USA
| | - Sara Palomo Diaz
- Global Health Medicines, GlaxoSmithKline, Severo Ochoa 2, 28760 Tres Cantos, Spain
| | | | - Tarrick Qahash
- Department of Biochemistry & Molecular Biology, Pennsylvania State University, University Park, PA 16802, USA
- Huck Center for Malaria Research, Pennsylvania State University, University Park, PA 16802, USA
| | - Nimisha Mittal
- Department of Pediatrics, School of Medicine, University of California, San Diego, La Jolla, California 92093, USA
| | - Sabine Ottilie
- Department of Pediatrics, School of Medicine, University of California, San Diego, La Jolla, California 92093, USA
| | - Jacquin Niles
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Marcus C. S. Lee
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, CB10 1SA, UK
| | - Manuel Llinas
- Department of Biochemistry & Molecular Biology, Pennsylvania State University, University Park, PA 16802, USA
- Huck Center for Malaria Research, Pennsylvania State University, University Park, PA 16802, USA
- Department of Chemistry, Pennsylvania State University, University Park, PA 16802, USA
| | - Nobutaka Kato
- The Global Health Drug Discovery Institute, Tsinghua University 30 Shuangqing Rd, Haidian District, Beijing, China
| | - John Okombo
- Department of Microbiology and Immunology, Columbia University Irving Medical Center, New York, New York 10032, USA
| | - David A. Fidock
- Department of Microbiology and Immunology, Columbia University Irving Medical Center, New York, New York 10032, USA
- Center for Malaria Therapeutics and Antimicrobial Resistance, Division of Infectious Diseases, Department of Medicine, Columbia University Irving Medical Center, New York, New York 10032, USA
| | - Paul Schimmel
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA
| | | | - Daniel E. Goldberg
- Departments of Medicine and Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63130, USA
| | - Elizabeth A. Winzeler
- Department of Pediatrics, School of Medicine, University of California, San Diego, La Jolla, California 92093, USA
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The Trisubstituted Isoxazole MMV688766 Exerts Broad-Spectrum Activity against Drug-Resistant Fungal Pathogens through Inhibition of Lipid Homeostasis. mBio 2022; 13:e0273022. [PMID: 36300931 PMCID: PMC9765174 DOI: 10.1128/mbio.02730-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Candida species are among the most prevalent causes of systemic fungal infection, posing a growing threat to public health. While Candida albicans is the most common etiological agent of systemic candidiasis, the frequency of infections caused by non-albicans Candida species is rising. Among these is Candida auris, which has emerged as a particular concern. Since its initial discovery in 2009, it has been identified worldwide and exhibits resistance to all three principal antifungal classes. Here, we endeavored to identify compounds with novel bioactivity against C. auris from the Medicines for Malaria Venture's Pathogen Box library. Of the five hits identified, the trisubstituted isoxazole MMV688766 emerged as the only compound displaying potent fungicidal activity against C. auris, as well as other evolutionarily divergent fungal pathogens. Chemogenomic profiling, as well as subsequent metabolomic and phenotypic analyses, revealed that MMV688766 disrupts cellular lipid homeostasis, driving a decrease in levels of early sphingolipid intermediates and fatty acids and a concomitant increase in lysophospholipids. Experimental evolution to further probe MMV688766's mode of action in the model fungus Saccharomyces cerevisiae revealed that loss of function of the transcriptional regulator HAL9 confers resistance to MMV688766, in part through the upregulation of the lipid-binding chaperone HSP12, a response that appears to assist in tolerating MMV688766-induced stress. The novel mode of action we have uncovered for MMV688766 against drug-resistant fungal pathogens highlights the broad utility of targeting lipid homeostasis to disrupt fungal growth and how screening structurally-diverse chemical libraries can provide new insights into resistance-conferring stress responses of fungi. IMPORTANCE As widespread antimicrobial resistance threatens to propel the world into a postantibiotic era, there is a pressing need to identify mechanistically distinct antimicrobial agents. This is of particular concern when considering the limited arsenal of drugs available to treat fungal infections, coupled with the emergence of highly drug-resistant fungal pathogens, including Candida auris. In this work, we demonstrate that existing libraries of drug-like chemical matter can be rich resources for antifungal molecular scaffolds. We discovered that the small molecule MMV688766, from the Pathogen Box library, displays previously undescribed broad-spectrum fungicidal activity through perturbation of lipid homeostasis. Characterization of the mode of action of MMV688766 provided new insight into the protective mechanisms fungi use to cope with the disruption of lipid homeostasis. Our findings highlight that elucidating the genetic circuitry required to survive in the presence of cellular stress offers powerful insights into the biological pathways that govern this important phenotype.
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