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O'Meara TR. Going fishing: how to get what you want from a fungal genetic screen. mSphere 2024:e0063823. [PMID: 38958459 DOI: 10.1128/msphere.00638-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/04/2024] Open
Abstract
Five years ago, as I was starting my lab, I wrote about two functional genomic screens in fungi that had inspired me (mSphere 4:e00299-19, https://doi.org/10.1128/mSphere.00299-19). Now, I want to discuss some of the principles and questions that I ask myself and my students as we embark on our own screens. A good screen, whether it is a genetic or chemical screen, can be the starting point for new discovery and an excellent basis for the beginning of a scientific research project. However, screens are often criticized for being "fishing expeditions." To stretch this metaphor to the extreme, this is because people are worried that we do not know how to fish, that we will come home without any fish, bring home the wrong fish, or not know what to do with a fish if we caught it. How you set up the screen and analyze the results determines whether the screen will be useful. In this mini-review, and in the spirit of teaching a scientist to fish, I will discuss recent excellent fungal genetic and chemical screens that illustrate some of the key aspects of a successful screen.
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Affiliation(s)
- Teresa R O'Meara
- Department of Microbiology and Immunology, University of Michigan, Ann Arbor, Michigan, USA
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2
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Saha D, Gregor JB, Hoda S, Eastman KE, Navarrete M, Wisecaver JH, Briggs SD. Candida glabrata maintains two Hap1 homologs, Zcf27 and Zcf4, for distinct roles in ergosterol gene regulation to mediate sterol homeostasis under azole and hypoxic conditions. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.20.599910. [PMID: 38979343 PMCID: PMC11230168 DOI: 10.1101/2024.06.20.599910] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/10/2024]
Abstract
Candida glabrata exhibits innate resistance to azole antifungal drugs but also has the propensity to rapidly develop clinical drug resistance. Azole drugs, which target Erg11, is one of the three major classes of antifungals used to treat Candida infections. Despite their widespread use, the mechanism controlling azole-induced ERG gene expression and drug resistance in C. glabrata has primarily revolved around Upc2 and/or Pdr1. In this study, we determined the function of two zinc cluster transcription factors, Zcf27 and Zcf4, as direct but distinct regulators of ERG genes. Our phylogenetic analysis revealed C. glabrata Zcf27 and Zcf4 as the closest homologs to Saccharomyces cerevisiae Hap1. Hap1 is a known zinc cluster transcription factor in S. cerevisiae in controlling ERG gene expression under aerobic and hypoxic conditions. Interestingly, when we deleted HAP1 or ZCF27 in either S. cerevisiae or C. glabrata, respectively, both deletion strains showed altered susceptibility to azole drugs, whereas the strain deleted for ZCF4 did not exhibit azole susceptibility. We also determined that the increased azole susceptibility in a zcf27Δ strain is attributed to decreased azole-induced expression of ERG genes, resulting in decreased levels of total ergosterol. Surprisingly, Zcf4 protein expression is barely detected under aerobic conditions but is specifically induced under hypoxic conditions. However, under hypoxic conditions, Zcf4 but not Zcf27 was directly required for the repression of ERG genes. This study provides the first demonstration that Zcf27 and Zcf4 have evolved to serve distinct roles allowing C. glabrata to adapt to specific host and environmental conditions.
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Affiliation(s)
| | | | | | | | | | | | - Scott D. Briggs
- Department of Biochemistry
- Purdue University Institute for Cancer Research
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3
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Nickels TJ, Gale AP, Harrington AA, Timp W, Cunningham KW. Tn-seq of the Candida glabrata reference strain CBS138 reveals epigenetic plasticity, structural variation, and intrinsic mechanisms of resistance to micafungin. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.02.592251. [PMID: 38746084 PMCID: PMC11092758 DOI: 10.1101/2024.05.02.592251] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2024]
Abstract
C. glabrata is an opportunistic pathogen that can resist common antifungals and rapidly acquire multidrug resistance. A large amount of genetic variation exists between isolates, which complicates generalizations. Portable Tn-seq methods can efficiently provide genome-wide information on strain differences and genetic mechanisms. Using the Hermes transposon, the CBS138 reference strain and a commonly studied derivative termed 2001 were subjected to Tn-seq in control conditions and after exposure to varying doses of the clinical antifungal micafungin. The approach revealed large differences between these strains, including a 131 kb tandem duplication and a variety of fitness differences. Additionally, both strains exhibited up to 1000-fold increased transposon accessibility in subtelomeric regions relative to the BG2 strain, indicative of open subtelomeric chromatin in these isolates and large epigenetic variation within the species. Unexpectedly, the Pdr1 transcription factor conferred resistance to micafungin through targets other than CDR1 . Other micafungin resistance pathways were also revealed including mannosyltransferase activity and biosynthesis of the lipid precursor sphingosine, the drugging of which by SDZ 90-215 or myriocin enhanced the potency of micafungin in vitro . These findings provide insights into complexity of the C. glabrata species as well as strategies for improving antifungal efficacy. Summary Candida glabrata is an emerging pathogen with large genetic diversity and genome plasticity. The type strain CBS138 and a laboratory derivative were mutagenized with the Hermes transposon and profiled using Tn-seq. Numerous genes that regulate innate and acquired resistance to an important clinical antifungal were uncovered, including a pleiotropic drug resistance gene (PDR1) and a duplication of part of one chromosome. Compounds that target PDR1 and other genes may augment the potency of existing antifungals.
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4
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Chow EWL, Song Y, Wang H, Xu X, Gao J, Wang Y. Genome-wide profiling of piggyBac transposon insertion mutants reveals loss of the F 1F 0 ATPase complex causes fluconazole resistance in Candida glabrata. Mol Microbiol 2024; 121:781-797. [PMID: 38242855 DOI: 10.1111/mmi.15229] [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: 12/14/2023] [Revised: 01/04/2024] [Accepted: 01/07/2024] [Indexed: 01/21/2024]
Abstract
Invasive candidiasis caused by non-albicans species has been on the rise, with Candida glabrata emerging as the second most common etiological agent. Candida glabrata possesses an intrinsically lower susceptibility to azoles and an alarming propensity to rapidly develop high-level azole resistance during treatment. In this study, we have developed an efficient piggyBac (PB) transposon-mediated mutagenesis system in C. glabrata to conduct genome-wide genetic screens and applied it to profile genes that contribute to azole resistance. When challenged with the antifungal drug fluconazole, PB insertion into 270 genes led to significant resistance. A large subset of these genes has a role in the mitochondria, including almost all genes encoding the subunits of the F1F0 ATPase complex. We show that deleting ATP3 or ATP22 results in increased azole resistance but does not affect susceptibility to polyenes and echinocandins. The increased azole resistance is due to increased expression of PDR1 that encodes a transcription factor known to promote drug efflux pump expression. Deleting PDR1 in the atp3Δ or atp22Δ mutant resulted in hypersensitivity to fluconazole. Our results shed light on the mechanisms contributing to azole resistance in C. glabrata. This PB transposon-mediated mutagenesis system can significantly facilitate future genome-wide genetic screens.
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Affiliation(s)
- Eve W L Chow
- A*STAR Infectious Diseases Labs (A*STAR ID Labs), Agency for Science and Technology Research (A*STAR), Singapore, Singapore
| | - Yabing Song
- School of Life Sciences, Tsinghua University, Beijing, China
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Haitao Wang
- A*STAR Infectious Diseases Labs (A*STAR ID Labs), Agency for Science and Technology Research (A*STAR), Singapore, Singapore
| | - Xiaoli Xu
- A*STAR Infectious Diseases Labs (A*STAR ID Labs), Agency for Science and Technology Research (A*STAR), Singapore, Singapore
| | - Jiaxin Gao
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Yue Wang
- A*STAR Infectious Diseases Labs (A*STAR ID Labs), Agency for Science and Technology Research (A*STAR), Singapore, Singapore
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
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5
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Pavesic MW, Gale AN, Nickels TJ, Harrington AA, Bussey M, Cunningham KW. Calcineurin-dependent contributions to fitness in the opportunistic pathogen Candida glabrata. mSphere 2024; 9:e0055423. [PMID: 38171022 PMCID: PMC10826367 DOI: 10.1128/msphere.00554-23] [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: 09/22/2023] [Accepted: 11/19/2023] [Indexed: 01/05/2024] Open
Abstract
The protein phosphatase calcineurin is vital for the virulence of the opportunistic fungal pathogen Candida glabrata. The host-induced stresses that activate calcineurin signaling are unknown, as are the targets of calcineurin relevant to virulence. To potentially shed light on these processes, millions of transposon insertion mutants throughout the genome of C. glabrata were profiled en masse for fitness defects in the presence of FK506, a specific inhibitor of calcineurin. Eighty-seven specific gene deficiencies depended on calcineurin signaling for full viability in vitro both in wild-type and pdr1∆ null strains lacking pleiotropic drug resistance. Three genes involved in cell wall biosynthesis (FKS1, DCW1, FLC1) possess co-essential paralogs whose expression depended on calcineurin and Crz1 in response to micafungin, a clinical antifungal that interferes with cell wall biogenesis. Interestingly, 80% of the FK506-sensitive mutants were deficient in different aspects of vesicular trafficking, such as endocytosis, exocytosis, sorting, and biogenesis of secretory proteins in the endoplasmic reticulum (ER). In response to the experimental antifungal manogepix that blocks GPI-anchor biosynthesis in the ER, calcineurin signaling increased and strongly prevented cell death independent of Crz1, one of its major targets. Comparisons between manogepix, micafungin, and the ER-stressing tunicamycin reveal a correlation between the degree of calcineurin signaling and the degree of cell survival. These findings suggest that calcineurin plays major roles in mitigating stresses of vesicular trafficking. Such stresses may arise during host infection and in response to antifungal therapies.IMPORTANCECalcineurin plays critical roles in the virulence of most pathogenic fungi. This study sheds light on those roles in the opportunistic pathogen Candida glabrata using a genome-wide analysis in vitro. The findings could lead to antifungal developments that also avoid immunosuppression.
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Affiliation(s)
- Matthew W. Pavesic
- Department of Biology, Johns Hopkins University, Baltimore, Maryland, USA
| | - Andrew N. Gale
- Department of Biology, Johns Hopkins University, Baltimore, Maryland, USA
| | - Timothy J. Nickels
- Department of Biology, Johns Hopkins University, Baltimore, Maryland, USA
| | | | - Maya Bussey
- Department of Biology, Johns Hopkins University, Baltimore, Maryland, USA
| | - Kyle W. Cunningham
- Department of Biology, Johns Hopkins University, Baltimore, Maryland, USA
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Chow EWL, Song Y, Chen J, Xu X, Wang J, Chen K, Gao J, Wang Y. The transcription factor Rpn4 activates its own transcription and induces efflux pump expression to confer fluconazole resistance in Candida auris. mBio 2023; 14:e0268823. [PMID: 38014938 PMCID: PMC10746192 DOI: 10.1128/mbio.02688-23] [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: 10/03/2023] [Accepted: 10/17/2023] [Indexed: 11/29/2023] Open
Abstract
IMPORTANCE Candida auris is a recently emerged pathogenic fungus of grave concern globally due to its resistance to conventional antifungals. This study takes a whole-genome approach to explore how C. auris overcomes growth inhibition imposed by the common antifungal drug fluconazole. We focused on gene disruptions caused by a "jumping genetic element" called transposon, leading to fluconazole resistance. We identified mutations in two genes, each encoding a component of the Ubr2/Mub1 ubiquitin-ligase complex, which marks the transcription regulator Rpn4 for degradation. When either protein is absent, stable Rpn4 accumulates in the cell. We found that Rpn4 activates the expression of itself as well as the main drug efflux pump gene CDR1 by binding to a PACE element in the promoter. Furthermore, we identified an amino acid change in Ubr2 in many resistant clinical isolates, contributing to Rpn4 stabilization and increased fluconazole resistance.
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Affiliation(s)
- Eve W. L. Chow
- Infectious Diseases Labs, Agency for Science, Technology and Research, Singapore, Singapore
| | - Yabing Song
- School of Life Sciences, Tsinghua University, Beijing, China
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Jinxin Chen
- School of Life Sciences, Tsinghua University, Beijing, China
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Xiaoli Xu
- Infectious Diseases Labs, Agency for Science, Technology and Research, Singapore, Singapore
| | - Jianbin Wang
- School of Life Sciences, Tsinghua University, Beijing, China
- Beijing Frontier Research Center for Biological Structure, Tsinghua University, Beijing, China
| | - Kun Chen
- Translational Medical Center for Stem Cell Therapy, Institute for Regenerative Medicine, Shanghai East Hospital, School of Life Sciences and Technology, Tongji University, Shanghai, China
- Shanghai Key Laboratory of Signaling and Disease Research, Frontier Science Center for Stem Cell Research, School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Jiaxin Gao
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Yue Wang
- Infectious Diseases Labs, Agency for Science, Technology and Research, Singapore, Singapore
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
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Vu BG, Simonicova L, Moye-Rowley WS. Calcineurin is required for Candida glabrata Pdr1 transcriptional activation. mBio 2023; 14:e0241623. [PMID: 37943042 PMCID: PMC10746151 DOI: 10.1128/mbio.02416-23] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Accepted: 10/04/2023] [Indexed: 11/10/2023] Open
Abstract
Fluconazole is one of the most commonly used antifungals today. A result of this has been the inevitable selection of fluconazole-resistant organisms. This is an especially acute problem in the pathogenic yeast Candida glabrata. Elevated minimal inhibitory concentrations for fluconazole in C. glabrata are frequently associated with substitution mutations within the Zn2Cys6 zinc cluster-containing transcription factor-encoding gene PDR1. These mutant Pdr1 regulators drive constitutively high expression of target genes like CDR1 that encodes an ATP-binding cassette transporter thought to act as a drug efflux pump. Exposure of C. glabrata to fluconazole induced expression of both Pdr1 and CDR1, although little is known of the molecular basis underlying the upstream signals that trigger Pdr1 activation. Here, we show that the protein phosphatase calcineurin is required for fluconazole-dependent induction of Pdr1 transcriptional regulation. Calcineurin catalytic activity is required for normal Pdr1 regulation, and a hyperactive form of this phosphatase can decrease susceptibility to the echinocandin caspofungin but does not show a similar change for fluconazole susceptibility. Loss of calcineurin from strains expressing two different gain-of-function forms of Pdr1 also caused a decrease in CDR1 expression and increased fluconazole susceptibility, demonstrating that even these hyperactive Pdr1 regulatory mutants cannot bypass the requirement for calcineurin. Our data implicate calcineurin activity as a link tying azole and echinocandin susceptibility together via the control of transcription factor activity.IMPORTANCEDrug-resistant microorganisms are a problem in the treatment of all infectious diseases; this is an especially acute problem with fungi due to the existence of only three major classes of antifungal drugs, including the azole drug fluconazole. In the pathogenic yeast Candida glabrata, mutant forms of a transcription factor called Pdr1 are commonly associated with decreased fluconazole susceptibility and poor clinical outcomes. Here, we identify a protein phosphatase called calcineurin that is required for fluconazole-dependent induction of Pdr1 transcriptional activation and associated drug susceptibility. Gain-of-function mutant forms of Pdr1 still required the presence of calcineurin to confer normally decreased fluconazole susceptibility. Previous studies showed that calcineurin controls susceptibility to the echinocandin class of antifungal drugs, and our data demonstrate that this protein phosphatase is also required for normal azole drug susceptibility. Calcineurin plays a central role in susceptibility to two of the three major classes of antifungal drugs in C. glabrata.
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Affiliation(s)
- Bao Gia Vu
- Department of Molecular Physiology and Biophysics, Carver College of Medicine University of Iowa, Iowa City, Iowa, USA
| | - Lucia Simonicova
- Department of Molecular Physiology and Biophysics, Carver College of Medicine University of Iowa, Iowa City, Iowa, USA
| | - W. Scott Moye-Rowley
- Department of Molecular Physiology and Biophysics, Carver College of Medicine University of Iowa, Iowa City, Iowa, USA
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8
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Milholland KL, Gregor JB, Hoda S, Píriz-Antúnez S, Dueñas-Santero E, Vu BG, Patel KP, Moye-Rowley WS, Vázquez de Aldana CR, Correa-Bordes J, Briggs SD, Hall MC. Rapid, efficient auxin-inducible protein degradation in Candida pathogens. mSphere 2023; 8:e0028323. [PMID: 37594261 PMCID: PMC10597344 DOI: 10.1128/msphere.00283-23] [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: 05/25/2023] [Accepted: 06/30/2023] [Indexed: 08/19/2023] Open
Abstract
A variety of inducible protein degradation (IPD) systems have been developed as powerful tools for protein functional characterization. IPD systems provide a convenient mechanism for rapid inactivation of almost any target protein of interest. Auxin-inducible degradation (AID) is one of the most common IPD systems and has been established in diverse eukaryotic research model organisms. Thus far, IPD tools have not been developed for use in pathogenic fungal species. Here, we demonstrate that the original AID and the second generation, AID2, systems work efficiently and rapidly in the human pathogenic yeasts, Candida albicans and Candida glabrata. We developed a collection of plasmids that support AID system use in laboratory strains of these pathogens. These systems can induce >95% degradation of target proteins within minutes. In the case of AID2, maximal degradation was achieved at low nanomolar concentrations of the synthetic auxin analog 5-adamantyl-indole-3-acetic acid. Auxin-induced target degradation successfully phenocopied gene deletions in both species. The system should be readily adaptable to other fungal species and to clinical pathogen strains. Our results define the AID system as a powerful and convenient functional genomics tool for protein characterization in fungal pathogens. IMPORTANCE Life-threatening fungal infections are an escalating human health problem, complicated by limited treatment options and the evolution of drug resistant pathogen strains. Identification of new targets for therapeutics to combat invasive fungal infections, including those caused by Candida species, is an urgent need. In this report, we establish and validate an inducible protein degradation methodology in Candida albicans and Candida glabrata that provides a new tool for protein functional characterization in these, and likely other, fungal pathogen species. We expect this tool will ultimately be useful for the identification and characterization of promising drug targets and factors involved in virulence and drug resistance.
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Affiliation(s)
| | - Justin B. Gregor
- Department of Biochemistry, Purdue University, West Lafayette, Indiana, USA
| | - Smriti Hoda
- Department of Biochemistry, Purdue University, West Lafayette, Indiana, USA
| | | | - Encarnación Dueñas-Santero
- Institute of Functional Biology and Genomics, Consejo Superior de Investigaciones Científicas (CSIC), Universidad de Salamanca (USAL), Salamanca, Spain
| | - Bao Gia Vu
- Department of Molecular Physiology and Biophysics, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Krishna P. Patel
- Department of Biochemistry, Purdue University, West Lafayette, Indiana, USA
| | - W. Scott Moye-Rowley
- Department of Molecular Physiology and Biophysics, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Carlos R. Vázquez de Aldana
- Institute of Functional Biology and Genomics, Consejo Superior de Investigaciones Científicas (CSIC), Universidad de Salamanca (USAL), Salamanca, Spain
| | - Jaime Correa-Bordes
- Department of Biomedical Sciences, Universidad de Extremadura, Badajoz, Spain
| | - Scott D. Briggs
- Department of Biochemistry, Purdue University, West Lafayette, Indiana, USA
- Institute for Cancer Research, Purdue University, West Lafayette, Indiana, USA
| | - Mark C. Hall
- Department of Biochemistry, Purdue University, West Lafayette, Indiana, USA
- Institute for Cancer Research, Purdue University, West Lafayette, Indiana, USA
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9
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Gale AN, Pavesic MW, Nickels TJ, Xu Z, Cormack BP, Cunningham KW. Redefining pleiotropic drug resistance in a pathogenic yeast: Pdr1 functions as a sensor of cellular stresses in Candida glabrata. mSphere 2023; 8:e0025423. [PMID: 37358297 PMCID: PMC10449514 DOI: 10.1128/msphere.00254-23] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Accepted: 05/09/2023] [Indexed: 06/27/2023] Open
Abstract
Candida glabrata is a prominent opportunistic fungal pathogen of humans. The increasing incidence of C. glabrata infections is attributed to both innate and acquired resistance to antifungals. Previous studies suggest the transcription factor Pdr1 and several target genes encoding ABC transporters are critical elements of pleiotropic defense against azoles and other antifungals. This study utilizes Hermes transposon insertion profiling to investigate Pdr1-independent and Pdr1-dependent mechanisms that alter susceptibility to the frontline antifungal fluconazole. Several new genes were found to alter fluconazole susceptibility independent of Pdr1 (CYB5, SSK1, SSK2, HOG1, TRP1). A bZIP transcription repressor of mitochondrial function (CIN5) positively regulated Pdr1 while hundreds of genes encoding mitochondrial proteins were confirmed as negative regulators of Pdr1. The antibiotic oligomycin activated Pdr1 and antagonized fluconazole efficacy likely by interfering with mitochondrial processes in C. glabrata. Unexpectedly, disruption of many 60S ribosomal proteins also activated Pdr1, thus mimicking the effects of the mRNA translation inhibitors. Cycloheximide failed to fully activate Pdr1 in a cycloheximide-resistant Rpl28-Q38E mutant. Similarly, fluconazole failed to fully activate Pdr1 in a strain expressing a low-affinity variant of Erg11. Fluconazole activated Pdr1 with very slow kinetics that correlated with the delayed onset of cellular stress. These findings are inconsistent with the idea that Pdr1 directly senses xenobiotics and support an alternative hypothesis where Pdr1 senses cellular stresses that arise only after engagement of xenobiotics with their targets. IMPORTANCE Candida glabrata is an opportunistic pathogenic yeast that causes discomfort and death. Its incidence has been increasing because of natural defenses to our common antifungal medications. This study explores the entire genome for impacts on resistance to fluconazole. We find several new and unexpected genes can impact susceptibility to fluconazole. Several antibiotics can also alter the efficacy of fluconazole. Most importantly, we find that Pdr1-a key determinant of fluconazole resistance-is not regulated directly through binding of fluconazole and instead is regulated indirectly by sensing the cellular stresses caused by fluconazole blockage of sterol biosynthesis. This new understanding of drug resistance mechanisms could improve the outcomes of current antifungals and accelerate the development of novel therapeutics.
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Affiliation(s)
- Andrew N. Gale
- Department of Biology, Johns Hopkins University, Baltimore, Maryland, USA
| | - Matthew W. Pavesic
- Department of Biology, Johns Hopkins University, Baltimore, Maryland, USA
| | - Timothy J. Nickels
- Department of Biology, Johns Hopkins University, Baltimore, Maryland, USA
| | - Zhuwei Xu
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Brendan P. Cormack
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Kyle W. Cunningham
- Department of Biology, Johns Hopkins University, Baltimore, Maryland, USA
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10
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Avecilla G, Spealman P, Matthews J, Caudal E, Schacherer J, Gresham D. Copy number variation alters local and global mutational tolerance. Genome Res 2023; 33:1340-1353. [PMID: 37652668 PMCID: PMC10547251 DOI: 10.1101/gr.277625.122] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Accepted: 07/07/2023] [Indexed: 09/02/2023]
Abstract
Copy number variants (CNVs), duplications and deletions of genomic sequences, contribute to evolutionary adaptation but can also confer deleterious effects and cause disease. Whereas the effects of amplifying individual genes or whole chromosomes (i.e., aneuploidy) have been studied extensively, much less is known about the genetic and functional effects of CNVs of differing sizes and structures. Here, we investigated Saccharomyces cerevisiae (yeast) strains that acquired adaptive CNVs of variable structures and copy numbers following experimental evolution in glutamine-limited chemostats. Although beneficial in the selective environment, CNVs result in decreased fitness compared with the euploid ancestor in rich media. We used transposon mutagenesis to investigate mutational tolerance and genome-wide genetic interactions in CNV strains. We find that CNVs increase mutational target size, confer increased mutational tolerance in amplified essential genes, and result in novel genetic interactions with unlinked genes. We validated a novel genetic interaction between different CNVs and BMH1 that was common to multiple strains. We also analyzed global gene expression and found that transcriptional dosage compensation does not affect most genes amplified by CNVs, although gene-specific transcriptional dosage compensation does occur for ∼12% of amplified genes. Furthermore, we find that CNV strains do not show previously described transcriptional signatures of aneuploidy. Our study reveals the extent to which local and global mutational tolerance is modified by CNVs with implications for genome evolution and CNV-associated diseases, such as cancer.
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Affiliation(s)
- Grace Avecilla
- Department of Biology, New York University, New York, New York 10003, USA
- Center for Genomics and Systems Biology, New York University, New York, New York 10003, USA
| | - Pieter Spealman
- Department of Biology, New York University, New York, New York 10003, USA
- Center for Genomics and Systems Biology, New York University, New York, New York 10003, USA
| | - Julia Matthews
- Department of Biology, New York University, New York, New York 10003, USA
- Center for Genomics and Systems Biology, New York University, New York, New York 10003, USA
| | - Elodie Caudal
- Université de Strasbourg, CNRS, GMGM UMR, 7156 Strasbourg, France
| | - Joseph Schacherer
- Université de Strasbourg, CNRS, GMGM UMR, 7156 Strasbourg, France
- Institut Universitaire de France (IUF), 75231 Paris Cedex 05, France
| | - David Gresham
- Department of Biology, New York University, New York, New York 10003, USA;
- Center for Genomics and Systems Biology, New York University, New York, New York 10003, USA
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11
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Ramesh A, Trivedi V, Lee S, Tafrishi A, Schwartz C, Mohseni A, Li M, Lonardi S, Wheeldon I. acCRISPR: an activity-correction method for improving the accuracy of CRISPR screens. Commun Biol 2023; 6:617. [PMID: 37291233 PMCID: PMC10250353 DOI: 10.1038/s42003-023-04996-8] [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: 10/09/2022] [Accepted: 05/30/2023] [Indexed: 06/10/2023] Open
Abstract
High throughput CRISPR screens are revolutionizing the way scientists unravel the genetic underpinnings of engineered and evolved phenotypes. One of the critical challenges in accurately assessing screening outcomes is accounting for the variability in sgRNA cutting efficiency. Poorly active guides targeting genes essential to screening conditions obscure the growth defects that are expected from disrupting them. Here, we develop acCRISPR, an end-to-end pipeline that identifies essential genes in pooled CRISPR screens using sgRNA read counts obtained from next-generation sequencing. acCRISPR uses experimentally determined cutting efficiencies for each guide in the library to provide an activity correction to the screening outcomes via calculation of an optimization metric, thus determining the fitness effect of disrupted genes. CRISPR-Cas9 and -Cas12a screens were carried out in the non-conventional oleaginous yeast Yarrowia lipolytica and acCRISPR was used to determine a high-confidence set of essential genes for growth under glucose, a common carbon source used for the industrial production of oleochemicals. acCRISPR was also used in screens quantifying relative cellular fitness under high salt conditions to identify genes that were related to salt tolerance. Collectively, this work presents an experimental-computational framework for CRISPR-based functional genomics studies that may be expanded to other non-conventional organisms of interest.
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Affiliation(s)
- Adithya Ramesh
- Department of Chemical and Environmental Engineering, University of California, Riverside, CA, 92521, USA
| | - Varun Trivedi
- Department of Chemical and Environmental Engineering, University of California, Riverside, CA, 92521, USA
| | - Sangcheon Lee
- Department of Chemical and Environmental Engineering, University of California, Riverside, CA, 92521, USA
| | - Aida Tafrishi
- Department of Chemical and Environmental Engineering, University of California, Riverside, CA, 92521, USA
| | - Cory Schwartz
- Department of Chemical and Environmental Engineering, University of California, Riverside, CA, 92521, USA
- iBio Inc., San Diego, CA, USA
| | - Amirsadra Mohseni
- Department of Computer Science and Engineering, University of California, Riverside, CA, 92521, USA
| | - Mengwan Li
- Department of Chemical and Environmental Engineering, University of California, Riverside, CA, 92521, USA
| | - Stefano Lonardi
- Department of Computer Science and Engineering, University of California, Riverside, CA, 92521, USA
- Integrative Institute for Genome Biology, University of California, Riverside, CA, 92521, USA
| | - Ian Wheeldon
- Department of Chemical and Environmental Engineering, University of California, Riverside, CA, 92521, USA.
- Integrative Institute for Genome Biology, University of California, Riverside, CA, 92521, USA.
- Center for Industrial Biotechnology, University of California, Riverside, CA, 92521, USA.
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12
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Gale AN, Pavesic MW, Nickels TJ, Xu Z, Cormack BP, Cunningham KW. Redefining Pleiotropic Drug Resistance in a Pathogenic Yeast: Pdr1 Functions as a Sensor of Cellular Stresses in Candida glabrata. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.07.539747. [PMID: 37214952 PMCID: PMC10197522 DOI: 10.1101/2023.05.07.539747] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Candida glabrata is a prominent opportunistic fungal pathogen of humans. The increasing incidence of C. glabrata infections is attributed to both innate and acquired resistance to antifungals. Previous studies suggest the transcription factor Pdr1 and several target genes encoding ABC transporters are critical elements of pleiotropic defense against azoles and other antifungals. This study utilizes Hermes transposon insertion profiling to investigate Pdr1-independent and Pdr1-dependent mechanisms that alter susceptibility to the frontline antifungal fluconazole. Several new genes were found to alter fluconazole susceptibility independent of Pdr1 ( CYB5 , SSK1 , SSK2 , HOG1 , TRP1 ). A bZIP transcription repressor of mitochondrial function ( CIN5 ) positively regulated Pdr1 while hundreds of genes encoding mitochondrial proteins were confirmed as negative regulators of Pdr1. The antibiotic oligomycin activated Pdr1 and antagonized fluconazole efficacy likely by interfering with mitochondrial processes in C. glabrata . Unexpectedly, disruption of many 60S ribosomal proteins also activated Pdr1, thus mimicking the effects of the mRNA translation inhibitors. Cycloheximide failed to fully activate Pdr1 in a cycloheximide-resistant Rpl28-Q38E mutant. Similarly, fluconazole failed to fully activate Pdr1 in a strain expressing a low-affinity variant of Erg11. Fluconazole activated Pdr1 with very slow kinetics that correlated with the delayed onset of cellular stress. These findings are inconsistent with the idea that Pdr1 directly senses xenobiotics and support an alternative hypothesis where Pdr1 senses cellular stresses that arise only after engagement of xenobiotics with their targets. Importance Candida glabrata is an opportunistic pathogenic yeast that causes discomfort and death. Its incidence has been increasing because of natural defenses to our common antifungal medications. This study explores the entire genome for impacts on resistance to fluconazole. We find several new and unexpected genes can impact susceptibility to fluconazole. Several antibiotics can also alter the efficacy of fluconazole. Most importantly, we find that Pdr1 - a key determinant of fluconazole resistance - is not regulated directly through binding of fluconazole and instead is regulated indirectly by sensing the cellular stresses caused by fluconazole blockage of sterol biosynthesis. This new understanding of drug resistance mechanisms could improve the outcomes of current antifungals and accelerate the development of novel therapeutics.
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13
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Billerbeck S, Prins RC, Marquardt M. A Modular Cloning Toolkit Including CRISPRi for the Engineering of the Human Fungal Pathogen and Biotechnology Host Candida glabrata. ACS Synth Biol 2023; 12:1358-1363. [PMID: 37043632 PMCID: PMC10127446 DOI: 10.1021/acssynbio.2c00560] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/14/2023]
Abstract
The yeast Candida glabrata is an emerging, often drug-resistant opportunistic human pathogen that can cause severe systemic infections in immunocompromised individuals. At the same time, it is a valuable biotechnology host that naturally accumulates high levels of pyruvate─a valuable chemical precursor. Tools for the facile engineering of this yeast could greatly accelerate studies on its pathogenicity and its optimization for biotechnology. While a few tools for plasmid-based expression and genome engineering have been developed, there is no well-characterized cloning toolkit that would allow the modular assembly of pathways or genetic circuits. Here, by characterizing the Saccharomyces cerevisiae-based yeast molecular cloning toolkit (YTK) in C. glabrata and by adding missing components, we build a well-characterized CgTK (C. glabrata toolkit). We used the CgTK to build a CRISPR interference system for C. glabrata that can be used to generate selectable phenotypes via single-gRNA targeting such as is required for genome-wide library screens.
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Affiliation(s)
- Sonja Billerbeck
- Department for Molecular Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands
| | - Rianne C Prins
- Department for Molecular Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands
| | - Malte Marquardt
- Department for Molecular Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands
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14
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Genome-wide quantification of contributions to sexual fitness identifies genes required for spore viability and health in fission yeast. PLoS Genet 2022; 18:e1010462. [DOI: 10.1371/journal.pgen.1010462] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Revised: 11/16/2022] [Accepted: 10/03/2022] [Indexed: 11/07/2022] Open
Abstract
Numerous genes required for sexual reproduction remain to be identified even in simple model species like Schizosaccharomyces pombe. To address this, we developed an assay in S. pombe that couples transposon mutagenesis with high-throughput sequencing (TN-seq) to quantitatively measure the fitness contribution of nonessential genes across the genome to sexual reproduction. This approach identified 532 genes that contribute to sex, including more than 200 that were not previously annotated to be involved in the process, of which more than 150 have orthologs in vertebrates. Among our verified hits was an uncharacterized gene, ifs1 (important for sex), that is required for spore viability. In two other hits, plb1 and alg9, we observed a novel mutant phenotype of poor spore health wherein viable spores are produced, but the spores exhibit low fitness and are rapidly outcompeted by wild type. Finally, we fortuitously discovered that a gene previously thought to be essential, sdg1 (social distancing gene), is instead required for growth at low cell densities and can be rescued by conditioned medium. Our assay will be valuable in further studies of sexual reproduction in S. pombe and identifies multiple candidate genes that could contribute to sexual reproduction in other eukaryotes, including humans.
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15
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Salazar SB, Pinheiro MJF, Sotti-Novais D, Soares AR, Lopes MM, Ferreira T, Rodrigues V, Fernandes F, Mira NP. Disclosing azole resistance mechanisms in resistant Candida glabrata strains encoding wild-type or gain-of-function CgPDR1 alleles through comparative genomics and transcriptomics. G3 (BETHESDA, MD.) 2022; 12:jkac110. [PMID: 35532173 PMCID: PMC9258547 DOI: 10.1093/g3journal/jkac110] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Accepted: 04/25/2022] [Indexed: 12/03/2022]
Abstract
The pathogenic yeast Candida glabrata is intrinsically resilient to azoles and rapidly acquires resistance to these antifungals, in vitro and in vivo. In most cases azole-resistant C. glabrata clinical strains encode hyperactive CgPdr1 variants, however, resistant strains encoding wild-type CgPDR1 alleles have also been isolated, although remaining to be disclosed the underlying resistance mechanism. In this study, we scrutinized the mechanisms underlying resistance to azoles of 8 resistant clinical C. glabrata strains, identified along the course of epidemiological surveys undertaken in Portugal. Seven of the strains were found to encode CgPdr1 gain-of-function variants (I392M, E555K, G558C, and I803T) with the substitutions I392M and I803T being herein characterized as hyper-activating mutations for the first time. While cells expressing the wild-type CgPDR1 allele required the mediator subunit Gal11A to enhance tolerance to fluconazole, this was dispensable for cells expressing the I803T variant indicating that the CgPdr1 interactome is shaped by different gain-of-function substitutions. Genomic and transcriptomic profiling of the sole azole-resistant C. glabrata isolate encoding a wild-type CgPDR1 allele (ISTB218) revealed that under fluconazole stress this strain over-expresses various genes described to provide protection against this antifungal, while also showing reduced expression of genes described to increase sensitivity to these drugs. The overall role in driving the azole-resistance phenotype of the ISTB218 C. glabrata isolate played by these changes in the transcriptome and genome of the ISTB218 isolate are discussed shedding light into mechanisms of resistance that go beyond the CgPdr1-signalling pathway and that may alone, or in combination, pave the way for the acquisition of resistance to azoles in vivo.
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Affiliation(s)
- Sara B Salazar
- iBB, Institute for Bioengineering and Biosciences, Instituto Superior Técnico—Department of Bioengineering, Universidade de Lisboa, Lisboa 1049-001, Portugal
- Associate Laboratory i4HB—Institute for Health and Bioeconomy at Instituto Superior Técnico, Universidade de Lisboa, Lisboa 1049-001, Portugal
| | - Maria Joana F Pinheiro
- iBB, Institute for Bioengineering and Biosciences, Instituto Superior Técnico—Department of Bioengineering, Universidade de Lisboa, Lisboa 1049-001, Portugal
- Associate Laboratory i4HB—Institute for Health and Bioeconomy at Instituto Superior Técnico, Universidade de Lisboa, Lisboa 1049-001, Portugal
| | - Danielle Sotti-Novais
- iBB, Institute for Bioengineering and Biosciences, Instituto Superior Técnico—Department of Bioengineering, Universidade de Lisboa, Lisboa 1049-001, Portugal
- Associate Laboratory i4HB—Institute for Health and Bioeconomy at Instituto Superior Técnico, Universidade de Lisboa, Lisboa 1049-001, Portugal
| | - Ana R Soares
- Department of Medical Sciences, Institute of Biomedicine (iBiMED), University of Aveiro, Aveiro 3810, Portugal
| | - Maria M Lopes
- Departamento de Microbiologia e Imunologia, Faculdade de Farmácia da Universidade de Lisboa, Lisboa 1649-003, Portugal
| | - Teresa Ferreira
- Laboratório de Microbiologia, Hospital Dona Estefânia (Centro Hospitalar Universitário Lisboa Central), Lisboa 1169-045, Portugal
| | - Vitória Rodrigues
- Seção de Microbiologia, Laboratório SYNLAB—Lisboa, Grupo SYNLAB Portugal, Lisboa 1070-061, Portugal
| | - Fábio Fernandes
- iBB, Institute for Bioengineering and Biosciences, Instituto Superior Técnico—Department of Bioengineering, Universidade de Lisboa, Lisboa 1049-001, Portugal
- Associate Laboratory i4HB—Institute for Health and Bioeconomy at Instituto Superior Técnico, Universidade de Lisboa, Lisboa 1049-001, Portugal
| | - Nuno P Mira
- iBB, Institute for Bioengineering and Biosciences, Instituto Superior Técnico—Department of Bioengineering, Universidade de Lisboa, Lisboa 1049-001, Portugal
- Associate Laboratory i4HB—Institute for Health and Bioeconomy at Instituto Superior Técnico, Universidade de Lisboa, Lisboa 1049-001, Portugal
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16
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Schrevens S, Durandau E, Tran VDT, Sanglard D. Using in vivo transcriptomics and RNA enrichment to identify genes involved in virulence of Candida glabrata. Virulence 2022; 13:1285-1303. [PMID: 35795910 PMCID: PMC9348041 DOI: 10.1080/21505594.2022.2095716] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Candida species are the most commonly isolated opportunistic fungal pathogens in humans. Candida albicans causes most of the diagnosed infections, closely followed by Candida glabrata. C. albicans is well studied, and many genes have been shown to be important for infection and colonization of the host. It is however less clear how C. glabrata infects the host. With the help of fungal RNA enrichment, we here investigated for the first time the transcriptomic profile of C. glabrata during urinary tract infection (UTI) in mice. In the UTI model, bladders and kidneys are major target organs and therefore fungal transcriptomes were addressed in these organs. Our results showed that, next to adhesins and proteases, nitrogen metabolism and regulation play a vital role during C. glabrata UTI. Genes involved in nitrogen metabolism were upregulated and among them we show that DUR1,2 (urea amidolyase) and GAP1 (amino acid permease) were important for virulence. Furthermore, we confirmed the importance of the glyoxylate cycle in the host and identified MLS1 (malate synthase) as an important gene necessary for C. glabrata virulence. In conclusion, our study shows with the support of in vivo transcriptomics how C. glabrata adapts to host conditions.
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Affiliation(s)
- Sanne Schrevens
- Institute of Microbiology, University of Lausanne and University Hospital, CH-1011 Lausanne, Switzerland
| | - Eric Durandau
- Institute of Microbiology, University of Lausanne and University Hospital, CH-1011 Lausanne, Switzerland
| | - Van Du T Tran
- Vital-IT Group, SIB Swiss Institute of Bioinformatics, CH-1015 Lausanne, Switzerland
| | - Dominique Sanglard
- Institute of Microbiology, University of Lausanne and University Hospital, CH-1011 Lausanne, Switzerland
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17
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Michel AH, Kornmann B. SAturated Transposon Analysis in Yeast (SATAY) for Deep Functional Mapping of Yeast Genomes. Methods Mol Biol 2022; 2477:349-379. [PMID: 35524127 DOI: 10.1007/978-1-0716-2257-5_20] [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] [Indexed: 06/14/2023]
Abstract
Genome-wide transposon mutagenesis followed by deep sequencing allows the genome-wide mapping of growth-affecting loci in a straightforward and time-efficient way.SAturated Transposon Analysis in Yeast (SATAY) takes advantage of a modified maize transposon that is highly mobilizable in S. cerevisiae. SATAY allows not only the genome-wide mapping of genes required for growth in select conditions (such as genetic interactions or drug sensitivity/resistance), but also of protein sub-domains, as well as the creation of gain- and separation-of-function alleles. From strain preparation to the mapping of sequencing reads, we detail all the steps for the making and analysis of SATAY libraries in any S. cerevisiae lab, requiring only ordinary equipment and access to a Next-Gen sequencing platform.
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Affiliation(s)
- Agnès H Michel
- Department of Biochemistry, University of Oxford, Oxford, UK.
| | - Benoît Kornmann
- Department of Biochemistry, University of Oxford, Oxford, UK.
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18
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Gervais NC, Halder V, Shapiro RS. A data library of Candida albicans functional genomic screens. FEMS Yeast Res 2021; 21:6433625. [PMID: 34864983 DOI: 10.1093/femsyr/foab060] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Accepted: 11/19/2021] [Indexed: 12/12/2022] Open
Abstract
Functional genomic screening of genetic mutant libraries enables the characterization of gene function in diverse organisms. For the fungal pathogen Candida albicans, several genetic mutant libraries have been generated and screened for diverse phenotypes, including tolerance to environmental stressors and antifungal drugs, and pathogenic traits such as cellular morphogenesis, biofilm formation and host-pathogen interactions. Here, we compile and organize C. albicans functional genomic screening data from ∼400 screens, to generate a data library of genetic mutant strains analyzed under diverse conditions. For quantitative screening data, we normalized these results to enable quantitative and comparative analysis of different genes across different phenotypes. Together, this provides a unique C. albicans genetic database, summarizing abundant phenotypic data from functional genomic screens in this critical fungal pathogen.
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Affiliation(s)
- Nicholas C Gervais
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Viola Halder
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Rebecca S Shapiro
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON N1G 2W1, Canada
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19
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Fu C, Zhang X, Veri AO, Iyer KR, Lash E, Xue A, Yan H, Revie NM, Wong C, Lin ZY, Polvi EJ, Liston SD, VanderSluis B, Hou J, Yashiroda Y, Gingras AC, Boone C, O’Meara TR, O’Meara MJ, Noble S, Robbins N, Myers CL, Cowen LE. Leveraging machine learning essentiality predictions and chemogenomic interactions to identify antifungal targets. Nat Commun 2021; 12:6497. [PMID: 34764269 PMCID: PMC8586148 DOI: 10.1038/s41467-021-26850-3] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Accepted: 10/22/2021] [Indexed: 02/08/2023] Open
Abstract
Fungal pathogens pose a global threat to human health, with Candida albicans among the leading killers. Systematic analysis of essential genes provides a powerful strategy to discover potential antifungal targets. Here, we build a machine learning model to generate genome-wide gene essentiality predictions for C. albicans and expand the largest functional genomics resource in this pathogen (the GRACE collection) by 866 genes. Using this model and chemogenomic analyses, we define the function of three uncharacterized essential genes with roles in kinetochore function, mitochondrial integrity, and translation, and identify the glutaminyl-tRNA synthetase Gln4 as the target of N-pyrimidinyl-β-thiophenylacrylamide (NP-BTA), an antifungal compound.
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Affiliation(s)
- Ci Fu
- grid.17063.330000 0001 2157 2938Department of Molecular Genetics, University of Toronto, Toronto, ON M5G 1M1 Canada
| | - Xiang Zhang
- grid.17635.360000000419368657Department of Computer Science and Engineering, University of Minnesota, Minneapolis, MN 55455 USA
| | - Amanda O. Veri
- grid.17063.330000 0001 2157 2938Department of Molecular Genetics, University of Toronto, Toronto, ON M5G 1M1 Canada
| | - Kali R. Iyer
- grid.17063.330000 0001 2157 2938Department of Molecular Genetics, University of Toronto, Toronto, ON M5G 1M1 Canada
| | - Emma Lash
- grid.17063.330000 0001 2157 2938Department of Molecular Genetics, University of Toronto, Toronto, ON M5G 1M1 Canada
| | - Alice Xue
- grid.17063.330000 0001 2157 2938Department of Molecular Genetics, University of Toronto, Toronto, ON M5G 1M1 Canada
| | - Huijuan Yan
- grid.266102.10000 0001 2297 6811Department of Microbiology and Immunology, UCSF School of Medicine, San Francisco, CA 94143 USA
| | - Nicole M. Revie
- grid.17063.330000 0001 2157 2938Department of Molecular Genetics, University of Toronto, Toronto, ON M5G 1M1 Canada
| | - Cassandra Wong
- grid.250674.20000 0004 0626 6184Lunenfeld-Tanenbaum Research Institute, Sinai Health System, Toronto, ON M5G 1X5, Canada
| | - Zhen-Yuan Lin
- grid.250674.20000 0004 0626 6184Lunenfeld-Tanenbaum Research Institute, Sinai Health System, Toronto, ON M5G 1X5, Canada
| | - Elizabeth J. Polvi
- grid.17063.330000 0001 2157 2938Department of Molecular Genetics, University of Toronto, Toronto, ON M5G 1M1 Canada
| | - Sean D. Liston
- grid.17063.330000 0001 2157 2938Department of Molecular Genetics, University of Toronto, Toronto, ON M5G 1M1 Canada
| | - Benjamin VanderSluis
- grid.17635.360000000419368657Department of Computer Science and Engineering, University of Minnesota, Minneapolis, MN 55455 USA
| | - Jing Hou
- grid.17063.330000 0001 2157 2938Department of Molecular Genetics, University of Toronto, Toronto, ON M5G 1M1 Canada ,grid.17063.330000 0001 2157 2938Donnelly Centre, University of Toronto, Toronto, ON M5S 3E1 Canada
| | - Yoko Yashiroda
- grid.509461.fRIKEN Center for Sustainable Resource Science, Wako, Saitama 351-0198 Japan
| | - Anne-Claude Gingras
- grid.17063.330000 0001 2157 2938Department of Molecular Genetics, University of Toronto, Toronto, ON M5G 1M1 Canada ,grid.250674.20000 0004 0626 6184Lunenfeld-Tanenbaum Research Institute, Sinai Health System, Toronto, ON M5G 1X5, Canada
| | - Charles Boone
- grid.17063.330000 0001 2157 2938Department of Molecular Genetics, University of Toronto, Toronto, ON M5G 1M1 Canada ,grid.17063.330000 0001 2157 2938Donnelly Centre, University of Toronto, Toronto, ON M5S 3E1 Canada ,grid.509461.fRIKEN Center for Sustainable Resource Science, Wako, Saitama 351-0198 Japan
| | - Teresa R. O’Meara
- grid.214458.e0000000086837370Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI 48109 USA
| | - Matthew J. O’Meara
- grid.214458.e0000000086837370Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, MI 48109 USA
| | - Suzanne Noble
- grid.266102.10000 0001 2297 6811Department of Microbiology and Immunology, UCSF School of Medicine, San Francisco, CA 94143 USA
| | - Nicole Robbins
- grid.17063.330000 0001 2157 2938Department of Molecular Genetics, University of Toronto, Toronto, ON M5G 1M1 Canada
| | - Chad L. Myers
- grid.17635.360000000419368657Department of Computer Science and Engineering, University of Minnesota, Minneapolis, MN 55455 USA
| | - Leah E. Cowen
- grid.17063.330000 0001 2157 2938Department of Molecular Genetics, University of Toronto, Toronto, ON M5G 1M1 Canada
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20
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Jezewski A, Alden KM, Esan TE, DeBouver ND, Abendroth J, Bullen JC, Calhoun BM, Potts KT, Murante DM, Hagen TJ, Fox D, Krysan DJ. Structural Characterization of the Reaction and Substrate Specificity Mechanisms of Pathogenic Fungal Acetyl-CoA Synthetases. ACS Chem Biol 2021; 16:1587-1599. [PMID: 34369755 PMCID: PMC8383264 DOI: 10.1021/acschembio.1c00484] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Accepted: 07/29/2021] [Indexed: 11/28/2022]
Abstract
Acetyl CoA synthetases (ACSs) are Acyl-CoA/NRPS/Luciferase (ANL) superfamily enzymes that couple acetate with CoA to generate acetyl CoA, a key component of central carbon metabolism in eukaryotes and prokaryotes. Normal mammalian cells are not dependent on ACSs, while tumor cells, fungi, and parasites rely on acetate as a precursor for acetyl CoA. Consequently, ACSs have emerged as a potential drug target. As part of a program to develop antifungal ACS inhibitors, we characterized fungal ACSs from five diverse human fungal pathogens using biochemical and structural studies. ACSs catalyze a two-step reaction involving adenylation of acetate followed by thioesterification with CoA. Our structural studies captured each step of these two half-reactions including the acetyl-adenylate intermediate of the first half-reaction in both the adenylation conformation and the thioesterification conformation and thus provide a detailed picture of the reaction mechanism. We also used a systematic series of increasingly larger alkyl adenosine esters as chemical probes to characterize the structural basis of the exquisite ACS specificity for acetate over larger carboxylic acid substrates. Consistent with previous biochemical and genetic data for other enzymes, structures of fungal ACSs with these probes bound show that a key tryptophan residue limits the size of the alkyl binding site and forces larger alkyl chains to adopt high energy conformers, disfavoring their efficient binding. Together, our analysis provides highly detailed structural models for both the reaction mechanism and substrate specificity that should be useful in designing selective inhibitors of eukaryotic ACSs as potential anticancer, antifungal, and antiparasitic drugs.
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Affiliation(s)
- Andrew
J. Jezewski
- Department
of Pediatrics Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242, United States
| | - Katy M. Alden
- Department
of Pediatrics Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242, United States
| | - Taiwo E. Esan
- Department
of Chemistry and Biochemistry, Northern
Illinois University, DeKalb, Illinois 60115, United States
| | - Nicholas D. DeBouver
- UCB
Pharma, 7869 NE Day Road West, Bainbridge Island, Washington 98110, United States
- Seattle
Structural Genomics Center for Infectious Disease (SSGCID), Seattle, Washington 98109, United States
| | - Jan Abendroth
- UCB
Pharma, 7869 NE Day Road West, Bainbridge Island, Washington 98110, United States
- Seattle
Structural Genomics Center for Infectious Disease (SSGCID), Seattle, Washington 98109, United States
| | - Jameson C. Bullen
- UCB
Pharma, 7869 NE Day Road West, Bainbridge Island, Washington 98110, United States
- Seattle
Structural Genomics Center for Infectious Disease (SSGCID), Seattle, Washington 98109, United States
| | - Brandy M. Calhoun
- UCB
Pharma, 7869 NE Day Road West, Bainbridge Island, Washington 98110, United States
- Seattle
Structural Genomics Center for Infectious Disease (SSGCID), Seattle, Washington 98109, United States
| | - Kristy T. Potts
- UCB
Pharma, 7869 NE Day Road West, Bainbridge Island, Washington 98110, United States
- Beryllium
Discovery Corp., 7869
NE Day Road West, Bainbridge Island, Washington 98110, United States
| | - Daniel M. Murante
- Department
of Pediatrics Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242, United States
| | - Timothy J. Hagen
- Department
of Chemistry and Biochemistry, Northern
Illinois University, DeKalb, Illinois 60115, United States
| | - David Fox
- UCB
Pharma, 7869 NE Day Road West, Bainbridge Island, Washington 98110, United States
- Beryllium
Discovery Corp., 7869
NE Day Road West, Bainbridge Island, Washington 98110, United States
- Seattle
Structural Genomics Center for Infectious Disease (SSGCID), Seattle, Washington 98109, United States
| | - Damian J. Krysan
- Department
of Pediatrics Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242, United States
- Microbiology/Immunology,
Carver College of Medicine, University of
Iowa, Iowa City, Iowa 52242, United States
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21
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Garcia-Rubio R, Hernandez RY, Clear A, Healey KR, Shor E, Perlin DS. Critical Assessment of Cell Wall Integrity Factors Contributing to in vivo Echinocandin Tolerance and Resistance in Candida glabrata. Front Microbiol 2021; 12:702779. [PMID: 34305871 PMCID: PMC8298035 DOI: 10.3389/fmicb.2021.702779] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Accepted: 06/09/2021] [Indexed: 12/22/2022] Open
Abstract
Fungal infections are on the rise, and emergence of drug-resistant Candida strains refractory to treatment is particularly alarming. Resistance to azole class antifungals, which have been extensively used worldwide for several decades, is so high in several prevalent fungal pathogens, that another drug class, the echinocandins, is now recommended as a first line antifungal treatment. However, resistance to echinocandins is also prominent, particularly in certain species, such as Candida glabrata. The echinocandins target 1,3-β-glucan synthase (GS), the enzyme responsible for producing 1,3-β-glucans, a major component of the fungal cell wall. Although echinocandins are considered fungicidal, C. glabrata exhibits echinocandin tolerance both in vitro and in vivo, where a subset of the cells survives and facilitates the emergence of echinocandin-resistant mutants, which are responsible for clinical failure. Despite this critical role of echinocandin tolerance, its mechanisms are still not well understood. Additionally, most studies of tolerance are conducted in vitro and are thus not able to recapitulate the fungal-host interaction. In this study, we focused on the role of cell wall integrity factors in echinocandin tolerance in C. glabrata. We identified three genes involved in the maintenance of cell wall integrity - YPS1, YPK2, and SLT2 - that promote echinocandin tolerance both in vitro and in a mouse model of gastrointestinal (GI) colonization. In particular, we show that mice colonized with strains carrying deletions of these genes were more effectively sterilized by daily caspofungin treatment relative to mice colonized with the wild-type parental strain. Furthermore, consistent with a role of tolerant cells serving as a reservoir for generating resistant mutations, a reduction in tolerance was associated with a reduction in the emergence of resistant strains. Finally, reduced susceptibility in these strains was due both to the well described FKS-dependent mechanisms and as yet unknown, FKS-independent mechanisms. Together, these results shed light on the importance of cell wall integrity maintenance in echinocandin tolerance and emergence of resistance and lay the foundation for future studies of the factors described herein.
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Affiliation(s)
- Rocio Garcia-Rubio
- Center for Discovery and Innovation, Hackensack Meridian Health, Nutley, NJ, United States
| | - Rosa Y. Hernandez
- Center for Discovery and Innovation, Hackensack Meridian Health, Nutley, NJ, United States
| | - Alissa Clear
- Center for Discovery and Innovation, Hackensack Meridian Health, Nutley, NJ, United States
| | - Kelley R. Healey
- Department of Biology, William Paterson University, Wayne, NJ, United States
| | - Erika Shor
- Center for Discovery and Innovation, Hackensack Meridian Health, Nutley, NJ, United States
- Department of Medical Sciences, Hackensack Meridian School of Medicine, Nutley, NJ, United States
| | - David S. Perlin
- Center for Discovery and Innovation, Hackensack Meridian Health, Nutley, NJ, United States
- Department of Medical Sciences, Hackensack Meridian School of Medicine, Nutley, NJ, United States
- Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC, United States
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LncRNA DINOR is a virulence factor and global regulator of stress responses in Candida auris. Nat Microbiol 2021; 6:842-851. [PMID: 34083769 DOI: 10.1038/s41564-021-00915-x] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Accepted: 04/29/2021] [Indexed: 11/08/2022]
Abstract
The emergent fungal pathogen Candida auris exhibits high resistance to antifungal drugs and environmental stresses, impeding treatment and decontamination1-3. The fungal factors mediating this stress tolerance are largely unknown. In the present study, we performed piggyBac, transposon-mediated, genome-wide mutagenesis and genetic screening in C. auris, and identified a mutant that grew constitutively in the filamentous form. Mapping the transposon insertion site revealed the disruption of a long non-coding RNA, named DINOR for DNA damage-inducible non-coding RNA. Deletion of DINOR caused DNA damage and an upregulation of genes involved in morphogenesis, DNA damage and DNA replication. The DNA checkpoint kinase Rad53 was hyperphosphorylated in dinorΔ mutants, and deletion of RAD53 abolished DNA damage-induced filamentation. DNA-alkylating agents, which cause similar filamentous growth, induced DINOR expression, suggesting a role for DINOR in maintaining genome integrity. Upregulation of DINOR also occurred during exposure to the antifungal drugs caspofungin and amphotericin B, macrophages, H2O2 and sodium dodecylsulfate, indicating that DINOR orchestrates multiple stress responses. Consistently, dinorΔ mutants displayed increased sensitivity to these stresses and were attenuated for virulence in mice. Moreover, genome-wide genetic interaction studies revealed links between the function of DINOR and TOR signalling, an evolutionarily conserved pathway that regulates the stress response. Identification of the mechanism(s) by which DINOR regulates stress responses in C. auris may provide future opportunities for the development of therapeutics.
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23
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Schrevens S, Sanglard D. Hijacking Transposable Elements for Saturation Mutagenesis in Fungi. FRONTIERS IN FUNGAL BIOLOGY 2021; 2:633876. [PMID: 37744130 PMCID: PMC10512250 DOI: 10.3389/ffunb.2021.633876] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Accepted: 03/15/2021] [Indexed: 09/26/2023]
Abstract
Transposable elements are present in almost all known genomes, these endogenous transposons have recently been referred to as the mobilome. They are now increasingly used in research in order to make extensive mutant libraries in different organisms. Fungi are an essential part of our lives on earth, they influence the availability of our food and they live inside our own bodies both as commensals and pathogenic organisms. Only few fungal species have been studied extensively, mainly due to the lack of appropriate molecular genetic tools. The use of transposon insertion libraries can however help to rapidly advance our knowledge of (conditional) essential genes, compensatory mutations and drug target identification in fungi. Here we give an overview of some recent developments in the use of different transposons for saturation mutagenesis in different fungi.
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Affiliation(s)
| | - Dominique Sanglard
- Institute of Microbiology, University of Lausanne and Lausanne University Hospital, Lausanne, Switzerland
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24
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Fungal Genetics & Genomics: a call for manuscript submissions. G3 GENES|GENOMES|GENETICS 2021; 11:6131402. [PMID: 33585876 PMCID: PMC8022971 DOI: 10.1093/g3journal/jkaa040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Accepted: 12/09/2020] [Indexed: 11/12/2022]
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25
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Fungal Genetics & Genomics: a call for manuscript submissions. Genetics 2021. [DOI: 10.1093/genetics/iyaa032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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26
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Dalisay DS, Rogers EW, Molinski TF. Oceanapiside, a Marine Natural Product, Targets the Sphingolipid Pathway of Fluconazole-Resistant Candida glabrata. Mar Drugs 2021; 19:md19030126. [PMID: 33652774 PMCID: PMC7996939 DOI: 10.3390/md19030126] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2020] [Revised: 02/19/2021] [Accepted: 02/19/2021] [Indexed: 12/16/2022] Open
Abstract
Oceanapiside (OPS), a marine natural product with a novel bifunctional sphingolipid structure, is fungicidal against fluconazole-resistant Candida glabrata at 10 μg/mL (15.4 μM). The fungicidal effect was observed at 3 to 4 h after exposure to cells. Cytological and morphological studies revealed that OPS affects the budding patterns of treated yeast cells with a significant increase in the number of cells with single small buds. In addition, this budding morphology was found to be sensitive in the presence of OPS. Moreover, the number of cells with single medium-sized buds and cells with single large buds were decreased significantly, indicating that fewer cells were transformed to these budding patterns, suggestive of inhibition of polarized growth. OPS was also observed to disrupt the organized actin assembly in C. glabrata, which correlates with inhibition of budding and polarized growth. It was also demonstrated that phytosphingosine (PHS) reversed the antifungal activity of oceanapiside. We quantified the amount of long chain-bases (LCBs) and phytoceramide from the crude extracts of treated cells using LC-ESI-MS. PHS concentration was elevated in extracts of cells treated with OPS when compared with cells treated with miconazole and amphotericin B. Elevated levels of PHS in OPS-treated cells confirms that OPS affects the pathway at a step downstream of PHS synthesis. These results also demonstrated that OPS has a mechanism of action different to those of miconazole and amphotericin B and interdicts fungal sphingolipid metabolism by specifically inhibiting the step converting PHS to phytoceramide.
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Affiliation(s)
- Doralyn S. Dalisay
- Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA; (D.S.D.); (E.W.R.)
- Center for Chemical Biology and Biotechnology (C2B2) and Department of Biology, College of Liberal Arts, Sciences and Education, University of San Agustin, Iloilo City 5000, Philippines
| | - Evan W. Rogers
- Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA; (D.S.D.); (E.W.R.)
| | - Tadeusz F. Molinski
- Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA; (D.S.D.); (E.W.R.)
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
- Correspondence: ; Tel.: +1-858-534-7115; Fax: +1-858-822-0368
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