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Sauters TJC, Roth C, Murray D, Sun S, Floyd Averette A, Onyishi CU, May RC, Heitman J, Magwene PM. Amoeba predation of Cryptococcus: A quantitative and population genomic evaluation of the accidental pathogen hypothesis. PLoS Pathog 2023; 19:e1011763. [PMID: 37956179 PMCID: PMC10681322 DOI: 10.1371/journal.ppat.1011763] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Revised: 11/27/2023] [Accepted: 10/18/2023] [Indexed: 11/15/2023] Open
Abstract
The "Amoeboid Predator-Fungal Animal Virulence Hypothesis" posits that interactions with environmental phagocytes shape the evolution of virulence traits in fungal pathogens. In this hypothesis, selection to avoid predation by amoeba inadvertently selects for traits that contribute to fungal escape from phagocytic immune cells. Here, we investigate this hypothesis in the human fungal pathogens Cryptococcus neoformans and Cryptococcus deneoformans. Applying quantitative trait locus (QTL) mapping and comparative genomics, we discovered a cross-species QTL region that is responsible for variation in resistance to amoeba predation. In C. neoformans, this same QTL was found to have pleiotropic effects on melanization, an established virulence factor. Through fine mapping and population genomic comparisons, we identified the gene encoding the transcription factor Bzp4 that underlies this pleiotropic QTL and we show that decreased expression of this gene reduces melanization and increases susceptibility to amoeba predation. Despite the joint effects of BZP4 on amoeba resistance and melanin production, we find no relationship between BZP4 genotype and escape from macrophages or virulence in murine models of disease. Our findings provide new perspectives on how microbial ecology shapes the genetic architecture of fungal virulence, and suggests the need for more nuanced models for the evolution of pathogenesis that account for the complexities of both microbe-microbe and microbe-host interactions.
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Affiliation(s)
- Thomas J. C. Sauters
- Department of Biology, Duke University, Durham, North Carolina, United States of America
- University Program in Genetics and Genomics, Duke University, Durham, North Carolina, United States of America
| | - Cullen Roth
- Department of Biology, Duke University, Durham, North Carolina, United States of America
- University Program in Genetics and Genomics, Duke University, Durham, North Carolina, United States of America
| | - Debra Murray
- Department of Biology, Duke University, Durham, North Carolina, United States of America
| | - Sheng Sun
- Department of Molecular Genetics and Microbiology, Duke University, Durham, North Carolina, United States of America
| | - Anna Floyd Averette
- Department of Molecular Genetics and Microbiology, Duke University, Durham, North Carolina, United States of America
| | - Chinaemerem U. Onyishi
- School of Biosciences, College of Life and Environmental Sciences, The University of Birmingham, Birmingham, United Kingdom
| | - Robin C. May
- School of Biosciences, College of Life and Environmental Sciences, The University of Birmingham, Birmingham, United Kingdom
| | - Joseph Heitman
- Department of Molecular Genetics and Microbiology, Duke University, Durham, North Carolina, United States of America
| | - Paul M. Magwene
- Department of Biology, Duke University, Durham, North Carolina, United States of America
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Rivera A, Young Lim W, Park E, Dome PA, Hoy MJ, Spasojevic I, Sun S, Averette AF, Pina-Oviedo S, Juvvadi PR, Steinbach WJ, Ciofani M, Hong J, Heitman J. Enhanced fungal specificity and in vivo therapeutic efficacy of a C-22-modified FK520 analog against C. neoformans. mBio 2023; 14:e0181023. [PMID: 37737622 PMCID: PMC10653846 DOI: 10.1128/mbio.01810-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Accepted: 07/19/2023] [Indexed: 09/23/2023] Open
Abstract
IMPORTANCE Fungal infections cause significant morbidity and mortality globally. The therapeutic armamentarium against these infections is limited, and the development of antifungal drugs has been hindered by the evolutionary conservation between fungi and the human host. With rising resistance to the current antifungal arsenal and an increasing at-risk population, there is an urgent need for the development of new antifungal compounds. The FK520 analogs described in this study display potent antifungal activity as a novel class of antifungals centered on modifying an existing orally active FDA-approved therapy. This research advances the development of much-needed newer antifungal treatment options with novel mechanisms of action.
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Affiliation(s)
- Angela Rivera
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina, USA
| | - Won Young Lim
- Department of Chemistry, Duke University, Durham, North Carolina, USA
| | - Eunchong Park
- Department of Integrative Immunobiology, Duke University Medical Center, Durham, North Carolina, USA
| | - Patrick A. Dome
- Department of Chemistry, Duke University, Durham, North Carolina, USA
| | - Michael J. Hoy
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, USA
| | - Ivan Spasojevic
- Department of Medicine, Duke University Medical Center, Durham, North Carolina, USA
| | - Sheng Sun
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, USA
| | - Anna Floyd Averette
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, USA
| | - Sergio Pina-Oviedo
- Department of Pathology, Duke University Medical Center, Durham, North Carolina, USA
| | - Praveen R. Juvvadi
- Department of Pediatrics, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - William J. Steinbach
- Department of Pediatrics, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Maria Ciofani
- Department of Integrative Immunobiology, Duke University Medical Center, Durham, North Carolina, USA
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, USA
| | - Jiyong Hong
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina, USA
- Department of Chemistry, Duke University, Durham, North Carolina, USA
| | - Joseph Heitman
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina, USA
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, USA
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Rivera A, Lim WY, Park E, Dome PA, Hoy MJ, Spasojevic I, Sun S, Averette AF, Pina-Oviedo S, Juvvadi PR, Steinbach WJ, Ciofani M, Hong J, Heitman J. Enhanced fungal specificity and in vivo therapeutic efficacy of a C-22 modified FK520 analog against C. neoformans. bioRxiv 2023:2023.06.05.543712. [PMID: 37333270 PMCID: PMC10274662 DOI: 10.1101/2023.06.05.543712] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/20/2023]
Abstract
Fungal infections are of mounting global concern, and the current limited treatment arsenal poses challenges when treating such infections. In particular, infections by Cryptococcus neoformans are associated with high mortality, emphasizing the need for novel therapeutic options. Calcineurin is a protein phosphatase that mediates fungal stress responses, and calcineurin inhibition by the natural product FK506 blocks C. neoformans growth at 37°C. Calcineurin is also required for pathogenesis. However, because calcineurin is conserved in humans, and inhibition with FK506 results in immunosuppression, the use of FK506 as an anti-infective agent is precluded. We previously elucidated the structures of multiple fungal calcineurin-FK506-FKBP12 complexes and implicated the C-22 position on FK506 as a key point for differential modification of ligand inhibition of the mammalian versus fungal target proteins. Through in vitro antifungal and immunosuppressive testing of FK520 (a natural analog of FK506) derivatives, we identified JH-FK-08 as a lead candidate for further antifungal development. JH-FK-08 exhibited significantly reduced immunosuppressive activity and both reduced fungal burden and prolonged survival of infected animals. JH-FK-08 exhibited additive activity in combination with fluconazole in vivo . These findings further advance calcineurin inhibition as an antifungal therapeutic approach. Importance Fungal infections cause significant morbidity and mortality globally. The therapeutic armamentarium against these infections is limited and development of antifungal drugs has been hindered by the evolutionary conservation between fungi and the human host. With rising resistance to the current antifungal arsenal and an increasing at-risk population, there is an urgent need for the development of new antifungal compounds. The FK520 analogs described in this study display potent antifungal activity as a novel class of antifungals centered on modifying an existing orally-active FDA approved therapy. This research advances the development of much needed newer antifungal treatment options with novel mechanisms of action.
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4
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Sun S, Roth C, Floyd Averette A, Magwene PM, Heitman J. Epistatic genetic interactions govern morphogenesis during sexual reproduction and infection in a global human fungal pathogen. Proc Natl Acad Sci U S A 2022; 119:e2122293119. [PMID: 35169080 PMCID: PMC8872808 DOI: 10.1073/pnas.2122293119] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Accepted: 01/11/2022] [Indexed: 12/12/2022] Open
Abstract
Cellular development is orchestrated by evolutionarily conserved signaling pathways, which are often pleiotropic and involve intra- and interpathway epistatic interactions that form intricate, complex regulatory networks. Cryptococcus species are a group of closely related human fungal pathogens that grow as yeasts yet transition to hyphae during sexual reproduction. Additionally, during infection they can form large, polyploid titan cells that evade immunity and develop drug resistance. Multiple known signaling pathways regulate cellular development, yet how these are coordinated and interact with genetic variation is less well understood. Here, we conducted quantitative trait locus (QTL) analyses of a mapping population generated by sexual reproduction of two parents, only one of which is unisexually fertile. We observed transgressive segregation of the unisexual phenotype among progeny, as well as a large-cell phenotype under mating-inducing conditions. These large-cell progeny were found to produce titan cells both in vitro and in infected animals. Two major QTLs and corresponding quantitative trait genes (QTGs) were identified: RIC8 (encoding a guanine-exchange factor) and CNC06490 (encoding a putative Rho-GTPase activator), both involved in G protein signaling. The two QTGs interact epistatically with each other and with the mating-type locus in phenotypic determination. These findings provide insights into the complex genetics of morphogenesis during unisexual reproduction and pathogenic titan cell formation and illustrate how QTL analysis can be applied to identify epistasis between genes. This study shows that phenotypic outcomes are influenced by the genetic background upon which mutations arise, implicating dynamic, complex genotype-to-phenotype landscapes in fungal pathogens and beyond.
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Affiliation(s)
- Sheng Sun
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710
| | - Cullen Roth
- Department of Biology, Duke University, Durham, NC 27708
| | - Anna Floyd Averette
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710
| | - Paul M Magwene
- Department of Biology, Duke University, Durham, NC 27708
| | - Joseph Heitman
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710;
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Passer AR, Clancey SA, Shea T, David-Palma M, Averette AF, Boekhout T, Porcel BM, Nowrousian M, Cuomo CA, Sun S, Heitman J, Coelho MA. Obligate sexual reproduction of a homothallic fungus closely related to the Cryptococcus pathogenic species complex. eLife 2022; 11:79114. [PMID: 35713948 PMCID: PMC9296135 DOI: 10.7554/elife.79114] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Accepted: 06/15/2022] [Indexed: 12/03/2022] Open
Abstract
<title>eLife digest</title>. Fungi are enigmatic organisms that flourish in soil, on decaying plants, or during infection of animals or plants. Growing in myriad forms, from single-celled yeast to multicellular molds and mushrooms, fungi have also evolved a variety of strategies to reproduce. Normally, fungi reproduce in one of two ways: either they reproduce asexually, with one individual producing a new individual identical to itself, or they reproduce sexually, with two individuals of different 'mating types' contributing to produce a new individual. However, individuals of some species exhibit 'homothallism' or self-fertility: these individuals can produce reproductive cells that are universally compatible, and therefore can reproduce sexually with themselves or with any other cell in the population. Homothallism has evolved multiple times throughout the fungal kingdom, suggesting it confers advantage when population numbers are low or mates are hard to find. Yet some homothallic fungi been overlooked compared to heterothallic species, whose mating types have been well characterised. Understanding the genetic basis of homothallism and how it evolved in different species can provide insights into pathogenic species that cause fungal disease. With that in mind, Passer, Clancey et al. explored the genetic basis of homothallism in Cryptococcus depauperatus, a close relative of C. neoformans, a species that causes fungal infections in humans. A combination of genetic sequencing techniques and experiments were applied to analyse, compare, and manipulate C. depauperatus' genome to see how this species evolved self-fertility. Passer, Clancey et al. showed that C. depauperatus evolved the ability to reproduce sexually by itself via a unique evolutionary pathway. The result is a form of homothallism never reported in fungi before. C. depauperatus lost some of the genes that control mating in other species of fungi, and acquired genes from the opposing mating types of a heterothallic ancestor to become self-fertile. Passer, Clancey et al. also found that, unlike other Cryptococcus species that switch between asexual and sexual reproduction, C. depauperatus grows only as long, branching filaments called hyphae, a sexual form. The species reproduces sexually with itself throughout its life cycle and is unable to produce a yeast (asexual) form, in contrast to other closely related species. This work offers new insights into how different modes of sexual reproduction have evolved in fungi. It also provides another interesting case of how genome plasticity and evolutionary pressures can produce similar outcomes, homothallism, via different evolutionary paths. Lastly, assembling the complete genome of C. depauperatus will foster comparative studies between pathogenic and non-pathogenic Cryptococcus species.
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Affiliation(s)
- Andrew Ryan Passer
- Department of Molecular Genetics and Microbiology, Duke University Medical CenterDurhamUnited States
| | - Shelly Applen Clancey
- Department of Molecular Genetics and Microbiology, Duke University Medical CenterDurhamUnited States
| | - Terrance Shea
- Broad Institute of MIT and HarvardCambridgeUnited States
| | - Márcia David-Palma
- Department of Molecular Genetics and Microbiology, Duke University Medical CenterDurhamUnited States
| | - Anna Floyd Averette
- Department of Molecular Genetics and Microbiology, Duke University Medical CenterDurhamUnited States
| | - Teun Boekhout
- Westerdijk Fungal Biodiversity InstituteUtrechtNetherlands,Institute of Biodiversity and Ecosystem Dynamics (IBED), University of AmsterdamAmsterdamNetherlands
| | - Betina M Porcel
- Génomique Métabolique, CNRS, University Evry, Université Paris-SaclayEvryFrance
| | - Minou Nowrousian
- Lehrstuhl für Molekulare und Zelluläre Botanik, Ruhr-Universität BochumBochumGermany
| | | | - Sheng Sun
- Department of Molecular Genetics and Microbiology, Duke University Medical CenterDurhamUnited States
| | - Joseph Heitman
- Department of Molecular Genetics and Microbiology, Duke University Medical CenterDurhamUnited States
| | - Marco A Coelho
- Department of Molecular Genetics and Microbiology, Duke University Medical CenterDurhamUnited States
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6
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Juvvadi PR, Fox D, Bobay BG, Hoy MJ, Gobeil SMC, Venters RA, Chang Z, Lin JJ, Averette AF, Cole DC, Barrington BC, Wheaton JD, Ciofani M, Trzoss M, Li X, Lee SC, Chen YL, Mutz M, Spicer LD, Schumacher MA, Heitman J, Steinbach WJ. Harnessing calcineurin-FK506-FKBP12 crystal structures from invasive fungal pathogens to develop antifungal agents. Nat Commun 2019; 10:4275. [PMID: 31537789 PMCID: PMC6753081 DOI: 10.1038/s41467-019-12199-1] [Citation(s) in RCA: 67] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Accepted: 08/23/2019] [Indexed: 12/16/2022] Open
Abstract
Calcineurin is important for fungal virulence and a potential antifungal target, but compounds targeting calcineurin, such as FK506, are immunosuppressive. Here we report the crystal structures of calcineurin catalytic (CnA) and regulatory (CnB) subunits complexed with FK506 and the FK506-binding protein (FKBP12) from human fungal pathogens (Aspergillus fumigatus, Candida albicans, Cryptococcus neoformans and Coccidioides immitis). Fungal calcineurin complexes are similar to the mammalian complex, but comparison of fungal and human FKBP12 (hFKBP12) reveals conformational differences in the 40s and 80s loops. NMR analysis, molecular dynamic simulations, and mutations of the A. fumigatus CnA/CnB-FK506-FKBP12-complex identify a Phe88 residue, not conserved in hFKBP12, as critical for binding and inhibition of fungal calcineurin. These differences enable us to develop a less immunosuppressive FK506 analog, APX879, with an acetohydrazine substitution of the C22-carbonyl of FK506. APX879 exhibits reduced immunosuppressive activity and retains broad-spectrum antifungal activity and efficacy in a murine model of invasive fungal infection.
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Affiliation(s)
- Praveen R Juvvadi
- Division of Pediatric Infectious Diseases, Department of Pediatrics, Duke University Medical Center, Durham, NC, 27710, USA.
| | - David Fox
- Beryllium Discovery Corp., 7869 NE Day Road West, Bainbridge Island, WA, 98110, USA
- UCB Pharma., 7869 NE Day Road West, Bainbridge Island, WA, 98110, USA
- Seattle Structural Genomics Center for Infectious Disease (SSGCID), Seattle, WA, USA
| | - Benjamin G Bobay
- Duke University NMR Center, Duke University Medical Center, Durham, NC, 27710, USA
- Department of Biochemistry, Duke University, Durham, NC, 27710, USA
- Department of Radiology, Duke University, Durham, NC, 27710, USA
| | - Michael J Hoy
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC, 27710, USA
| | - Sophie M C Gobeil
- Department of Biochemistry, Duke University, Durham, NC, 27710, USA
- Department of Radiology, Duke University, Durham, NC, 27710, USA
| | - Ronald A Venters
- Duke University NMR Center, Duke University Medical Center, Durham, NC, 27710, USA
- Department of Biochemistry, Duke University, Durham, NC, 27710, USA
- Department of Radiology, Duke University, Durham, NC, 27710, USA
| | - Zanetta Chang
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC, 27710, USA
| | - Jackie J Lin
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC, 27710, USA
| | - Anna Floyd Averette
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC, 27710, USA
| | - D Christopher Cole
- Division of Pediatric Infectious Diseases, Department of Pediatrics, Duke University Medical Center, Durham, NC, 27710, USA
| | - Blake C Barrington
- Division of Pediatric Infectious Diseases, Department of Pediatrics, Duke University Medical Center, Durham, NC, 27710, USA
| | - Joshua D Wheaton
- Department of Immunology, Duke University Medical Center, Durham, NC, 27710, USA
| | - Maria Ciofani
- Department of Immunology, Duke University Medical Center, Durham, NC, 27710, USA
| | - Michael Trzoss
- Amplyx Pharmaceuticals, 3210 Merryfield Row, San Diego, CA, 92121, USA
| | - Xiaoming Li
- Amplyx Pharmaceuticals, 3210 Merryfield Row, San Diego, CA, 92121, USA
- Forge Therapeutics, Inc., 10578 Science Center Drive, San Diego, CA, 92121, USA
| | - Soo Chan Lee
- South Texas Center for Emerging Infectious Diseases, Department of Biology, The University of Texas at San Antonio, San Antonio, TX, 78249, USA
| | - Ying-Lien Chen
- Department of Plant Pathology and Microbiology, National Taiwan University, Taipei, 10617, Taiwan
| | - Mitchell Mutz
- Amplyx Pharmaceuticals, 3210 Merryfield Row, San Diego, CA, 92121, USA
- Genentech Inc., 1 DNA Way, San Francisco, CA, 94080, USA
| | - Leonard D Spicer
- Duke University NMR Center, Duke University Medical Center, Durham, NC, 27710, USA
- Department of Biochemistry, Duke University, Durham, NC, 27710, USA
- Department of Radiology, Duke University, Durham, NC, 27710, USA
| | | | - Joseph Heitman
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC, 27710, USA
| | - William J Steinbach
- Division of Pediatric Infectious Diseases, Department of Pediatrics, Duke University Medical Center, Durham, NC, 27710, USA.
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC, 27710, USA.
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7
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Passer AR, Coelho MA, Billmyre RB, Nowrousian M, Mittelbach M, Yurkov AM, Averette AF, Cuomo CA, Sun S, Heitman J. Genetic and Genomic Analyses Reveal Boundaries between Species Closely Related to Cryptococcus Pathogens. mBio 2019; 10:e00764-19. [PMID: 31186317 PMCID: PMC6561019 DOI: 10.1128/mbio.00764-19] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Accepted: 05/08/2019] [Indexed: 12/30/2022] Open
Abstract
Speciation is a central mechanism of biological diversification. While speciation is well studied in plants and animals, in comparison, relatively little is known about speciation in fungi. One fungal model is the Cryptococcus genus, which is best known for the pathogenic Cryptococcus neoformans/Cryptococcus gattii species complex that causes >200,000 new human infections annually. Elucidation of how these species evolved into important human-pathogenic species remains challenging and can be advanced by studying the most closely related nonpathogenic species, Cryptococcus amylolentus and Tsuchiyaea wingfieldii However, these species have only four known isolates, and available data were insufficient to determine species boundaries within this group. By analyzing full-length chromosome assemblies, we reappraised the phylogenetic relationships of the four available strains, confirmed the genetic separation of C. amylolentus and T. wingfieldii (now Cryptococcus wingfieldii), and revealed an additional cryptic species, for which the name Cryptococcus floricola is proposed. The genomes of the three species are ∼6% divergent and exhibit significant chromosomal rearrangements, including inversions and a reciprocal translocation that involved intercentromeric ectopic recombination, which together likely impose significant barriers to genetic exchange. Using genetic crosses, we show that while C. wingfieldii cannot interbreed with any of the other strains, C. floricola can still undergo sexual reproduction with C. amylolentus However, most of the resulting spores were inviable or sterile or showed reduced recombination during meiosis, indicating that intrinsic postzygotic barriers had been established. Our study and genomic data will foster additional studies addressing fungal speciation and transitions between nonpathogenic and pathogenic Cryptococcus lineages.IMPORTANCE The evolutionary drivers of speciation are critical to our understanding of how new pathogens arise from nonpathogenic lineages and adapt to new environments. Here we focus on the Cryptococcus amylolentus species complex, a nonpathogenic fungal lineage closely related to the human-pathogenic Cryptococcus neoformans/Cryptococcus gattii complex. Using genetic and genomic analyses, we reexamined the species boundaries of four available isolates within the C. amylolentus complex and revealed three genetically isolated species. Their genomes are ∼6% divergent and exhibit chromosome rearrangements, including translocations and small-scale inversions. Although two of the species (C. amylolentus and newly described C. floricola) were still able to interbreed, the resulting hybrid progeny were usually inviable or sterile, indicating that barriers to reproduction had already been established. These results advance our understanding of speciation in fungi and highlight the power of genomics in assisting our ability to correctly identify and discriminate fungal species.
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Affiliation(s)
- Andrew Ryan Passer
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, USA
| | - Marco A Coelho
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, USA
| | - Robert Blake Billmyre
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, USA
| | - Minou Nowrousian
- Lehrstuhl für Allgemeine und Molekulare Botanik, Ruhr-Universität Bochum, Bochum, Germany
| | - Moritz Mittelbach
- Geobotany, Faculty of Biology and Biotechnology, Ruhr-University Bochum, Bochum, Germany
| | - Andrey M Yurkov
- Leibniz Institute DSMZ-German Collection of Microorganisms and Cell Cultures, Braunschweig, Germany
| | - Anna Floyd Averette
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, USA
| | | | - Sheng Sun
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, USA
| | - Joseph Heitman
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, USA
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8
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Chow EWL, Clancey SA, Billmyre RB, Averette AF, Granek JA, Mieczkowski P, Cardenas ME, Heitman J. Elucidation of the calcineurin-Crz1 stress response transcriptional network in the human fungal pathogen Cryptococcus neoformans. PLoS Genet 2017; 13:e1006667. [PMID: 28376087 PMCID: PMC5380312 DOI: 10.1371/journal.pgen.1006667] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Accepted: 03/01/2017] [Indexed: 12/02/2022] Open
Abstract
Calcineurin is a highly conserved Ca2+/calmodulin-dependent serine/threonine-specific protein phosphatase that orchestrates cellular Ca2+ signaling responses. In Cryptococcus neoformans, calcineurin is activated by multiple stresses including high temperature, and is essential for stress adaptation and virulence. The transcription factor Crz1 is a major calcineurin effector in Saccharomyces cerevisiae and other fungi. Calcineurin dephosphorylates Crz1, thereby enabling Crz1 nuclear translocation and transcription of target genes. Here we show that loss of Crz1 confers phenotypes intermediate between wild-type and calcineurin mutants, and demonstrate that deletion of the calcineurin docking domain results in the inability of Crz1 to translocate into the nucleus under thermal stress. RNA-sequencing revealed 102 genes that are regulated in a calcineurin-Crz1-dependent manner at 37°C. The majority of genes were down-regulated in cna1Δ and crz1Δ mutants, indicating these genes are normally activated by the calcineurin-Crz1 pathway at high temperature. About 58% of calcineurin-Crz1 target genes have unknown functions, while genes with known or predicted functions are involved in cell wall remodeling, calcium transport, and pheromone production. We identified three calcineurin-dependent response element motifs within the promoter regions of calcineurin-Crz1 target genes, and show that Crz1 binding to target gene promoters is increased upon thermal stress in a calcineurin-dependent fashion. Additionally, we found a large set of genes independently regulated by calcineurin, and Crz1 regulates 59 genes independently of calcineurin. Given the intermediate crz1Δ mutant phenotype, and our recent evidence for a calcineurin regulatory network impacting mRNA in P-bodies and stress granules independently of Crz1, calcineurin likely acts on factors beyond Crz1 that govern mRNA expression/stability to operate a branched transcriptional/post-transcriptional stress response network necessary for fungal virulence. Taken together, our findings reveal the core calcineurin-Crz1 stress response cascade is maintained from ascomycetes to a pathogenic basidiomycete fungus, but its output in C. neoformans appears to be adapted to promote fungal virulence. The ubquitiously conserved serine/threonine-specific protein phosphatase calcineurin is crucial for virulence of several opportunistic human fungal pathogens including Candida albicans, Aspergillus fumigatus, and Cryptococcus neoformans. We show that Crz1 acts downstream of calcineurin, to 1) govern expression of genes involved in cell wall integrity, and calcium and small molecule transport, and 2) contribute to stress survival and virulence of C. neoformans. Our studies reveal that calcineurin also controls mRNA expression levels of other genes independently of Crz1. We propose that calcineurin operates in a branched signal transduction cascade controlling targets at both the transcriptional and post-transcriptional levels.
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Affiliation(s)
- Eve W. L. Chow
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Shelly A. Clancey
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - R. Blake Billmyre
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Anna Floyd Averette
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Joshua A. Granek
- Department of Biostatistics and Bioinformatics, Duke University Medical Center, Durham, North Carolina, United States of America
- Duke Center for the Genomics of Microbial Systems, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Piotr Mieczkowski
- High-Throughput Sequencing Facility, School of Medicine, University of North Carolina, Chapel Hill, North Carolina, United States of America
| | - Maria E. Cardenas
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Joseph Heitman
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, United States of America
- * E-mail:
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Wu G, Zhao H, Li C, Rajapakse MP, Wong WC, Xu J, Saunders CW, Reeder NL, Reilman RA, Scheynius A, Sun S, Billmyre BR, Li W, Averette AF, Mieczkowski P, Heitman J, Theelen B, Schröder MS, De Sessions PF, Butler G, Maurer-Stroh S, Boekhout T, Nagarajan N, Dawson TL. Genus-Wide Comparative Genomics of Malassezia Delineates Its Phylogeny, Physiology, and Niche Adaptation on Human Skin. PLoS Genet 2015; 11:e1005614. [PMID: 26539826 PMCID: PMC4634964 DOI: 10.1371/journal.pgen.1005614] [Citation(s) in RCA: 151] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2015] [Accepted: 09/27/2015] [Indexed: 01/27/2023] Open
Abstract
Malassezia is a unique lipophilic genus in class Malasseziomycetes in Ustilaginomycotina, (Basidiomycota, fungi) that otherwise consists almost exclusively of plant pathogens. Malassezia are typically isolated from warm-blooded animals, are dominant members of the human skin mycobiome and are associated with common skin disorders. To characterize the genetic basis of the unique phenotypes of Malassezia spp., we sequenced the genomes of all 14 accepted species and used comparative genomics against a broad panel of fungal genomes to comprehensively identify distinct features that define the Malassezia gene repertoire: gene gain and loss; selection signatures; and lineage-specific gene family expansions. Our analysis revealed key gene gain events (64) with a single gene conserved across all Malassezia but absent in all other sequenced Basidiomycota. These likely horizontally transferred genes provide intriguing gain-of-function events and prime candidates to explain the emergence of Malassezia. A larger set of genes (741) were lost, with enrichment for glycosyl hydrolases and carbohydrate metabolism, concordant with adaptation to skin’s carbohydrate-deficient environment. Gene family analysis revealed extensive turnover and underlined the importance of secretory lipases, phospholipases, aspartyl proteases, and other peptidases. Combining genomic analysis with a re-evaluation of culture characteristics, we establish the likely lipid-dependence of all Malassezia. Our phylogenetic analysis sheds new light on the relationship between Malassezia and other members of Ustilaginomycotina, as well as phylogenetic lineages within the genus. Overall, our study provides a unique genomic resource for understanding Malassezia niche-specificity and potential virulence, as well as their abundance and distribution in the environment and on human skin. Malassezia are the dominant eukaryotic residents of human skin and are associated with the most common skin disorders, including dandruff, atopic dermatitis, eczema, and others. Despite significant effort, the role of Malassezia in skin disease and homeostasis remains unclear. Malassezia are also unique among fungi by requiring lipids for growth, but the breadth and genetic basis of their lipophilic lifestyle has not been comprehensively studied. Here we report the complete genomes of all 14 Malassezia species (including multiple strains of the most common species found on humans) and systematically identify features that define the genus and its sub-lineages, including horizontally transferred genes likely to represent key gain-of-function events and which may have enabled evolution of the genus from plant to animal inhabitants. Genus wide expansion of lipid hydrolases and loss of carbohydrate metabolism genes underscore the entire genus’ gradual evolution to lipid-dependency, which was confirmed even in the previously thought to be lipophilic M. pachydermatis, via genomics with experimental confirmation. Finally, these reference genomes will serve as a valuable resource for future metagenomic investigations into the role of Malassezia species in normal healthy skin and diseases.
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Affiliation(s)
- Guangxi Wu
- Computational and Systems Biology, Genome Institute of Singapore, A*STAR, Singapore
| | - He Zhao
- Procter & Gamble Singapore Innovation Center, Singapore
| | - Chenhao Li
- Computational and Systems Biology, Genome Institute of Singapore, A*STAR, Singapore
| | | | | | - Jun Xu
- Procter & Gamble Mason Business Center, Mason, Ohio, United States of America
| | - Charles W. Saunders
- Procter & Gamble Mason Business Center, Mason, Ohio, United States of America
| | - Nancy L. Reeder
- Procter & Gamble Mason Business Center, Mason, Ohio, United States of America
| | - Raymond A. Reilman
- Procter & Gamble Mason Business Center, Mason, Ohio, United States of America
| | - Annika Scheynius
- Translational Immunology Unit, Department of Medicine Solna, Karolinska Institutet and University Hospital, Stockholm, Sweden
| | - Sheng Sun
- Duke University Medical Center, Durham, North Carolina, United States of America
| | | | - Wenjun Li
- National Center for Biotechnology Information, Bethesda, Maryland, United States of America
| | - Anna Floyd Averette
- Duke University Medical Center, Durham, North Carolina, United States of America
| | - Piotr Mieczkowski
- University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Joseph Heitman
- Duke University Medical Center, Durham, North Carolina, United States of America
| | - Bart Theelen
- Fungal Biodiversity Centre, CBS-KNAW, Utrecht, The Netherlands
| | | | | | | | - Sebastian Maurer-Stroh
- Bioinformatics Institute, A*STAR, Singapore
- School of Biological Sciences, Nanyang Technological University (NTU), Singapore
| | - Teun Boekhout
- Fungal Biodiversity Centre, CBS-KNAW, Utrecht, The Netherlands
| | - Niranjan Nagarajan
- Computational and Systems Biology, Genome Institute of Singapore, A*STAR, Singapore
- * E-mail: (NN); (TLD)
| | - Thomas L. Dawson
- Institute of Medical Biology, A*STAR, Singapore
- * E-mail: (NN); (TLD)
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Findley K, Sun S, Fraser JA, Hsueh YP, Averette AF, Li W, Dietrich FS, Heitman J. Discovery of a modified tetrapolar sexual cycle in Cryptococcus amylolentus and the evolution of MAT in the Cryptococcus species complex. PLoS Genet 2012; 8:e1002528. [PMID: 22359516 PMCID: PMC3280970 DOI: 10.1371/journal.pgen.1002528] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2011] [Accepted: 12/21/2011] [Indexed: 12/16/2022] Open
Abstract
Sexual reproduction in fungi is governed by a specialized genomic region called the mating-type locus (MAT). The human fungal pathogenic and basidiomycetous yeast Cryptococcus neoformans has evolved a bipolar mating system (a, α) in which the MAT locus is unusually large (>100 kb) and encodes >20 genes including homeodomain (HD) and pheromone/receptor (P/R) genes. To understand how this unique bipolar mating system evolved, we investigated MAT in the closely related species Tsuchiyaea wingfieldii and Cryptococcus amylolentus and discovered two physically unlinked loci encoding the HD and P/R genes. Interestingly, the HD (B) locus sex-specific region is restricted (∼2 kb) and encodes two linked and divergently oriented homeodomain genes in contrast to the solo HD genes (SXI1α, SXI2a) of C. neoformans and Cryptococcus gattii. The P/R (A) locus contains the pheromone and pheromone receptor genes but has expanded considerably compared to other outgroup species (Cryptococcus heveanensis) and is linked to many of the genes also found in the MAT locus of the pathogenic Cryptococcus species. Our discovery of a heterothallic sexual cycle for C. amylolentus allowed us to establish the biological roles of the sex-determining regions. Matings between two strains of opposite mating-types (A1B1×A2B2) produced dikaryotic hyphae with fused clamp connections, basidia, and basidiospores. Genotyping progeny using markers linked and unlinked to MAT revealed that meiosis and uniparental mitochondrial inheritance occur during the sexual cycle of C. amylolentus. The sexual cycle is tetrapolar and produces fertile progeny of four mating-types (A1B1, A1B2, A2B1, and A2B2), but a high proportion of progeny are infertile, and fertility is biased towards one parental mating-type (A1B1). Our studies reveal insights into the plasticity and transitions in both mechanisms of sex determination (bipolar versus tetrapolar) and sexual reproduction (outcrossing versus inbreeding) with implications for similar evolutionary transitions and processes in fungi, plants, and animals.
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Affiliation(s)
- Keisha Findley
- Genetics and Molecular Biology Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland, United States of America
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Sheng Sun
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - James A. Fraser
- School of Molecular and Microbial Sciences, University of Queensland, Brisbane, Australia
| | - Yen-Ping Hsueh
- Division of Biology, California Institute of Technology, Pasadena, California, United States of America
| | - Anna Floyd Averette
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Wenjun Li
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Fred S. Dietrich
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Joseph Heitman
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, United States of America
- * E-mail:
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