1
|
Guha S, Cristy SA, Buda De Cesare G, Cruz MR, Lorenz MC, Garsin DA. Optimization of the antifungal properties of the bacterial peptide EntV by variant analysis. mBio 2024; 15:e0057024. [PMID: 38587425 PMCID: PMC11077972 DOI: 10.1128/mbio.00570-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2024] [Accepted: 03/13/2024] [Indexed: 04/09/2024] Open
Abstract
Fungal resistance to commonly used medicines is a growing public health threat, and there is a dire need to develop new classes of antifungals. We previously described a peptide produced by Enterococcus faecalis, EntV, that restricts Candida albicans to a benign form rather than having direct fungicidal activity. Moreover, we showed that one 12-amino acid (aa) alpha helix of this peptide retained full activity, with partial activity down to the 10aa alpha helix. Using these peptides as a starting point, the current investigation sought to identify the critical features necessary for antifungal activity and to screen for new variants with enhanced activity using both biofilm and C. elegans infection assays. First, the short peptides were screened for residues with critical activity by generating alanine substitutions. Based on this information, we used synthetic molecular evolution (SME) to rationally vary the specific residues of the 10aa variant in combination to generate a library that was screened to identify variants with more potent antifungal activity than the parent template. Five gain-of-function peptides were identified. Additionally, chemical modifications to the peptides to increase stability, including substitutions of D-amino acids and hydrocarbon stapling, were investigated. The most promising peptides were additionally tested in mouse models of oropharyngeal and systemic candidiasis where their efficacy in preventing infection was demonstrated. The expectation is that these discoveries will contribute to the development of new therapeutics in the fight against antimicrobial resistant fungi. IMPORTANCE Since the early 1980s, the incidence of disseminated life-threatening fungal infections has been on the rise. Worldwide, Candida and Cryptococcus species are among the most common agents causing these infections. Simultaneously, with this rise of clinical incidence, there has also been an increased prevalence of antifungal resistance, making treatment of these infections very difficult. For example, there are now strains of Candida auris that are resistant to all three classes of currently used antifungal drugs. In this study, we report on a strategy that allows for the development of novel antifungal agents by using synthetic molecular evolution. These discoveries demonstrate that the enhancement of antifungal activity from naturally occurring peptides is possible and can result in clinically relevant agents that have efficacy in multiple in vivo models as well as the potential for broad-spectrum activity.
Collapse
Affiliation(s)
- Shantanu Guha
- Department of Microbiology and Molecular Genetics, The University of Texas Health Science Center at Houston, Houston, Texas, USA
| | - Shane A. Cristy
- Department of Microbiology and Molecular Genetics, The University of Texas Health Science Center at Houston, Houston, Texas, USA
| | - Giuseppe Buda De Cesare
- Department of Microbiology and Molecular Genetics, The University of Texas Health Science Center at Houston, Houston, Texas, USA
| | - Melissa R. Cruz
- Department of Microbiology and Molecular Genetics, The University of Texas Health Science Center at Houston, Houston, Texas, USA
| | - Michael C. Lorenz
- Department of Microbiology and Molecular Genetics, The University of Texas Health Science Center at Houston, Houston, Texas, USA
| | - Danielle A. Garsin
- Department of Microbiology and Molecular Genetics, The University of Texas Health Science Center at Houston, Houston, Texas, USA
| |
Collapse
|
2
|
Sirag B, Khidir ES, Dumyati M, Sindi B, Alsinnari M, Faidah H, Ahmed A. Cryptococcus neoformans and Other Opportunistic Cryptococcus Species in Pigeon Dropping in Saudi Arabia: Identification and Characterization by DNA Sequencing. Front Microbiol 2021; 12:726203. [PMID: 34707582 PMCID: PMC8544600 DOI: 10.3389/fmicb.2021.726203] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Accepted: 08/31/2021] [Indexed: 11/19/2022] Open
Abstract
The prevalent variants of Cryptococcus neoformans, and other Cryptococcus species in pigeon excreta in Western Region of Saudi Arabia were studied. Ninety pigeon dropping samples were plated directly on Niger seed agar, and suspected colonies were sequenced using Illumina MiSeq. Species identification was determined using sequence read mapping to reference genomes of the two C. neoformans variants. In addition, sequence reads were identified using the KmerFinder tool. internal transcribed spacer 2 in the rDNA was also used for fungal barcoding of none of the C. neoformans species using two fungal identification databases. Phylogeny was studied using CSI Phylogeny (Center for Genomic Epidemiology, Denmark). The C. neoformans var. grubii mitochondrion and chromosome 1 reference sequences (accession numbers NC_004336.1 and CP022321.1, respectively) were used for sequence comparison and variant calling. Fifteen Cryptococcus isolates were isolated, 11 were identified as C. neoformans var. grubii, and 4 were found to be other opportunistic Cryptococcus species. Phylogeny analysis of C. neoformans var. grubii isolates showed a high degree of similarity between the C. neoformans isolates especially at the mitochondrial genome level. This study supports the fact that pathogenic and opportunistic Cryptococcus species are prevalent in domestic bird excreta which is an easy source of infection in the susceptible population.
Collapse
Affiliation(s)
- Bashir Sirag
- Department of Microbiology, College of Medicine, Umm Al-Qura University, Makkah, Saudi Arabia
| | - El-Shiekh Khidir
- Laboratory Medicine Department, Faculty of Applied Medical Sciences, Umm Al-Qura University, Makkah, Saudi Arabia
| | - Mohammed Dumyati
- Department of Medicine, National Guard Health Affairs, King Abdulaziz Medical City, Jeddah, Saudi Arabia
| | - Basam Sindi
- Department of Medicine, King Fahad Armed Forces Hospital, Jeddah, Saudi Arabia
| | - Mahir Alsinnari
- Department of Anesthesia, Al Noor Specialist Hospital, Makkah, Saudi Arabia
| | - Hani Faidah
- Department of Microbiology, College of Medicine, Umm Al-Qura University, Makkah, Saudi Arabia
| | - Abdalla Ahmed
- Department of Microbiology, College of Medicine, Umm Al-Qura University, Makkah, Saudi Arabia
| |
Collapse
|
3
|
MycopathologiaGENOMES: The New 'Home' for the Publication of Fungal Genomes. Mycopathologia 2019; 184:551-554. [PMID: 31399887 DOI: 10.1007/s11046-019-00366-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Accepted: 07/20/2019] [Indexed: 10/26/2022]
Abstract
The wider availability of information on genomes has become essential for future advances in fungal biology, pathogenesis and epidemiology, and for the discovery of new drugs and diagnostics. MycopathologiaGENOMES is designed for the rapid publication of new genomes of human and animal pathogenic fungi using a checklist-based, standardized format.
Collapse
|
4
|
Jung KW, Lee KT, So YS, Bahn YS. Genetic Manipulation of Cryptococcus neoformans. ACTA ACUST UNITED AC 2018; 50:e59. [PMID: 30016567 DOI: 10.1002/cpmc.59] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Cryptococcus neoformans is an opportunistic fungal pathogen, which causes life-threatening meningoencephalitis in immunocompromised individuals and is responsible for more than 1,000,000 infections and 600,000 deaths annually worldwide. Nevertheless, anti-cryptococcal therapeutic options are limited, mainly because of the similarity between fungal and human cellular structures. Owing to advances in genetic and molecular techniques and bioinformatics in the past decade, C. neoformans, belonging to the phylum basidiomycota, is now a major pathogenic fungal model system. In particular, genetic manipulation is the first step in the identification and characterization of the function of genes for understanding the mechanisms underlying the pathogenicity of C. neoformans. This unit describes protocols for constructing target gene deletion mutants using double-joint (DJ) PCR, constitutive overexpression strains using the histone H3 gene promoter, and epitope/fluorescence protein-tagged strains in C. neoformans. © 2018 by John Wiley & Sons, Inc.
Collapse
Affiliation(s)
- Kwang-Woo Jung
- Research Division for Biotechnology, Korea Atomic Energy Research Institute, Jeongeup, Republic of Korea
| | - Kyung-Tae Lee
- Department of Biotechnology, Yonsei University, Seoul, Republic of Korea
| | - Yee-Seul So
- Department of Biotechnology, Yonsei University, Seoul, Republic of Korea
| | - Yong-Sun Bahn
- Department of Biotechnology, Yonsei University, Seoul, Republic of Korea
| |
Collapse
|
5
|
Janbon G, Ormerod KL, Paulet D, Byrnes EJ, Yadav V, Chatterjee G, Mullapudi N, Hon CC, Billmyre RB, Brunel F, Bahn YS, Chen W, Chen Y, Chow EWL, Coppée JY, Floyd-Averette A, Gaillardin C, Gerik KJ, Goldberg J, Gonzalez-Hilarion S, Gujja S, Hamlin JL, Hsueh YP, Ianiri G, Jones S, Kodira CD, Kozubowski L, Lam W, Marra M, Mesner LD, Mieczkowski PA, Moyrand F, Nielsen K, Proux C, Rossignol T, Schein JE, Sun S, Wollschlaeger C, Wood IA, Zeng Q, Neuvéglise C, Newlon CS, Perfect JR, Lodge JK, Idnurm A, Stajich JE, Kronstad JW, Sanyal K, Heitman J, Fraser JA, Cuomo CA, Dietrich FS. Analysis of the genome and transcriptome of Cryptococcus neoformans var. grubii reveals complex RNA expression and microevolution leading to virulence attenuation. PLoS Genet 2014; 10:e1004261. [PMID: 24743168 PMCID: PMC3990503 DOI: 10.1371/journal.pgen.1004261] [Citation(s) in RCA: 268] [Impact Index Per Article: 26.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2013] [Accepted: 02/07/2014] [Indexed: 02/07/2023] Open
Abstract
Cryptococcus neoformans is a pathogenic basidiomycetous yeast responsible for more than 600,000 deaths each year. It occurs as two serotypes (A and D) representing two varieties (i.e. grubii and neoformans, respectively). Here, we sequenced the genome and performed an RNA-Seq-based analysis of the C. neoformans var. grubii transcriptome structure. We determined the chromosomal locations, analyzed the sequence/structural features of the centromeres, and identified origins of replication. The genome was annotated based on automated and manual curation. More than 40,000 introns populating more than 99% of the expressed genes were identified. Although most of these introns are located in the coding DNA sequences (CDS), over 2,000 introns in the untranslated regions (UTRs) were also identified. Poly(A)-containing reads were employed to locate the polyadenylation sites of more than 80% of the genes. Examination of the sequences around these sites revealed a new poly(A)-site-associated motif (AUGHAH). In addition, 1,197 miscRNAs were identified. These miscRNAs can be spliced and/or polyadenylated, but do not appear to have obvious coding capacities. Finally, this genome sequence enabled a comparative analysis of strain H99 variants obtained after laboratory passage. The spectrum of mutations identified provides insights into the genetics underlying the micro-evolution of a laboratory strain, and identifies mutations involved in stress responses, mating efficiency, and virulence. Cryptococcus neoformans var. grubii is a major human pathogen responsible for deadly meningoencephalitis in immunocompromised patients. Here, we report the sequencing and annotation of its genome. Evidence for extensive intron splicing, antisense transcription, non-coding RNAs, and alternative polyadenylation indicates the potential for highly intricate regulation of gene expression in this opportunistic pathogen. In addition, detailed molecular, genetic, and genomic studies were performed to characterize structural features of the genome, including centromeres and origins of replication. Finally, the phenotypic and genome re-sequencing analysis of a collection of isolates of the reference H99 strain resulting from laboratory passage revealed that microevolutionary processes during in vitro culturing of pathogenic fungi can impact virulence.
Collapse
Affiliation(s)
- Guilhem Janbon
- Institut Pasteur, Unité Biologie et Pathogénicité Fongiques, Département Génomes et Génétique, Paris, France
- INRA, USC2019, Paris, France
- * E-mail: (GJ); (JH); (CAC); (FSD)
| | - Kate L. Ormerod
- University of Queensland, School of Chemistry and Molecular Biosciences, Brisbane, Queensland, Australia
| | - Damien Paulet
- Institut Pasteur, Plate-forme Transcriptome et Epigénome, Département Génomes et Génétique, Paris, France
| | - Edmond J. Byrnes
- Duke University Medical Center, Department of Molecular Genetics and Microbiology, Durham, North Carolina, United States of America
| | - Vikas Yadav
- Jawaharlal Nehru Centre for Advanced Scientific Research, Molecular Biology and Genetics Unit, Bangalore, India
| | - Gautam Chatterjee
- Jawaharlal Nehru Centre for Advanced Scientific Research, Molecular Biology and Genetics Unit, Bangalore, India
| | | | - Chung-Chau Hon
- Institut Pasteur, Unité Biologie Cellulaire du Parasitisme, Département Biologie Cellulaire et Infection, Paris, France
| | - R. Blake Billmyre
- Duke University Medical Center, Department of Molecular Genetics and Microbiology, Durham, North Carolina, United States of America
| | | | - Yong-Sun Bahn
- Yonsei University, Center for Fungal Pathogenesis, Department of Biotechnology, Seoul, Republic of Korea
| | - Weidong Chen
- Rutgers New Jersey Medical School, Department of Microbiology and Molecular Genetics, Newark, New Jersey, United States of America
| | - Yuan Chen
- Duke University Medical Center, Department of Molecular Genetics and Microbiology, Durham, North Carolina, United States of America
| | - Eve W. L. Chow
- University of Queensland, School of Chemistry and Molecular Biosciences, Brisbane, Queensland, Australia
| | - Jean-Yves Coppée
- Institut Pasteur, Plate-forme Transcriptome et Epigénome, Département Génomes et Génétique, Paris, France
| | - Anna Floyd-Averette
- Duke University Medical Center, Department of Molecular Genetics and Microbiology, Durham, North Carolina, United States of America
| | | | - Kimberly J. Gerik
- Washington University School of Medicine, Department of Molecular Microbiology, St. Louis, Missouri, United States of America
| | - Jonathan Goldberg
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts, United States of America
| | - Sara Gonzalez-Hilarion
- Institut Pasteur, Unité Biologie et Pathogénicité Fongiques, Département Génomes et Génétique, Paris, France
- INRA, USC2019, Paris, France
| | - Sharvari Gujja
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts, United States of America
| | - Joyce L. Hamlin
- University of Virginia, Department of Biochemistry and Molecular Genetics, Charlottesville, Virginia, United States of America
| | - Yen-Ping Hsueh
- Duke University Medical Center, Department of Molecular Genetics and Microbiology, Durham, North Carolina, United States of America
- California Institute of Technology, Division of Biology, Pasadena, California, United States of America
| | - Giuseppe Ianiri
- University of Missouri-Kansas City, School of Biological Sciences, Division of Cell Biology and Biophysics, Kansas City, Missouri, United States of America
| | - Steven Jones
- Canada's Michael Smith Genome Sciences Centre, BC Cancer Agency, Vancouver, British Columbia, Canada
| | - Chinnappa D. Kodira
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts, United States of America
| | - Lukasz Kozubowski
- Clemson University, Department of Genetics and Biochemistry, Clemson, South Carolina, United States of America
| | - Woei Lam
- Washington University School of Medicine, Department of Molecular Microbiology, St. Louis, Missouri, United States of America
| | - Marco Marra
- Canada's Michael Smith Genome Sciences Centre, BC Cancer Agency, Vancouver, British Columbia, Canada
| | - Larry D. Mesner
- University of Virginia, Department of Biochemistry and Molecular Genetics, Charlottesville, Virginia, United States of America
| | - Piotr A. Mieczkowski
- University of North Carolina, Department of Genetics, Chapel Hill, North Carolina, United States of America
| | - Frédérique Moyrand
- Institut Pasteur, Unité Biologie et Pathogénicité Fongiques, Département Génomes et Génétique, Paris, France
- INRA, USC2019, Paris, France
| | - Kirsten Nielsen
- Duke University Medical Center, Department of Molecular Genetics and Microbiology, Durham, North Carolina, United States of America
- University of Minnesota, Microbiology Department, Minneapolis, Minnesota, United States of America
| | - Caroline Proux
- Institut Pasteur, Plate-forme Transcriptome et Epigénome, Département Génomes et Génétique, Paris, France
| | | | - Jacqueline E. Schein
- Canada's Michael Smith Genome Sciences Centre, BC Cancer Agency, Vancouver, British Columbia, Canada
| | - Sheng Sun
- Duke University Medical Center, Department of Molecular Genetics and Microbiology, Durham, North Carolina, United States of America
| | - Carolin Wollschlaeger
- Institut Pasteur, Unité Biologie et Pathogénicité Fongiques, Département Génomes et Génétique, Paris, France
- INRA, USC2019, Paris, France
| | - Ian A. Wood
- University of Queensland, School of Mathematics and Physics, Brisbane, Queensland, Australia
| | - Qiandong Zeng
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts, United States of America
| | | | - Carol S. Newlon
- Rutgers New Jersey Medical School, Department of Microbiology and Molecular Genetics, Newark, New Jersey, United States of America
| | - John R. Perfect
- Duke University Medical Center, Duke Department of Medicine and Molecular Genetics and Microbiology, Durham, North Carolina, United States of America
| | - Jennifer K. Lodge
- Washington University School of Medicine, Department of Molecular Microbiology, St. Louis, Missouri, United States of America
| | - Alexander Idnurm
- University of Missouri-Kansas City, School of Biological Sciences, Division of Cell Biology and Biophysics, Kansas City, Missouri, United States of America
| | - Jason E. Stajich
- Duke University Medical Center, Department of Molecular Genetics and Microbiology, Durham, North Carolina, United States of America
- University of California, Department of Plant Pathology & Microbiology, Riverside, California, United States of America
| | - James W. Kronstad
- Michael Smith Laboratories, Department of Microbiology and Immunology, Vancouver, British Columbia, Canada
| | - Kaustuv Sanyal
- Jawaharlal Nehru Centre for Advanced Scientific Research, Molecular Biology and Genetics Unit, Bangalore, India
| | - Joseph Heitman
- Duke University Medical Center, Department of Molecular Genetics and Microbiology, Durham, North Carolina, United States of America
- * E-mail: (GJ); (JH); (CAC); (FSD)
| | - James A. Fraser
- University of Queensland, School of Chemistry and Molecular Biosciences, Brisbane, Queensland, Australia
| | - Christina A. Cuomo
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts, United States of America
- * E-mail: (GJ); (JH); (CAC); (FSD)
| | - Fred S. Dietrich
- Duke University Medical Center, Department of Molecular Genetics and Microbiology, Durham, North Carolina, United States of America
- * E-mail: (GJ); (JH); (CAC); (FSD)
| |
Collapse
|
6
|
Srikanta D, Santiago-Tirado FH, Doering TL. Cryptococcus neoformans: historical curiosity to modern pathogen. Yeast 2014; 31:47-60. [PMID: 24375706 PMCID: PMC3938112 DOI: 10.1002/yea.2997] [Citation(s) in RCA: 91] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2013] [Revised: 12/06/2013] [Accepted: 12/10/2013] [Indexed: 12/22/2022] Open
Abstract
The importance of the Basidiomycete Cryptococcus neoformans to human health has stimulated its development as an experimental model for both basic physiology and pathogenesis. We briefly review the history of this fascinating and versatile fungus, some notable aspects of its biology that contribute to virulence, and current tools available for its study.
Collapse
Affiliation(s)
- Deepa. Srikanta
- Department of Molecular Microbiology, Washington University School of Medicine
| | | | - Tamara L. Doering
- Department of Molecular Microbiology, Washington University School of Medicine
| |
Collapse
|
7
|
Zhai B, Zhu P, Foyle D, Upadhyay S, Idnurm A, Lin X. Congenic strains of the filamentous form of Cryptococcus neoformans for studies of fungal morphogenesis and virulence. Infect Immun 2013; 81:2626-37. [PMID: 23670559 PMCID: PMC3697605 DOI: 10.1128/iai.00259-13] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2013] [Accepted: 05/08/2013] [Indexed: 02/07/2023] Open
Abstract
Cryptococcus neoformans is an unconventional dimorphic fungus that can grow either as a yeast or in a filamentous form. To facilitate investigation of genetic factors important for its morphogenesis and pathogenicity, congenic a and α strains for a filamentous form were constructed. XL280 (α) was selected as the background strain because of its robust ability to undergo the morphological transition from yeast to the filamentous form. The MATa allele from a sequenced strain JEC20 was introgressed into the XL280 background to generate the congenic a and α pair strains. The resulting congenic strains were then used to test the impact of mating type on virulence. In both the inhalation and the intravenous infection models of murine cryptococcosis, the congenic a and α strains displayed comparable levels of high virulence. The a-α coinfections displayed equivalent virulence to the individual a or α infections in both animal models. Further analyses of the mating type distribution in a-α coinfected mice suggested no influence of a-α interactions on cryptococcal neurotropism, irrespective of the route of inoculation. Furthermore, deletion or overexpression of a known transcription factor, Znf2, in XL280 abolished or enhanced filamentation and biofilm formation, consistent with its established role. Overexpression of Znf2 in XL280 led to attenuation of virulence and a reduced abundance in the brain but not in other organs, suggesting that Znf2 might interfere with cryptococcal neurotropism upon extrapulmonary dissemination. In summary, the congenic strains provide a new resource for the exploration of the relationship in Cryptococcus between cellular morphology and pathogenesis.
Collapse
Affiliation(s)
- Bing Zhai
- Department of Biology, Texas A&M University, College Station, Texas, USA
| | - Pinkuan Zhu
- School of Biological Sciences, University of Missouri—Kansas City, Kansas City, Missouri, USA
- School of Life Science, East China Normal University, Shanghai, People's Republic of China
| | - Dylan Foyle
- Department of Biology, Texas A&M University, College Station, Texas, USA
| | - Srijana Upadhyay
- Department of Biology, Texas A&M University, College Station, Texas, USA
| | - Alexander Idnurm
- School of Biological Sciences, University of Missouri—Kansas City, Kansas City, Missouri, USA
| | - Xiaorong Lin
- Department of Biology, Texas A&M University, College Station, Texas, USA
| |
Collapse
|
8
|
Cogliati M. Global Molecular Epidemiology of Cryptococcus neoformans and Cryptococcus gattii: An Atlas of the Molecular Types. SCIENTIFICA 2013; 2013:675213. [PMID: 24278784 PMCID: PMC3820360 DOI: 10.1155/2013/675213] [Citation(s) in RCA: 157] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2012] [Accepted: 12/11/2012] [Indexed: 05/08/2023]
Abstract
Cryptococcosis is a fungal disease affecting more than one million people per year worldwide. The main etiological agents of cryptococcosis are the two sibling species Cryptococcus neoformans and Cryptococcus gattii that present numerous differences in geographical distribution, ecological niches, epidemiology, pathobiology, clinical presentation and molecular characters. Genotyping of the two Cryptococcus species at subspecies level supplies relevant information to understand how this fungus has spread worldwide, the nature of its population structure, and how it evolved to be a deadly pathogen. At present, nine major molecular types have been recognized: VNI, VNII, VNB, VNIII, and VNIV among C. neoformans isolates, and VGI, VGII, VGIII, and VGIV among C. gattii isolates. In this paper all the information available in the literature concerning the isolation of the two Cryptococcus species has been collected and analyzed on the basis of their geographical origin, source of isolation, level of identification, species, and molecular type. A detailed analysis of the geographical distribution of the major molecular types in each continent has been described and represented on thematic maps. This study represents a useful tool to start new epidemiological surveys on the basis of the present knowledge.
Collapse
Affiliation(s)
- Massimo Cogliati
- Lab. Micologia Medica, Dipartimento di Scienze Biomediche per la Salute, Università degli Studi di Milano, Via Pascal 36, 20133 Milano, Italy
- *Massimo Cogliati:
| |
Collapse
|
9
|
Powell JR, Ausubel FM. Models of Caenorhabditis elegans infection by bacterial and fungal pathogens. Methods Mol Biol 2008; 415:403-27. [PMID: 18370168 DOI: 10.1007/978-1-59745-570-1_24] [Citation(s) in RCA: 124] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The nematode Caenorhabditis elegans is a simple model host for studying the relationship between the animal innate immune system and a variety of bacterial and fungal pathogens. Extensive genetic and molecular tools are available in C. elegans, facilitating an in-depth analysis of host defense factors and pathogen virulence factors. Many of these factors are conserved in insects and mammals, indicating the relevance of the nematode model to the vertebrate innate immune response. Here, we describe pathogen assays for a selection of the most commonly studied bacterial and fungal pathogens using the C. elegans model system.
Collapse
Affiliation(s)
- Jennifer R Powell
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, USA
| | | |
Collapse
|
10
|
Mylonakis E, Moreno R, El Khoury JB, Idnurm A, Heitman J, Calderwood SB, Ausubel FM, Diener A. Galleria mellonella as a model system to study Cryptococcus neoformans pathogenesis. Infect Immun 2005; 73:3842-50. [PMID: 15972469 PMCID: PMC1168598 DOI: 10.1128/iai.73.7.3842-3850.2005] [Citation(s) in RCA: 336] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Evaluation of Cryptococcus neoformans virulence in a number of nonmammalian hosts suggests that C. neoformans is a nonspecific pathogen. We used the killing of Galleria mellonella (the greater wax moth) caterpillar by C. neoformans to develop an invertebrate host model system that can be used to study cryptococcal virulence, host immune responses to infection, and the effects of antifungal compounds. All varieties of C. neoformans killed G. mellonella. After injection into the insect hemocoel, C. neoformans proliferated and, despite successful phagocytosis by host hemocytes, killed caterpillars both at 37 degrees C and 30 degrees C. The rate and extent of killing depended on the cryptococcal strain and the number of fungal cells injected. The sequenced C. neoformans clinical strain H99 was the most virulent of the strains tested and killed caterpillars with inocula as low as 20 CFU/caterpillar. Several C. neoformans genes previously shown to be involved in mammalian virulence (CAP59, GPA1, RAS1, and PKA1) also played a role in G. mellonella killing. Combination antifungal therapy (amphotericin B plus flucytosine) administered before or after inoculation was more effective than monotherapy in prolonging survival and in decreasing the tissue burden of cryptococci in the hemocoel. The G. mellonella-C. neoformans pathogenicity model may be a substitute for mammalian models of infection with C. neoformans and may facilitate the in vivo study of fungal virulence and efficacy of antifungal therapies.
Collapse
Affiliation(s)
- Eleftherios Mylonakis
- Division of Infectious Diseases, Massachusetts General Hospital, Gray-Jackson 504, 55 Fruit St., Boston, Massachusetts 02114, USA.
| | | | | | | | | | | | | | | |
Collapse
|
11
|
Kupfer DM, Drabenstot SD, Buchanan KL, Lai H, Zhu H, Dyer DW, Roe BA, Murphy JW. Introns and splicing elements of five diverse fungi. EUKARYOTIC CELL 2005; 3:1088-100. [PMID: 15470237 PMCID: PMC522613 DOI: 10.1128/ec.3.5.1088-1100.2004] [Citation(s) in RCA: 202] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Genomic sequences and expressed sequence tag data for a diverse group of fungi (Saccharomyces cerevisiae, Schizosaccharomyces pombe, Aspergillus nidulans, Neurospora crassa, and Cryptococcus neoformans) provided the opportunity to accurately characterize conserved intronic elements. An examination of large intron data sets revealed that fungal introns in general are short, that 98% or more of them belong to the canonical splice site (ss) class (5'GU...AG3'), and that they have polypyrimidine tracts predominantly in the region between the 5' ss and the branch point. Information content is high in the 5' ss, branch site, and 3' ss regions of the introns but low in the exon regions adjacent to the introns in the fungi examined. The two yeasts have broader intron length ranges and correspondingly higher intron information content than the other fungi. Generally, as intron length increases in the fungi, so does intron information content. Homologs of U2AF spliceosomal proteins were found in all species except for S. cerevisiae, suggesting a nonconventional role for U2AF in the absence of canonical polypyrimidine tracts in the majority of introns. Our observations imply that splicing in fungi may be different from that in vertebrates and may require additional proteins that interact with polypyrimidine tracts upstream of the branch point. Theoretical protein homologs for Nam8p and TIA-1, two proteins that require U-rich regions upstream of the branch point to function, were found. There appear to be sufficient differences between S. cerevisiae and S. pombe introns and the introns of two filamentous members of the Ascomycota and one member of the Basidiomycota to warrant the development of new model organisms for studying the splicing mechanisms of fungi.
Collapse
Affiliation(s)
- Doris M Kupfer
- Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, P.O. Box 26901, BMSB 1053, Oklahoma City, OK 73190, USA
| | | | | | | | | | | | | | | |
Collapse
|
12
|
Apidianakis Y, Rahme LG, Heitman J, Ausubel FM, Calderwood SB, Mylonakis E. Challenge of Drosophila melanogaster with Cryptococcus neoformans and role of the innate immune response. EUKARYOTIC CELL 2004; 3:413-9. [PMID: 15075271 PMCID: PMC387633 DOI: 10.1128/ec.3.2.413-419.2004] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We found that the ingestion of Cryptococcus neoformans by Drosophila melanogaster resulted in the death of the fly but that the ingestion of Saccharomyces cerevisiae or the nonpathogenic Cryptococcus kuetzingii or Cryptococcus laurentii did not. The C. neoformans protein kinase A and RAS signal transduction pathways, previously shown to be involved in virulence in mammals, also played a role in killing Drosophila. Mutation of the Toll immune response pathway, the predominant antifungal pathway of the fly, did not play a role in Drosophila defense following ingestion of the yeast. However, the Toll pathway was necessary for the clearance of C. neoformans introduced directly into the hemolymph of D. melanogaster and for the survival of systemically infected flies.
Collapse
Affiliation(s)
- Yiorgos Apidianakis
- Department of Surgery, Massachusetts General Hospital. Shriner's Burns Institute, Boston, Massachusetts 02114, USA
| | | | | | | | | | | |
Collapse
|
13
|
Mylonakis E, Idnurm A, Moreno R, El Khoury J, Rottman JB, Ausubel FM, Heitman J, Calderwood SB. Cryptococcus neoformans Kin1 protein kinase homologue, identified through a Caenorhabditis elegans screen, promotes virulence in mammals. Mol Microbiol 2004; 54:407-19. [PMID: 15469513 DOI: 10.1111/j.1365-2958.2004.04310.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Cryptococcal infections are a global cause of significant morbidity and mortality. Recent studies support the hypothesis that virulence of Cryptococcus neoformans may have evolved via survival selection in environmental hosts, such as amoebae and free-living nematodes. We used killing of the nematode Caenorhabditis elegans by C. neoformans as an assay to screen a library of random C. neoformans insertion mutants. Of 350 mutants tested, seven were identified with attenuated virulence that persisted after crossing the mutation back into a wild-type strain. Genetic analysis of one strain revealed an insertion in a gene homologous to Saccharomyces cerevisiae KIN1, which encodes a serine/threonine protein kinase. C. neoformans kin1 mutants exhibited significant defects in virulence in murine inhalation and haematogenous infection models and displayed increased binding to alveolar and peritoneal macrophages. The kin1 mutant phenotypes were complemented by the wild-type KIN1 gene. These findings show that the C. neoformans Kin1 kinase homologue is required for full virulence in disparate hosts and that C. elegans can be used as a substitute host to identify novel factors involved in fungal pathogenesis in mammals.
Collapse
Affiliation(s)
- Eleftherios Mylonakis
- Division of Infectious Diseases, Massachusetts General Hospital, Boston, MA 02114, USA
| | | | | | | | | | | | | | | |
Collapse
|
14
|
Woyke T, Berens ME, Hoelzinger DB, Pettit GR, Winkelmann G, Pettit RK. Differential gene expression in auristatin PHE-treated Cryptococcus neoformans. Antimicrob Agents Chemother 2004; 48:561-7. [PMID: 14742210 PMCID: PMC321525 DOI: 10.1128/aac.48.2.561-567.2004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The antifungal pentapeptide auristatin PHE was recently shown to interfere with microtubule dynamics and nuclear and cellular division in the opportunistic pathogen Cryptococcus neoformans. To gain a broader understanding of the cellular response of C. neoformans to auristatin PHE, mRNA differential display (DD) and reverse transcriptase PCR (RT-PCR) were applied. Examination of approximately 60% of the cell transcriptome from cells treated with 1.5 times the MIC (7.89 micro M) of auristatin PHE for 90 min revealed 29 transcript expression differences between control and drug-treated populations. Differential expression of seven of the transcripts was confirmed by RT-PCR, as was drug-dependent modulation of an additional seven transcripts by RT-PCR only. Among genes found to be differentially expressed were those encoding proteins involved in transport, cell cycle regulation, signal transduction, cell stress, DNA repair, nucleotide metabolism, and capsule production. For example, RHO1 and an open reading frame (ORF) encoding a protein with 91% similarity to the Schizophyllum commune 14-3-3 protein, both involved in cell cycle regulation, were down-regulated, as was the gene encoding the multidrug efflux pump Afr1p. An ORF encoding a protein with 57% identity to the heat shock protein HSP104 in Pleurotus sajor-caju was up-regulated. Also, three transcripts of unknown function were responsive to auristatin PHE, which may eventually contribute to the elucidation of the function of their gene products. Further study of these differentially expressed genes and expression of their corresponding proteins are warranted to evaluate how they may be involved in the mechanism of action of auristatin PHE. This information may also contribute to an explanation of the selectivity of auristatin PHE for C. neoformans. This is the first report of drug action using DD in C. neoformans.
Collapse
MESH Headings
- Antifungal Agents/pharmacology
- Biological Transport, Active/drug effects
- Biological Transport, Active/genetics
- Cell Cycle/drug effects
- Cell Cycle/genetics
- Cloning, Molecular
- Cryptococcus neoformans/drug effects
- Cryptococcus neoformans/genetics
- Cryptococcus neoformans/metabolism
- Culture Media
- DNA Repair/drug effects
- DNA Repair/genetics
- DNA, Complementary/biosynthesis
- DNA, Complementary/genetics
- Fungal Proteins/biosynthesis
- Fungal Proteins/genetics
- Gene Expression Regulation, Fungal/drug effects
- Microbial Sensitivity Tests
- Oligopeptides/pharmacology
- Purines/biosynthesis
- RNA, Fungal/biosynthesis
- RNA, Fungal/isolation & purification
- RNA, Messenger/biosynthesis
- RNA, Messenger/genetics
- Reverse Transcriptase Polymerase Chain Reaction
- Signal Transduction/drug effects
- Signal Transduction/genetics
- Transcription, Genetic/drug effects
Collapse
Affiliation(s)
- Tanja Woyke
- Cancer Research Institute, Arizona State University, Tempe, Arizona 85287, USA
| | | | | | | | | | | |
Collapse
|
15
|
Abstract
Cryptococcus neoformans is a pathogenic fungus, distinguished by an elaborate polysaccharide capsule that is essential for its virulence. As part of an effort to understand the biosynthesis of this important structure, we initiated purification of an alpha-1,3-mannosyltransferase with appropriate specificity for a role in building the main capsule polysaccharide, glucuronoxylomannan. A pool of proteins that was 5,000-fold enriched in this activity included several polypeptides, which acted potentially as the catalytic protein. These were analyzed using sequence information and double-stranded RNA interference. Interference that targeted a sequence corresponding to part of a 46 kDa protein in the enriched fraction abolished the activity of interest and reduced the capsule on the affected cells. This gene was cloned and expressed in active form in Saccharomyces cerevisiae to confirm function, and was termed CMT1, for cryptococcal mannosyltransferase 1. CMT1 has no confirmed homologs in GenBank other than CAP59, a cryptococcal gene encoding a protein of unknown function that is required for capsule synthesis and virulence. The Cmt1p protein also co-purifies with a homolog of CAP64, a gene whose product has similarly been implicated in capsule synthesis and virulence. A strain disrupted in CMT1 was generated in C. neoformans; this had no effect on virulence in an animal model of cryptococcosis.
Collapse
Affiliation(s)
- Ulf Sommer
- Department of Molecular Microbiology, Washington University Medical School, St. Louis, Missouri 63110, USA
| | | | | |
Collapse
|
16
|
Bose I, Reese AJ, Ory JJ, Janbon G, Doering TL. A yeast under cover: the capsule of Cryptococcus neoformans. EUKARYOTIC CELL 2003; 2:655-63. [PMID: 12912884 PMCID: PMC178345 DOI: 10.1128/ec.2.4.655-663.2003] [Citation(s) in RCA: 164] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
- Indrani Bose
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri 63110, USA
| | | | | | | | | |
Collapse
|
17
|
Abstract
Cryptococcus neoformans is a pathogenic fungus that primarily afflicts immunocompromised patients, infecting the central nervous system to cause meningoencephalitis that is uniformly fatal if untreated. C. neoformans is a basidiomycetous fungus with a defined sexual cycle that has been linked to differentiation and virulence. Recent advances in classical and molecular genetic approaches have allowed molecular descriptions of the pathways that control cell type and virulence. An ongoing genome sequencing project promises to reveal much about the evolution of this human fungal pathogen into three distinct varieties or species. C. neoformans shares features with both model ascomycetous yeasts (Saccharomyces cerevisiae, Schizosaccharomyces pombe) and basidiomycetous pathogens and mushrooms (Ustilago maydis, Coprinus cinereus, Schizophyllum commune), yet ongoing studies reveal unique features associated with virulence and the arrangement of the mating type locus. These advances have catapulted C. neoformans to center stage as a model of both fungal pathogenesis and the interesting approaches to life that the kingdom of fungi has adopted.
Collapse
Affiliation(s)
- Christina M Hull
- Department of Molecular Genetics and Microbiology, Howard Hughes Medical Institute, Duke University Medical Center, Durham, North Carolina 27710, USA.
| | | |
Collapse
|
18
|
Mylonakis E, Ausubel FM, Perfect JR, Heitman J, Calderwood SB. Killing of Caenorhabditis elegans by Cryptococcus neoformans as a model of yeast pathogenesis. Proc Natl Acad Sci U S A 2002; 99:15675-80. [PMID: 12438649 PMCID: PMC137775 DOI: 10.1073/pnas.232568599] [Citation(s) in RCA: 220] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
We found that the well-studied nematode Caenorhabditis elegans can use various yeasts, including Cryptococcus laurentii and Cryptococcus kuetzingii, as a sole source of food, producing similar brood sizes compared with growth on its usual laboratory food source Escherichia coli OP50. C. elegans grown on these yeasts had a life span similar to (C. laurentii) or longer than (C. kuetzingii) those fed on E. coli. However, the human pathogenic yeast Cryptococcus neoformans killed C. elegans, and the C. neoformans polysaccharide capsule as well as several C. neoformans genes previously shown to be involved in mammalian virulence were also shown to play a role in C. elegans killing. These included genes associated with signal transduction pathways (GPA1, PKA1, PKR1, and RAS1), laccase production (LAC1), and the alpha mating type. C. neoformans adenine auxotrophs, which are less virulent in mammals, were also less virulent in C. elegans. These results support the model that mammalian pathogenesis of C. neoformans may be a consequence of adaptations that have evolved during the interaction of C. neoformans with environmental predators such as free-living nematodes and amoebae and suggest that C. elegans can be used as a simple model host in which C. neoformans pathogenesis can be readily studied.
Collapse
Affiliation(s)
- Eleftherios Mylonakis
- Division of Infectious Diseases and Department of Molecular Biology, Massachusetts General Hospital, Boston 02114, USA
| | | | | | | | | |
Collapse
|
19
|
Wickes BL. The role of mating type and morphology in Cryptococcus neoformans pathogenesis. Int J Med Microbiol 2002; 292:313-29. [PMID: 12452279 DOI: 10.1078/1438-4221-00216] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Cryptococcus neoformans is a major fungal pathogen of both humans and animals. The fungus can be divided into two varieties, with each variety being composed of two serotypes. A sexual phase has been identified, which classifies C. neoformans as a bipolar heterothallic fungus with two mating types, MATa and MATalpha. The analysis of mating and mating type in this organism is important for a number of reasons. Both clinical and environmental isolates display a severe bias of the MATalpha mating type over MATa. MATalpha cells are also more virulent than MATalpha cells. Molecular and genetic analyses of the genes that make up the mating pathway have revealed that some of these genes are required for virulence. Finally, although it is well known that infection begins in the lungs after inhalation of infectious particles, it still remains unclear what constitutes the infectious particle. This review will discuss current information about what is known about the role that mating type and morphology play in virulence.
Collapse
Affiliation(s)
- Brian L Wickes
- Department of Microbiology, The University of Texas Health Science Center at San Antonio, San Antonio, TX 78229-3900, USA.
| |
Collapse
|
20
|
Steen BR, Lian T, Zuyderduyn S, MacDonald WK, Marra M, Jones SJM, Kronstad JW. Temperature-regulated transcription in the pathogenic fungus Cryptococcus neoformans. Genome Res 2002; 12:1386-400. [PMID: 12213776 PMCID: PMC186651 DOI: 10.1101/gr.80202] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The basidiomycete fungus Cryptococcus neoformans is an opportunistic pathogen of worldwide importance that causes meningitis, leading to death in immunocompromised individuals. Unlike many basidiomycete fungi, C. neoformans is thermotolerant, and its ability to grow at 37 degrees C is considered to be a virulence factor. We used serial analysis of gene expression (SAGE) to characterize the transcriptomes of C. neoformans strains that represent two varieties with different polysaccharide capsule serotypes. These include a serotype D strain of the C. neoformans variety neoformans and a serotype A strain of variety grubii. In this report, we describe the construction and characterization of SAGE libraries from each strain grown at 25 degrees C and 37 degrees C. The SAGE data reveal transcriptome differences between the two strains, even at this early stage of analysis, and identify sets of genes with higher transcript levels at 25 degrees C or 37 degrees C. Notably, growth at the lower temperature increased transcript levels for histone genes, indicating a general influence of temperature on chromatin structure. At 37 degrees C, we noted elevated transcript levels for several genes encoding heat shock proteins and translation machinery. Some of these genes may play a role in temperature-regulated phenotypes in C. neoformans, such as the adaptation of the fungus to growth in the host and the dimorphic transition between budding and filamentous growth. Overall, this work provides the most comprehensive gene expression data available for C. neoformans; this information will be a critical resource both for gene discovery and genome annotation in this pathogen.
Collapse
Affiliation(s)
- Barbara R Steen
- Biotechnology Laboratory, Department of Microbiology and Immunology, and Faculty of Agricultural Sciences, The University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | | | | | | | | | | | | |
Collapse
|
21
|
Schein JE, Tangen KL, Chiu R, Shin H, Lengeler KB, MacDonald WK, Bosdet I, Heitman J, Jones SJM, Marra MA, Kronstad JW. Physical maps for genome analysis of serotype A and D strains of the fungal pathogen Cryptococcus neoformans. Genome Res 2002; 12:1445-53. [PMID: 12213782 PMCID: PMC186652 DOI: 10.1101/gr.81002] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2002] [Accepted: 07/03/2002] [Indexed: 11/25/2022]
Abstract
The basidiomycete fungus Cryptococcus neoformans is an important opportunistic pathogen of humans that poses a significant threat to immunocompromised individuals. Isolates of C. neoformans are classified into serotypes (A, B, C, D, and AD) based on antigenic differences in the polysaccharide capsule that surrounds the fungal cells. Genomic and EST sequencing projects are underway for the serotype D strain JEC21 and the serotype A strain H99. As part of a genomics program for C. neoformans, we have constructed fingerprinted bacterial artificial chromosome (BAC) clone physical maps for strains H99 and JEC21 to support the genomic sequencing efforts and to provide an initial comparison of the two genomes. The BAC clones represented an estimated 10-fold redundant coverage of the genomes of each serotype and allowed the assembly of 20 contigs each for H99 and JEC21. We found that the genomes of the two strains are sufficiently distinct to prevent coassembly of the two maps when combined fingerprint data are used to construct contigs. Hybridization experiments placed 82 markers on the JEC21 map and 102 markers on the H99 map, enabling contigs to be linked with specific chromosomes identified by electrophoretic karyotyping. These markers revealed both extensive similarity in gene order (conservation of synteny) between JEC21 and H99 as well as examples of chromosomal rearrangements including inversions and translocations. Sequencing reads were generated from the ends of the BAC clones to allow correlation of genomic shotgun sequence data with physical map contigs. The BAC maps therefore represent a valuable resource for the generation, assembly, and finishing of the genomic sequence of both JEC21 and H99. The physical maps also serve as a link between map-based and sequence-based data, providing a powerful resource for continued genomic studies
Collapse
Affiliation(s)
- Jacqueline E Schein
- Genome Sciences Centre, BC Cancer Agency, Vancouver, British Columbia V5Z 4E6, Canada
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
22
|
Davidson RC, Blankenship JR, Kraus PR, de Jesus Berrios M, Hull CM, D'Souza C, Wang P, Heitman J. A PCR-based strategy to generate integrative targeting alleles with large regions of homology. MICROBIOLOGY (READING, ENGLAND) 2002; 148:2607-2615. [PMID: 12177355 DOI: 10.1099/00221287-148-8-2607] [Citation(s) in RCA: 254] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Cryptococcus neoformans is an opportunistic fungal pathogen with a defined sexual cycle for which genetic and molecular techniques are well developed. The entire genome sequence of one C. neoformans strain is nearing completion. The efficient use of this sequence is dependent upon the development of methods to perform more rapid genetic analysis including gene-disruption techniques. A modified PCR overlap technique to generate targeting constructs for gene disruption that contain large regions of gene homology is described. This technique was used to disrupt or delete more than a dozen genes with efficiencies comparable to those previously reported using cloning technology to generate targeting constructs. Moreover, it is shown that disruptions can be made using this technique in a variety of strain backgrounds, including the pathogenic serotype A isolate H99 and recently characterized stable diploid strains. In combination with the availability of the complete genomic sequence, this gene-disruption technique should pave the way for higher throughput genetic analysis of this important pathogenic fungus.
Collapse
Affiliation(s)
- Robert C Davidson
- Departments of Molecular Genetics and Microbiology, Pharmacology and Cancer Biology, and Medicine, and the Howard Hughes Medical Institute, Duke University Medical Center, Research Drive, Durham, NC 27710, USA1
| | - Jill R Blankenship
- Departments of Molecular Genetics and Microbiology, Pharmacology and Cancer Biology, and Medicine, and the Howard Hughes Medical Institute, Duke University Medical Center, Research Drive, Durham, NC 27710, USA1
| | - Peter R Kraus
- Departments of Molecular Genetics and Microbiology, Pharmacology and Cancer Biology, and Medicine, and the Howard Hughes Medical Institute, Duke University Medical Center, Research Drive, Durham, NC 27710, USA1
| | - Marisol de Jesus Berrios
- Departments of Molecular Genetics and Microbiology, Pharmacology and Cancer Biology, and Medicine, and the Howard Hughes Medical Institute, Duke University Medical Center, Research Drive, Durham, NC 27710, USA1
| | - Christina M Hull
- Departments of Molecular Genetics and Microbiology, Pharmacology and Cancer Biology, and Medicine, and the Howard Hughes Medical Institute, Duke University Medical Center, Research Drive, Durham, NC 27710, USA1
| | - Cletus D'Souza
- Departments of Molecular Genetics and Microbiology, Pharmacology and Cancer Biology, and Medicine, and the Howard Hughes Medical Institute, Duke University Medical Center, Research Drive, Durham, NC 27710, USA1
| | - Ping Wang
- Departments of Molecular Genetics and Microbiology, Pharmacology and Cancer Biology, and Medicine, and the Howard Hughes Medical Institute, Duke University Medical Center, Research Drive, Durham, NC 27710, USA1
| | - Joseph Heitman
- Departments of Molecular Genetics and Microbiology, Pharmacology and Cancer Biology, and Medicine, and the Howard Hughes Medical Institute, Duke University Medical Center, Research Drive, Durham, NC 27710, USA1
| |
Collapse
|
23
|
Liu H, Cottrell TR, Pierini LM, Goldman WE, Doering TL. RNA interference in the pathogenic fungus Cryptococcus neoformans. Genetics 2002; 160:463-70. [PMID: 11861553 PMCID: PMC1461992 DOI: 10.1093/genetics/160.2.463] [Citation(s) in RCA: 139] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Cryptococcus neoformans is a pathogenic fungus responsible for serious disease in immunocompromised individuals. This organism has recently been developed as an experimental system, with initiation of a genome project among other molecular advances. However, investigations of Cryptococcus are hampered by the technical difficulty of specific gene replacements. RNA interference, a process in which the presence of double-stranded RNA homologous to a gene of interest results in specific degradation of the corresponding message, may help solve this problem. We have shown that expression of double-stranded RNA corresponding to portions of the cryptococcal CAP59 and ADE2 genes results in reduced mRNA levels for those genes, with phenotypic consequences similar to that of gene disruption. The two genes could also be subjected to simultaneous interference through expression of chimeric double-stranded RNA. Specific modulation of protein expression through introduction of double-stranded RNA thus operates in C. neoformans, which is the first demonstration of this technique in a fungal organism. Use of RNA interference in Cryptococcus should allow manipulation of mRNA levels for functional analysis of genes of interest and enable efficient exploration of genes discovered by genome sequencing.
Collapse
Affiliation(s)
- Hong Liu
- Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, Missouri 63110, USA
| | | | | | | | | |
Collapse
|
24
|
Waugh MS, Nichols CB, DeCesare CM, Cox GM, Heitman J, Alspaugh JA. Ras1 and Ras2 contribute shared and unique roles in physiology and virulence of Cryptococcus neoformans. MICROBIOLOGY (READING, ENGLAND) 2002; 148:191-201. [PMID: 11782511 DOI: 10.1099/00221287-148-1-191] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The Ras1 signal transduction pathway controls the ability of the pathogenic fungus Cryptococcus neoformans to grow at high temperatures and to mate. A second RAS gene was identified in this organism. RAS2 is expressed at a very low level compared to RAS1, and a ras2 mutation caused no alterations in vegetative growth rate, differentiation or virulence factor expression. The ras2 mutant strain was equally virulent to the wild-type strain in the murine inhalational model of cryptococcosis. Although a ras1 ras2 double mutant strain is viable, mutation of both RAS genes results in a decreased growth rate at all temperatures compared to strains with either single mutation. Overexpression of the RAS2 gene completely suppressed the ras1 mutant mating defect and partially suppressed its high temperature growth defect. After prolonged incubation at a restrictive temperature, the ras1 mutant demonstrated actin polarity defects that were also partially suppressed by RAS2 overexpression. These studies indicate that the C. neoformans Ras1 and Ras2 proteins share overlapping functions, but also play distinct signalling roles. Our findings also suggest a mechanism by which Ras1 controls growth of this pathogenic fungus at 37 degrees C, supporting a conserved role for Ras homologues in microbial cellular differentiation, morphogenesis and virulence.
Collapse
Affiliation(s)
- Michael S Waugh
- Howard Hughes Medical Institute, Duke University Medical Center, Durham, NC, USA5
- Department of Genetics, Duke University Medical Center, Durham, NC, USA2
- Department of Medicine, Duke University Medical Center, Durham, NC, USA1
| | - Connie B Nichols
- Howard Hughes Medical Institute, Duke University Medical Center, Durham, NC, USA5
- Department of Genetics, Duke University Medical Center, Durham, NC, USA2
| | - Cameron M DeCesare
- Department of Medicine, Duke University Medical Center, Durham, NC, USA1
| | - Gary M Cox
- Department of Microbiology, Duke University Medical Center, Durham, NC, USA3
- Department of Medicine, Duke University Medical Center, Durham, NC, USA1
| | - Joseph Heitman
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC, USA4
- Howard Hughes Medical Institute, Duke University Medical Center, Durham, NC, USA5
- Department of Medicine, Duke University Medical Center, Durham, NC, USA1
- Department of Genetics, Duke University Medical Center, Durham, NC, USA2
- Department of Microbiology, Duke University Medical Center, Durham, NC, USA3
| | - J Andrew Alspaugh
- Department of Medicine, Duke University Medical Center, Durham, NC, USA1
| |
Collapse
|
25
|
Bar-Peled M, Griffith CL, Doering TL. Functional cloning and characterization of a UDP- glucuronic acid decarboxylase: the pathogenic fungus Cryptococcus neoformans elucidates UDP-xylose synthesis. Proc Natl Acad Sci U S A 2001; 98:12003-8. [PMID: 11593010 PMCID: PMC59757 DOI: 10.1073/pnas.211229198] [Citation(s) in RCA: 123] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
UDP-xylose is a sugar donor required for the synthesis of diverse and important glycan structures in animals, plants, fungi, and bacteria. Xylose-containing glycans are particularly abundant in plants and in the polysaccharide capsule that is the major virulence factor of the pathogenic fungus Cryptococcus neoformans. Biosynthesis of UDP-xylose is mediated by UDP-glucuronic acid decarboxylase, which converts UDP-glucuronic acid to UDP-xylose. Although this enzymatic activity was described over 40 years ago it has never been fully purified, and the gene encoding it has not been identified. We used homology to a bacterial gene, hypothesized to encode a related function, to identify a cryptococcal sequence as putatively encoding a UDP-glucuronic acid decarboxylase. A soluble 47-kDa protein derived from bacteria expressing the C. neoformans gene catalyzed conversion of UDP-glucuronic acid to UDP-xylose, as confirmed by NMR analysis. NADH, UDP, and UDP-xylose inhibit the activity. Close homologs of the cryptococcal gene, which we termed UXS1, appear in genome sequence data from organisms ranging from bacteria to humans.
Collapse
Affiliation(s)
- M Bar-Peled
- Complex Carbohydrate Research Center and Department of Botany, University of Georgia, Athens, GA 30602, USA.
| | | | | |
Collapse
|
26
|
Abstract
The filamentous fungal genetics community has enthusiastically embraced the utilization of genomics technologies to resolve long-standing issues in fungal biology. For example, such technologies have been proposed to study the mechanics of tip growth, photoreception, gene silencing, the molecular basis of conidiation, the pathway leading to sexual reproduction, and mechanisms of pathogenesis. These studies have provided a refreshing change of pace in research on filamentous fungi, which has lagged behind that on other eukaryotes in the exploitation of genome-wide methodologies. Despite the late start, several fungal genome sequencing projects are underway. The resulting databases will allow the comprehensive analysis of developmental processes that are characteristic of fungi, including the molecular nature of pathogenicity. DNA databases underpin analyses of the fungal transcriptome, proteome, and metabolome. This combined information will contribute to our basic understanding of not only the mechanics of infection but also the evolution of pathogenicity.
Collapse
Affiliation(s)
- O C Yoder
- Torrey Mesa Research Institute, 3115 Merryfield Row, La Jolla, California 92121, USA.
| | | |
Collapse
|
27
|
Current Awareness. Yeast 2001. [DOI: 10.1002/yea.683] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
|
28
|
Current Awareness on Comparative and Functional Genomics. Comp Funct Genomics 2001. [PMCID: PMC2447210 DOI: 10.1002/cfg.57] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
|
29
|
Lengeler KB, Wang P, Cox GM, Perfect JR, Heitman J. Identification of the MATa mating-type locus of Cryptococcus neoformans reveals a serotype A MATa strain thought to have been extinct. Proc Natl Acad Sci U S A 2000; 97:14455-60. [PMID: 11121047 PMCID: PMC18940 DOI: 10.1073/pnas.97.26.14455] [Citation(s) in RCA: 120] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Cryptococcus neoformans is an opportunistic fungal pathogen with a defined sexual cycle involving mating between haploid MATa and MATalpha cells. Here we describe the isolation of part of the MATa mating-type locus encoding a Ste20 kinase homolog, Ste20a. We show that the STE20a gene cosegregates with the MATa mating type in genetic crosses, maps within the mating-type locus on a 1.8-Mb chromosome, and is allelic with the MATalpha locus. We identify the first MATa isolate of the most common pathogenic variety of C. neoformans (serotype A, variety grubii) which had been thought to be extinct. This serotype A MATa strain is sterile, fails to produce mating pheromone, and is less virulent than a serotype A MATalpha strain in an animal model. Our studies illustrate an association of mating type with virulence and suggest that, like Candida albicans, pathogenic isolates of C. neoformans may be largely asexual.
Collapse
Affiliation(s)
- K B Lengeler
- Departments of Genetics, Howard Hughes Medical Institute, Duke University Medical Center, Durham, NC 27710, USA
| | | | | | | | | |
Collapse
|