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Phosphate Acquisition and Virulence in Human Fungal Pathogens. Microorganisms 2017; 5:microorganisms5030048. [PMID: 28829379 PMCID: PMC5620639 DOI: 10.3390/microorganisms5030048] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Revised: 08/15/2017] [Accepted: 08/16/2017] [Indexed: 01/23/2023] Open
Abstract
The ability of pathogenic fungi to acquire essential macro and micronutrients during infection is a well-established virulence trait. Recent studies in the major human fungal pathogens Candida albicans and Cryptococcus neoformans have revealed that acquisition of the essential macronutrient, phosphate, is essential for virulence. The phosphate sensing and acquisition pathway in fungi, known as the PHO pathway, has been extensively characterized in the model yeast Saccharomyces cerevisiae. In this review, we highlight recent advances in phosphate sensing and signaling mechanisms, and use the S. cerevisiae PHO pathway as a platform from which to compare the phosphate acquisition and storage strategies employed by several human pathogenic fungi. We also explore the multi-layered roles of phosphate acquisition in promoting fungal stress resistance to pH, cationic, and oxidative stresses, and describe emerging roles for the phosphate storage molecule polyphosphate (polyP). Finally, we summarize the recent studies supporting the necessity of phosphate acquisition in mediating the virulence of human fungal pathogens, highlighting the concept that this requirement is intimately linked to promoting resistance to host-imposed stresses.
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A new rapid and efficient system with dominant selection developed to inactivate and conditionally express genes in Candida albicans. Curr Genet 2016; 62:213-35. [PMID: 26497136 DOI: 10.1007/s00294-015-0526-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Revised: 10/08/2015] [Accepted: 10/09/2015] [Indexed: 01/30/2023]
Abstract
Candida albicans is an important human fungal pathogen but its study has been hampered for being a natural diploid that lacks a complete sexual cycle. Gene knock-out and essential gene repression are used to study gene function in C. albicans. To effectively study essential genes in wild-type C. albicans, we took advantage of the compatible effects of the antibiotics hygromycin B and nourseothricin, the recyclable CaSAT1-flipper and the tetracycline-repressible (Tet-off) system. To allow deleting two alleles simultaneously, we created a cassette with a C. albicans HygB resistance gene (CaHygB) flanked with the FLP recombinase target sites that can be operated alongside the CaSAT1-flipper. Additionally, to enable conditionally switching off essential genes, we created a CaHygB-based Tet-off cassette that consisted of the CaTDH3 promoter, which is used for the constitutive expression of the tetracycline-regulated transactivator and a tetracycline response operator. To validate the new systems, all strains were constructed based on the wild-type strain and selected by the two dominant selectable markers, CaHygB and CaSAT1. The C. albicans general transcriptional activator CaGCN4 and its negative regulator CaPCL5 genes were targeted for gene deletion, and the essential cyclin-dependent kinase CaPHO85 gene was placed under the Tet-off system. Cagcn4, Capcl5, the conditional Tet-off CaPHO85 mutants, and mutants bearing two out of the three mutations were generated. By subjecting the mutants to various stress conditions, the functional relationship of the genes was revealed. This new system can efficiently delete genes and conditionally switch off essential genes in wild-type C. albicans to assess functional interaction between genes.
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Kanno T, Takekawa D, Miyakawa Y. Analysis of the essentiality of ROM2
genes in the pathogenic yeasts Candida glabrata
and Candida albicans
using temperature-sensitive mutants. J Appl Microbiol 2015; 118:851-63. [DOI: 10.1111/jam.12745] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Revised: 11/26/2014] [Accepted: 01/02/2015] [Indexed: 12/19/2022]
Affiliation(s)
- T. Kanno
- Division of Biotechnology; Interdisciplinary Graduate School of Medicine and Engineering; University of Yamanashi; Kofu Yamanashi Japan
| | - D. Takekawa
- Division of Biotechnology; Interdisciplinary Graduate School of Medicine and Engineering; University of Yamanashi; Kofu Yamanashi Japan
| | - Y. Miyakawa
- Division of Biotechnology; Interdisciplinary Graduate School of Medicine and Engineering; University of Yamanashi; Kofu Yamanashi Japan
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Abstract
In budding yeast, Saccharomyces cerevisiae, the phosphate signalling and response pathway, known as PHO pathway, monitors phosphate cytoplasmic levels by controlling genes involved in scavenging, uptake and utilization of phosphate. Recent attempts to understand the phosphate starvation response in other ascomycetes have suggested the existence of both common and novel components of the budding yeast PHO pathway in these ascomycetes. In this review, we discuss the components of PHO pathway, their roles in maintaining phosphate homeostasis in yeast and their conservation across ascomycetes. The role of high-affinity transporter, Pho84, in sensing and signalling of phosphate has also been discussed.
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Affiliation(s)
- Parul Tomar
- Department of Biological Sciences, Tata Institute of Fundamental Research, Mumbai 400 005, India
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Defects in phosphate acquisition and storage influence virulence of Cryptococcus neoformans. Infect Immun 2014; 82:2697-712. [PMID: 24711572 DOI: 10.1128/iai.01607-14] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Nutrient acquisition and sensing are critical aspects of microbial pathogenesis. Previous transcriptional profiling indicated that the fungal pathogen Cryptococcus neoformans, which causes meningoencephalitis in immunocompromised individuals, encounters phosphate limitation during proliferation in phagocytic cells. We therefore tested the hypothesis that phosphate acquisition and polyphosphate metabolism are important for cryptococcal virulence. Deletion of the high-affinity uptake system interfered with growth on low-phosphate medium, perturbed the formation of virulence factors (capsule and melanin), reduced survival in macrophages, and attenuated virulence in a mouse model of cryptococcosis. Additionally, analysis of nutrient sensing functions for C. neoformans revealed regulatory connections between phosphate acquisition and storage and the iron regulator Cir1, cyclic AMP (cAMP)-dependent protein kinase A (PKA), and the calcium-calmodulin-activated protein phosphatase calcineurin. Deletion of the VTC4 gene encoding a polyphosphate polymerase blocked the ability of C. neoformans to produce polyphosphate. The vtc4 mutant behaved like the wild-type strain in interactions with macrophages and in the mouse infection model. However, the fungal load in the lungs was significantly increased in mice infected with vtc4 deletion mutants. In addition, the mutant was impaired in the ability to trigger blood coagulation in vitro, a trait associated with polyphosphate. Overall, this study reveals that phosphate uptake in C. neoformans is critical for virulence and that its regulation is integrated with key signaling pathways for nutrient sensing.
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Chibana H, Uno J, Cho T, Mikami Y. Mutation inIRO1Tightly Linked withURA3Gene Reduces Virulence ofCandida albicans. Microbiol Immunol 2013; 49:937-9. [PMID: 16237272 DOI: 10.1111/j.1348-0421.2005.tb03686.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Gene deletion in the pathogenic fungus Candida albicans has relied heavily on a URA3 cassette and a recipient delta ura3 strain CAI4. The IRO1 gene adjacent to URA3 was inadvertently deleted during construction of CAI4. We report here that a mutation in IRO1 reduces virulence of C. albicans.
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Affiliation(s)
- Hiroji Chibana
- Research Center for Pathogenic Fungi and Microbial Toxicoses, Chiba University, Chiba, Japan.
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Miyakawa Y, Hara T, Iimura Y. Establishment of a screening system for essential genes from the pathogenic yeastCandida glabrata: identification of a putativeTEM1homologue. Lett Appl Microbiol 2009; 49:317-23. [DOI: 10.1111/j.1472-765x.2009.02661.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Miyakawa Y, Ozawa T. A New Type of DNA Polymorphism Identified in the Species-Specific DNA Region Originating from the Candida albicans Mitochondrial Genome. Curr Microbiol 2009; 58:438-42. [DOI: 10.1007/s00284-008-9337-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2008] [Revised: 11/11/2008] [Accepted: 11/24/2008] [Indexed: 11/27/2022]
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Simple method to accurately differentiate Candida albicans isolates concurrently using polymorphic patterns of PCR-amplified, species-specific nuclear and mitochondrial targets. Curr Microbiol 2008; 58:164-9. [PMID: 19018592 DOI: 10.1007/s00284-008-9300-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2008] [Revised: 08/18/2008] [Accepted: 09/19/2008] [Indexed: 10/21/2022]
Abstract
We describe a simple method to accurately differentiate Candida albicans isolates by concurrent use of the restriction enzyme digestion patterns for PCR products, targeting two species-specific DNA regions originating from genetically different sources, the nuclear and mitochondrial genomes. The target sequence we used as the nuclear gene was derived from the PHO85 gene, a negative regulator of the PHO system, in which we found a restriction size polymorphism within the two alleles of PHO85 in the diploid genome of this fungus. The mitochondrial target was derived from EO3, a species-specific DNA fragment possessing a small size polymorphism among various clinical isolates. Our results should provide a new tool for molecular epidemiological surveys of patients suffering from candidiasis caused by C. albicans.
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Castillo-Lluva S, Alvarez-Tabarés I, Weber I, Steinberg G, Pérez-Martín J. Sustained cell polarity and virulence in the phytopathogenic fungus Ustilago maydis depends on an essential cyclin-dependent kinase from the Cdk5/Pho85 family. J Cell Sci 2007; 120:1584-95. [PMID: 17405809 DOI: 10.1242/jcs.005314] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cyclin-dependent kinases from the Cdk5/Pho85 family are thought to play important roles in morphogenesis in organisms as diverse as yeast and humans. Here we used the corn smut fungus Ustilago maydis to address the role of Cdk5/Pho85 kinases in the morphogenesis and virulence of dimorphic phytopathogens. We found that Cdk5 is essential for growth in U. maydis. A temperature-sensitive cdk5 mutant caused cell wall and morphology defects at the restrictive temperature. Actin patches labeled with a fimbrin-GFP fusion protein were delocalized and a GFP-Myo5 fusion was directed towards the growing cell pole and rapidly dissociated from the tip. These defects were found to be due to an impairment in the maintenance of cell polarity. Our results indicated that Cdk5 is required for the activity of Rac1, probably at the level of the localization of its GEF, Cdc24. Cdk5 was required for full virulence, probably because mutant cells are unable to sustain the dramatic polar growth required for the formation of the infective structures. These results support a major role for morphogenesis in the virulence program of dimorphic fungi.
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Affiliation(s)
- Sonia Castillo-Lluva
- Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología CSIC, 28049 Madrid, Spain
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Miyakawa Y, Chibana H, Uno J, Mikami Y, Nakayama H. [Essential genes as potential targets of antifungal agents in pathogenic yeast Candida]. ACTA ACUST UNITED AC 2007; 47:269-74. [PMID: 17086158 DOI: 10.3314/jjmm.47.269] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
An important point in the development of an antimicrobial agent is whether its target molecules are essential for growth of the microorganism. From this viewpoint, we focused attention on essential genes as potential targets of antifungal agents in the pathogenic yeast Candida. Here we introduce recent attempts for screening, identification, and characterization of essential genes from a haploid yeast Candida glabrata, using temperature-sensitive mutants. Our experimental results suggesting the essentiality of C. albicans PHO85, the homologue of which is known as a negative regulator of the PHO system and as a non-essential gene in Saccharomyces cerevisiae are also described.
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Affiliation(s)
- Yozo Miyakawa
- Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Japan
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Takeo K, Virtudazo E, Ohkusu M, Kawamoto S, Ito-Kuwa S, Aoki S. [Cell cycle control and CDC28/Cdc2 homologue and related gene cloning of Cryptococcus neoformans]. ACTA ACUST UNITED AC 2007; 47:257-62. [PMID: 17086156 DOI: 10.3314/jjmm.47.257] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
In Cryptococcus neoformans the DNA content of cells having tiny buds varied rather widely, depending on growth phases and strains used. Typically, buds of C. neoformans emerged soon after initiation of DNA synthesis in the early exponential phase. However, bud emergence was delayed to G2 during transition to the stationary phase, and in the early stationary phase budding scarcely occurred, although roughly half of the cells completed DNA synthesis. The timing of budding in C. neoformans was shifted to later cell cycle points with progression of the growth phase of the culture. Similarly, a deficit in oxygen was demonstrated to delay the timing of budding, prolong the G2 phase and cause accumulation of cells after DNA synthesis, but before commitment to budding. The C. neoformans homologue of the main cell cycle control gene CDC28/Cdc2 was isolated using degenerate RT-PCR. The full-length coding region was then amplified using primers to target the regions around the start and stop codons. The gene was called CnCdk1 and was found to have high homologies to S. cerevisiae CDC28 and S. pombe cdc2. To determine its function, its ability to rescue S. cerevisiae cdc28-temperature sensitive mutants was tested. S. cerevisiae cdc28-4 and cdc28-1N strains transformed with the pYES2-CnCdk1 construct exhibited growth at the restrictive temperature. Results of the sequence analysis and the ability of CnCdk1 to complement the S. cerevisiae cdc28-ts mutations support its assumed role as the CDC28/cdc2 homologue in C. neoformans.
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Affiliation(s)
- Kanji Takeo
- Research Center for Pathogenic Fungi and Microbial Toxicoses, Chiba University, Japan
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Heinisch JJ. Baker's yeast as a tool for the development of antifungal kinase inhibitors—targeting protein kinase C and the cell integrity pathway. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2005; 1754:171-82. [PMID: 16216564 DOI: 10.1016/j.bbapap.2005.07.032] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2005] [Revised: 07/15/2005] [Accepted: 07/16/2005] [Indexed: 01/27/2023]
Abstract
Today, the yeast Saccharomyces cerevisiae is probably the best-studied eukaryotic organism. This review first focuses on the signaling process which is mediated by the unique yeast protein kinase C (Pkc1p) and a downstream mitogen-activated protein kinase (MAPK) cascade. This pathway ensures cellular integrity by sensing cell surface stress and controlling cell wall biosynthesis and progression through the cell cycle. The domain structure of Pkc1p is conserved from yeast to humans. A yeast system for heterologous expression of specific domains in a chimeric yeast/mammalian PKC enzyme ("domain shuffling") is depicted. It is also proposed how this system could be employed for the study of protein kinase inhibitors in high-throughput screens. Moreover, a reporter assay that allows a quantitative readout of the activity of the cell integrity signaling pathway is introduced. Since a variety of protein kinases take part in the signal transduction, this broadens the range of targets for potential inhibitors.
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Affiliation(s)
- Jürgen J Heinisch
- Universität Osnabrück, Fachbereich Biologie/Chemie, AG Genetik, Barbarastr. 11, D-49069 Osnabrück, Germany.
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Gildor T, Shemer R, Atir-Lande A, Kornitzer D. Coevolution of cyclin Pcl5 and its substrate Gcn4. EUKARYOTIC CELL 2005; 4:310-8. [PMID: 15701793 PMCID: PMC549342 DOI: 10.1128/ec.4.2.310-318.2005] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Gcn4, a transcription factor that plays a key role in the response of Saccharomyces cerevisiae to amino acid starvation, is regulated at both the levels of translation and of protein stability. Regulated degradation of Gcn4 depends on its phosphorylation by the cyclin-dependent kinase Pho85, in conjunction with the cyclin Pcl5. The pathogenic yeast Candida albicans contains a functional homolog of Gcn4, which is involved in amino acid metabolism, as well as in the regulation of filamentous growth in response to starvation. Here, we show that C. albicans Gcn4 (CaGcn4) is rapidly degraded and that this degradation depends on a Pho85 cyclin homolog, CaPcl5. The regulatory loop that includes Gcn4 and Pcl5 is conserved in C. albicans: like in S. cerevisiae, CaPcl5 is transcriptionally induced by CaGcn4 and is required for CaGcn4 degradation. However, the proteins have coevolved so that there is no cross-recognition between the proteins from the two species: phosphorylation-dependent degradation of CaGcn4 occurs only in the presence of CaPcl5, and S. cerevisiae Gcn4 (ScGcn4) requires ScPcl5 for its degradation. Phenotypic analysis of the Capcl5 mutant indicates that CaPcl5 also modulates the filamentous response of C. albicans in amino acid-rich media.
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Affiliation(s)
- Tsvia Gildor
- Department of Molecular Microbiology, B. Rappaport Faculty of Medicine, Technion-IIT, Rappaport Institute for Research in the Medical Sciences, Haifa, 31096, Israel
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Takeo K, Ogura Y, Virtudazo E, Raclavsky V, Kawamoto S. Isolation of a CDC28 homologue from Cryptococcus neoformans that is able to complement cdc28 temperature-sensitive mutants of Saccharomyces cerevisiae. FEMS Yeast Res 2004; 4:737-44. [PMID: 15093777 DOI: 10.1016/j.femsyr.2004.01.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2003] [Revised: 01/19/2004] [Accepted: 01/25/2004] [Indexed: 11/30/2022] Open
Abstract
A partial cDNA fragment of the Cryptococcus neoformans homologue of the main cell cycle control gene CDC28/cdc2 was isolated using degenerate primer RT-PCR. A subsequent search in the C. neoformans genome database identified several sequences similar to CDC28/cdc2. A part of the sequence which showed the highest similarity to CDC28/cdc2 turned out to be identical to the partial cyclin-dependent kinase (Cdk) cDNA fragment isolated by degenerate RT-PCR. The full-length coding region of this Cdk homologue was amplified by RT-PCR using primers designed to target regions around start and stop codons, and the gene was named CnCdk1. To determine its function, an analysis of deduced amino acid sequence of the CnCdk1 was performed and its ability to rescue Saccharomyces cerevisiae cdc28-temperature sensitive mutants was tested. S. cerevisiae cdc28-4 and cdc28-1N strains transformed with the pYES2- CnCdk1 construct exhibited growth at 36.5 degrees C in galactose-raffinose medium, but not in glucose medium. Results of the sequence analysis and the fact that CnCdk1 is able to complement the S. cerevisiae cdc28-ts mutation support its assumed role as the CDC28/cdc2 homologue in C. neoformans.
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Affiliation(s)
- Kanji Takeo
- Research Center for Pathogenic Fungi and Microbial Toxicoses, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8673, Japan.
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de Jesús-Berríos M, Rodríguez-del Valle N. Expression of a Pho85 cyclin-dependent kinase is repressed during the dimorphic transition in Sporothrix schenckii. Fungal Genet Biol 2002; 37:39-48. [PMID: 12223188 DOI: 10.1016/s1087-1845(02)00031-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Sporothrix schenckii is a pathogenic fungus that undergoes a dimorphic transition from yeast to mycelium in response to environmental conditions such as cell density, temperature, and calcium. We identified a homolog of the Pho85 cyclin-dependent kinase (Cdk) that mediates cellular responses to environmental conditions in other organisms. By Western blot, three proteins containing the PSTAIRE motif, which characterize the cyclin-dependent protein kinases, were identified in S. schenckii. The gene encoding a Pho85 homolog, PhoSs, was identified and sequenced. The phoSs gene consists of 990bp, contains one intron, and encodes a protein of 306 amino acids. The S. schenckii Pho85 homolog shares features with Cdks, including the PSTAIRE motif, an ATP binding domain, and a serine-threonine kinase domain. By quantitative competitive RT-PCR, expression of the phoSs gene was found to decrease 30-fold during the yeast to mycelium transition. The addition of extracellular calcium accelerated the dimorphic transition and restored phoSs expression. These findings suggest PhoSs may participate in the control of the yeast to mycelium transition in S. schenckii.
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Affiliation(s)
- Marisol de Jesús-Berríos
- Department of Microbiology and Medical Zoology, Medical Sciences Campus, University of Puerto Rico, San Juan 00936, USA.
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