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Reslan L, Araj GF, Finianos M, El Asmar R, Hrabak J, Dbaibo G, Bitar I. Molecular Characterization of Candida auris Isolates at a Major Tertiary Care Center in Lebanon. Front Microbiol 2022; 12:770635. [PMID: 35145489 PMCID: PMC8822126 DOI: 10.3389/fmicb.2021.770635] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2021] [Accepted: 11/23/2021] [Indexed: 12/28/2022] Open
Abstract
Background The globally emerging Candida auris pathogens poses heavy burden to the healthcare system. Their molecular analyses assist in understanding their epidemiology, dissemination, treatment, and control. This study was warranted to describe the genomic features and drug resistance profiles using whole genome sequencing (WGS) among C. auris isolates from Lebanon. Methods A total of 28 C. auris clinical isolates, from different hospital units, were phenotypically identified by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) and tested for antifungal resistance using Vitek-2 system and E test. The complete genomes were determined by WGS using long reads sequencing (PacBio) to reveal the clade distribution and antifungal resistance genes. Results Candida auris revealed uniform resistance to fluconazole and amphotericin B, with full susceptibility to echinocandins. Among key resistance genes studied, only two mutations were detected: Y132F in ERG11 gene and a novel mutation, D709E, found in CDR1 gene encoding for an ABC efflux pump. Phylogenetically, C. auris genomes belonged to South Asian clade I and showed limited genetic diversity, suggesting person to person transmission. Conclusion This characterization of C. auris isolates from Lebanon revealed the exclusivity of clade I lineage together with uniform resistance to fluconazole and amphotericin B. The control of such highly resistant pathogen necessitates an appropriate and rapid recovery and identification to contain spread and outbreaks.
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Affiliation(s)
- Lina Reslan
- American University of Beirut, Center for Infectious Diseases Research (CIDR) and WHO Collaborating Center for Reference and Research on Bacterial Pathogens, Beirut, Lebanon
| | - George F. Araj
- American University of Beirut, Center for Infectious Diseases Research (CIDR) and WHO Collaborating Center for Reference and Research on Bacterial Pathogens, Beirut, Lebanon
- Department of Pathology and Laboratory Medicine, American University of Beirut Medical Center, Beirut, Lebanon
- *Correspondence: George F. Araj,
| | - Marc Finianos
- Department of Microbiology, Faculty of Medicine and University Hospital in Plzen, Charles University, Plzeň, Czechia
| | - Rima El Asmar
- Department of Pathology and Laboratory Medicine, American University of Beirut Medical Center, Beirut, Lebanon
| | - Jaroslav Hrabak
- Department of Microbiology, Faculty of Medicine and University Hospital in Plzen, Charles University, Plzeň, Czechia
| | - Ghassan Dbaibo
- American University of Beirut, Center for Infectious Diseases Research (CIDR) and WHO Collaborating Center for Reference and Research on Bacterial Pathogens, Beirut, Lebanon
- Department of Pediatrics and Adolescent Medicine, Faculty of Medicine, American University of Beirut, Beirut, Lebanon
| | - Ibrahim Bitar
- Department of Microbiology, Faculty of Medicine and University Hospital in Plzen, Charles University, Plzeň, Czechia
- Ibrahim Bitar,
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2
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Cao C, Xue C. More Than Just Cleaning: Ubiquitin-Mediated Proteolysis in Fungal Pathogenesis. Front Cell Infect Microbiol 2021; 11:774613. [PMID: 34858882 PMCID: PMC8631298 DOI: 10.3389/fcimb.2021.774613] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2021] [Accepted: 10/25/2021] [Indexed: 12/14/2022] Open
Abstract
Ubiquitin-proteasome mediated protein turnover is an important regulatory mechanism of cellular function in eukaryotes. Extensive studies have linked the ubiquitin-proteasome system (UPS) to human diseases, and an array of proteasome inhibitors have been successfully developed for cancer therapy. Although still an emerging field, research on UPS regulation of fungal development and virulence has been rapidly advancing and has generated considerable excitement in its potential as a target for novel drugs. In this review, we summarize UPS composition and regulatory function in pathogenic fungi, especially in stress responses, host adaption, and fungal pathogenesis. Emphasis will be given to UPS regulation of pathogenic factors that are important for fungal pathogenesis. We also discuss future potential therapeutic strategies for fungal infections based on targeting UPS pathways.
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Affiliation(s)
- Chengjun Cao
- Public Health Research Institute, Rutgers University, New Brunswick, NJ, United States
| | - Chaoyang Xue
- Public Health Research Institute, Rutgers University, New Brunswick, NJ, United States
- Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers University, Newark, NJ, United States
- Rutgers Center for Lipid Research, Rutgers University, New Brunswick, NJ, United States
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3
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Molecular targets for antifungals in amino acid and protein biosynthetic pathways. Amino Acids 2021; 53:961-991. [PMID: 34081205 PMCID: PMC8241756 DOI: 10.1007/s00726-021-03007-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Accepted: 05/17/2021] [Indexed: 01/22/2023]
Abstract
Fungi cause death of over 1.5 million people every year, while cutaneous mycoses are among the most common infections in the world. Mycoses vary greatly in severity, there are long-term skin (ringworm), nail or hair infections (tinea capitis), recurrent like vaginal candidiasis or severe, life-threatening systemic, multiorgan infections. In the last few years, increasing importance is attached to the health and economic problems caused by fungal pathogens. There is a growing need for improvement of the availability of antifungal drugs, decreasing their prices and reducing side effects. Searching for novel approaches in this respect, amino acid and protein biosynthesis pathways appear to be competitive. The route that leads from amino acid biosynthesis to protein folding and its activation is rich in enzymes that are descriptive of fungi. Blocking the action of those enzymes often leads to avirulence or growth inhibition. In this review, we want to trace the principal processes of fungi vitality. We present the data of genes encoding enzymes involved in amino acid and protein biosynthesis, potential molecular targets in antifungal chemotherapy, and describe the impact of inhibitors on fungal organisms.
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The Vacuolar Morphogenesis Protein Vam6-Like Protein Vlp1 Is Required for Pathogenicity of Cryptococcus neoformans. J Fungi (Basel) 2021; 7:jof7060418. [PMID: 34072011 PMCID: PMC8228526 DOI: 10.3390/jof7060418] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Revised: 05/25/2021] [Accepted: 05/25/2021] [Indexed: 12/25/2022] Open
Abstract
Cryptococcus neoformans is an encapsulated yeast pathogen that infects immunocompromised patients to cause fungal meningitis, resulting in hundreds of thousands of deaths each year. F-box protein Fbp1, the key component of the E3 ubiquitin ligase, plays a critical role in fungal development and virulence in fungal pathogens. In this study, we identified a potential substrate of Fbp1, the vacuolar morphogenesis protein Vam6-like protein Vlp1, and evaluated its role in virulence in C. neoformans. Deletion or overexpression of the VLP1 gene results in abnormal capsule formation and melanin production of C. neoformans. Stress tolerance assay showed that the vlp1Δ mutant was sensitive to SDS and NaCl but not to CFW or Congo red, indicating that Vlp1 might regulate the cell membrane integrity in C. neoformans. Fungal virulence assay showed that Vlp1 was essential for the pathogenicity of C. neoformans, as vlp1Δ mutants are avirulent in the mouse systematic infection model of cryptococcosis. The progression of fungal infection revealed that the vlp1Δ mutants were gradually eliminated from the lungs of the mice after infection. Moreover, the vlp1Δ mutants showed a proliferation defect inside macrophages and a viability defect in the host complement system, which likely contributes to the virulence attenuation of the vlp1Δ mutants. In summary, our results revealed that the vacuolar morphogenesis protein Vam6-like protein Vlp1 is essential for the pathogenicity of C. neoformans.
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Han LT, Wu L, Liu TB. A Predicted Mannoprotein Cmp1 Regulates Fungal Virulence in Cryptococcus neoformans. Pathogens 2020; 9:pathogens9110881. [PMID: 33114434 PMCID: PMC7692273 DOI: 10.3390/pathogens9110881] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2020] [Revised: 10/18/2020] [Accepted: 10/23/2020] [Indexed: 01/08/2023] Open
Abstract
The capsule of the fungal pathogen Cryptococcus neoformans consists of glucuronoxylomannan (GXM), glucuronoxylomannogalactan (GXMGal), and mannoproteins (MPs). MPs are a kind of glycoproteins with low content but high immunogenicity, which can stimulate the immune protection of the host. However, there is not much information about the role of mannoproteins in virulence of the human fungal pathogen C. neoformans. In this study, we reported the identification and functional analysis of a predicted mannoprotein Cmp1 that regulates fungal virulence in C. neoformans. Gene expression pattern analysis indicates that the CMP1 gene was ubiquitously expressed at all stages of cryptococcal development. Subcellular localization analysis indicated that Cmp1 was localized in the cytoplasm of cryptococcal cells. Disruption or overexpression of CMP1 results in impairing capsule formation in Cryptococcus, but it does not affect the melanin production and sensitivity under various stress conditions, nor does it affect the sexual reproduction process of Cryptococcus. Survival assay showed that the pathogenicity of the cmp1Δ mutant or the CMP1 overexpression strain was significantly attenuated in a murine inhalation model of cryptococcosis. In conclusion, our findings implied that the mannoprotein Cmp1 is required for the virulence of C. neoformans.
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Affiliation(s)
- Lian-Tao Han
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing 400715, China; (L.-T.H.); (L.W.)
- Chongqing Key Laboratory of Microsporidia Infection and Control, Southwest University, Chongqing 400715, China
| | - Lei Wu
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing 400715, China; (L.-T.H.); (L.W.)
| | - Tong-Bao Liu
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing 400715, China; (L.-T.H.); (L.W.)
- Chongqing Key Laboratory of Microsporidia Infection and Control, Southwest University, Chongqing 400715, China
- Correspondence: ; Tel.: +86-23-6825-1088
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Oliver JC, Laghi L, Parolin C, Foschi C, Marangoni A, Liberatore A, Dias ALT, Cricca M, Vitali B. Metabolic profiling of Candida clinical isolates of different species and infection sources. Sci Rep 2020; 10:16716. [PMID: 33028931 PMCID: PMC7541501 DOI: 10.1038/s41598-020-73889-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Accepted: 09/22/2020] [Indexed: 12/27/2022] Open
Abstract
Candida species are the most common cause of opportunistic fungal infections. Rapid identification and novel approaches for the characterization of these fungi are of great interest to improve the diagnosis and the knowledge about their pathogenic properties. This study aimed to characterize clinical isolates of Candida spp. by proteomics (MALDI-TOF MS) and metabolomics (1H-NMR), and to correlate their metabolic profiles with Candida species, source of infection and different virulence associated parameters. In particular, 49 Candida strains from different sources (blood, n = 15; vagina, n = 18; respiratory tract, n = 16), belonging mainly to C. albicans complex (61%), C. glabrata (20%) and C. parapsilosis (12%) species were used. Several extracellular and intracellular metabolites showed significantly different concentrations among isolates recovered from different sources of infection, as well as among different Candida species. These metabolites were mainly related to the glycolysis or gluconeogenesis, tricarboxylic acid cycle, nucleic acid synthesis and amino acid and lipid metabolism. Moreover, we found specific metabolic fingerprints associated with the ability to form biofilm, the antifungal resistance (i.e. caspofungin and fluconazole) and the production of secreted aspartyl proteinase. In conclusion, 1H-NMR-based metabolomics can be useful to deepen Candida spp. virulence and pathogenicity properties.
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Affiliation(s)
- Josidel Conceição Oliver
- Department of Pharmacy and Biotechnology, Alma Mater Studiorum, University of Bologna, Bologna, Italy
- Department of Microbiology and Immunology, Federal University of Alfenas, Minas Gerais, Brazil
| | - Luca Laghi
- Centre of Foodomics, Department of Agro-Food Science and Technology, Alma Mater Studiorum, University of Bologna, Cesena, Italy
| | - Carola Parolin
- Department of Pharmacy and Biotechnology, Alma Mater Studiorum, University of Bologna, Bologna, Italy
| | - Claudio Foschi
- Microbiology, DIMES, Alma Mater Studiorum, University of Bologna, Bologna, Italy
| | - Antonella Marangoni
- Microbiology, DIMES, Alma Mater Studiorum, University of Bologna, Bologna, Italy
| | - Andrea Liberatore
- Microbiology, DIMES, Alma Mater Studiorum, University of Bologna, Bologna, Italy
| | | | - Monica Cricca
- Microbiology, DIMES, Alma Mater Studiorum, University of Bologna, Bologna, Italy.
| | - Beatrice Vitali
- Department of Pharmacy and Biotechnology, Alma Mater Studiorum, University of Bologna, Bologna, Italy
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7
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The regulation of the sulfur amino acid biosynthetic pathway in Cryptococcus neoformans: the relationship of Cys3, Calcineurin, and Gpp2 phosphatases. Sci Rep 2019; 9:11923. [PMID: 31417135 PMCID: PMC6695392 DOI: 10.1038/s41598-019-48433-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2019] [Accepted: 08/01/2019] [Indexed: 01/02/2023] Open
Abstract
Cryptococcosis is a fungal disease caused by C. neoformans. To adapt and survive in diverse ecological niches, including the animal host, this opportunistic pathogen relies on its ability to uptake nutrients, such as carbon, nitrogen, iron, phosphate, sulfur, and amino acids. Genetic circuits play a role in the response to environmental changes, modulating gene expression and adjusting the microbial metabolism to the nutrients available for the best energy usage and survival. We studied the sulfur amino acid biosynthesis and its implications on C. neoformans biology and virulence. CNAG_04798 encodes a BZip protein and was annotated as CYS3, which has been considered an essential gene. However, we demonstrated that CYS3 is not essential, in fact, its knockout led to sulfur amino acids auxotroph. Western blots and fluorescence microscopy indicated that GFP-Cys3, which is expressed from a constitutive promoter, localizes to the nucleus in rich medium (YEPD); the addition of methionine and cysteine as sole nitrogen source (SD-N + Met/Cys) led to reduced nuclear localization and protein degradation. By proteomics, we identified and confirmed physical interaction among Gpp2, Cna1, Cnb1 and GFP-Cys3. Deletion of the calcineurin and GPP2 genes in a GFP-Cys3 background demonstrated that calcineurin is required to maintain Cys3 high protein levels in YEPD and that deletion of GPP2 causes GFP-Cys3 to persist in the presence of sulfur amino acids. Global transcriptional profile of mutant and wild type by RNAseq revealed that Cys3 controls all branches of the sulfur amino acid biosynthesis, and sulfur starvation leads to induction of several amino acid biosynthetic routes. In addition, we found that Cys3 is required for virulence in Galleria mellonella animal model.
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8
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Role of Amino Acid Metabolism in the Virulence of Human Pathogenic Fungi. CURRENT CLINICAL MICROBIOLOGY REPORTS 2019. [DOI: 10.1007/s40588-019-00124-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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9
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Calvete CL, Martho KF, Felizardo G, Paes A, Nunes JM, Ferreira CO, Vallim MA, Pascon RC. Amino acid permeases in Cryptococcus neoformans are required for high temperature growth and virulence; and are regulated by Ras signaling. PLoS One 2019; 14:e0211393. [PMID: 30682168 PMCID: PMC6347259 DOI: 10.1371/journal.pone.0211393] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Accepted: 01/11/2019] [Indexed: 11/22/2022] Open
Abstract
Cryptococcosis is an Invasive Fungal Infection (IFI) caused by Cryptococcus neoformans, mainly in immunocompromised patients. Therapeutic failure due to pathogen drug resistance, treatment inconstancy and few antifungal options is a problem. The study of amino acid biosynthesis and uptake represents an opportunity to explore possible development of novel antifungals. C. neoformans has 10 amino acids permeases, two of them (Aap3 and Aap7) not expressed at the conditions tested, and five were studied previously (Aap2, Aap4, Aap5, Mup1 and Mup3). Our previous results showed that Aap4 and Aap5 are major permeases with overlapping functions. The aap4Δ/aap5Δ double mutant fails to grow in amino acids as sole nitrogen source and is avirulent in animal model. Here, we deleted the remaining amino acid permeases (AAP1, AAP6, AAP8) that showed gene expression modulation by nutritional condition and created a double mutant (aap1Δ/aap2Δ). We studied the virulence attributes of these mutants and explored the regulatory mechanism behind amino acid uptake in C. neoformans. The aap1Δ/aap2Δ strain had reduced growth at 37°C in L-amino acids, reduced capsule production and was hypovirulent in the Galleria mellonella animal model. Our data, along with previous studies, (i) complement the analysis for all 10 amino acid permeases mutants, (ii) corroborate the idea that these transporters behave as global permeases, (iii) are required during heat and nutritional stress, and (iv) are important for virulence. Our study also indicates a new possible link between Ras1 signaling and amino acids uptake.
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Affiliation(s)
- Crislaine Lambiase Calvete
- Universidade de São Paulo, Biotechnology Graduate Program, São Paulo, SP, Brazil
- Universidade Federal de São Paulo, Campus Diadema, Department of Biological Sciences, Diadema, SP, Brazil
| | - Kevin Felipe Martho
- Universidade Federal de São Paulo, Campus Diadema, Department of Biological Sciences, Diadema, SP, Brazil
| | - Gabrielle Felizardo
- Universidade Federal de São Paulo, Campus Diadema, Department of Biological Sciences, Diadema, SP, Brazil
| | - Alexandre Paes
- Universidade Federal de São Paulo, Campus Diadema, Department of Biological Sciences, Diadema, SP, Brazil
| | - João Miguel Nunes
- Universidade Federal de São Paulo, Campus Diadema, Department of Biological Sciences, Diadema, SP, Brazil
| | - Camila Oliveira Ferreira
- Universidade Federal de São Paulo, Campus Diadema, Department of Biological Sciences, Diadema, SP, Brazil
| | - Marcelo A. Vallim
- Universidade Federal de São Paulo, Campus Diadema, Department of Biological Sciences, Diadema, SP, Brazil
| | - Renata C. Pascon
- Universidade Federal de São Paulo, Campus Diadema, Department of Biological Sciences, Diadema, SP, Brazil
- * E-mail:
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10
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Lee YT, Fang YY, Sun YW, Hsu HC, Weng SM, Tseng TL, Lin TH, Shieh JC. THR1 mediates GCN4 and CDC4 to link morphogenesis with nutrient sensing and the stress response in Candida albicans. Int J Mol Med 2018; 42:3193-3208. [PMID: 30320368 PMCID: PMC6202100 DOI: 10.3892/ijmm.2018.3930] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Accepted: 10/08/2018] [Indexed: 12/31/2022] Open
Abstract
Candida albicans (C. albicans) CDC4 (CaCDC4), encoding the F-box protein for the substrate specificity of the Skp1-cullin-F-box E3 ubiquitin ligase complex, suppresses the yeast-to-filament transition in C. albicans. In our previous study, Thr1 was identified as a CaCdc4-associated protein using affinity purification. THR1 encodes a homoserine kinase, which is involved in the threonine biosynthesis pathway. The present study generated a strain with repressible CaCDC4 expression and continuous THR1 expression. Colony and cell morphology analyses, as well as immunoblotting, revealed that the Thr1 protein was detectable under conditions in which the expression of CaCDC4 was repressed and that the filaments resulting from the repressed expression of CaCDC4 were suppressed by the constitutive expression of THR1 in C. albicans. Additionally, by using the CaSAT1-flipper method, the present study produced null mutants of THR1, GCN4, and CaCDC4. The phenotypic consequences were evaluated by growth curves, spotting assays, microscopic analysis, reverse transcription-polymerase chain reaction and XTT-based biofilm formation ability. The results revealed that fewer cells lacking THR1 entered the stationary phase but had no apparent morphological alteration. It was observed that the expression of THR1 was upregulated concurrently with GCN4 during nutrient depletion and that cells lacking GCN4 rescued the lethality of cells in the absence of THR1 in conditions accumulating homoserine in the threonine biosynthesis pathway. Of note, it was found that cells with either CaCDC4 or THR1 loss were sensitive to oxidative stress and osmotic stress, with those with THR1 loss being more sensitive. In addition, it was observed that cells with loss of either CaCDC4 or THR1 exhibited the ability to increase biofilm formation, with those lacking CaCDC4 exhibiting a greater extent of enhancement. It was concluded that CaCDC4 is important in the coordination of morphogenesis, nutrient sensing, and the stress response through THR1 in C. albicans.
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Affiliation(s)
- Yuan-Ti Lee
- Institute of Medicine and School of Medicine, Chung Shan Medical University, Taichung City 40201, Taiwan, R.O.C
| | - Yi-Ya Fang
- Department of Biomedical Sciences, Chung Shan Medical University, Taichung City 40201, Taiwan, R.O.C
| | - Yu Wen Sun
- Department of Biomedical Sciences, Chung Shan Medical University, Taichung City 40201, Taiwan, R.O.C
| | - Hsiao-Chi Hsu
- Department of Biomedical Sciences, Chung Shan Medical University, Taichung City 40201, Taiwan, R.O.C
| | - Shan-Mei Weng
- Department of Biomedical Sciences, Chung Shan Medical University, Taichung City 40201, Taiwan, R.O.C
| | - Tzu-Ling Tseng
- Department of Biomedical Sciences, Chung Shan Medical University, Taichung City 40201, Taiwan, R.O.C
| | - Ting-Hui Lin
- Department of Biomedical Sciences, Chung Shan Medical University, Taichung City 40201, Taiwan, R.O.C
| | - Jia-Ching Shieh
- Department of Biomedical Sciences, Chung Shan Medical University, Taichung City 40201, Taiwan, R.O.C
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11
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Potential targets for the development of new antifungal drugs. J Antibiot (Tokyo) 2018; 71:978-991. [DOI: 10.1038/s41429-018-0100-9] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Revised: 07/26/2018] [Accepted: 08/31/2018] [Indexed: 12/19/2022]
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12
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Genome-Wide Screen for Saccharomyces cerevisiae Genes Contributing to Opportunistic Pathogenicity in an Invertebrate Model Host. G3-GENES GENOMES GENETICS 2018; 8:63-78. [PMID: 29122853 PMCID: PMC5765367 DOI: 10.1534/g3.117.300245] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Environmental opportunistic pathogens can exploit vulnerable hosts through expression of traits selected for in their natural environments. Pathogenicity is itself a complicated trait underpinned by multiple complex traits, such as thermotolerance, morphology, and stress response. The baker's yeast, Saccharomyces cerevisiae, is a species with broad environmental tolerance that has been increasingly reported as an opportunistic pathogen of humans. Here we leveraged the genetic resources available in yeast and a model insect species, the greater waxmoth Galleria mellonella, to provide a genome-wide analysis of pathogenicity factors. Using serial passaging experiments of genetically marked wild-type strains, a hybrid strain was identified as the most fit genotype across all replicates. To dissect the genetic basis for pathogenicity in the hybrid isolate, bulk segregant analysis was performed which revealed eight quantitative trait loci significantly differing between the two bulks with alleles from both parents contributing to pathogenicity. A second passaging experiment with a library of deletion mutants for most yeast genes identified a large number of mutations whose relative fitness differed in vivovs.in vitro, including mutations in genes controlling cell wall integrity, mitochondrial function, and tyrosine metabolism. Yeast is presumably subjected to a massive assault by the innate insect immune system that leads to melanization of the host and to a large bottleneck in yeast population size. Our data support that resistance to the innate immune response of the insect is key to survival in the host and identifies shared genetic mechanisms between S. cerevisiae and other opportunistic fungal pathogens.
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Novel biosynthetic pathway for sulfur amino acids in Cryptococcus neoformans. Curr Genet 2017; 64:681-696. [PMID: 29159425 DOI: 10.1007/s00294-017-0783-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Revised: 11/01/2017] [Accepted: 11/16/2017] [Indexed: 12/27/2022]
Abstract
We elucidated a unique feature of sulfur metabolism in Cryptococcus neoformans. C. neoformans produces cysteine solely by the O-acetylserine pathway that consists of serine-O-acetyl transferase and cysteine synthase. We designated the gene encoding the former enzyme CYS2 (locus tag CNE02740) and the latter enzyme CYS1 (locus tag CNL05880). The cys1Δmutant strain was found to be avirulent in a murine infection model. Methionine practically does not support growth of the cys1Δ strain, and cysteine does not serve as a methionine source, indicating that the transsulfuration pathway does not contribute to sulfur amino acid synthesis in C. neoformans. Among the genes encoding enzymes catalyzing the reactions from homoserine to methionine, the gene corresponding to the Saccharomyces cerevisiae MET17 encoding O-acetylhomoserine sulfhydrylase (Met17p) had remained to be identified in C. neoformans. By genetic analysis of Met- mutants obtained by Agrobacterium tumefaciens-mediated mutagenesis, we concluded that Cnc01220, most similar to Str2p (36% identity), cystathionine-γ-synthase, in the Saccharomyces genome, is the C. neoformans version of O-acetylhomoserine sulfhydrylase. We designated CNC01220 as MET17. The C. neoformans met3Δ mutant defective in the first step of the sulfate assimilation pathway, sulfate adenylyltransferase, barely uses methionine as a sulfur source, whereas it uses cysteine efficiently. The poor utilization of methionine by the met3Δ mutant is most probably due to the absence of the transsulfuration pathway, causing an incapability of C. neoformans to produce cysteine and hydrogen sulfide from methionine. When cysteine is used as a sulfur source, methionine is likely produced de novo by using hydrogen sulfide derived from cysteine via an unidentified pathway. Altogether, the unique features of sulfur amino acid metabolism in C. neoformans will make this fungus a valuable experimental system to develop anti-fungal agents and to investigate physiology of hydrogen sulfide.
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Nutritional Requirements and Their Importance for Virulence of Pathogenic Cryptococcus Species. Microorganisms 2017; 5:microorganisms5040065. [PMID: 28974017 PMCID: PMC5748574 DOI: 10.3390/microorganisms5040065] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Revised: 09/27/2017] [Accepted: 09/27/2017] [Indexed: 12/12/2022] Open
Abstract
Cryptococcus sp. are basidiomycete yeasts which can be found widely, free-living in the environment. Interactions with natural predators, such as amoebae in the soil, are thought to have promoted the development of adaptations enabling the organism to survive inside human macrophages. Infection with Cryptococcus in humans occurs following inhalation of desiccated yeast cells or spore particles and may result in fatal meningoencephalitis. Human disease is caused almost exclusively by the Cryptococcus neoformans species complex, which predominantly infects immunocompromised patients, and the Cryptococcus gattii species complex, which is capable of infecting immunocompetent individuals. The nutritional requirements of Cryptococcus are critical for its virulence in animals. Cryptococcus has evolved a broad range of nutrient acquisition strategies, many if not most of which also appear to contribute to its virulence, enabling infection of animal hosts. In this review, we summarise the current understanding of nutritional requirements and acquisition in Cryptococcus and offer perspectives to its evolution as a significant pathogen of humans.
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Martho KFC, de Melo AT, Takahashi JPF, Guerra JM, Santos DCDS, Purisco SU, Melhem MDSC, Fazioli RDA, Phanord C, Sartorelli P, Vallim MA, Pascon RC. Amino Acid Permeases and Virulence in Cryptococcus neoformans. PLoS One 2016; 11:e0163919. [PMID: 27695080 PMCID: PMC5047642 DOI: 10.1371/journal.pone.0163919] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Accepted: 09/17/2016] [Indexed: 11/19/2022] Open
Abstract
Fungal opportunistic pathogens colonize various environments, from plants and wood to human and animal tissue. Regarding human pathogens, one great challenge during contrasting niche occupation is the adaptation to different conditions, such as temperature, osmolarity, salinity, pressure, oxidative stress and nutritional availability, which may constitute sources of stress that need to be tolerated and overcome. As an opportunistic pathogen, C. neoformans faces exactly these situations during the transition from the environment to the human host, encountering nutritional constraints. Our previous and current research on amino acid biosynthetic pathways indicates that amino acid permeases are regulated by the presence of the amino acids, nitrogen and temperature. Saccharomyces cerevisiae and Candida albicans have twenty-four and twenty-seven genes encoding amino acid permeases, respectively; conversely, they are scarce in number in Basidiomycetes (C. neoformans, Coprinopsis cinerea and Ustilago maydis), where nine to ten permease genes can be found depending on the species. In this study, we have demonstrated that two amino acid permeases are essential for virulence in C. neoformans. Our data showed that C. neoformans uses two global and redundant amino acid permeases, Aap4 and Aap5 to respond correctly to thermal and oxidative stress. Double deletion of these permeases causes growth arrest in C. neoformans at 37°C and in the presence of hydrogen peroxide. The inability to uptake amino acid at a higher temperature and under oxidative stress also led to virulence attenuation in vivo. Our data showed that thermosensitivity caused by the lack of permeases Aap4 and Aap5 can be remedied by alkaline conditions (higher pH) and salinity. Permeases Aap4 and Aap5 are also required during fluconazole stress and they are the target of the plant secondary metabolite eugenol, a potent antifungal inhibitor that targets amino acid permeases. In summary, our work unravels (i) interesting physiological property of C. neoformans regarding its amino acid uptake system; (ii) an important aspect of virulence, which is the need for amino acid permeases during thermal and oxidative stress resistance and, hence, host invasion and colonization; and (iii) provides a convenient prototype for antifungal development, which are the amino acid permeases Aap4/Aap5 and their inhibitor.
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Affiliation(s)
- Kevin Felipe Cruz Martho
- Instituto de Ciências Ambientais, Química e Farmacêuticas, Universidade Federal de São Paulo, Rua Arthur Ridel, 275, Diadema, SP, Brazil
| | - Amanda Teixeira de Melo
- Instituto de Ciências Ambientais, Química e Farmacêuticas, Universidade Federal de São Paulo, Rua Arthur Ridel, 275, Diadema, SP, Brazil
| | | | | | | | - Sônia Ueda Purisco
- Mycology Unit, Adolfo Lutz Institute, Secretary of Health, São Paulo, Brazil
| | | | | | - Clerlune Phanord
- Instituto de Ciências Ambientais, Química e Farmacêuticas, Universidade Federal de São Paulo, Rua Arthur Ridel, 275, Diadema, SP, Brazil
| | - Patrícia Sartorelli
- Instituto de Ciências Ambientais, Química e Farmacêuticas, Universidade Federal de São Paulo, Rua Arthur Ridel, 275, Diadema, SP, Brazil
| | - Marcelo A. Vallim
- Instituto de Ciências Ambientais, Química e Farmacêuticas, Universidade Federal de São Paulo, Rua Arthur Ridel, 275, Diadema, SP, Brazil
| | - Renata C. Pascon
- Instituto de Ciências Ambientais, Química e Farmacêuticas, Universidade Federal de São Paulo, Rua Arthur Ridel, 275, Diadema, SP, Brazil
- * E-mail:
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Tsai PW, Chien CY, Yeh YC, Tung L, Chen HF, Chang TH, Lan CY. Candida albicans Hom6 is a homoserine dehydrogenase involved in protein synthesis and cell adhesion. JOURNAL OF MICROBIOLOGY, IMMUNOLOGY, AND INFECTION = WEI MIAN YU GAN RAN ZA ZHI 2016; 50:863-871. [PMID: 27089825 DOI: 10.1016/j.jmii.2016.03.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Revised: 02/22/2016] [Accepted: 03/09/2016] [Indexed: 10/22/2022]
Abstract
BACKGROUND/PURPOSE Candida albicans is a common fungal pathogen in humans. In healthy individuals, C. albicans represents a harmless commensal organism, but infections can be life threatening in immunocompromised patients. The complete genome sequence of C. albicans is extremely useful for identifying genes that may be potential drug targets and important for pathogenic virulence. However, there are still many uncharacterized genes in the Candida genome database. In this study, we investigated C. albicans Hom6, the functions of which remain undetermined experimentally. METHODS HOM6-deleted and HOM6-reintegrated mutant strains were constructed. The mutant strains were compared with wild-type in their growth in various media and enzyme activity. Effects of HOM6 deletion on translation were further investigated by cell susceptibility to hygromycin B or cycloheximide, as well as by polysome profiling, and cell adhesion to polystyrene was also determined. RESULTS C. albicans Hom6 exhibits homoserine dehydrogenase activity and is involved in the biosynthesis of methionine and threonine. HOM6 deletion caused translational arrest in cells grown under amino acid starvation conditions. Additionally, Hom6 protein was found in both cytosolic and cell-wall fractions of cultured cells. Furthermore, HOM6 deletion reduced C. albicans cell adhesion to polystyrene, which is a common plastic used in many medical devices. CONCLUSION Given that there is no Hom6 homologue in mammalian cells, our results provided an important foundation for future development of new antifungal drugs.
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Affiliation(s)
- Pei-Wen Tsai
- Institute of Molecular and Cellular Biology, National Tsing Hua University, Hsinchu, Taiwan
| | - Chu-Yang Chien
- Institute of Molecular and Cellular Biology, National Tsing Hua University, Hsinchu, Taiwan
| | - Ying-Chieh Yeh
- Institute of Molecular and Cellular Biology, National Tsing Hua University, Hsinchu, Taiwan
| | - Luh Tung
- Genomics Research Center, Academia Sinica, Nankang, Taipei, Taiwan
| | - Hsueh-Fen Chen
- Institute of Molecular and Cellular Biology, National Tsing Hua University, Hsinchu, Taiwan
| | - Tien-Hsien Chang
- Genomics Research Center, Academia Sinica, Nankang, Taipei, Taiwan
| | - Chung-Yu Lan
- Institute of Molecular and Cellular Biology, National Tsing Hua University, Hsinchu, Taiwan; Department of Life Science, National Tsing Hua University, Hsinchu, Taiwan.
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Xu X, Chen J, Wang Q, Duan C, Li Y, Wang R, Yang S. Mutagenesis of Key Residues in the Binding Center of l-Aspartate-b-Semialdehyde Dehydrogenase from Escherichia coli Enhances Utilization of the Cofactor NAD(H). Chembiochem 2015; 17:56-64. [PMID: 26662025 DOI: 10.1002/cbic.201500534] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Indexed: 11/07/2022]
Abstract
L-Aspartate-β-semialdehyde dehydrogenase (ASADH) is a key enzyme in the aspartate pathway. In bacteria, ASADH is highly specific for the cofactor NADP(+) rather than NAD(+). Limited information on cofactor utilization is available, and neither the wild-type protein nor the available mutants could utilize NAD(+) efficiently. In this study, we identified several residues crucial for cofactor utilization by Escherichia coli ASADH (ecASADH) by mutating residues within the cofactor binding center. Among the investigated mutants, ecASADH-Q350N and ecASADH-Q350N/H171A, which exhibited markedly improved NAD(+) utilization, were further investigated by various biochemical approaches and molecular modeling. Relative to the wild type, the two mutants showed approximately 44-fold and 66-fold increases, respectively, in the constant kcat /Km of NAD(+). As desired, they could also utilize NADH efficiently to synthesize l-homoserine in cascade reactions in vitro.
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Affiliation(s)
- Xiaoshu Xu
- Key Laboratory of Synthetic Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 300 Fenglin Road, Shanghai, 200032, China
| | - Jun Chen
- Key Laboratory of Synthetic Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 300 Fenglin Road, Shanghai, 200032, China
| | - Qingzhuo Wang
- Key Laboratory of Synthetic Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 300 Fenglin Road, Shanghai, 200032, China
| | - Chunlan Duan
- Key Laboratory of Synthetic Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 300 Fenglin Road, Shanghai, 200032, China
| | - Yan Li
- State Key Laboratory of Bioorganic and Natural Products Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai, 200032, China
| | - Renxiao Wang
- State Key Laboratory of Bioorganic and Natural Products Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai, 200032, China
| | - Sheng Yang
- Key Laboratory of Synthetic Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 300 Fenglin Road, Shanghai, 200032, China. .,Shanghai Collaborative Innovation Center for Biomanufacturing Technology, 30 Meilong Road, Shanghai, 200237, China.
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Fernandes JDS, Martho K, Tofik V, Vallim MA, Pascon RC. The Role of Amino Acid Permeases and Tryptophan Biosynthesis in Cryptococcus neoformans Survival. PLoS One 2015; 10:e0132369. [PMID: 26162077 PMCID: PMC4498599 DOI: 10.1371/journal.pone.0132369] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2015] [Accepted: 06/14/2015] [Indexed: 01/25/2023] Open
Abstract
Metabolic diversity is an important factor during microbial adaptation to different environments. Among metabolic processes, amino acid biosynthesis has been demonstrated to be relevant for survival for many microbial pathogens, whereas the association between pathogenesis and amino acid uptake and recycling are less well-established. Cryptococcus neoformans is an opportunistic fungal pathogen with many habitats. As a result, it faces frequent metabolic shifts and challenges during its life cycle. Here we studied the C. neoformans tryptophan biosynthetic pathway and found that the pathway is essential. RNAi indicated that interruptions in the biosynthetic pathway render strains inviable. However, auxotroph complementation can be partially achieved by tryptophan uptake when a non preferred nitrogen source and lower growth temperature are applied, suggesting that amino acid permeases may be the target of nitrogen catabolism repression (NCR). We used bioinformatics to search for amino acid permeases in the C. neoformans and found eight potential global permeases (AAP1 to AAP8). The transcriptional profile of them revealed that they are subjected to regulatory mechanisms which are known to respond to nutritional status in other fungi, such as (i) quality of nitrogen (Nitrogen Catabolism Repression, NCR) and carbon sources (Carbon Catabolism Repression, CCR), (ii) amino acid availability in the extracellular environment (SPS-sensing) and (iii) nutritional deprivation (Global Amino Acid Control, GAAC). This study shows that C. neoformans has fewer amino acid permeases than other model yeasts, and that these proteins may be subjected to complex regulatory mechanisms. Our data suggest that the C. neoformans tryptophan biosynthetic pathway is an excellent pharmacological target. Furthermore, inhibitors of this pathway cause Cryptococcus growth arrest in vitro.
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Affiliation(s)
- João Daniel Santos Fernandes
- Departamento de Ciências Biológicas, Instituto de Ciências Ambientais, Químicas e Farmacêuticas, Universidade Federal de São Paulo, Campus Diadema, Laboratório de Interações Microbianas (Laboratory 29), Rua Arthur Ridel, 275, 09972–270, Bairro Eldorado, Diadema, SP, Brazil
- Universidade de São Paulo, Avenida Prof. Lineu Prestes, 2415 Edifício ICB – III, Cidade Universitária, CEP 05508–900, São Paulo, SP, Brazil
| | - Kevin Martho
- Departamento de Ciências Biológicas, Instituto de Ciências Ambientais, Químicas e Farmacêuticas, Universidade Federal de São Paulo, Campus Diadema, Laboratório de Interações Microbianas (Laboratory 29), Rua Arthur Ridel, 275, 09972–270, Bairro Eldorado, Diadema, SP, Brazil
| | - Veridiana Tofik
- Departamento de Ciências Biológicas, Instituto de Ciências Ambientais, Químicas e Farmacêuticas, Universidade Federal de São Paulo, Campus Diadema, Laboratório de Interações Microbianas (Laboratory 29), Rua Arthur Ridel, 275, 09972–270, Bairro Eldorado, Diadema, SP, Brazil
| | - Marcelo A. Vallim
- Departamento de Ciências Biológicas, Instituto de Ciências Ambientais, Químicas e Farmacêuticas, Universidade Federal de São Paulo, Campus Diadema, Laboratório de Interações Microbianas (Laboratory 29), Rua Arthur Ridel, 275, 09972–270, Bairro Eldorado, Diadema, SP, Brazil
| | - Renata C. Pascon
- Departamento de Ciências Biológicas, Instituto de Ciências Ambientais, Químicas e Farmacêuticas, Universidade Federal de São Paulo, Campus Diadema, Laboratório de Interações Microbianas (Laboratory 29), Rua Arthur Ridel, 275, 09972–270, Bairro Eldorado, Diadema, SP, Brazil
- * E-mail:
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Tseng TL, Lai WC, Lee TL, Hsu WH, Sun YW, Li WC, Cheng CW, Shieh JC. A role of Candida albicans CDC4 in the negative regulation of biofilm formation. Can J Microbiol 2014; 61:247-55. [PMID: 25719926 DOI: 10.1139/cjm-2014-0526] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The CDC4 gene is nonessential in Candida albicans and plays a role in suppressing filamentous growth, in contrast to its homologues, which are involved in the G1-S transition of the cell cycle. While characterizing the function of C. albicans CDC4 (CaCDC4), we found that the loss of CaCDC4 resulted in a reduction in cell flocculation, indicating a possible role for CaCDC4 in biofilm formation. To elucidate the role of CaCDC4 in biofilm formation, Cacdc4 null mutant strains were constructed by using the mini-Ura-blaster method. To create a CaCDC4 rescued strain, the plasmid p6HF-ACT1p-CaCDC4 capable of constitutively expressing CaCDC4 was introduced into the Cacdc4 homozygous null mutant. To determine the biofilm formation ability, an in vitro XTT (2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-5-[(phenylamino)carbonyl]-2H-tetrazolium-5-carboxanilide) reduction assay was used. Compared with the parental auxotrophic strain BWP17, the Cacdc4 homozygous null mutant was able to enhance biofilm formation significantly. This enhancement of biofilm formation in the Cacdc4 homozygous null mutant could be reversed by constitutively expressing CaCDC4. We conclude that CaCDC4 has a role in suppressing biofilm formation in C. albicans.
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Affiliation(s)
- Tzu-Ling Tseng
- Department of Biomedical Sciences, Chung Shan Medical University, No. 110, Sec. 1, Jianguo N. Road, Taichung City 40201, Taiwan
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Ong HB, Lee WS, Patterson S, Wyllie S, Fairlamb AH. Homoserine and quorum-sensing acyl homoserine lactones as alternative sources of threonine: a potential role for homoserine kinase in insect-stage Trypanosoma brucei. Mol Microbiol 2014; 95:143-56. [PMID: 25367138 PMCID: PMC4460637 DOI: 10.1111/mmi.12853] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/01/2014] [Indexed: 12/29/2022]
Abstract
De novo synthesis of threonine from aspartate occurs via the β-aspartyl phosphate pathway in plants, bacteria and fungi. However, the Trypanosoma brucei genome encodes only the last two steps in this pathway: homoserine kinase (HSK) and threonine synthase. Here, we investigated the possible roles for this incomplete pathway through biochemical, genetic and nutritional studies. Purified recombinant TbHSK specifically phosphorylates L-homoserine and displays kinetic properties similar to other HSKs. HSK null mutants generated in bloodstream forms displayed no growth phenotype in vitro or loss of virulence in vivo. However, following transformation into procyclic forms, homoserine, homoserine lactone and certain acyl homoserine lactones (AHLs) were found to substitute for threonine in growth media for wild-type procyclics, but not HSK null mutants. The tsetse fly is considered to be an unlikely source of these nutrients as it feeds exclusively on mammalian blood. Bioinformatic studies predict that tsetse endosymbionts possess part (up to homoserine in Wigglesworthia glossinidia) or all of the β-aspartyl phosphate pathway (Sodalis glossinidius). In addition S. glossinidius is known to produce 3-oxohexanoylhomoserine lactone which also supports trypanosome growth. We propose that T. brucei has retained HSK and threonine synthase in order to salvage these nutrients when threonine availability is limiting.
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Affiliation(s)
- Han B Ong
- Division of Biological Chemistry & Drug Discovery, College of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK
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Inhibitors of amino acids biosynthesis as antifungal agents. Amino Acids 2014; 47:227-49. [PMID: 25408465 PMCID: PMC4302243 DOI: 10.1007/s00726-014-1873-1] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Accepted: 11/05/2014] [Indexed: 12/22/2022]
Abstract
Fungal microorganisms, including the human pathogenic yeast and filamentous fungi, are able to synthesize all proteinogenic amino acids, including nine that are essential for humans. A number of enzymes catalyzing particular steps of human-essential amino acid biosynthesis are fungi specific. Numerous studies have shown that auxotrophic mutants of human pathogenic fungi impaired in biosynthesis of particular amino acids exhibit growth defect or at least reduced virulence under in vivo conditions. Several chemical compounds inhibiting activity of one of these enzymes exhibit good antifungal in vitro activity in minimal growth media, which is not always confirmed under in vivo conditions. This article provides a comprehensive overview of the present knowledge on pathways of amino acids biosynthesis in fungi, with a special emphasis put on enzymes catalyzing particular steps of these pathways as potential targets for antifungal chemotherapy.
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Rawal Y, Qiu H, Hinnebusch AG. Accumulation of a threonine biosynthetic intermediate attenuates general amino acid control by accelerating degradation of Gcn4 via Pho85 and Cdk8. PLoS Genet 2014; 10:e1004534. [PMID: 25079372 PMCID: PMC4117449 DOI: 10.1371/journal.pgen.1004534] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2014] [Accepted: 06/11/2014] [Indexed: 11/19/2022] Open
Abstract
Gcn4 is a master transcriptional regulator of amino acid and vitamin biosynthetic enzymes subject to the general amino acid control (GAAC), whose expression is upregulated in response to amino acid starvation in Saccharomyces cerevisiae. We found that accumulation of the threonine pathway intermediate β-aspartate semialdehyde (ASA), substrate of homoserine dehydrogenase (Hom6), attenuates the GAAC transcriptional response by accelerating degradation of Gcn4, already an exceedingly unstable protein, in cells starved for isoleucine and valine. The reduction in Gcn4 abundance on ASA accumulation requires Cdk8/Srb10 and Pho85, cyclin-dependent kinases (CDKs) known to mediate rapid turnover of Gcn4 by the proteasome via phosphorylation of the Gcn4 activation domain under nonstarvation conditions. Interestingly, rescue of Gcn4 abundance in hom6 cells by elimination of SRB10 is not accompanied by recovery of transcriptional activation, while equivalent rescue of UAS-bound Gcn4 in hom6 pho85 cells restores greater than wild-type activation of Gcn4 target genes. These and other findings suggest that the two CDKs target different populations of Gcn4 on ASA accumulation, with Srb10 clearing mostly inactive Gcn4 molecules at the promoter that are enriched for sumoylation of the activation domain, and Pho85 clearing molecules unbound to the UAS that include both fully functional and inactive Gcn4 species. Transcriptional activator Gcn4 maintains amino acid homeostasis in budding yeast by inducing multiple amino acid biosynthetic pathways in response to starvation for any amino acid—the general amino acid control. Gcn4 abundance is tightly regulated by the interplay between an intricate translational control mechanism, which induces Gcn4 synthesis in starved cells, and a pathway of phosphorylation and ubiquitylation that mediates its rapid degradation by the proteasome. Here, we discovered that accumulation of a threonine biosynthetic pathway intermediate, β-aspartate semialdehyde (ASA), in hom6Δ mutant cells impairs general amino acid control in cells starved for isoleucine and valine by accelerating the already rapid degradation of Gcn4, in a manner requiring its phosphorylation by cyclin-dependent kinases Cdk8/Srb10 and Pho85. Interestingly, our results unveil a division of labor between these two kinases wherein Srb10 primarily targets inactive Gcn4 molecules—presumably damaged under conditions of ASA excess—while Pho85 clears a greater proportion of functional Gcn4 species from the cell. The ability of ASA to inhibit transcriptional induction of threonine pathway enzymes by Gcn4, dampening ASA accumulation and its toxic effects on cell physiology, should be adaptive in the wild when yeast encounters natural antibiotics that target Hom6 enzymatic activity.
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Affiliation(s)
- Yashpal Rawal
- Laboratory of Gene Regulation and Development, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Hongfang Qiu
- Laboratory of Gene Regulation and Development, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Alan G. Hinnebusch
- Laboratory of Gene Regulation and Development, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, United States of America
- * E-mail:
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The role of the de novo pyrimidine biosynthetic pathway in Cryptococcus neoformans high temperature growth and virulence. Fungal Genet Biol 2014; 70:12-23. [PMID: 25011011 DOI: 10.1016/j.fgb.2014.06.003] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2014] [Revised: 06/09/2014] [Accepted: 06/14/2014] [Indexed: 11/21/2022]
Abstract
Fungal infections are often difficult to treat due to the inherent similarities between fungal and animal cells and the resulting host toxicity from many antifungal compounds. Cryptococcus neoformans is an opportunistic fungal pathogen of humans that causes life-threatening disease, primarily in immunocompromised patients. Since antifungal therapy for this microorganism is limited, many investigators have explored novel drug targets aim at virulence factors, such as the ability to grow at mammalian physiological temperature (37°C). To address this issue, we used the Agrobacterium tumefaciens gene delivery system to create a random insertion mutagenesis library that was screened for altered growth at elevated temperatures. Among several mutants unable to grow at 37°C, we explored one bearing an interruption in the URA4 gene. This gene encodes dihydroorotase (DHOase) that is involved in the de novo synthesis of pyrimidine ribonucleotides. Loss of the C. neoformans Ura4 protein, by targeted gene interruption, resulted in an expected uracil/uridine auxotrophy and an unexpected high temperature growth defect. In addition, the ura4 mutant displayed phenotypic defects in other prominent virulence factors (melanin, capsule and phospholipase) and reduced stress response compared to wild type and reconstituted strains. Accordingly, this mutant had a decreased survival rate in macrophages and attenuated virulence in a murine model of cryptococcal infection. Quantitative PCR analysis suggests that this biosynthetic pathway is induced during the transition from 30°C to 37°C, and that transcriptional regulation of de novo and salvage pyrimidine pathway are under the control of the Ura4 protein.
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Guo W, Cui YP, Li YR, Che YZ, Yuan L, Zou LF, Zou HS, Chen GY. Identification of seven Xanthomonas oryzae pv. oryzicola genes potentially involved in pathogenesis in rice. Microbiology (Reading) 2012; 158:505-518. [DOI: 10.1099/mic.0.050419-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Wei Guo
- Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education of China), College of Plant Protection, Nanjing Agricultural University, 1 Weigang Road, Nanjing 210095, PR China
| | - Yi-ping Cui
- Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education of China), College of Plant Protection, Nanjing Agricultural University, 1 Weigang Road, Nanjing 210095, PR China
| | - Yu-rong Li
- Key Laboratory of Urban (South) by Ministry of Agriculture, School of Agriculture and Biology, Shanghai Jiaotong University, 800 Dongchuan Road, Shanghai 200240, PR China
| | - Yi-zhou Che
- Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education of China), College of Plant Protection, Nanjing Agricultural University, 1 Weigang Road, Nanjing 210095, PR China
| | - Liang Yuan
- Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education of China), College of Plant Protection, Nanjing Agricultural University, 1 Weigang Road, Nanjing 210095, PR China
| | - Li-fang Zou
- Key Laboratory of Urban (South) by Ministry of Agriculture, School of Agriculture and Biology, Shanghai Jiaotong University, 800 Dongchuan Road, Shanghai 200240, PR China
| | - Hua-song Zou
- Key Laboratory of Urban (South) by Ministry of Agriculture, School of Agriculture and Biology, Shanghai Jiaotong University, 800 Dongchuan Road, Shanghai 200240, PR China
| | - Gong-you Chen
- Key Laboratory of Urban (South) by Ministry of Agriculture, School of Agriculture and Biology, Shanghai Jiaotong University, 800 Dongchuan Road, Shanghai 200240, PR China
- Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education of China), College of Plant Protection, Nanjing Agricultural University, 1 Weigang Road, Nanjing 210095, PR China
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De Pascale G, Griffiths EJ, Shakya T, Nazi I, Wright GD. Identification and Characterization of New Inhibitors of Fungal Homoserine Kinase. Chembiochem 2011; 12:1179-82. [DOI: 10.1002/cbic.201100121] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2011] [Indexed: 11/09/2022]
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De Pascale G, Nazi I, Harrison PHM, Wright GD. β-Lactone natural products and derivatives inactivate homoserine transacetylase, a target for antimicrobial agents. J Antibiot (Tokyo) 2011; 64:483-7. [DOI: 10.1038/ja.2011.37] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Current awareness on yeast. Yeast 2010. [DOI: 10.1002/yea.1721] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Homoserine toxicity in Saccharomyces cerevisiae and Candida albicans homoserine kinase (thr1Delta) mutants. EUKARYOTIC CELL 2010; 9:717-28. [PMID: 20305002 DOI: 10.1128/ec.00044-10] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
In addition to threonine auxotrophy, mutation of the Saccharomyces cerevisiae threonine biosynthetic genes THR1 (encoding homoserine kinase) and THR4 (encoding threonine synthase) results in a plethora of other phenotypes. We investigated the basis for these other phenotypes and found that they are dependent on the toxic biosynthetic intermediate homoserine. Moreover, homoserine is also toxic for Candida albicans thr1Delta mutants. Since increasing levels of threonine, but not other amino acids, overcome the homoserine toxicity of thr1Delta mutants, homoserine may act as a toxic threonine analog. Homoserine-mediated lethality of thr1Delta mutants is blocked by cycloheximide, consistent with a role for protein synthesis in this lethality. We identified various proteasome and ubiquitin pathway components that either when mutated or present in high copy numbers suppressed the thr1Delta mutant homoserine toxicity. Since the doa4Delta and proteasome mutants identified have reduced ubiquitin- and/or proteasome-mediated proteolysis, the degradation of a particular protein or subset of proteins likely contributes to homoserine toxicity.
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