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Pokharel M, Konarzewska P, Roberge JY, Han GS, Wang Y, Carman GM, Xue C. The Anticancer Drug Bleomycin Shows Potent Antifungal Activity by Altering Phospholipid Biosynthesis. Microbiol Spectr 2022; 10:e0086222. [PMID: 36036637 PMCID: PMC9602507 DOI: 10.1128/spectrum.00862-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Accepted: 08/10/2022] [Indexed: 12/30/2022] Open
Abstract
Invasive fungal infections are difficult to treat with limited drug options, mainly because fungi are eukaryotes and share many cellular mechanisms with the human host. Most current antifungal drugs are either fungistatic or highly toxic. Therefore, there is a critical need to identify important fungal specific drug targets for novel antifungal development. Numerous studies have shown the fungal phosphatidylserine (PS) biosynthetic pathway to be a potential target. It is synthesized from CDP-diacylglycerol and serine, and the fungal PS synthesis route is different from that in mammalian cells, in which preexisting phospholipids are utilized to produce PS in a base-exchange reaction. In this study, we utilized a Saccharomyces cerevisiae heterologous expression system to screen for inhibitors of Cryptococcus PS synthase Cho1, a fungi-specific enzyme essential for cell viability. We identified an anticancer compound, bleomycin, as a positive candidate that showed a phospholipid-dependent antifungal effect. Its inhibition on fungal growth can be restored by ethanolamine supplementation. Further exploration of the mechanism of action showed that bleomycin treatment damaged the mitochondrial membrane in yeast cells, leading to increased generation of reactive oxygen species (ROS), whereas supplementation with ethanolamine helped to rescue bleomycin-induced damage. Our results indicate that bleomycin does not specifically inhibit the PS synthase enzyme; however, it may affect phospholipid biosynthesis through disruption of mitochondrial function, namely, the synthesis of phosphatidylethanolamine (PE) and phosphatidylcholine (PC), which helps cells maintain membrane composition and functionality. IMPORTANCE Invasive fungal pathogens cause significant morbidity and mortality, with over 1.5 million deaths annually. Because fungi are eukaryotes that share much of their cellular machinery with the host, our armamentarium of antifungal drugs is highly limited, with only three classes of antifungal drugs available. Drug toxicity and emerging resistance have limited their use. Hence, targeting fungi-specific enzymes that are important for fungal survival, growth, or virulence poses a strategy for novel antifungal development. In this study, we developed a heterologous expression system to screen for chemical compounds with activity against Cryptococcus phosphatidylserine synthase, Cho1, a fungi-specific enzyme that is essential for viability in C. neoformans. We confirmed the feasibility of this screen method and identified a previously unexplored role of the anticancer compound bleomycin in disrupting mitochondrial function and inhibiting phospholipid synthesis.
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Affiliation(s)
- Mona Pokharel
- Public Health Research Institute, New Jersey Medical School, Rutgers University, Newark, New Jersey, USA
| | - Paulina Konarzewska
- Public Health Research Institute, New Jersey Medical School, Rutgers University, Newark, New Jersey, USA
| | - Jacques Y. Roberge
- Molecular Design and Synthesis Core, Rutgers University Biomolecular Innovations Cores, Office for Research, Rutgers University, Piscataway, New Jersey, USA
| | - Gil-Soo Han
- Rutgers Center for Lipid Research, New Jersey Institute for Food, Nutrition and Health, Rutgers University, New Brunswick, New Jersey, USA
| | - Yina Wang
- Public Health Research Institute, New Jersey Medical School, Rutgers University, Newark, New Jersey, USA
| | - George M. Carman
- Rutgers Center for Lipid Research, New Jersey Institute for Food, Nutrition and Health, Rutgers University, New Brunswick, New Jersey, USA
| | - Chaoyang Xue
- Public Health Research Institute, New Jersey Medical School, Rutgers University, Newark, New Jersey, USA
- Rutgers Center for Lipid Research, New Jersey Institute for Food, Nutrition and Health, Rutgers University, New Brunswick, New Jersey, USA
- Department of Microbiology, Biochemistry and Molecular Genetics, New Jersey Medical School, Rutgers University, Newark, New Jersey, USA
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Konarzewska P, Wang Y, Han GS, Goh KJ, Gao YG, Carman GM, Xue C. Phosphatidylserine synthesis is essential for viability of the human fungal pathogen Cryptococcus neoformans. J Biol Chem 2019; 294:2329-2339. [PMID: 30602568 DOI: 10.1074/jbc.ra118.006738] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Revised: 12/28/2018] [Indexed: 11/06/2022] Open
Abstract
Phospholipids are an integral part of the cellular membrane structure and can be produced by a de novo biosynthetic pathway and, alternatively, by the Kennedy pathway. Studies in several yeast species have shown that the phospholipid phosphatidylserine (PS) is synthesized from CDP-diacylglycerol and serine, a route that is different from its synthesis in mammalian cells, involving a base-exchange reaction from preexisting phospholipids. Fungal-specific PS synthesis has been shown to play an important role in fungal virulence and has been proposed as an attractive drug target. However, PS synthase, which catalyzes this reaction, has not been studied in the human fungal pathogen Cryptococcus neoformans Here, we identified and characterized the PS synthase homolog (Cn Cho1) in this fungus. Heterologous expression of Cn CHO1 in a Saccharomyces cerevisiae cho1Δ mutant rescued the mutant's growth defect in the absence of ethanolamine supplementation. Moreover, an Sc cho1Δ mutant expressing Cn CHO1 had PS synthase activity, confirming that the Cn CHO1 encodes PS synthase. We also found that PS synthase in C. neoformans is localized to the endoplasmic reticulum and that it is essential for mitochondrial function and cell viability. Of note, its deficiency could not be complemented by ethanolamine or choline supplementation for the synthesis of phosphatidylethanolamine (PE) or phosphatidylcholine (PC) via the Kennedy pathway. These findings improve our understanding of phospholipid synthesis in a pathogenic fungus and indicate that PS synthase may be a useful target for antifungal drugs.
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Affiliation(s)
| | - Yina Wang
- From the Public Health Research Institute and
| | - Gil-Soo Han
- the Rutgers Center for Lipid Research and.,Department of Food Science, Rutgers University, New Brunswick, New Jersey 08901, and
| | - Kwok Jian Goh
- the School of Biological Sciences, Nanyang Technological University, Singapore 117597, Singapore
| | - Yong-Gui Gao
- the School of Biological Sciences, Nanyang Technological University, Singapore 117597, Singapore
| | - George M Carman
- the Rutgers Center for Lipid Research and.,Department of Food Science, Rutgers University, New Brunswick, New Jersey 08901, and
| | - Chaoyang Xue
- From the Public Health Research Institute and .,the Rutgers Center for Lipid Research and.,Department of Microbiology, Biochemistry and Molecular Genetics, New Jersey Medical School, Rutgers University, Newark, New Jersey 07103
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Konarzewska P, Sherr GL, Ahmed S, Ursomanno B, Shen CH. Vma3p protects cells from programmed cell death through the regulation of Hxk2p expression. Biochem Biophys Res Commun 2017; 493:233-239. [PMID: 28899778 DOI: 10.1016/j.bbrc.2017.09.041] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2017] [Accepted: 09/08/2017] [Indexed: 10/18/2022]
Abstract
In yeast, the vacuolar proton-pumping ATPase (V-ATPase) acidifies vacuoles to maintain pH of cytoplasm. Yeast cells lacking V-ATPase activity, due to a disruption of any VMA (vacuolar membrane ATPase) gene, remain viable but demonstrate growth defects. Although it has been suggested that VMA genes are critical for phospholipid biosynthesis, the link between VMA genes and phospholipid biosynthesis is still uncertain. Here, we found that cells lacking Vma3p, one of the major V-ATPase assembly genes, had a growth defect in the absence of inositol, suggesting that Vma3p is important in phospholipid biosynthesis. Through real-time PCR, we found that cells lacking Vma3p down-regulated HXK2 expression. Furthermore, acetic acid sensitivity assay showed that cells lacking Vma3p were more sensitive to acetic acid than WT cells. HXK2 encodes hexokinase 2 which can phosphorylate glucose during phospholipid biosynthesis. Since cells lacking HXK2 are sensitive to acetic acid and this is an indicator of programmed cell death, our observations suggest that Vma3p plays an important role in programmed cell death. Taken together, we have proposed a working model to describe how Vma3p protects cells against apoptosis through the regulation of HXK2 expression.
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Affiliation(s)
- Paulina Konarzewska
- Department of Biology, College of Staten Island, City University of New York, 2800 Victory Blvd, Staten Island, NY 10314, USA; PhD Program in Biology, The Graduate Center, City University of New York, 365 Fifth Avenue, New York 10016, USA
| | - Goldie Libby Sherr
- Department of Biology, College of Staten Island, City University of New York, 2800 Victory Blvd, Staten Island, NY 10314, USA; PhD Program in Biology, The Graduate Center, City University of New York, 365 Fifth Avenue, New York 10016, USA
| | - Suzanne Ahmed
- Department of Biology, College of Staten Island, City University of New York, 2800 Victory Blvd, Staten Island, NY 10314, USA
| | - Brendon Ursomanno
- Department of Biology, College of Staten Island, City University of New York, 2800 Victory Blvd, Staten Island, NY 10314, USA
| | - Chang-Hui Shen
- Department of Biology, College of Staten Island, City University of New York, 2800 Victory Blvd, Staten Island, NY 10314, USA; PhD Program in Biology, The Graduate Center, City University of New York, 365 Fifth Avenue, New York 10016, USA; Institute for Macromolecular Assemblies, City University of New York, 160 Convent Avenue, New York, NY 10031, USA.
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Konarzewska P, Esposito M, Shen CH. INO1 induction requires chromatin remodelers Ino80p and Snf2p but not the histone acetylases. Biochem Biophys Res Commun 2012; 418:483-8. [PMID: 22281492 DOI: 10.1016/j.bbrc.2012.01.044] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2011] [Accepted: 01/08/2012] [Indexed: 11/19/2022]
Abstract
Transcriptional co-activators contribute to gene expression through different mechanisms. We used various biochemical tools available for Saccharomyces cerevisiae to examine the mechanism of INO1 expression. INO1 encodes inositol-3-phosphate synthase, which catalyzes the rate-limiting step in the synthesis of inositol, a key player in phospholipid biosynthesis. Herein, we had demonstrated that the recruitment of histone acetylases Gcn5p and Esa1p mainly relied on the presence of transcriptional activator Ino2p during INO1 activation. However, the presence of the chromatin remodelers, Ino80p and Snf2p, may contribute to the additive effect of Gcn5p recruitment. We also showed that the recruitment of chromatin remodelers, Ino80p and Snf2p, is independent of the presence of histone acetylases. Furthermore, INO1 expression can be activated exclusively by the activator and chromatin remodelers, suggesting a dispensable role of histone acetylases in INO1 induction. Therefore, our data provide a mechanism for cross talk within transcriptional co-activators during INO1 activation.
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Affiliation(s)
- Paulina Konarzewska
- Department of Biology, College of Staten Island, City University of New York, 2800 Victory Blvd., Staten Island, NY 10314, United States
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Esposito M, Konarzewska P, Odeyale O, Shen CH. Gene-wide histone acetylation at the yeast INO1 requires the transcriptional activator Ino2p. Biochem Biophys Res Commun 2010; 391:1285-90. [DOI: 10.1016/j.bbrc.2009.12.063] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2009] [Accepted: 12/10/2009] [Indexed: 10/20/2022]
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