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Toplis B, Bosch C, Schwartz IS, Kenyon C, Boekhout T, Perfect JR, Botha A. The virulence factor urease and its unexplored role in the metabolism of Cryptococcus neoformans. FEMS Yeast Res 2021; 20:5850754. [PMID: 32490521 DOI: 10.1093/femsyr/foaa031] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Accepted: 06/01/2020] [Indexed: 12/25/2022] Open
Abstract
Cryptococcal urease is believed to be important for the degradation of exogenous urea that the yeast encounters both in its natural environment and within the human host. Endogenous urea produced by the yeast's own metabolic reactions, however, may also serve as a substrate for the urease enzyme. Using wild-type, urease-deletion mutant and urease-reconstituted strains of Cryptococcus neoformans H99, we studied reactions located up- and downstream from endogenous urea. We demonstrated that urease is important for cryptococcal growth and that, compared to nutrient-rich conditions at 26°C, urease activity is higher under nutrient-limited conditions at 37°C. Compared to cells with a functional urease enzyme, urease-deficient cells had significantly higher intracellular urea levels and also showed more arginase activity, which may act as a potential source of endogenous urea. Metabolic reactions linked to arginase were also affected, since urease-positive and urease-negative cells differed with respect to agmatinase activity, polyamine synthesis, and intracellular levels of proline and reactive oxygen species. Lastly, urease-deficient cells showed higher melanin levels at 26°C than wild-type cells, while the inverse was observed at 37°C. These results suggest that cryptococcal urease is associated with the functioning of key metabolic pathways within the yeast cell.
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Affiliation(s)
- Barbra Toplis
- Department of Microbiology, Stellenbosch University, Matieland 7602, Stellenbosch, South Africa
| | - Caylin Bosch
- Department of Microbiology, Stellenbosch University, Matieland 7602, Stellenbosch, South Africa
| | - Ilan S Schwartz
- Division of Infectious Diseases, Department of Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada, T6G 2G3
| | - Chris Kenyon
- Sexually Transmitted Infection Unit, Institute of Tropical Medicine, 2000 Antwerp, Belgium.,Department of Medicine, University of Cape Town, Cape Town 7925, South Africa
| | - Teun Boekhout
- Westerdijk Fungal Biodiversity Institute, 3584CT Utrecht, The Netherlands.,Institute for Biodiversity and Ecosystem Dynamics (IBED), University of Amsterdam, 1090 GE Amsterdam, The Netherlands
| | - John R Perfect
- Division of Infectious Diseases, Duke University Medical Center, Durham, NC 27710-1000, North Carolina, USA
| | - Alfred Botha
- Department of Microbiology, Stellenbosch University, Matieland 7602, Stellenbosch, South Africa
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Toplis B, Bosch C, Stander M, Taylor M, Perfect JR, Botha A. A link between urease and polyamine metabolism in Cryptococcus neoformans. Microb Pathog 2021; 158:105076. [PMID: 34216740 DOI: 10.1016/j.micpath.2021.105076] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Revised: 05/05/2021] [Accepted: 06/24/2021] [Indexed: 01/09/2023]
Abstract
The urease enzyme of Cryptococcus neoformans is linked to different metabolic pathways within the yeast cell, several of which are involved in polyamine metabolism. Cryptococcal biogenic amine production is, however, largely unexplored and is yet to be investigated in relation to urease. The aim of this study was therefore to explore and compare polyamine metabolism in wild-type, urease-negative and urease-reconstituted strains of C. neoformans. Mass spectrometry analysis showed that agmatine and spermidine were the major extra- and intracellular polyamines of C. neoformans and significant differences were observed between 26 and 37 °C. In addition, compared to the wild-type, the relative percentages of extracellular putrescine and spermidine were found to be lower and agmatine higher in cultures of the urease-deficient mutant. The inverse was true for intracellular spermidine and agmatine. Cyclohexylamine was a more potent polyamine inhibitor compared to DL-α-difluoromethylornithine and inhibitory effects were more pronounced at 37 °C than at 26 °C. At both temperatures, the urease-deficient mutant was less susceptible to cyclohexylamine treatment compared to the wild-type. For both inhibitors, growth inhibition was alleviated with polyamine supplementation. This study has provided novel insight into the polyamine metabolism of C. neoformans, highlighting the involvement of urease in biogenic amine production.
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Affiliation(s)
- Barbra Toplis
- Department of Microbiology, University of Stellenbosch, Matieland, 7602, Stellenbosch, South Africa
| | - Caylin Bosch
- Department of Microbiology, University of Stellenbosch, Matieland, 7602, Stellenbosch, South Africa
| | - Marietjie Stander
- Mass Spectrometry Unit, Central Analytical Facilities, University of Stellenbosch, Matieland, 7602, Stellenbosch, South Africa
| | - Malcolm Taylor
- Mass Spectrometry Unit, Central Analytical Facilities, University of Stellenbosch, Matieland, 7602, Stellenbosch, South Africa
| | - John R Perfect
- Division of Infectious Diseases, Duke University Medical Centre, Durham, NC, 27710-1000, USA
| | - Alfred Botha
- Department of Microbiology, University of Stellenbosch, Matieland, 7602, Stellenbosch, South Africa.
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Kingsbury JM, Yang Z, Ganous TM, Cox GM, McCusker JH. Novel chimeric spermidine synthase-saccharopine dehydrogenase gene (SPE3-LYS9) in the human pathogen Cryptococcus neoformans. EUKARYOTIC CELL 2005; 3:752-63. [PMID: 15189996 PMCID: PMC420128 DOI: 10.1128/ec.3.3.752-763.2004] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The Cryptococcus neoformans LYS9 gene (encoding saccharopine dehydrogenase) was cloned and found to be part of an evolutionarily conserved chimera with SPE3 (encoding spermidine synthase). spe3-lys9, spe3-LYS9, and SPE3-lys9 mutants were constructed, and these were auxotrophic for lysine and spermidine, spermidine, and lysine, respectively. Thus, SPE3-LYS9 encodes functional spermidine synthase and saccharopine dehydrogenase gene products. In contrast to Saccharomyces cerevisiae spe3 mutants, the polyamine auxotrophy of C. neoformans spe3-LYS9 mutants was not satisfied by spermine. In vitro phenotypes of spe3-LYS9 mutants included reduced capsule and melanin production and growth rate, while SPE3-lys9 mutants grew slowly at 30 degrees C, were temperature sensitive in rich medium, and died upon lysine starvation. Consistent with the importance of saccharopine dehydrogenase and spermidine synthase in vitro, spe3-lys9 mutants were avirulent and unable to survive in vivo and both functions individually contributed to virulence. SPE3-LYS9 mRNA levels showed little evidence of being influenced by exogenous spermidine or lysine or starvation for spermidine or lysine; thus, any regulation is likely to be posttranscriptional. Expression in S. cerevisiae of the full-length C. neoformans SPE3-LYS9 cDNA complemented a lys9 mutant but not a spe3 mutant. However, expression in S. cerevisiae of a truncated gene product, consisting of only C. neoformans SPE3, complemented a spe3 mutant, suggesting possible modes of regulation. Therefore, we identified and describe a novel chimeric SPE3-LYS9 gene, which may link spermidine and lysine biosynthesis in C. neoformans.
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Affiliation(s)
- Joanne M Kingsbury
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710, USA
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Cardenas ME, Cruz MC, Del Poeta M, Chung N, Perfect JR, Heitman J. Antifungal activities of antineoplastic agents: Saccharomyces cerevisiae as a model system to study drug action. Clin Microbiol Rev 1999; 12:583-611. [PMID: 10515904 PMCID: PMC88926 DOI: 10.1128/cmr.12.4.583] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Recent evolutionary studies reveal that microorganisms including yeasts and fungi are more closely related to mammals than was previously appreciated. Possibly as a consequence, many natural-product toxins that have antimicrobial activity are also toxic to mammalian cells. While this makes it difficult to discover antifungal agents without toxic side effects, it also has enabled detailed studies of drug action in simple genetic model systems. We review here studies on the antifungal actions of antineoplasmic agents. Topics covered include the mechanisms of action of inhibitors of topoisomerases I and II; the immunosuppressants rapamycin, cyclosporin A, and FK506; the phosphatidylinositol 3-kinase inhibitor wortmannin; the angiogenesis inhibitors fumagillin and ovalicin; the HSP90 inhibitor geldanamycin; and agents that inhibit sphingolipid metabolism. In general, these natural products inhibit target proteins conserved from microorganisms to humans. These studies highlight the potential of microorganisms as screening tools to elucidate the mechanisms of action of novel pharmacological agents with unique effects against specific mammalian cell types, including neoplastic cells. In addition, this analysis suggests that antineoplastic agents and derivatives might find novel indications in the treatment of fungal infections, for which few agents are presently available, toxicity remains a serious concern, and drug resistance is emerging.
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Affiliation(s)
- M E Cardenas
- Department of Genetics, Duke University Medical Center, Durham, North Carolina 27710, USA
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Groll AH, Piscitelli SC, Walsh TJ. Clinical pharmacology of systemic antifungal agents: a comprehensive review of agents in clinical use, current investigational compounds, and putative targets for antifungal drug development. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 1998; 44:343-500. [PMID: 9547888 DOI: 10.1016/s1054-3589(08)60129-5] [Citation(s) in RCA: 288] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- A H Groll
- Immunocompromised Host Section, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
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Merali S, Clarkson AB. Polyamine content of Pneumocystis carinii and response to the ornithine decarboxylase inhibitor DL-alpha-difluoromethylornithine. Antimicrob Agents Chemother 1996; 40:973-8. [PMID: 8849262 PMCID: PMC163241 DOI: 10.1128/aac.40.4.973] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Difluoromethylornithine (DFMO; eflornithine hydrochloride [Ornidyl]), a suicide inhibitor of the key polyamine biosynthesis enzyme ornithine decarboxylase (ODC), is effective in treating Pneumocystis carinii pneumonia, a common opportunistic infection associated with AIDS. Despite DFMO's specificity for ODC, the reason for its selective toxicity against P. carinii is unknown since both host and parasite are dependent on the same enzyme for polyamine biosynthesis. A new high-performance liquid chromatography method was used with P. carinii cells isolated from infected rat lungs to measure polyamine content, to confirm the presence of ODC, and to examine the effect of DFMO on polyamine concentrations. Putrescine, spermidine, and spermine were found to be present at 2.00 +/- 0.54, 1.26 +/- 0.51, and 1.59 +/- 0.91 nmol (mg of protein)-1, respectively, neither unusually high nor low values. ODC's specific activity was 79 +/- 11 pmol (mg of protein)-1 h-1, again not a remarkable value. However, the rates of both DFMO-induced polyamine depletion and subsequent repletion upon DFMO removal were unusually high. A 3-h exposure to 1 mM DFMO in vitro caused the depletion of putrescine, spermidine, and spermine to levels 12, 29, and 16%, respectively, of that of control cells. After DFMO removal and incubation for 1 h in serum-free media, polyamine levels returned to 78, 88, and 64%, respectively, of that of the control cells not exposed to DFMO. Since such depletions and repletions usually occur over periods of days rather than hours, these rapid changes may provide a clue to the selective action of DFMO against P. carinii and may guide the development of new compounds and an optimal drug administration schedule for DFMO.
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Affiliation(s)
- S Merali
- Department of Medical and Molecular Parasitology, New York University School of Medicine, New York 10016, USA
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7
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Rajam B, Rajam MV. Inhibition of polyamine biosynthesis and growth in plant pathogenic fungi in vitro. Mycopathologia 1996; 133:95-103. [DOI: 10.1007/bf00439120] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/1995] [Accepted: 12/15/1995] [Indexed: 11/29/2022]
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Georgopapadakou NH, Walsh TJ. Antifungal agents: chemotherapeutic targets and immunologic strategies. Antimicrob Agents Chemother 1996; 40:279-91. [PMID: 8834867 PMCID: PMC163103 DOI: 10.1128/aac.40.2.279] [Citation(s) in RCA: 330] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Affiliation(s)
- N H Georgopapadakou
- Department of Oncology, Roche Research Center, Nutley, New Jersey 07110, USA
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Fellah Y, Mandin D, Dubois P, Ombetta-Goka JE, Guenzet J, Chaumont JP, Frangin Y. Growth inhibition of Cryptococcus neoformans by 2-(1-piperazinyl)-5-(1,2-diarylethyl)-4,6-dichloropyrimidines: synthesis and in vitro studies. Eur J Med Chem 1996. [DOI: 10.1016/s0223-5234(96)80010-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Douglas GC, Hu J, Thirkill TL, Hovanes K, Fuller M, King BF. Cyclohexylamine inhibits the adhesion of lymphocytic cells to human syncytiotrophoblast. BIOCHIMICA ET BIOPHYSICA ACTA 1995; 1266:229-34. [PMID: 7766708 DOI: 10.1016/0167-4889(95)00025-n] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
We have previously shown that lymphocytic cells adhere to cultured syncytiotrophoblast and that this may be important in the lymphocyte-mediated infection of trophoblast with the human immunodeficiency virus (HIV). During the course of studies aimed at investigating the role of cell surface carbohydrates in adhesion, it was discovered that a contaminant of commercial fucose-1-phosphate, dicyclohexylamine, inhibited MOLT-trophoblast adhesion. Dicyclohexylamine and the related compounds, cyclohexylamine and hexylamine, inhibited adhesion in a dose-responsive manner with half-maximal inhibition seen at about 4 mM. While the pressor effects of cyclohexylamine, the principal metabolite of cyclamate, are well known, this is the first report of an effect of this and related compounds on cell adhesion activity. The inhibitory effect was reversible and, at concentrations less than 25 mM, did not result in loss of cell viability. Several possible mechanisms of action of cyclohexylamine were examined in an attempt to explain the effect on adhesion. No evidence was found to suggest that the effects of cyclohexylamine were due to inhibition of polyamine synthesis, increase in intracellular Ca2+ concentration or to a lysosomotropic effect. The concentrations of cyclohexylamine used are within the range of plasma concentrations attainable in humans, raising the possibility that the in vitro effects described here may also occur in vivo. The results also suggest that caution should be used in the interpretation of results obtained from experiments where cell adhesion is blocked using exogenous monosaccharides that are in the form of dicyclohexylammonium salts. Appropriate controls must be included or, if possible, sodium, potassium or barium salts should be chosen.
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Affiliation(s)
- G C Douglas
- Department of Cell Biology and Human Anatomy, School of Medicine, University of California, Davis 95616-8643, USA
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12
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Abstract
Interest in ornithine decarboxylase (ODC) and the therapeutic effects of its inhibition with the consequent depletion of polyamine biosynthesis has been widespread since the late 1970s and 1980s. This review covers new information about the properties of ODC, recent findings with ODC inhibitors and a discussion of the mechanism of inactivation of ODC by eflornithine. Recent in vivo therapeutic approaches of ODC inhibition are also discussed including: cancer and cancer chemoprevention; autoimmune diseases; polyamines and the blood-brain barrier, ischemia and hyperplasia; the NMDA receptor and modulation by polyamines; hearing loss; African trypanosomiasis; Pneumocystis carinii pneumonia and Cryptosporidium in AIDS; and other infectious diseases/organisms.
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Affiliation(s)
- P P McCann
- Marion Merrell Dow Inc., Indianapolis, IN 46268-0470
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Polak A, Hartman PG. Antifungal chemotherapy--are we winning? PROGRESS IN DRUG RESEARCH. FORTSCHRITTE DER ARZNEIMITTELFORSCHUNG. PROGRES DES RECHERCHES PHARMACEUTIQUES 1991; 37:181-269. [PMID: 1763183 DOI: 10.1007/978-3-0348-7139-6_5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- A Polak
- F. Hoffmann-La Roche Ltd, Basel, Switzerland
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