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Bowring BG, Sethiya P, Desmarini D, Lev S, Tran Le L, Bahn YS, Lee SH, Toh-E A, Proschogo N, Savage T, Djordjevic JT. Dysregulating PHO Signaling via the CDK Machinery Differentially Impacts Energy Metabolism, Calcineurin Signaling, and Virulence in C. neoformans. mBio 2023; 14:e0355122. [PMID: 37017534 PMCID: PMC10127591 DOI: 10.1128/mbio.03551-22] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/06/2023] Open
Abstract
Fungal pathogens uniquely regulate phosphate homeostasis via the cyclin-dependent kinase (CDK) signaling machinery of the phosphate acquisition (PHO) pathway (Pho85 kinase-Pho80 cyclin-CDK inhibitor Pho81), providing drug-targeting opportunities. Here, we investigate the impact of a PHO pathway activation-defective Cryptococcus neoformans mutant (pho81Δ) and a constitutively activated PHO pathway mutant (pho80Δ) on fungal virulence. Irrespective of phosphate availability, the PHO pathway was derepressed in pho80Δ with all phosphate acquisition pathways upregulated and much of the excess phosphate stored as polyphosphate (polyP). Elevated phosphate in pho80Δ coincided with elevated metal ions, metal stress sensitivity, and a muted calcineurin response, all of which were ameliorated by phosphate depletion. In contrast, metal ion homeostasis was largely unaffected in the pho81Δ mutant, and Pi, polyP, ATP, and energy metabolism were reduced, even under phosphate-replete conditions. A similar decline in polyP and ATP suggests that polyP supplies phosphate for energy production even when phosphate is available. Using calcineurin reporter strains in the wild-type, pho80Δ, and pho81Δ background, we also demonstrate that phosphate deprivation stimulates calcineurin activation, most likely by increasing the bioavailability of calcium. Finally, we show that blocking, as opposed to permanently activating, the PHO pathway reduced fungal virulence in mouse infection models to a greater extent and that this is most likely attributable to depleted phosphate stores and ATP, and compromised cellular bioenergetics, irrespective of phosphate availability. IMPORTANCE Invasive fungal diseases cause more than 1.5 million deaths per year, with an estimated 181,000 of these deaths attributable to Cryptococcal meningitis. Despite the high mortality, treatment options are limited. In contrast to humans, fungal cells maintain phosphate homeostasis via a CDK complex, providing drug-targeting opportunities. To investigate which CDK components are the best targets for potential antifungal therapy, we used strains with a constitutively active (pho80Δ) and an activation-defective (pho81Δ) PHO pathway, to investigate the impact of dysregulated phosphate homeostasis on cellular function and virulence. Our studies suggest that inhibiting the function of Pho81, which has no human homologue, would have the most detrimental impact on fungal growth in the host due to depletion of phosphate stores and ATP, irrespective of phosphate availability in the host.
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Affiliation(s)
- Bethany Grace Bowring
- Centre for Infectious Diseases and Microbiology, The Westmead Institute for Medical Research, Westmead, NSW, Australia
- Sydney Institute for Infectious Diseases, University of Sydney, Sydney, NSW, Australia
| | - Pooja Sethiya
- Centre for Infectious Diseases and Microbiology, The Westmead Institute for Medical Research, Westmead, NSW, Australia
- Sydney Institute for Infectious Diseases, University of Sydney, Sydney, NSW, Australia
| | - Desmarini Desmarini
- Centre for Infectious Diseases and Microbiology, The Westmead Institute for Medical Research, Westmead, NSW, Australia
- Sydney Institute for Infectious Diseases, University of Sydney, Sydney, NSW, Australia
| | - Sophie Lev
- Centre for Infectious Diseases and Microbiology, The Westmead Institute for Medical Research, Westmead, NSW, Australia
- Sydney Institute for Infectious Diseases, University of Sydney, Sydney, NSW, Australia
| | - Lisa Tran Le
- Centre for Infectious Diseases and Microbiology, The Westmead Institute for Medical Research, Westmead, NSW, Australia
- Sydney Institute for Infectious Diseases, University of Sydney, Sydney, NSW, Australia
| | - Yong-Sun Bahn
- Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul, Republic of Korea
| | - Seung-Heon Lee
- Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul, Republic of Korea
| | - Akio Toh-E
- Medical Mycology Research Center, Chiba University, Chiba City, Chiba, Japan
| | | | - Tom Savage
- School of Geosciences, University of Sydney, Sydney, NSW, Australia
| | - Julianne Teresa Djordjevic
- Centre for Infectious Diseases and Microbiology, The Westmead Institute for Medical Research, Westmead, NSW, Australia
- Sydney Institute for Infectious Diseases, University of Sydney, Sydney, NSW, Australia
- Western Sydney Local Health District, Westmead, NSW, Australia
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Lev S, Bowring B, Desmarini D, Djordjevic JT. Inositol polyphosphate-protein interactions: Implications for microbial pathogenicity. Cell Microbiol 2021; 23:e13325. [PMID: 33721399 PMCID: PMC9286782 DOI: 10.1111/cmi.13325] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Revised: 03/03/2021] [Accepted: 03/07/2021] [Indexed: 11/29/2022]
Abstract
Inositol polyphosphates (IPs) and inositol pyrophosphates (PP-IPs) regulate diverse cellular processes in eukaryotic cells. IPs and PP-IPs are highly negatively charged and exert their biological effects by interacting with specific protein targets. Studies performed predominantly in mammalian cells and model yeasts have shown that IPs and PP-IPs modulate target function through allosteric regulation, by promoting intra- and intermolecular stabilization and, in the case of PP-IPs, by donating a phosphate from their pyrophosphate (PP) group to the target protein. Technological advances in genetics have extended studies of IP function to microbial pathogens and demonstrated that disrupting PP-IP biosynthesis and PP-IP-protein interaction has a profound impact on pathogenicity. This review summarises the complexity of IP-mediated regulation in eukaryotes, including microbial pathogens. It also highlights examples of poor conservation of IP-protein interaction outcome despite the presence of conserved IP-binding domains in eukaryotic proteomes.
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Affiliation(s)
- Sophie Lev
- Centre for Infectious Diseases and Microbiology, The Westmead Institute for Medical Research, Sydney, New South Wales, Australia.,Sydney Medical School-Westmead, University of Sydney, Sydney, New South Wales, Australia.,Marie Bashir Institute for Infectious Diseases and Biosecurity, University of Sydney, Sydney, New South Wales, Australia
| | - Bethany Bowring
- Centre for Infectious Diseases and Microbiology, The Westmead Institute for Medical Research, Sydney, New South Wales, Australia.,Sydney Medical School-Westmead, University of Sydney, Sydney, New South Wales, Australia.,Marie Bashir Institute for Infectious Diseases and Biosecurity, University of Sydney, Sydney, New South Wales, Australia
| | - Desmarini Desmarini
- Centre for Infectious Diseases and Microbiology, The Westmead Institute for Medical Research, Sydney, New South Wales, Australia.,Sydney Medical School-Westmead, University of Sydney, Sydney, New South Wales, Australia.,Marie Bashir Institute for Infectious Diseases and Biosecurity, University of Sydney, Sydney, New South Wales, Australia
| | - Julianne Teresa Djordjevic
- Centre for Infectious Diseases and Microbiology, The Westmead Institute for Medical Research, Sydney, New South Wales, Australia.,Sydney Medical School-Westmead, University of Sydney, Sydney, New South Wales, Australia.,Marie Bashir Institute for Infectious Diseases and Biosecurity, University of Sydney, Sydney, New South Wales, Australia
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Squizani ED, Reuwsaat JCV, Lev S, Motta H, Sperotto J, Kaufman-Francis K, Desmarini D, Vainstein MH, Staats CC, Djordjevic JT, Kmetzsch L. Calcium Binding Protein Ncs1 Is Calcineurin Regulated in Cryptococcus neoformans and Essential for Cell Division and Virulence. mSphere 2020; 5:e00761-20. [PMID: 32907953 PMCID: PMC7485688 DOI: 10.1128/msphere.00761-20] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [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: 07/23/2020] [Accepted: 08/28/2020] [Indexed: 12/24/2022] Open
Abstract
Intracellular calcium (Ca2+) is crucial for signal transduction in Cryptococcus neoformans, the major cause of fatal fungal meningitis. The calcineurin pathway is the only Ca2+-requiring signaling cascade implicated in cryptococcal stress adaptation and virulence, with Ca2+ binding mediated by the EF-hand domains of the Ca2+ sensor protein calmodulin. In this study, we identified the cryptococcal ortholog of neuronal calcium sensor 1 (Ncs1) as a member of the EF-hand superfamily. We demonstrated that Ncs1 has a role in Ca2+ homeostasis under stress and nonstress conditions, as the ncs1Δ mutant is sensitive to a high Ca2+ concentration and has an elevated basal Ca2+ level. Furthermore, NCS1 expression is induced by Ca2+, with the Ncs1 protein adopting a punctate subcellular distribution. We also demonstrate that, in contrast to the case with Saccharomyces cerevisiae, NCS1 expression in C. neoformans is regulated by the calcineurin pathway via the transcription factor Crz1, as NCS1 expression is reduced by FK506 treatment and CRZ1 deletion. Moreover, the ncs1Δ mutant shares a high temperature and high Ca2+ sensitivity phenotype with the calcineurin and calmodulin mutants (cna1Δ and cam1Δ), and the NCS1 promoter contains two calcineurin/Crz1-dependent response elements (CDRE1). Ncs1 deficiency coincided with reduced growth, characterized by delayed bud emergence and aberrant cell division, and hypovirulence in a mouse infection model. In summary, our data show that Ncs1 has a significant role as a Ca2+ sensor in C. neoformans, working with calcineurin to regulate Ca2+ homeostasis and, consequently, promote fungal growth and virulence.IMPORTANCECryptococcus neoformans is the major cause of fungal meningitis in HIV-infected patients. Several studies have highlighted the important contributions of Ca2+ signaling and homeostasis to the virulence of C. neoformans Here, we identify the cryptococcal ortholog of neuronal calcium sensor 1 (Ncs1) and demonstrate its role in Ca2+ homeostasis, bud emergence, cell cycle progression, and virulence. We also show that Ncs1 function is regulated by the calcineurin/Crz1 signaling cascade. Our work provides evidence of a link between Ca2+ homeostasis and cell cycle progression in C. neoformans.
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Affiliation(s)
- Eamim Daidrê Squizani
- Centro de Biotecnologia, Universidade Federal do Rio Grande do Sul, UFRGS, Porto Alegre, Rio Grande do Sul, Brazil
| | | | - Sophie Lev
- Centre for Infectious Diseases and Microbiology, The Westmead Institute for Medical Research, Sydney, New South Wales, Australia
- Sydney Medical School-Westmead, University of Sydney, Sydney, New South Wales, Australia
- Marie Bashir Institute for Infectious Diseases and Biosecurity, University of Sydney, Sydney, New South Wales, Australia
| | - Heryk Motta
- Centro de Biotecnologia, Universidade Federal do Rio Grande do Sul, UFRGS, Porto Alegre, Rio Grande do Sul, Brazil
| | - Julia Sperotto
- Centro de Biotecnologia, Universidade Federal do Rio Grande do Sul, UFRGS, Porto Alegre, Rio Grande do Sul, Brazil
| | - Keren Kaufman-Francis
- Centre for Infectious Diseases and Microbiology, The Westmead Institute for Medical Research, Sydney, New South Wales, Australia
- Sydney Medical School-Westmead, University of Sydney, Sydney, New South Wales, Australia
- Marie Bashir Institute for Infectious Diseases and Biosecurity, University of Sydney, Sydney, New South Wales, Australia
| | - Desmarini Desmarini
- Centre for Infectious Diseases and Microbiology, The Westmead Institute for Medical Research, Sydney, New South Wales, Australia
- Sydney Medical School-Westmead, University of Sydney, Sydney, New South Wales, Australia
- Marie Bashir Institute for Infectious Diseases and Biosecurity, University of Sydney, Sydney, New South Wales, Australia
| | - Marilene Henning Vainstein
- Centro de Biotecnologia, Universidade Federal do Rio Grande do Sul, UFRGS, Porto Alegre, Rio Grande do Sul, Brazil
| | - Charley Christian Staats
- Centro de Biotecnologia, Universidade Federal do Rio Grande do Sul, UFRGS, Porto Alegre, Rio Grande do Sul, Brazil
| | - Julianne T Djordjevic
- Centre for Infectious Diseases and Microbiology, The Westmead Institute for Medical Research, Sydney, New South Wales, Australia
- Sydney Medical School-Westmead, University of Sydney, Sydney, New South Wales, Australia
- Marie Bashir Institute for Infectious Diseases and Biosecurity, University of Sydney, Sydney, New South Wales, Australia
| | - Lívia Kmetzsch
- Centro de Biotecnologia, Universidade Federal do Rio Grande do Sul, UFRGS, Porto Alegre, Rio Grande do Sul, Brazil
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Lev S, Li C, Desmarini D, Liuwantara D, Sorrell TC, Hawthorne WJ, Djordjevic JT. Monitoring Glycolysis and Respiration Highlights Metabolic Inflexibility of Cryptococcus neoformans. Pathogens 2020; 9:pathogens9090684. [PMID: 32839374 PMCID: PMC7559270 DOI: 10.3390/pathogens9090684] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Revised: 08/13/2020] [Accepted: 08/20/2020] [Indexed: 12/14/2022] Open
Abstract
Cryptococcus neoformans is a human fungal pathogen that adapts its metabolism to cope with limited oxygen availability, nutrient deprivation and host phagocytes. To gain insight into cryptococcal metabolism, we optimized a protocol for the Seahorse Analyzer, which measures extracellular acidification rate (ECAR) and oxygen consumption rate (OCR) as indications of glycolytic and respiratory activities. In doing so we achieved effective immobilization of encapsulated cryptococci, established Rotenone/Antimycin A and 2-deoxyglucose as effective inhibitors of mitochondrial respiration and glycolysis, respectively, and optimized a microscopy-based method of data normalization. We applied the protocol to monitor metabolic changes in the pathogen alone and in co-culture with human blood-derived monocytes. We also compared metabolic flux in wild-type C. neoformans, its isogenic 5-PP-IP5/IP7-deficient metabolic mutant kcs1∆, the sister species of C. neoformans, Cryptococcus deuterogattii/VGII, and two other yeasts, Saccharomyces cerevisiae and Candida albicans. Our findings show that in contrast to monocytes and C. albicans, glycolysis and respiration are tightly coupled in C. neoformans and C. deuterogattii, as no compensatory increase in glycolysis occurred following inhibition of respiration. We also demonstrate that kcs1∆ has reduced metabolic activity that correlates with reduced mitochondrial function. Metabolic inflexibility in C. neoformans is therefore consistent with its obligate aerobe status and coincides with phagocyte tolerance of ingested cryptococcal cells.
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Affiliation(s)
- Sophie Lev
- Centre for Infectious Diseases and Microbiology, The Westmead Institute for Medical Research, Westmead, NSW 2145, Australia; (S.L.); (C.L.); (D.D.); (T.C.S.)
- Sydney Medical School—Westmead, The University of Sydney, Westmead, NSW 2145, Australia;
- Marie Bashir Institute for Infectious Diseases and Biosecurity, University of Sydney, Sydney, NSW 2050, Australia
| | - Cecilia Li
- Centre for Infectious Diseases and Microbiology, The Westmead Institute for Medical Research, Westmead, NSW 2145, Australia; (S.L.); (C.L.); (D.D.); (T.C.S.)
- Sydney Medical School—Westmead, The University of Sydney, Westmead, NSW 2145, Australia;
| | - Desmarini Desmarini
- Centre for Infectious Diseases and Microbiology, The Westmead Institute for Medical Research, Westmead, NSW 2145, Australia; (S.L.); (C.L.); (D.D.); (T.C.S.)
- Sydney Medical School—Westmead, The University of Sydney, Westmead, NSW 2145, Australia;
- Marie Bashir Institute for Infectious Diseases and Biosecurity, University of Sydney, Sydney, NSW 2050, Australia
| | - David Liuwantara
- Centre for Transplant and Renal Research, The Westmead Institute for Medical Research, Westmead, NSW 2145, Australia;
| | - Tania C. Sorrell
- Centre for Infectious Diseases and Microbiology, The Westmead Institute for Medical Research, Westmead, NSW 2145, Australia; (S.L.); (C.L.); (D.D.); (T.C.S.)
- Sydney Medical School—Westmead, The University of Sydney, Westmead, NSW 2145, Australia;
- Marie Bashir Institute for Infectious Diseases and Biosecurity, University of Sydney, Sydney, NSW 2050, Australia
| | - Wayne J. Hawthorne
- Sydney Medical School—Westmead, The University of Sydney, Westmead, NSW 2145, Australia;
- Centre for Transplant and Renal Research, The Westmead Institute for Medical Research, Westmead, NSW 2145, Australia;
| | - Julianne T. Djordjevic
- Centre for Infectious Diseases and Microbiology, The Westmead Institute for Medical Research, Westmead, NSW 2145, Australia; (S.L.); (C.L.); (D.D.); (T.C.S.)
- Sydney Medical School—Westmead, The University of Sydney, Westmead, NSW 2145, Australia;
- Marie Bashir Institute for Infectious Diseases and Biosecurity, University of Sydney, Sydney, NSW 2050, Australia
- Correspondence:
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5
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Lev S, Li C, Desmarini D, Sorrell TC, Saiardi A, Djordjevic JT. Fungal Kinases With a Sweet Tooth: Pleiotropic Roles of Their Phosphorylated Inositol Sugar Products in the Pathogenicity of Cryptococcus neoformans Present Novel Drug Targeting Opportunities. Front Cell Infect Microbiol 2019; 9:248. [PMID: 31380293 PMCID: PMC6660261 DOI: 10.3389/fcimb.2019.00248] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Accepted: 06/26/2019] [Indexed: 12/17/2022] Open
Abstract
Invasive fungal pathogens cause more than 300 million serious human infections and 1.6 million deaths per year. A clearer understanding of the mechanisms by which these fungi cause disease is needed to identify novel targets for urgently needed therapies. Kinases are key components of the signaling and metabolic circuitry of eukaryotic cells, which include fungi, and kinase inhibition is currently being exploited for the treatment of human diseases. Inhibiting evolutionarily divergent kinases in fungal pathogens is a promising avenue for antifungal drug development. One such group of kinases is the phospholipase C1-dependent inositol polyphosphate kinases (IPKs), which act sequentially to transfer a phosphoryl group to a pre-phosphorylated inositol sugar (IP). This review focuses on the roles of fungal IPKs and their IP products in fungal pathogenicity, as determined predominantly from studies performed in the model fungal pathogen Cryptococcus neoformans, and compares them to what is known in non-pathogenic model fungi and mammalian cells to highlight potential drug targeting opportunities.
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Affiliation(s)
- Sophie Lev
- Centre for Infectious Diseases and Microbiology, The Westmead Institute for Medical Research, Sydney, NSW, Australia.,Sydney Medical School-Westmead, The University of Sydney, Sydney, NSW, Australia.,Marie Bashir Institute for Infectious Diseases and Biosecurity, University of Sydney, Sydney, NSW, Australia
| | - Cecilia Li
- Sydney Medical School-Westmead, The University of Sydney, Sydney, NSW, Australia.,Centre for Infectious Diseases and Microbiology-Public Health, NSW Health Pathology, Westmead Hospital, Sydney, NSW, Australia
| | - Desmarini Desmarini
- Centre for Infectious Diseases and Microbiology, The Westmead Institute for Medical Research, Sydney, NSW, Australia.,Sydney Medical School-Westmead, The University of Sydney, Sydney, NSW, Australia.,Marie Bashir Institute for Infectious Diseases and Biosecurity, University of Sydney, Sydney, NSW, Australia
| | - Tania C Sorrell
- Centre for Infectious Diseases and Microbiology, The Westmead Institute for Medical Research, Sydney, NSW, Australia.,Sydney Medical School-Westmead, The University of Sydney, Sydney, NSW, Australia.,Marie Bashir Institute for Infectious Diseases and Biosecurity, University of Sydney, Sydney, NSW, Australia
| | - Adolfo Saiardi
- MRC Laboratory for Molecular Cell Biology, University College London, London, United Kingdom
| | - Julianne T Djordjevic
- Centre for Infectious Diseases and Microbiology, The Westmead Institute for Medical Research, Sydney, NSW, Australia.,Sydney Medical School-Westmead, The University of Sydney, Sydney, NSW, Australia.,Marie Bashir Institute for Infectious Diseases and Biosecurity, University of Sydney, Sydney, NSW, Australia
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Lev S, Rupasinghe T, Desmarini D, Kaufman-Francis K, Sorrell TC, Roessner U, Djordjevic JT. The PHO signaling pathway directs lipid remodeling in Cryptococcus neoformans via DGTS synthase to recycle phosphate during phosphate deficiency. PLoS One 2019; 14:e0212651. [PMID: 30789965 PMCID: PMC6383925 DOI: 10.1371/journal.pone.0212651] [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] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Accepted: 02/06/2019] [Indexed: 12/16/2022] Open
Abstract
The phosphate sensing and acquisition (PHO) pathway of Cryptococcus neoformans is essential for growth in phosphate-limiting conditions and for dissemination of infection in a mouse model. Its key transcription factor, Pho4, regulates expression of genes controlling the acquisition of phosphate from both external and cellular sources. One such gene, BTA1, is highly up-regulated during phosphate starvation. Given that a significant proportion of cellular phosphate is incorporated into phospholipids, and that the Pho4-dependent BTA1 gene encodes an enzyme predicted to catalyse production of a phosphorus-free betaine lipid, we investigated whether phospholipids provide an accessible reservoir of phosphate during phosphate deficiency. By comparing lipid profiles of phosphate-starved WT C. neoformans, PHO4 (pho4Δ) and BTA1 (bta1Δ) deletion mutants using thin layer chromatography and liquid chromatography mass spectrometry, we showed that phosphatidylcholine (PC) is substituted by the phosphorus-free betaine lipids diacylglyceryl-N,N,N-trimethylhomoserine (DGTS) and diacylgyceryl hydroxymethyl-N,N,N-trimethyl-beta-alanine (DGTA) in a Pho4- and Bta1-dependent manner, and that BTA1 encodes a functional DGTS synthase. Synthesis of DGTA tightly correlated with that of DGTS, consistent with DGTS being the precursor of DGTA. Similar to pho4Δ, bta1Δ grew more slowly than WT in cell culture medium (RPMI) and was hypovirulent in a murine model of cryptococcosis. In contrast to pho4Δ, bta1Δ tolerated alkaline pH and disseminated to the brain. Our results demonstrate that Bta1-dependent substitution of PC by betaine lipids is tightly regulated in C. neoformans by the PHO pathway, to conserve phosphate and preserve membrane integrity and function. This phospholipid remodeling strategy may also contribute to cryptococcal virulence during host infection.
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Affiliation(s)
- Sophie Lev
- Centre for Infectious Diseases and Microbiology, Fungal Pathogenesis Group, Westmead Institute for Medical Research, Westmead, New South Wales, Australia
- Sydney Medical School-Westmead, University of Sydney at Westmead Hospital, Westmead, New South Wales, Australia
- Marie Bashir Institute for Infectious Diseases and Biosecurity, University of Sydney, Sydney, New South Wales, Australia
| | - Thusitha Rupasinghe
- Metabolomics Australia, School of Biosciences, The University of Melbourne, Melbourne, Victoria, Australia
| | - Desmarini Desmarini
- Centre for Infectious Diseases and Microbiology, Fungal Pathogenesis Group, Westmead Institute for Medical Research, Westmead, New South Wales, Australia
| | - Keren Kaufman-Francis
- Centre for Infectious Diseases and Microbiology, Fungal Pathogenesis Group, Westmead Institute for Medical Research, Westmead, New South Wales, Australia
- Sydney Medical School-Westmead, University of Sydney at Westmead Hospital, Westmead, New South Wales, Australia
- Marie Bashir Institute for Infectious Diseases and Biosecurity, University of Sydney, Sydney, New South Wales, Australia
| | - Tania Christine Sorrell
- Centre for Infectious Diseases and Microbiology, Fungal Pathogenesis Group, Westmead Institute for Medical Research, Westmead, New South Wales, Australia
- Sydney Medical School-Westmead, University of Sydney at Westmead Hospital, Westmead, New South Wales, Australia
- Marie Bashir Institute for Infectious Diseases and Biosecurity, University of Sydney, Sydney, New South Wales, Australia
| | - Ute Roessner
- Metabolomics Australia, School of Biosciences, The University of Melbourne, Melbourne, Victoria, Australia
| | - Julianne Teresa Djordjevic
- Centre for Infectious Diseases and Microbiology, Fungal Pathogenesis Group, Westmead Institute for Medical Research, Westmead, New South Wales, Australia
- Sydney Medical School-Westmead, University of Sydney at Westmead Hospital, Westmead, New South Wales, Australia
- Marie Bashir Institute for Infectious Diseases and Biosecurity, University of Sydney, Sydney, New South Wales, Australia
- * E-mail:
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Chia SZ, Lai YW, Yagoub D, Lev S, Hamey JJ, Pang CNI, Desmarini D, Chen Z, Djordjevic JT, Erce MA, Hart-Smith G, Wilkins MR. Knockout of the Hmt1p Arginine Methyltransferase in Saccharomyces cerevisiae Leads to the Dysregulation of Phosphate-associated Genes and Processes. Mol Cell Proteomics 2018; 17:2462-2479. [PMID: 30206180 DOI: 10.1074/mcp.ra117.000214] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [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: 07/26/2017] [Revised: 08/14/2018] [Indexed: 11/06/2022] Open
Abstract
Hmt1p is the predominant arginine methyltransferase in Saccharomyces cerevisiae Its substrate proteins are involved in transcription, transcriptional regulation, nucleocytoplasmic transport and RNA splicing. Hmt1p-catalyzed methylation can also modulate protein-protein interactions. Hmt1p is conserved from unicellular eukaryotes through to mammals where its ortholog, PRMT1, is lethal upon knockout. In yeast, however, the effect of knockout on the transcriptome and proteome has not been described. Transcriptome analysis revealed downregulation of phosphate-responsive genes in hmt1Δ, including acid phosphatases PHO5, PHO11, and PHO12, phosphate transporters PHO84 and PHO89 and the vacuolar transporter chaperone VTC3 Analysis of the hmt1Δ proteome revealed decreased abundance of phosphate-associated proteins including phosphate transporter Pho84p, vacuolar alkaline phosphatase Pho8p, acid phosphatase Pho3p and subunits of the vacuolar transporter chaperone complex Vtc1p, Vtc3p and Vtc4p. Consistent with this, phosphate homeostasis was dysregulated in hmt1Δ cells, showing decreased extracellular phosphatase levels and decreased total Pi in phosphate-depleted medium. In vitro, we showed that transcription factor Pho4p can be methylated at Arg-241, which could explain phosphate dysregulation in hmt1Δ if interplay exists with phosphorylation at Ser-242 or Ser-243, or if Arg-241 methylation affects the capacity of Pho4p to homodimerize or interact with Pho2p. However, the Arg-241 methylation site was not validated in vivo and the localization of a Pho4p-GFP fusion in hmt1Δ was not different from wild type. To our knowledge, this is the first study to reveal an association between Hmt1p and phosphate homeostasis and one which suggests a regulatory link between S-adenosyl methionine and intracellular phosphate.
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Affiliation(s)
- Samantha Z Chia
- Systems Biology Initiative, School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia
| | - Yu-Wen Lai
- Systems Biology Initiative, School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia
| | - Daniel Yagoub
- Systems Biology Initiative, School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia
| | - Sophie Lev
- Centre for Infectious Diseases and Microbiology, Westmead Millennium Institute and Sydney Medical School, University of Sydney at Westmead Hospital, Westmead, New South Wales, Australia
| | - Joshua J Hamey
- Systems Biology Initiative, School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia
| | - Chi Nam Ignatius Pang
- Systems Biology Initiative, School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia
| | - Desmarini Desmarini
- Centre for Infectious Diseases and Microbiology, Westmead Millennium Institute and Sydney Medical School, University of Sydney at Westmead Hospital, Westmead, New South Wales, Australia
| | - Zhiliang Chen
- Systems Biology Initiative, School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia
| | - Julianne T Djordjevic
- Centre for Infectious Diseases and Microbiology, Westmead Millennium Institute and Sydney Medical School, University of Sydney at Westmead Hospital, Westmead, New South Wales, Australia
| | - Melissa A Erce
- Systems Biology Initiative, School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia
| | - Gene Hart-Smith
- Systems Biology Initiative, School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia
| | - Marc R Wilkins
- Systems Biology Initiative, School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia.
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Li C, Lev S, Desmarini D, Kaufman-Francis K, Saiardi A, Silva APG, Mackay JP, Thompson PE, Sorrell TC, Djordjevic JT. IP 3-4 kinase Arg1 regulates cell wall homeostasis and surface architecture to promote clearance of Cryptococcus neoformans infection in a mouse model. Virulence 2017; 8:1833-1848. [PMID: 28976803 DOI: 10.1080/21505594.2017.1385692] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
Abstract
We previously identified a series of inositol polyphosphate kinases (IPKs), Arg1, Ipk1, Kcs1 and Asp1, in the opportunistic fungal pathogen Cryptococcus neoformans. Using gene deletion analysis, we characterized Arg1, Ipk1 and Kcs1 and showed that they act sequentially to convert IP3 to PP-IP5 (IP7), a key metabolite promoting stress tolerance, metabolic adaptation and fungal dissemination to the brain. We have now directly characterized the enzymatic activity of Arg1, demonstrating that it is a dual specificity (IP3/IP4) kinase producing IP5. We showed previously that IP5 is further phosphorylated by Ipk1 to produce IP6, which is a substrate for the synthesis of PP-IP5 by Kcs1. Phenotypic comparison of the arg1Δ and kcs1Δ deletion mutants (both PP-IP5-deficient) reveals that arg1Δ has the most deleterious phenotype: while PP-IP5 is essential for metabolic and stress adaptation in both mutant strains, PP-IP5 is dispensable for virulence-associated functions such as capsule production, cell wall organization, and normal N-linked mannosylation of the virulence factor, phospholipase B1, as these phenotypes were defective only in arg1Δ. The more deleterious arg1Δ phenotype correlated with a higher rate of arg1Δ phagocytosis by human peripheral blood monocytes and rapid arg1Δ clearance from lung in a mouse model. This observation is in contrast to kcs1Δ, which we previously reported establishes a chronic, confined lung infection. In summary, we show that Arg1 is the most crucial IPK for cryptococcal virulence, conveying PP-IP5-dependent and novel PP-IP5-independent functions.
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Affiliation(s)
- Cecilia Li
- a Centre for Infectious Diseases and Microbiology, The Westmead Institute for Medical Research , 176 Hawkesbury road, Westmead NSW 2145 , Australia.,b Sydney Medical School-Westmead, The University of Sydney , Westmead NSW 2145 , Australia.,c Marie Bashir Institute for Infectious Diseases and Biosecurity, University of Sydney , NSW Australia
| | - Sophie Lev
- a Centre for Infectious Diseases and Microbiology, The Westmead Institute for Medical Research , 176 Hawkesbury road, Westmead NSW 2145 , Australia.,b Sydney Medical School-Westmead, The University of Sydney , Westmead NSW 2145 , Australia.,c Marie Bashir Institute for Infectious Diseases and Biosecurity, University of Sydney , NSW Australia
| | - Desmarini Desmarini
- a Centre for Infectious Diseases and Microbiology, The Westmead Institute for Medical Research , 176 Hawkesbury road, Westmead NSW 2145 , Australia
| | - Keren Kaufman-Francis
- a Centre for Infectious Diseases and Microbiology, The Westmead Institute for Medical Research , 176 Hawkesbury road, Westmead NSW 2145 , Australia.,c Marie Bashir Institute for Infectious Diseases and Biosecurity, University of Sydney , NSW Australia
| | - Adolfo Saiardi
- d Medical Research Council Laboratory for Molecular Cell Biology, University College London , Gower street, London WC1E 6BT , UK
| | - Ana P G Silva
- e School of Life and Environmental Sciences, The University of Sydney , Camperdown , NSW 2006 , Australia
| | - Joel P Mackay
- e School of Life and Environmental Sciences, The University of Sydney , Camperdown , NSW 2006 , Australia
| | - Philip E Thompson
- f Medicinal Chemistry, Faculty of Pharmacy and Pharmaceutical Sciences , Monash University , 381 Royal Parade, Parkville , VIC 3052 , Australia
| | - Tania C Sorrell
- a Centre for Infectious Diseases and Microbiology, The Westmead Institute for Medical Research , 176 Hawkesbury road, Westmead NSW 2145 , Australia.,b Sydney Medical School-Westmead, The University of Sydney , Westmead NSW 2145 , Australia.,c Marie Bashir Institute for Infectious Diseases and Biosecurity, University of Sydney , NSW Australia.,g Westmead Hospital , Westmead , NSW 2145 , Australia
| | - Julianne T Djordjevic
- a Centre for Infectious Diseases and Microbiology, The Westmead Institute for Medical Research , 176 Hawkesbury road, Westmead NSW 2145 , Australia.,b Sydney Medical School-Westmead, The University of Sydney , Westmead NSW 2145 , Australia.,c Marie Bashir Institute for Infectious Diseases and Biosecurity, University of Sydney , NSW Australia.,g Westmead Hospital , Westmead , NSW 2145 , Australia
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Raj S, Nazemidashtarjandi S, Kim J, Joffe L, Zhang X, Singh A, Mor V, Desmarini D, Djordjevic J, Raleigh DP, Rodrigues ML, London E, Del Poeta M, Farnoud AM. Changes in glucosylceramide structure affect virulence and membrane biophysical properties of Cryptococcus neoformans. Biochim Biophys Acta Biomembr 2017; 1859:2224-2233. [PMID: 28865794 DOI: 10.1016/j.bbamem.2017.08.017] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Revised: 08/03/2017] [Accepted: 08/27/2017] [Indexed: 11/19/2022]
Abstract
Fungal glucosylceramide (GlcCer) is a plasma membrane sphingolipid in which the sphingosine backbone is unsaturated in carbon position 8 (C8) and methylated in carbon position 9 (C9). Studies in the fungal pathogen, Cryptococcus neoformans, have shown that loss of GlcCer synthase activity results in complete loss of virulence in the mouse model. However, whether the loss of virulence is due to the lack of the enzyme or to the loss of the sphingolipid is not known. In this study, we used genetic engineering to alter the chemical structure of fungal GlcCer and studied its effect on fungal growth and pathogenicity. Here we show that unsaturation in C8 and methylation in C9 is required for virulence in the mouse model without affecting fungal growth in vitro or common virulence factors. However, changes in GlcCer structure led to a dramatic susceptibility to membrane stressors resulting in increased cell membrane permeability and rendering the fungal mutant unable to grow within host macrophages. Biophysical studies using synthetic vesicles containing GlcCer revealed that the saturated and unmethylated sphingolipid formed vesicles with higher lipid order that were more likely to phase separate into ordered domains. Taken together, these studies show for the first time that a specific structure of GlcCer is a major regulator of membrane permeability required for fungal pathogenicity.
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Affiliation(s)
- Shriya Raj
- Department of Mycology, Institut Pasteur, Paris, France
| | | | - Jihyun Kim
- Department of Chemistry and Biochemistry, Stony Brook University, Stony Brook, NY, USA
| | - Luna Joffe
- Departamento de Microbiologia Geral, Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro (UFRJ), Brazil
| | - Xiaoxue Zhang
- Department of Chemistry and Biochemistry, Stony Brook University, Stony Brook, NY, USA
| | - Ashutosh Singh
- Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, NY, USA
| | - Visesato Mor
- Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, NY, USA
| | - Desmarini Desmarini
- Fungal Pathogenesis Laboratory, Centre for Infectious Diseases and Microbiology, The Westmead Institute for Medical Research, Westmead, NSW, Australia
| | - Julianne Djordjevic
- Fungal Pathogenesis Laboratory, Centre for Infectious Diseases and Microbiology, The Westmead Institute for Medical Research, Westmead, NSW, Australia; Westmead Clinical School, University of Sydney at Westmead Hospital, Westmead, NSW, Australia; Marie Bashir Institute for Infectious Diseases and Biosecurity, University of Sydney, NSW, Australia
| | - Daniel P Raleigh
- Department of Chemistry and Biochemistry, Stony Brook University, Stony Brook, NY, USA
| | - Marcio L Rodrigues
- Departamento de Microbiologia Geral, Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro (UFRJ), Brazil; Centro de Desenvolvimento Tecnológico em Saúde (CDTS) da Fundação Oswaldo Cruz (Fiocruz), Rio de Janeiro, Brazil
| | - Erwin London
- Department of Chemistry and Biochemistry, Stony Brook University, Stony Brook, NY, USA
| | - Maurizio Del Poeta
- Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, NY, USA; Veterans Administration Medical Center, Northport, NY, USA; Division of Infectious Diseases, Stony Brook University, Stony Brook, NY, USA.
| | - Amir M Farnoud
- Department of Chemical and Biomolecular Engineering, Ohio University, Athens, OH, USA.
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Li C, Lev S, Saiardi A, Desmarini D, Sorrell TC, Djordjevic JT. Inositol Polyphosphate Kinases, Fungal Virulence and Drug Discovery. J Fungi (Basel) 2016; 2:jof2030024. [PMID: 29376941 PMCID: PMC5753137 DOI: 10.3390/jof2030024] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Revised: 08/23/2016] [Accepted: 08/30/2016] [Indexed: 12/31/2022] Open
Abstract
Opportunistic fungi are a major cause of morbidity and mortality world-wide, particularly in immunocompromised individuals. Developing new treatments to combat invasive fungal disease is challenging given that fungal and mammalian host cells are eukaryotic, with similar organization and physiology. Even therapies targeting unique fungal cell features have limitations and drug resistance is emerging. New approaches to the development of antifungal drugs are therefore needed urgently. Cryptococcus neoformans, the commonest cause of fungal meningitis worldwide, is an accepted model for studying fungal pathogenicity and driving drug discovery. We recently characterized a phospholipase C (Plc1)-dependent pathway in C. neoformans comprising of sequentially-acting inositol polyphosphate kinases (IPK), which are involved in synthesizing inositol polyphosphates (IP). We also showed that the pathway is essential for fungal cellular function and pathogenicity. The IP products of the pathway are structurally diverse, each consisting of an inositol ring, with phosphate (P) and pyrophosphate (PP) groups covalently attached at different positions. This review focuses on (1) the characterization of the Plc1/IPK pathway in C. neoformans; (2) the identification of PP-IP₅ (IP₇) as the most crucial IP species for fungal fitness and virulence in a mouse model of fungal infection; and (3) why IPK enzymes represent suitable candidates for drug development.
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Affiliation(s)
- Cecilia Li
- Centre for Infectious Diseases and Microbiology, The Westmead Institute for Medical Research, The University of Sydney, Westmead, NSW 2145, Australia.
| | - Sophie Lev
- Centre for Infectious Diseases and Microbiology, The Westmead Institute for Medical Research, The University of Sydney, Westmead, NSW 2145, Australia.
| | - Adolfo Saiardi
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, London WC1E 6BT, UK.
| | - Desmarini Desmarini
- Centre for Infectious Diseases and Microbiology, The Westmead Institute for Medical Research, The University of Sydney, Westmead, NSW 2145, Australia.
| | - Tania C Sorrell
- Centre for Infectious Diseases and Microbiology, The Westmead Institute for Medical Research, The University of Sydney, Westmead, NSW 2145, Australia.
- Marie Bashir Institute for Infectious Diseases and Biosecurity, University of Sydney, Westmead, NSW 2145, Australia.
- Westmead Hospital, Westmead, NSW 2145, Australia.
| | - Julianne T Djordjevic
- Centre for Infectious Diseases and Microbiology, The Westmead Institute for Medical Research, The University of Sydney, Westmead, NSW 2145, Australia.
- Marie Bashir Institute for Infectious Diseases and Biosecurity, University of Sydney, Westmead, NSW 2145, Australia.
- Westmead Hospital, Westmead, NSW 2145, Australia.
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McMullan BJ, Desmarini D, Djordjevic JT, Chen SCA, Roper M, Sorrell TC. Rapid microscopy and use of vital dyes: potential to determine viability of Cryptococcus neoformans in the clinical laboratory. PLoS One 2015; 10:e0117186. [PMID: 25625210 PMCID: PMC4308066 DOI: 10.1371/journal.pone.0117186] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2014] [Accepted: 12/19/2014] [Indexed: 11/19/2022] Open
Abstract
Background Cryptococcus neoformans is the commonest cause of fungal meningitis, with a substantial mortality despite appropriate therapy. Quantitative culture of cryptococci in cerebrospinal fluid (CSF) during antifungal therapy is of prognostic value and has therapeutic implications, but is slow and not practicable in many resource-poor countries. Methods We piloted two rapid techniques for quantifying viable cryptococci using mixtures of live and heat-killed cryptococci cultured in vitro: (i) quantitative microscopy with exclusion staining using trypan blue dye, and (ii) flow cytometry, using the fluorescent dye 2′-7′-Bis-(2-carboxyethyl)-5-(6)-carboxyfluorescein, acetoxymethyl ester (BCECF-AM). Results were compared with standard quantitative cryptococcal cultures. Quantitative microscopy was also performed on cerebrospinal fluid (CSF) samples. Results Both microscopy and flow cytometry distinguished between viable and non-viable cryptococci. Cell counting (on log scale) by microscopy and by quantitative culture were significantly linearly associated (p<0.0001) and Bland-Altman analysis showed a high level of agreement. Proportions of viable cells (on logit scale), as detected by flow cytometry were significantly linearly associated with proportions detected by microscopy (p<0.0001) and Bland-Altman analysis showed a high level of agreement. Conclusions Direct microscopic examination of trypan blue-stained cryptococci and flow-cytometric assessment of BCECF-AM-stained cryptococci were in good agreement with quantitative cultures. These are promising strategies for rapid determination of the viability of cryptococci, and should be investigated in clinical practice.
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Affiliation(s)
- Brendan J. McMullan
- Centre for Infectious Diseases and Microbiology, Westmead Millennium Institute, University of Sydney at Westmead Hospital, Westmead, NSW, Australia
- Centre for Infectious Diseases and Microbiology Laboratory Services, Westmead Hospital, Westmead, NSW, Australia
- * E-mail:
| | - Desmarini Desmarini
- Centre for Infectious Diseases and Microbiology, Westmead Millennium Institute, University of Sydney at Westmead Hospital, Westmead, NSW, Australia
- Marie Bashir Institute for Infectious Diseases and Biosecurity, University of Sydney, Westmead, NSW, Australia
| | - Julianne T. Djordjevic
- Centre for Infectious Diseases and Microbiology, Westmead Millennium Institute, University of Sydney at Westmead Hospital, Westmead, NSW, Australia
- Marie Bashir Institute for Infectious Diseases and Biosecurity, University of Sydney, Westmead, NSW, Australia
| | - Sharon C-A. Chen
- Centre for Infectious Diseases and Microbiology, Westmead Millennium Institute, University of Sydney at Westmead Hospital, Westmead, NSW, Australia
- Centre for Infectious Diseases and Microbiology Laboratory Services, Westmead Hospital, Westmead, NSW, Australia
- ICPMR–Pathology West, Westmead Hospital, Westmead, NSW, Australia
| | - Michael Roper
- Discipline of Infectious Diseases and Immunology, Westmead Clinical School, Sydney Medical School, The University of Sydney, Westmead, NSW, Australia
| | - Tania C. Sorrell
- Centre for Infectious Diseases and Microbiology, Westmead Millennium Institute, University of Sydney at Westmead Hospital, Westmead, NSW, Australia
- Marie Bashir Institute for Infectious Diseases and Biosecurity, University of Sydney, Westmead, NSW, Australia
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Lev S, Desmarini D, Chayakulkeeree M, Sorrell TC, Djordjevic JT. The Crz1/Sp1 transcription factor of Cryptococcus neoformans is activated by calcineurin and regulates cell wall integrity. PLoS One 2012; 7:e51403. [PMID: 23251520 PMCID: PMC3520850 DOI: 10.1371/journal.pone.0051403] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2012] [Accepted: 11/01/2012] [Indexed: 11/22/2022] Open
Abstract
Cryptococcus neoformans survives host temperature and regulates cell wall integrity via a calcium-dependent phosphatase, calcineurin. However, downstream effectors of C. neoformans calcineurin are largely unknown. In S. cerevisiae and other fungal species, a calcineurin-dependent transcription factor Crz1, translocates to nuclei upon activation and triggers expression of target genes. We now show that the C. neoformans Crz1 ortholog (Crz1/Sp1), previously identified as a protein kinase C target during starvation, is a bona fide target of calcineurin under non-starvation conditions, during cell wall stress and growth at high temperature. Both the calcineurin-defective mutant, Δcna1, and a CRZ1/SP1 mutant (Δcrz1) were susceptible to cell wall perturbing agents. Furthermore, expression of the chitin synthase encoding gene, CHS6, was reduced in both mutants. We tracked the subcellular localization of Crz1-GFP in WT C. neoformans and Δcna1 in response to different stimuli, in the presence and absence of the calcineurin inhibitor, FK506. Exposure to elevated temperature (30–37°C vs 25°C) and extracellular calcium caused calcineurin-dependent nuclear accumulation of Crz1-GFP. Unexpectedly, 1M salt and heat shock triggered calcineurin-independent Crz1-GFP sequestration within cytosolic and nuclear puncta. To our knowledge, punctate cytosolic distribution, as opposed to nuclear targeting, is a unique feature of C. neoformans Crz1. We conclude that Crz1 is selectively activated by calcium/calcineurin-dependent and independent signals depending on the environmental conditions.
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Affiliation(s)
- Sophie Lev
- Centre for Infectious Diseases and Microbiology, Sydney Medical School and Westmead Millennium Institute, University of Sydney, Westmead, New South Wales, Australia
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Zuo X, Djordjevic JT, Bijosono Oei J, Desmarini D, Schibeci SD, Jolliffe KA, Sorrell TC. Miltefosine induces apoptosis-like cell death in yeast via Cox9p in cytochrome c oxidase. Mol Pharmacol 2011; 80:476-85. [PMID: 21610197 DOI: 10.1124/mol.111.072322] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Miltefosine has antifungal properties and potential for development as a therapeutic for invasive fungal infections. However, its mode of action in fungi is poorly understood. We demonstrate that miltefosine is rapidly incorporated into yeast, where it penetrates the mitochondrial inner membrane, disrupting mitochondrial membrane potential and leading to an apoptosis-like cell death. COX9, which encodes subunit VIIa of the cytochrome c oxidase (COX) complex in the electron transport chain of the mitochondrial membrane, was identified as a potential target of miltefosine from a genomic library screen of the model yeast Saccharomyces cerevisiae. When overexpressed in S. cerevisiae, COX9, but not COX7 or COX8, led to a miltefosine-resistant phenotype. The effect of miltefosine on COX activity was assessed in cells expressing different levels of COX9. Miltefosine inhibited COX activity in a dose-dependent manner in Cox9p-positive cells. This inhibition most likely contributed to the miltefosine-induced apoptosis-like cell death.
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Affiliation(s)
- Xiaoming Zuo
- Centre for Infectious Diseases and Microbiology, Westmead Millennium Institute and Sydney Emerging Infections and Biosecurity Institute, University of Sydney, Australia
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