1
|
Dancis A, Pandey AK, Pain D. Mitochondria function in cytoplasmic FeS protein biogenesis. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2024; 1871:119733. [PMID: 38641180 DOI: 10.1016/j.bbamcr.2024.119733] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2023] [Revised: 03/18/2024] [Accepted: 04/12/2024] [Indexed: 04/21/2024]
Abstract
Iron‑sulfur (FeS) clusters are cofactors of numerous proteins involved in essential cellular functions including respiration, protein translation, DNA synthesis and repair, ribosome maturation, anti-viral responses, and isopropylmalate isomerase activity. Novel FeS proteins are still being discovered due to the widespread use of cryogenic electron microscopy (cryo-EM) and elegant genetic screens targeted at protein discovery. A complex sequence of biochemical reactions mediated by a conserved machinery controls biosynthesis of FeS clusters. In eukaryotes, a remarkable epistasis has been observed: the mitochondrial machinery, termed ISC (Iron-Sulfur Cluster), lies upstream of the cytoplasmic machinery, termed CIA (Cytoplasmic Iron‑sulfur protein Assembly). The basis for this arrangement is the production of a hitherto uncharacterized intermediate, termed X-S or (Fe-S)int, produced in mitochondria by the ISC machinery, exported by the mitochondrial ABC transporter Atm1 (ABCB7 in humans), and then utilized by the CIA machinery for the cytoplasmic/nuclear FeS cluster assembly. Genetic and biochemical findings supporting this sequence of events are herein presented. New structural views of the Atm1 transport phases are reviewed. The key compartmental roles of glutathione in cellular FeS cluster biogenesis are highlighted. Finally, data are presented showing that every one of the ten core components of the mitochondrial ISC machinery and Atm1, when mutated or depleted, displays similar phenotypes: mitochondrial and cytoplasmic FeS clusters are both rendered deficient, consistent with the epistasis noted above.
Collapse
Affiliation(s)
- Andrew Dancis
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School, Rutgers University, Newark, NJ 07103, USA.
| | - Ashutosh K Pandey
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School, Rutgers University, Newark, NJ 07103, USA
| | - Debkumar Pain
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School, Rutgers University, Newark, NJ 07103, USA
| |
Collapse
|
2
|
Braymer JJ, Stehling O, Stümpfig M, Rösser R, Spantgar F, Blinn CM, Mühlenhoff U, Pierik AJ, Lill R. Requirements for the biogenesis of [2Fe-2S] proteins in the human and yeast cytosol. Proc Natl Acad Sci U S A 2024; 121:e2400740121. [PMID: 38743629 PMCID: PMC11126956 DOI: 10.1073/pnas.2400740121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2024] [Accepted: 04/16/2024] [Indexed: 05/16/2024] Open
Abstract
The biogenesis of iron-sulfur (Fe/S) proteins entails the synthesis and trafficking of Fe/S clusters, followed by their insertion into target apoproteins. In eukaryotes, the multiple steps of biogenesis are accomplished by complex protein machineries in both mitochondria and cytosol. The underlying biochemical pathways have been elucidated over the past decades, yet the mechanisms of cytosolic [2Fe-2S] protein assembly have remained ill-defined. Similarly, the precise site of glutathione (GSH) requirement in cytosolic and nuclear Fe/S protein biogenesis is unclear, as is the molecular role of the GSH-dependent cytosolic monothiol glutaredoxins (cGrxs). Here, we investigated these questions in human and yeast cells by various in vivo approaches. [2Fe-2S] cluster assembly of cytosolic target apoproteins required the mitochondrial ISC machinery, the mitochondrial transporter Atm1/ABCB7 and GSH, yet occurred independently of both the CIA system and cGrxs. This mechanism was strikingly different from the ISC-, Atm1/ABCB7-, GSH-, and CIA-dependent assembly of cytosolic-nuclear [4Fe-4S] proteins. One notable exception to this cytosolic [2Fe-2S] protein maturation pathway defined here was yeast Apd1 which used the CIA system via binding to the CIA targeting complex through its C-terminal tryptophan. cGrxs, although attributed as [2Fe-2S] cluster chaperones or trafficking proteins, were not essential in vivo for delivering [2Fe-2S] clusters to either CIA components or target apoproteins. Finally, the most critical GSH requirement was assigned to Atm1-dependent export, i.e. a step before GSH-dependent cGrxs function. Our findings extend the general model of eukaryotic Fe/S protein biogenesis by adding the molecular requirements for cytosolic [2Fe-2S] protein maturation.
Collapse
Affiliation(s)
- Joseph J. Braymer
- Institut für Zytobiologie und Zytopathologie, Fachbereich Medizin, Philipps-Universität Marburg, Marburg35032, Germany
- Zentrum für Synthetische Mikrobiologie Synmikro, Philipps-Universität Marburg, Marburg35032, Germany
| | - Oliver Stehling
- Institut für Zytobiologie und Zytopathologie, Fachbereich Medizin, Philipps-Universität Marburg, Marburg35032, Germany
- Zentrum für Synthetische Mikrobiologie Synmikro, Philipps-Universität Marburg, Marburg35032, Germany
| | - Martin Stümpfig
- Institut für Zytobiologie und Zytopathologie, Fachbereich Medizin, Philipps-Universität Marburg, Marburg35032, Germany
- Zentrum für Synthetische Mikrobiologie Synmikro, Philipps-Universität Marburg, Marburg35032, Germany
| | - Ralf Rösser
- Institut für Zytobiologie und Zytopathologie, Fachbereich Medizin, Philipps-Universität Marburg, Marburg35032, Germany
- Zentrum für Synthetische Mikrobiologie Synmikro, Philipps-Universität Marburg, Marburg35032, Germany
| | - Farah Spantgar
- Institut für Zytobiologie und Zytopathologie, Fachbereich Medizin, Philipps-Universität Marburg, Marburg35032, Germany
- Zentrum für Synthetische Mikrobiologie Synmikro, Philipps-Universität Marburg, Marburg35032, Germany
| | - Catharina M. Blinn
- Department of Chemistry, Rheinland-Pfälzische Technische Universität Kaiserslautern-Landau, Kaiserslautern67663, Germany
| | - Ulrich Mühlenhoff
- Institut für Zytobiologie und Zytopathologie, Fachbereich Medizin, Philipps-Universität Marburg, Marburg35032, Germany
- Zentrum für Synthetische Mikrobiologie Synmikro, Philipps-Universität Marburg, Marburg35032, Germany
| | - Antonio J. Pierik
- Department of Chemistry, Rheinland-Pfälzische Technische Universität Kaiserslautern-Landau, Kaiserslautern67663, Germany
| | - Roland Lill
- Institut für Zytobiologie und Zytopathologie, Fachbereich Medizin, Philipps-Universität Marburg, Marburg35032, Germany
- Zentrum für Synthetische Mikrobiologie Synmikro, Philipps-Universität Marburg, Marburg35032, Germany
| |
Collapse
|
3
|
Liu Z, Jin T, Qin B, Li R, Shang J, Huang Y. The deletion of ppr2 interferes iron sensing and leads to oxidative stress response in Schizosaccharomyces pombe. Mitochondrion 2024; 76:101875. [PMID: 38499131 DOI: 10.1016/j.mito.2024.101875] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2023] [Revised: 03/09/2024] [Accepted: 03/15/2024] [Indexed: 03/20/2024]
Abstract
Pentatricopeptide repeat proteins are involved in mitochondrial both transcriptional and posttranscriptional regulation. Schizosaccharomyces pombe Ppr2 is a general mitochondrial translation factor that plays a critical role in the synthesis of all mitochondrial DNA-encoded oxidative phosphorylation subunits, which are essential for mitochondrial respiration. Our previous analysis showed that ppr2 deletion resulted in increased expression of iron uptake genes and caused ferroptosis-like cell death in S. pombe. In the present work, we showed that deletion of ppr2 reduced viability on glycerol- and galactose-containing media.Php4 is a transcription repressor that regulates iron homeostasis in fission yeast. We found that in the ppr2 deletion strain, Php4 was constitutively active and accumulated in the nucleus in the stationary phase. We also found that deletion of ppr2 decreased the ferroptosis-related protein Gpx1 in the mitochondria. Overexpression of Gpx1 improves the viability of Δppr2 cells. We showed that the deletion of ppr2 increased the production of ROS, downregulated heme synthesis and iron-sulfur cluster proteins, and induced stress proteins. Finally, we observed the nuclear accumulation of Pap1-GFP and Sty1-GFP, suggesting that Sty1 and Pap1 in response to cellular stress in the ppr2 deletion strain. These results suggest thatppr2 deletion may cause mitochondrial dysfunction, which is likely to lead to iron-sensing defect and iron starvation response, resulting in perturbation of iron homeostasis and increased hydroxyl radical production. The increased hydroxyl radical production triggers cellular responses in theppr2 deletion strain.
Collapse
Affiliation(s)
- Zecheng Liu
- Jiangsu Key Laboratory for Microbes and Functional Genetics, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China; School of Public Health, Hubei University of Medicine, Shiyan 442000, China
| | - Ting Jin
- Jiangsu Key Laboratory for Microbes and Functional Genetics, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China
| | - Bingxin Qin
- Jiangsu Key Laboratory for Microbes and Functional Genetics, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China
| | - Rongrong Li
- Jiangsu Key Laboratory for Microbes and Functional Genetics, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China
| | - Jinjie Shang
- Jiangsu Key Laboratory for Microbes and Functional Genetics, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China.
| | - Ying Huang
- Jiangsu Key Laboratory for Microbes and Functional Genetics, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China.
| |
Collapse
|
4
|
Lindahl PA. Iron Homeostatic Regulation in Saccharomyces cerevisiae: Introduction to a Computational Modeling Method. Methods Mol Biol 2024; 2839:3-29. [PMID: 39008245 DOI: 10.1007/978-1-0716-4043-2_1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/16/2024]
Abstract
Over the past 30 years, much has been learned regarding iron homeostatic regulation in budding yeast, S. cerevisiae, including the identity of many of the proteins and molecular-level regulatory mechanisms involved. Most advances have involved inferring such mechanisms based on the analysis of iron-dysregulation phenotypes arising in various genetic mutant strains. Still lacking is a cellular- or system-level understanding of iron homeostasis. These experimental advances are summarized in this review, and a method for developing cellular-level regulatory mechanisms in yeast is presented. The method employs the results of Mössbauer spectroscopy of whole cells and organelles, iron quantification of the same, and ordinary differential equation-based mathematical models. Current models are simplistic when compared to the complexity of iron homeostasis in real cells, yet they hold promise as a useful, perhaps even required, complement to the popular genetics-based approach. The fundamental problem in comprehending cellular regulatory mechanisms is that, given the complexities involved, different molecular-level mechanisms can often give rise to virtually indistinguishable cellular phenotypes. Mathematical models cannot eliminate this problem, but they can minimize it.
Collapse
Affiliation(s)
- Paul A Lindahl
- Departments of Chemistry and of Biochemistry and Biophysics, Texas A&M University, College Station, TX, USA.
| |
Collapse
|
5
|
Murante D, Demers EG, Kurbessoian T, Ruzic M, Ashare A, Stajich JE, Hogan DA. Mrs4 loss of function in fungi during adaptation to the cystic fibrosis lung. mBio 2023; 14:e0117123. [PMID: 37432019 PMCID: PMC10470810 DOI: 10.1128/mbio.01171-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Accepted: 05/25/2023] [Indexed: 07/12/2023] Open
Abstract
The genetic disease cystic fibrosis (CF) frequently leads to chronic lung infections by bacteria and fungi. We identified three individuals with CF with persistent lung infections dominated by Clavispora (Candida) lusitaniae. Whole-genome sequencing analysis of multiple isolates from each infection found evidence for selection for mutants in the gene MRS4 in all three distinct lung-associated populations. In each population, we found one or two unfixed, non-synonymous mutations in MRS4 relative to the reference allele found in multiple environmental and clinical isolates including the type strain. Genetic and phenotypic analyses found that all evolved alleles led to loss of function (LOF) of Mrs4, a mitochondrial iron transporter. RNA-seq analyses found that Mrs4 variants with decreased activity led to increased expression of genes involved in iron acquisition mechanisms in both low iron and replete iron conditions. Furthermore, surface iron reductase activity and intracellular iron were much higher in strains with Mrs4 LOF variants. Parallel studies found that a subpopulation of a CF-associated Exophiala dermatitidis infection also had a non-synonymous LOF mutation in MRS4. Together, these data suggest that MRS4 mutations may be beneficial during chronic CF lung infections in diverse fungi, perhaps, for the purposes of adaptation to an iron-restricted environment with chronic infections. IMPORTANCE The identification of MRS4 mutations in Clavispora (Candida) lusitaniae and Exophiala dermatitidis in individuals with cystic fibrosis (CF) highlights a possible adaptive mechanism for fungi during chronic CF lung infections. The findings of this study suggest that loss of function of the mitochondrial iron transporter Mrs4 can lead to increased activity of iron acquisition mechanisms, which may be advantageous for fungi in iron-restricted environments during chronic infections. This study provides valuable information for researchers working toward a better understanding of the pathogenesis of chronic lung infections and more effective therapies to treat them.
Collapse
Affiliation(s)
- Daniel Murante
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| | - Elora G. Demers
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| | - Tania Kurbessoian
- Department of Microbiology & Plant Pathology and Institute for Integrative Genome Biology, University of California-Riverside, Riverside, California, USA
| | - Marina Ruzic
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| | - Alix Ashare
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
- Department of Medicine, Dartmouth Health, Lebanon, New Hampshire, USA
| | - Jason E. Stajich
- Department of Microbiology & Plant Pathology and Institute for Integrative Genome Biology, University of California-Riverside, Riverside, California, USA
| | - Deborah A. Hogan
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| |
Collapse
|
6
|
Shepherd RE, Kreinbrink AC, Njimoh CL, Vali SW, Lindahl PA. Yeast Mitochondria Import Aqueous Fe II and, When Activated for Iron-Sulfur Cluster Assembly, Export or Release Low-Molecular-Mass Iron and Also Export Iron That Incorporates into Cytosolic Proteins. J Am Chem Soc 2023. [PMID: 37339084 DOI: 10.1021/jacs.2c13439] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/22/2023]
Abstract
Iron-sulfur cluster (ISC) assembly occurs in both mitochondria and cytosol. Mitochondria are thought to export a low-molecular-mass (LMM) iron and/or sulfur species which is used as a substrate for cytosolic ISC assembly. This species, called X-S or (Fe-S)int, has not been directly detected. Here, an assay was developed in which mitochondria were isolated from 57Fe-enriched cells and incubated in various buffers. Thereafter, mitochondria were separated from the supernatant, and both fractions were investigated by ICP-MS-detected size exclusion liquid chromatography. Aqueous 54FeII in the buffer declined upon exposure to intact 57Fe-enriched mitochondria. Some 54Fe was probably surface-absorbed but some was incorporated into mitochondrial iron-containing proteins when mitochondria were activated for ISC biosynthesis. When activated, mitochondria exported/released two LMM nonproteinaceous iron complexes. One species, which comigrated with an Fe-ATP complex, developed faster than the other Fe species, which also comigrated with phosphorus. Both were enriched in 54Fe and 57Fe, suggesting that the added 54Fe entered a pre-existing pool of 57Fe, which was also the source of the exported species. When 54Fe-loaded 57Fe-enriched mitochondria were mixed with isolated cytosol and activated, multiple cytosolic proteins became enriched with Fe. No incorporation was observed when 54Fe was added directly to the cytosol in the absence of mitochondria. This suggests that a different Fe source in mitochondria, the one enriched mainly with 57Fe, was used to export a species that was ultimately incorporated into cytosolic proteins. Iron from buffer was imported into mitochondria fastest, followed by mitochondrial ISC assembly, LMM iron export, and cytosolic ISC assembly.
Collapse
Affiliation(s)
- Rachel E Shepherd
- Department of Chemistry, Texas A&M University, College Station, Texas 77843-3255, United States
| | - Alexia C Kreinbrink
- Department of Biochemistry and Biophysics, Texas A&M University, College Station Texas 77843, United States
| | - Cybele Lemuh Njimoh
- Department of Biochemistry and Biophysics, Texas A&M University, College Station Texas 77843, United States
| | - Shaik Waseem Vali
- Department of Biochemistry and Biophysics, Texas A&M University, College Station Texas 77843, United States
| | - Paul A Lindahl
- Department of Chemistry, Texas A&M University, College Station, Texas 77843-3255, United States
- Department of Biochemistry and Biophysics, Texas A&M University, College Station Texas 77843, United States
| |
Collapse
|
7
|
XUE P, SÁNCHEZ-LEÓN E, DAMOO D, HU G, JUNG WH, KRONSTAD JW. Heme sensing and trafficking in fungi. FUNGAL BIOL REV 2023; 43:100286. [PMID: 37781717 PMCID: PMC10540271 DOI: 10.1016/j.fbr.2022.09.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Fungal pathogens cause life-threatening diseases in humans, and the increasing prevalence of these diseases emphasizes the need for new targets for therapeutic intervention. Nutrient acquisition during infection is a promising target, and recent studies highlight the contributions of endomembrane trafficking, mitochondria, and vacuoles in the sensing and acquisition of heme by fungi. These studies have been facilitated by genetically encoded biosensors and other tools to quantitate heme in subcellular compartments and to investigate the dynamics of trafficking in living cells. In particular, the applications of biosensors in fungi have been extended beyond the detection of metabolites, cofactors, pH, and redox status to include the detection of heme. Here, we focus on studies that make use of biosensors to examine mechanisms of heme uptake and degradation, with guidance from the model fungus Saccharomyces cerevisiae and an emphasis on the pathogenic fungi Candida albicans and Cryptococcus neoformans that threaten human health. These studies emphasize a role for endocytosis in heme uptake, and highlight membrane contact sites involving mitochondria, the endoplasmic reticulum and vacuoles as mediators of intracellular iron and heme trafficking.
Collapse
Affiliation(s)
- Peng XUE
- Michael Smith Laboratories, Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Eddy SÁNCHEZ-LEÓN
- Michael Smith Laboratories, Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Djihane DAMOO
- Michael Smith Laboratories, Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Guanggan HU
- Michael Smith Laboratories, Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Won Hee JUNG
- Department of Systems Biotechnology, Chung-Ang University, Anseong 17546, Korea
| | - James W. KRONSTAD
- Michael Smith Laboratories, Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada
| |
Collapse
|
8
|
da Silva AA, Galego L, Arraiano CM. New Perspectives on BolA: A Still Mysterious Protein Connecting Morphogenesis, Biofilm Production, Virulence, Iron Metabolism, and Stress Survival. Microorganisms 2023; 11:microorganisms11030632. [PMID: 36985206 PMCID: PMC10051749 DOI: 10.3390/microorganisms11030632] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Revised: 02/09/2023] [Accepted: 02/27/2023] [Indexed: 03/06/2023] Open
Abstract
The BolA-like protein family is widespread among prokaryotes and eukaryotes. BolA was originally described in E. coli as a gene induced in the stationary phase and in stress conditions. The BolA overexpression makes cells spherical. It was characterized as a transcription factor modulating cellular processes such as cell permeability, biofilm production, motility, and flagella assembly. BolA is important in the switch between motile and sedentary lifestyles having connections with the signaling molecule c-di-GMP. BolA was considered a virulence factor in pathogens such as Salmonella Typhimurium and Klebsiella pneumoniae and it promotes bacterial survival when facing stresses due to host defenses. In E. coli, the BolA homologue IbaG is associated with resistance to acidic stress, and in Vibrio cholerae, IbaG is important for animal cell colonization. Recently, it was demonstrated that BolA is phosphorylated and this modification is important for the stability/turnover of BolA and its activity as a transcription factor. The results indicate that there is a physical interaction between BolA-like proteins and the CGFS-type Grx proteins during the biogenesis of Fe-S clusters, iron trafficking and storage. We also review recent progress regarding the cellular and molecular mechanisms by which BolA/Grx protein complexes are involved in the regulation of iron homeostasis in eukaryotes and prokaryotes.
Collapse
|
9
|
Schulz V, Freibert SA, Boss L, Mühlenhoff U, Stehling O, Lill R. Mitochondrial [2Fe-2S] ferredoxins: new functions for old dogs. FEBS Lett 2023; 597:102-121. [PMID: 36443530 DOI: 10.1002/1873-3468.14546] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Revised: 11/23/2022] [Accepted: 11/23/2022] [Indexed: 12/02/2022]
Abstract
Ferredoxins (FDXs) comprise a large family of iron-sulfur proteins that shuttle electrons from NADPH and FDX reductases into diverse biological processes. This review focuses on the structure, function and specificity of mitochondrial [2Fe-2S] FDXs that are related to bacterial FDXs due to their endosymbiotic inheritance. Their classical function in cytochrome P450-dependent steroid transformations was identified around 1960, and is exemplified by mammalian FDX1 (aka adrenodoxin). Thirty years later the essential function in cellular Fe/S protein biogenesis was discovered for the yeast mitochondrial FDX Yah1 that is additionally crucial for the formation of haem a and ubiquinone CoQ6 . In mammals, Fe/S protein biogenesis is exclusively performed by the FDX1 paralog FDX2, despite the high structural similarity of both proteins. Recently, additional and specific roles of human FDX1 in haem a and lipoyl cofactor biosyntheses were described. For lipoyl synthesis, FDX1 transfers electrons to the radical S-adenosyl methionine-dependent lipoyl synthase to kickstart its radical chain reaction. The high target specificity of the two mammalian FDXs is contained within small conserved sequence motifs, that upon swapping change the target selection of these electron donors.
Collapse
Affiliation(s)
- Vinzent Schulz
- Institut für Zytobiologie, Philipps-Universität Marburg, Germany.,Zentrum für Synthetische Mikrobiologie Synmikro, Marburg, Germany
| | - Sven-A Freibert
- Institut für Zytobiologie, Philipps-Universität Marburg, Germany.,Zentrum für Synthetische Mikrobiologie Synmikro, Marburg, Germany
| | - Linda Boss
- Institut für Zytobiologie, Philipps-Universität Marburg, Germany.,Zentrum für Synthetische Mikrobiologie Synmikro, Marburg, Germany
| | - Ulrich Mühlenhoff
- Institut für Zytobiologie, Philipps-Universität Marburg, Germany.,Zentrum für Synthetische Mikrobiologie Synmikro, Marburg, Germany
| | - Oliver Stehling
- Institut für Zytobiologie, Philipps-Universität Marburg, Germany.,Zentrum für Synthetische Mikrobiologie Synmikro, Marburg, Germany
| | - Roland Lill
- Institut für Zytobiologie, Philipps-Universität Marburg, Germany.,Zentrum für Synthetische Mikrobiologie Synmikro, Marburg, Germany
| |
Collapse
|
10
|
Hu Y, Luo Y, Yin D, Zhao L, Wang Y, Yao R, Zhang P, Wu X, Li M, Hidalgo E, Huang Y. Schizosaccharomyces pombe MAP kinase Sty1 promotes survival of Δppr10 cells with defective mitochondrial protein synthesis. Int J Biochem Cell Biol 2022; 152:106308. [PMID: 36174923 DOI: 10.1016/j.biocel.2022.106308] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Revised: 09/09/2022] [Accepted: 09/23/2022] [Indexed: 11/19/2022]
Abstract
Deletion of the Schizosaccharomyces pombe pentatricopeptide repeat gene ppr10 severely impairs mitochondrial translation, resulting in defective oxidative phosphorylation (OXPHOS). ppr10 deletion also induces iron starvation response, resulting in increased reactive oxygen species (ROS) production and reduced viability under fermentative conditions. S. pombe has two principal stress-response pathways, which are mediated by the mitogen-activated protein kinase Sty1 and the basic leucine zipper transcription factor Pap1, respectively. In this study, we examined the roles of Sty1 and Pap1 in the cellular response to the mitochondrial translation defect caused by ppr10 deletion. We found that ppr10 deletion resulted in two waves of stress protein activation. The early response occurred in exponential phase and resulted in the expression of a subset of stress proteins including Gst2 and Obr1. The upregulation of some of these stress proteins in Δppr10 cells in early response is dependent on the basal nuclear levels of Sty1 or Pap1. The late response occurred in early stationary phase and coincided with the stable localization of Sty1 and Pap1 in the nucleus, presumably resulting in persistent activation of a large set of stress proteins. Deletion of sty1 in Δppr10 cells caused severe defects in cell division and growth, and further impaired cell viability. Deletion of the mitochondrial superoxide dismutase gene sod2 whose expression is controlled by Sty1 severely inhibited the growth of Δppr10 cells. Overexpression of sod2 improves the viability of Δppr10 cells. Our results support an important role for Sty1 in counteracting stress induced by ppr10 deletion under fermentative growth conditions.
Collapse
Affiliation(s)
- Yue Hu
- Jiangsu Key Laboratory for Microbes and Functional Genetics, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China
| | - Ying Luo
- Jiangsu Key Laboratory for Microbes and Functional Genetics, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China
| | - Dan Yin
- Jiangsu Key Laboratory for Microbes and Functional Genetics, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China
| | - Lan Zhao
- Jiangsu Key Laboratory for Microbes and Functional Genetics, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China
| | - Yirong Wang
- Jiangsu Key Laboratory for Microbes and Functional Genetics, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China
| | - Rui Yao
- Jiangsu Key Laboratory for Microbes and Functional Genetics, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China
| | - Pan Zhang
- Jiangsu Key Laboratory for Microbes and Functional Genetics, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China
| | - Xiaoyu Wu
- Jiangsu Key Laboratory for Microbes and Functional Genetics, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China
| | - Minjie Li
- Jiangsu Key Laboratory for Microbes and Functional Genetics, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China
| | - Elena Hidalgo
- Departament de Ciènces Experimentals i de la Salut, Universitat Pompeu Fabra, Barcelona, Spain
| | - Ying Huang
- Jiangsu Key Laboratory for Microbes and Functional Genetics, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China.
| |
Collapse
|
11
|
Fernandez S, Wofford JD, Shepherd RE, Vali SW, Dancis A, Lindahl PA. Yeast cells depleted of the frataxin homolog Yfh1 redistribute cellular iron: Studies using Mössbauer spectroscopy and mathematical modeling. J Biol Chem 2022; 298:101921. [PMID: 35413285 PMCID: PMC9130540 DOI: 10.1016/j.jbc.2022.101921] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Revised: 04/05/2022] [Accepted: 04/06/2022] [Indexed: 11/27/2022] Open
Abstract
The neurodegenerative disease Friedreich's ataxia arises from a deficiency of frataxin, a protein that promotes iron-sulfur cluster (ISC) assembly in mitochondria. Here, primarily using Mössbauer spectroscopy, we investigated the iron content of a yeast strain in which expression of yeast frataxin homolog 1 (Yfh1), oxygenation conditions, iron concentrations, and metabolic modes were varied. We found that aerobic fermenting Yfh1-depleted cells grew slowly and accumulated FeIII nanoparticles, unlike WT cells. Under hypoxic conditions, the same mutant cells grew at rates similar to WT cells, had similar iron content, and were dominated by FeII rather than FeIII nanoparticles. Furthermore, mitochondria from mutant hypoxic cells contained approximately the same levels of ISCs as WT cells, confirming that Yfh1 is not required for ISC assembly. These cells also did not accumulate excessive iron, indicating that iron accumulation into yfh1-deficient mitochondria is stimulated by O2. In addition, in aerobic WT cells, we found that vacuoles stored FeIII, whereas under hypoxic fermenting conditions, vacuolar iron was reduced to FeII. Under respiring conditions, vacuoles of Yfh1-deficient cells contained FeIII, and nanoparticles accumulated only under aerobic conditions. Taken together, these results informed a mathematical model of iron trafficking and regulation in cells that could semiquantitatively simulate the Yfh1-deficiency phenotype. Simulations suggested partially independent regulation in which cellular iron import is regulated by ISC activity in mitochondria, mitochondrial iron import is regulated by a mitochondrial FeII pool, and vacuolar iron import is regulated by cytosolic FeII and mitochondrial ISC activity.
Collapse
Affiliation(s)
- Salvador Fernandez
- Department of Chemistry, Texas A&M University, College Station, Texas, USA
| | - Joshua D Wofford
- Department of Chemistry, College of Science and Mathematics, Charleston Southern University, Charleston South Carolina, USA
| | - Rachel E Shepherd
- Department of Chemistry, Texas A&M University, College Station, Texas, USA
| | - Shaik Waseem Vali
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, USA
| | - Andrew Dancis
- Department of Medicine, Division of Hematology-Oncology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Paul A Lindahl
- Department of Chemistry, Texas A&M University, College Station, Texas, USA; Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, USA.
| |
Collapse
|
12
|
Rocamora F, Gupta P, Istvan ES, Luth MR, Carpenter EF, Kümpornsin K, Sasaki E, Calla J, Mittal N, Carolino K, Owen E, Llinás M, Ottilie S, Goldberg DE, Lee MCS, Winzeler EA. PfMFR3: A Multidrug-Resistant Modulator in Plasmodium falciparum. ACS Infect Dis 2021; 7:811-825. [PMID: 33715347 PMCID: PMC8042660 DOI: 10.1021/acsinfecdis.0c00676] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
![]()
In
malaria, chemical genetics is a powerful method for assigning
function to uncharacterized genes. MMV085203 and GNF-Pf-3600 are two
structurally related napthoquinone phenotypic screening hits that
kill both blood- and sexual-stage P. falciparum parasites in the low nanomolar to low micromolar range. In order
to understand their mechanism of action, parasites from two different
genetic backgrounds were exposed to sublethal concentrations of MMV085203
and GNF-Pf-3600 until resistance emerged. Whole genome sequencing
revealed all 17 resistant clones acquired nonsynonymous mutations
in the gene encoding the orphan apicomplexan transporter PF3D7_0312500
(pfmfr3) predicted to encode a member of the major
facilitator superfamily (MFS). Disruption of pfmfr3 and testing against a panel of antimalarial compounds showed decreased
sensitivity to MMV085203 and GNF-Pf-3600 as well as other compounds
that have a mitochondrial mechanism of action. In contrast, mutations
in pfmfr3 provided no protection against compounds
that act in the food vacuole or the cytosol. A dihydroorotate dehydrogenase
rescue assay using transgenic parasite lines, however, indicated a
different mechanism of action for both MMV085203 and GNF-Pf-3600 than
the direct inhibition of cytochrome bc1. Green fluorescent protein
(GFP) tagging of PfMFR3 revealed that it localizes to the parasite
mitochondrion. Our data are consistent with PfMFR3 playing roles in
mitochondrial transport as well as drug resistance for clinically
relevant antimalarials that target the mitochondria. Furthermore,
given that pfmfr3 is naturally polymorphic, naturally
occurring mutations may lead to differential sensitivity to clinically
relevant compounds such as atovaquone.
Collapse
Affiliation(s)
- Frances Rocamora
- Department of Pediatrics, School of Medicine, University of California, San Diego, La Jolla, California 92093, United States
| | - Purva Gupta
- VA San Diego Healthcare System, Medical and Research Sections, La Jolla, California 92161, United States
- Department of Medicine, Division of Pulmonary and Critical Care, University of California, San Diego, La Jolla, California 92037, United States
| | - Eva S. Istvan
- Departments of Medicine and Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri 63130, United States
| | - Madeline R. Luth
- Department of Pediatrics, School of Medicine, University of California, San Diego, La Jolla, California 92093, United States
| | | | | | - Erika Sasaki
- Department of Pediatrics, School of Medicine, University of California, San Diego, La Jolla, California 92093, United States
| | - Jaeson Calla
- Department of Pediatrics, School of Medicine, University of California, San Diego, La Jolla, California 92093, United States
| | - Nimisha Mittal
- Department of Pediatrics, School of Medicine, University of California, San Diego, La Jolla, California 92093, United States
| | - Krypton Carolino
- Department of Pediatrics, School of Medicine, University of California, San Diego, La Jolla, California 92093, United States
| | - Edward Owen
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Huck Center for Malaria Research, Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Manuel Llinás
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Huck Center for Malaria Research, Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Department of Chemistry, Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Sabine Ottilie
- Department of Pediatrics, School of Medicine, University of California, San Diego, La Jolla, California 92093, United States
| | - Daniel E. Goldberg
- Departments of Medicine and Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri 63130, United States
| | | | - Elizabeth A. Winzeler
- Department of Pediatrics, School of Medicine, University of California, San Diego, La Jolla, California 92093, United States
| |
Collapse
|
13
|
Kim JE, Vali SW, Nguyen TQ, Dancis A, Lindahl PA. Mössbauer and LC-ICP-MS investigation of iron trafficking between vacuoles and mitochondria in vma2ΔSaccharomyces cerevisiae. J Biol Chem 2020; 296:100141. [PMID: 33268384 PMCID: PMC7948489 DOI: 10.1074/jbc.ra120.015907] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Revised: 11/24/2020] [Accepted: 12/02/2020] [Indexed: 01/09/2023] Open
Abstract
Vacuoles are acidic organelles that store FeIII polyphosphate, participate in iron homeostasis, and have been proposed to deliver iron to mitochondria for iron–sulfur cluster (ISC) and heme biosynthesis. Vma2Δ cells have dysfunctional V-ATPases, rendering their vacuoles nonacidic. These cells have mitochondria that are iron-dysregulated, suggesting disruption of a putative vacuole-to-mitochondria iron trafficking pathway. To investigate this potential pathway, we examined the iron content of a vma2Δ mutant derived from W303 cells using Mössbauer and EPR spectroscopies and liquid chromatography interfaced with inductively-coupled-plasma mass spectrometry. Relative to WT cells, vma2Δ cells contained WT concentrations of iron but nonheme FeII dominated the iron content of fermenting and respiring vma2Δ cells, indicating that the vacuolar FeIII ions present in WT cells had been reduced. However, vma2Δ cells synthesized WT levels of ISCs/hemes and had normal aconitase activity. The iron content of vma2Δ mitochondria was similar to WT, all suggesting that iron delivery to mitochondria was not disrupted. Chromatograms of cytosolic flow–through solutions exhibited iron species with apparent masses of 600 and 800 Da for WT and vma2∆, respectively. Mutant cells contained high copper concentrations and high concentrations of a species assigned to metallothionein, indicating copper dysregulation. vma2Δ cells from previously studied strain BY4741 exhibited iron-associated properties more consistent with prior studies, suggesting subtle strain differences. Vacuoles with functional V-ATPases appear unnecessary in W303 cells for iron to enter mitochondria and be used in ISC/heme biosynthesis; thus, there appears to be no direct or dedicated vacuole-to-mitochondria iron trafficking pathway. The vma2Δ phenotype may arise from alterations in trafficking of iron directly from cytosol to mitochondria.
Collapse
Affiliation(s)
- Joshua E Kim
- Department of Chemistry, Texas A&M University, College Station, Texas, USA
| | - Shaik Waseem Vali
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, USA
| | - Trang Q Nguyen
- Department of Chemistry, Texas A&M University, College Station, Texas, USA
| | - Andrew Dancis
- Department of Pharmacology, Physiology, and Neuroscience, New Jersey Medical School, Rutgers University, Newark, New Jersey, USA; Division of Hematology-Oncology, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Paul A Lindahl
- Department of Chemistry, Texas A&M University, College Station, Texas, USA; Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, USA.
| |
Collapse
|
14
|
Misslinger M, Hortschansky P, Brakhage AA, Haas H. Fungal iron homeostasis with a focus on Aspergillus fumigatus. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2020; 1868:118885. [PMID: 33045305 DOI: 10.1016/j.bbamcr.2020.118885] [Citation(s) in RCA: 64] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 09/15/2020] [Accepted: 10/01/2020] [Indexed: 02/08/2023]
Abstract
To maintain iron homeostasis, fungi have to balance iron acquisition, storage, and utilization to ensure sufficient supply and to avoid toxic excess of this essential trace element. As pathogens usually encounter iron limitation in the host niche, this metal plays a particular role during virulence. Siderophores are iron-chelators synthesized by most, but not all fungal species to sequester iron extra- and intracellularly. In recent years, the facultative human pathogen Aspergillus fumigatus has become a model for fungal iron homeostasis of siderophore-producing fungal species. This article summarizes the knowledge on fungal iron homeostasis and its links to virulence with a focus on A. fumigatus. It covers mechanisms for iron acquisition, storage, and detoxification, as well as the modes of transcriptional iron regulation and iron sensing in A. fumigatus in comparison to other fungal species. Moreover, potential translational applications of the peculiarities of fungal iron metabolism for treatment and diagnosis of fungal infections is addressed.
Collapse
Affiliation(s)
- Matthias Misslinger
- Institute of Molecular Biology - Biocenter, Medical University of Innsbruck, Innsbruck, Austria
| | - Peter Hortschansky
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology-Hans Knöll Institute (HKI), Jena, Germany
| | - Axel A Brakhage
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology-Hans Knöll Institute (HKI), Jena, Germany; Department Microbiology and Molecular Biology, Institute of Microbiology, Friedrich Schiller University Jena, Jena, Germany
| | - Hubertus Haas
- Institute of Molecular Biology - Biocenter, Medical University of Innsbruck, Innsbruck, Austria.
| |
Collapse
|
15
|
Jain A, Nilatawong P, Mamak N, Jensen LT, Jensen AN. Disruption in iron homeostasis and impaired activity of iron-sulfur cluster containing proteins in the yeast model of Shwachman-Diamond syndrome. Cell Biosci 2020; 10:105. [PMID: 32944219 PMCID: PMC7488397 DOI: 10.1186/s13578-020-00468-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Accepted: 09/04/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Shwachman-Diamond syndrome (SDS) is a congenital disease that affects the bone marrow, skeletal system, and pancreas. The majority of patients with SDS have mutations in the SBDS gene, involved in ribosome biogenesis as well as other processes. A Saccharomyces cerevisiae model of SDS, lacking Sdo1p the yeast orthologue of SBDS, was utilized to better understand the molecular pathogenesis in the development of this disease. RESULTS Deletion of SDO1 resulted in a three-fold over-accumulation of intracellular iron. Phenotypes associated with impaired iron-sulfur (ISC) assembly, up-regulation of the high affinity iron uptake pathway, and reduced activities of ISC containing enzymes aconitase and succinate dehydrogenase, were observed in sdo1∆ yeast. In cells lacking Sdo1p, elevated levels of reactive oxygen species (ROS) and protein oxidation were reduced with iron chelation, using a cell impermeable iron chelator. In addition, the low activity of manganese superoxide dismutase (Sod2p) seen in sdo1∆ cells was improved with iron chelation, consistent with the presence of reactive iron from the ISC assembly pathway. In yeast lacking Sdo1p, the mitochondrial voltage-dependent anion channel (VDAC) Por1p is over-expressed and its deletion limits iron accumulation and increases activity of aconitase and succinate dehydrogenase. CONCLUSIONS We propose that oxidative stress from POR1 over-expression, resulting in impaired activity of ISC containing proteins and disruptions in iron homeostasis, may play a role in disease pathogenesis in SDS patients.
Collapse
Affiliation(s)
- Ayushi Jain
- Department of Pathobiology, Faculty of Science, Mahidol University, 272 Rama 6 Road, Bangkok, 10400 Thailand
| | - Phubed Nilatawong
- Department of Pathobiology, Faculty of Science, Mahidol University, 272 Rama 6 Road, Bangkok, 10400 Thailand
- Division of Biopharmacy, Faculty of Pharmaceutical Sciences, Ubon Ratchathani University, Ubon Ratchathani, 34190 Thailand
| | - Narinrat Mamak
- Toxicology Graduate Program, Faculty of Science, Mahidol University, Bangkok, 10400 Thailand
| | - Laran T. Jensen
- Department of Biochemistry, Faculty of Science, Mahidol University, Bangkok, 10400 Thailand
| | - Amornrat Naranuntarat Jensen
- Department of Pathobiology, Faculty of Science, Mahidol University, 272 Rama 6 Road, Bangkok, 10400 Thailand
- Pathology Information and Learning Center, Department of Pathobiology, Faculty of Science, Mahidol University, Bangkok, 10400 Thailand
- Center of Excellence on Environmental Health and Toxicology (EHT), Bangkok, Thailand
| |
Collapse
|
16
|
Ramos-Alonso L, Romero AM, Martínez-Pastor MT, Puig S. Iron Regulatory Mechanisms in Saccharomyces cerevisiae. Front Microbiol 2020; 11:582830. [PMID: 33013818 PMCID: PMC7509046 DOI: 10.3389/fmicb.2020.582830] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Accepted: 08/20/2020] [Indexed: 12/21/2022] Open
Abstract
Iron is an essential micronutrient for all eukaryotic organisms because it participates as a redox cofactor in many cellular processes. However, excess iron can damage cells since it promotes the generation of reactive oxygen species. The budding yeast Saccharomyces cerevisiae has been used as a model organism to study the adaptation of eukaryotic cells to changes in iron availability. Upon iron deficiency, yeast utilizes two transcription factors, Aft1 and Aft2, to activate the expression of a set of genes known as the iron regulon, which are implicated in iron uptake, recycling and mobilization. Moreover, Aft1 and Aft2 activate the expression of Cth2, an mRNA-binding protein that limits the expression of genes encoding for iron-containing proteins or that participate in iron-using processes. Cth2 contributes to prioritize iron utilization in particular pathways over other highly iron-consuming and non-essential processes including mitochondrial respiration. Recent studies have revealed that iron deficiency also alters many other metabolic routes including amino acid and lipid synthesis, the mitochondrial retrograde response, transcription, translation and deoxyribonucleotide synthesis; and activates the DNA damage and general stress responses. At high iron levels, the yeast Yap5, Msn2, and Msn4 transcription factors activate the expression of a vacuolar iron importer called Ccc1, which is the most important high-iron protecting factor devoted to detoxify excess cytosolic iron that is stored into the vacuole for its mobilization upon scarcity. The complete sequencing and annotation of many yeast genomes is starting to unveil the diversity and evolution of the iron homeostasis network in this species.
Collapse
Affiliation(s)
- Lucía Ramos-Alonso
- Departamento de Biotecnología, Instituto de Agroquímica y Tecnología de Alimentos (IATA), Consejo Superior de Investigaciones Científicas (CSIC), Valencia, Spain
| | - Antonia María Romero
- Departamento de Biotecnología, Instituto de Agroquímica y Tecnología de Alimentos (IATA), Consejo Superior de Investigaciones Científicas (CSIC), Valencia, Spain
| | | | - Sergi Puig
- Departamento de Biotecnología, Instituto de Agroquímica y Tecnología de Alimentos (IATA), Consejo Superior de Investigaciones Científicas (CSIC), Valencia, Spain
| |
Collapse
|
17
|
Martínez-Pastor MT, Puig S. Adaptation to iron deficiency in human pathogenic fungi. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2020; 1867:118797. [PMID: 32663505 DOI: 10.1016/j.bbamcr.2020.118797] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Revised: 06/13/2020] [Accepted: 07/05/2020] [Indexed: 02/08/2023]
Abstract
Iron is an essential micronutrient for virtually all eukaryotic organisms and plays a central role during microbial infections. Invasive fungal diseases are associated with strikingly high rates of mortality, but their impact on human health is usually underestimated. Upon a fungal infection, hosts restrict iron availability in order to limit the growth and virulence of the pathogen. Here, we use two model yeasts, Saccharomyces cerevisiae and Schizosaccharomyces pombe, to delve into the response to iron deficiency of human fungal pathogens, such as Candida glabrata, Candida albicans, Aspergillus fumigatus and Cryptococcus neoformans. Fungi possess common and species-specific mechanisms to acquire iron and to control the response to iron limitation. Upon iron scarcity, fungi activate a wide range of elegant strategies to capture and import exogenous iron, mobilize iron from intracellular stores, and modulate their metabolism to economize and prioritize iron utilization. Hence, iron homeostasis genes represent remarkable virulence factors that can be used as targets for the development of novel antifungal treatments.
Collapse
Affiliation(s)
| | - Sergi Puig
- Departamento de Biotecnología, Instituto de Agroquímica y Tecnología de Alimentos (IATA), Consejo Superior de Investigaciones Científicas (CSIC), Paterna, Valencia, Spain.
| |
Collapse
|
18
|
Interactions of GMP with Human Glrx3 and with Saccharomyces cerevisiae Grx3 and Grx4 Converge in the Regulation of the Gcn2 Pathway. Appl Environ Microbiol 2020; 86:AEM.00221-20. [PMID: 32414791 DOI: 10.1128/aem.00221-20] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Accepted: 04/24/2020] [Indexed: 11/20/2022] Open
Abstract
The human monothiol glutaredoxin Glrx3 (PICOT) is ubiquitously distributed in cytoplasm and nuclei in mammalian cells. Its overexpression has been associated with the development of several types of tumors, whereas its deficiency might cause retardation in embryogenesis. Its exact biological role has not been well resolved, although a function as a chaperone distributing iron/sulfur clusters is currently accepted. Yeast humanization and the use of a mouse library have allowed us to find a new partner for PICOT: the human GMP synthase (hGMPs). Both proteins carry out collaborative functions regarding the downregulation of the Saccharomyces cerevisiae Gcn2 pathway under conditions of nutritional stress. Glrx3/hGMPs interact through conserved residues that bridge iron/sulfur clusters and glutathione. This mechanism is also conserved in budding yeast, whose proteins Grx3/Grx4, along with GUA1 (S. cerevisiae GMPs), also downregulate the integrated stress response (ISR) pathway. The heterologous expression of Glrx3/hGMPs efficiently complements Grx3/Grx4. Moreover, the heterologous expression of Glrx3 efficiently complements the novel participation in chronological life span that has been characterized for both Grx3 and Grx4. Our results underscore that the Glrx3/Grx3/Grx4 family presents an evolutionary and functional conservation in signaling events that is partly related to GMP function and contributes to cell life extension.IMPORTANCE Saccharomyces cerevisiae is an optimal eukaryotic microbial model to study biological processes in higher organisms despite the divergence in evolution. The molecular function of yeast glutaredoxins Grx3 and Grx4 is enormously interesting, since both proteins are required to maintain correct iron homeostasis and an efficient response to oxidative stress. The human orthologous Glrx3 (PICOT) is involved in a number of human diseases, including cancer. Our research expanded its utility to human cells. Yeast has allowed the characterization of GMP synthase as a new interacting partner for Glrx3 and also for yeast Grx3 and Grx4, the complex monothiol glutaredoxins/GMPs that participate in the downregulation of the activity of the Gcn2 stress pathway. This mechanism is conserved in yeast and humans. Here, we also show that this family of glutaredoxins, Grx3/Grx4/Glrx3, also has a function related to life extension.
Collapse
|
19
|
Glia maturation factor-γ regulates murine macrophage iron metabolism and M2 polarization through mitochondrial ROS. Blood Adv 2020; 3:1211-1225. [PMID: 30971398 DOI: 10.1182/bloodadvances.2018026070] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Accepted: 02/16/2019] [Indexed: 12/19/2022] Open
Abstract
In macrophages, cellular iron metabolism status is tightly integrated with macrophage phenotype and associated with mitochondrial function. However, how molecular events regulate mitochondrial activity to integrate regulation of iron metabolism and macrophage phenotype remains unclear. Here, we explored the important role of the actin-regulatory protein glia maturation factor-γ (GMFG) in the regulation of cellular iron metabolism and macrophage phenotype. We found that GMFG was downregulated in murine macrophages by exposure to iron and hydrogen peroxide. GMFG knockdown altered the expression of iron metabolism proteins and increased iron levels in murine macrophages and concomitantly promoted their polarization toward an anti-inflammatory M2 phenotype. GMFG-knockdown macrophages exhibited moderately increased levels of mitochondrial reactive oxygen species (mtROS), which were accompanied by decreased expression of some mitochondrial respiration chain components, including the iron-sulfur cluster assembly scaffold protein ISCU as well as the antioxidant enzymes SOD1 and SOD2. Importantly, treatment of GMFG-knockdown macrophages with the antioxidant N-acetylcysteine reversed the altered expression of iron metabolism proteins and significantly inhibited the enhanced gene expression of M2 macrophage markers, suggesting that mtROS is mechanistically linked to cellular iron metabolism and macrophage phenotype. Finally, GMFG interacted with the mitochondrial membrane ATPase ATAD3A, suggesting that GMFG knockdown-induced mtROS production might be attributed to alteration of mitochondrial function in macrophages. Our findings suggest that GMFG is an important regulator in cellular iron metabolism and macrophage phenotype and could be a novel therapeutic target for modulating macrophage function in immune and metabolic disorders.
Collapse
|
20
|
Jordá T, Romero AM, Perea-García A, Rozès N, Puig S. The lipid composition of yeast cells modulates the response to iron deficiency. Biochim Biophys Acta Mol Cell Biol Lipids 2020; 1865:158707. [PMID: 32251724 DOI: 10.1016/j.bbalip.2020.158707] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2020] [Revised: 03/18/2020] [Accepted: 03/31/2020] [Indexed: 01/19/2023]
Abstract
Iron is a vital micronutrient for all eukaryotes because it participates as a redox cofactor in multiple metabolic pathways, including lipid biosynthesis. In response to iron deficiency, the Saccharomyces cerevisiae iron-responsive transcription factor Aft1 accumulates in the nucleus and activates a set of genes that promote iron acquisition at the cell surface. In this study, we report that yeast cells lacking the transcription factor Mga2, which promotes the expression of the iron-dependent Δ9-fatty acid desaturase Ole1, display a defect in the activation of the iron regulon during the adaptation to iron limitation. Supplementation with exogenous unsaturated fatty acids (UFAs) or OLE1 expression rescues the iron regulon activation defect of mga2Δ cells. These observations and fatty acid measurements suggest that the mga2Δ defect in iron regulon expression is due to low UFA levels. Subcellular localization studies reveal that low UFAs cause a mislocalization of Aft1 protein to the vacuole upon iron deprivation that prevents its nuclear accumulation. These results indicate that Mga2 and Ole1 are essential to maintain the UFA levels required for Aft1-dependent activation of the iron regulon in response to iron deficiency, and directly connect the biosynthesis of fatty acids to the response to iron depletion.
Collapse
Affiliation(s)
- Tania Jordá
- Departamento de Biotecnología, Instituto de Agroquímica y Tecnología de Alimentos (IATA), , Consejo Superior de Investigaciones Científicas (CSIC), Paterna, Valencia, Spain
| | - Antonia María Romero
- Departamento de Biotecnología, Instituto de Agroquímica y Tecnología de Alimentos (IATA), , Consejo Superior de Investigaciones Científicas (CSIC), Paterna, Valencia, Spain
| | - Ana Perea-García
- Departamento de Biotecnología, Instituto de Agroquímica y Tecnología de Alimentos (IATA), , Consejo Superior de Investigaciones Científicas (CSIC), Paterna, Valencia, Spain
| | - Nicolas Rozès
- Departament de Bioquímica i Biotecnología, Facultat d'Enologia, Universitat Rovira i Virgili, Tarragona, Spain
| | - Sergi Puig
- Departamento de Biotecnología, Instituto de Agroquímica y Tecnología de Alimentos (IATA), , Consejo Superior de Investigaciones Científicas (CSIC), Paterna, Valencia, Spain.
| |
Collapse
|
21
|
Chen KL, Ven TN, Crane MM, Brunner MLC, Pun AK, Helget KL, Brower K, Chen DE, Doan H, Dillard-Telm JD, Huynh E, Feng YC, Yan Z, Golubeva A, Hsu RA, Knight R, Levin J, Mobasher V, Muir M, Omokehinde V, Screws C, Tunali E, Tran RK, Valdez L, Yang E, Kennedy SR, Herr AJ, Kaeberlein M, Wasko BM. Loss of vacuolar acidity results in iron-sulfur cluster defects and divergent homeostatic responses during aging in Saccharomyces cerevisiae. GeroScience 2020; 42:749-764. [PMID: 31975050 PMCID: PMC7205917 DOI: 10.1007/s11357-020-00159-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2019] [Accepted: 01/14/2020] [Indexed: 01/31/2023] Open
Abstract
The loss of vacuolar/lysosomal acidity is an early event during aging that has been linked to mitochondrial dysfunction. However, it is unclear how loss of vacuolar acidity results in age-related dysfunction. Through unbiased genetic screens, we determined that increased iron uptake can suppress the mitochondrial respiratory deficiency phenotype of yeast vma mutants, which have lost vacuolar acidity due to genetic disruption of the vacuolar ATPase proton pump. Yeast vma mutants exhibited nuclear localization of Aft1, which turns on the iron regulon in response to iron-sulfur cluster (ISC) deficiency. This led us to find that loss of vacuolar acidity with age in wild-type yeast causes ISC defects and a DNA damage response. Using microfluidics to investigate aging at the single-cell level, we observe grossly divergent trajectories of iron homeostasis within an isogenic and environmentally homogeneous population. One subpopulation of cells fails to mount the expected compensatory iron regulon gene expression program, and suffers progressively severe ISC deficiency with little to no activation of the iron regulon. In contrast, other cells show robust iron regulon activity with limited ISC deficiency, which allows extended passage and survival through a period of genomic instability during aging. These divergent trajectories suggest that iron regulation and ISC homeostasis represent a possible target for aging interventions.
Collapse
Affiliation(s)
- Kenneth L Chen
- Department of Pathology, University of Washington, Seattle, WA, 98195, USA
| | - Toby N Ven
- Department of Pathology, University of Washington, Seattle, WA, 98195, USA
| | - Matthew M Crane
- Department of Pathology, University of Washington, Seattle, WA, 98195, USA
| | | | - Adrian K Pun
- Department of Pathology, University of Washington, Seattle, WA, 98195, USA
| | - Kathleen L Helget
- Department of Biology and Biotechnology, University of Houston-Clear Lake, Houston, TX, 77058, USA
| | - Katherine Brower
- Department of Pathology, University of Washington, Seattle, WA, 98195, USA
| | - Dexter E Chen
- Department of Pathology, University of Washington, Seattle, WA, 98195, USA
| | - Ha Doan
- Department of Pathology, University of Washington, Seattle, WA, 98195, USA
| | | | - Ellen Huynh
- Department of Pathology, University of Washington, Seattle, WA, 98195, USA
| | - Yen-Chi Feng
- Department of Pathology, University of Washington, Seattle, WA, 98195, USA
| | - Zili Yan
- Department of Pathology, University of Washington, Seattle, WA, 98195, USA
| | - Alexandra Golubeva
- Department of Pathology, University of Washington, Seattle, WA, 98195, USA
| | - Roy A Hsu
- Department of Pathology, University of Washington, Seattle, WA, 98195, USA
| | - Raheem Knight
- Department of Pathology, University of Washington, Seattle, WA, 98195, USA
| | - Jessie Levin
- Department of Pathology, University of Washington, Seattle, WA, 98195, USA
| | - Vesal Mobasher
- Department of Pathology, University of Washington, Seattle, WA, 98195, USA
| | - Michael Muir
- Department of Pathology, University of Washington, Seattle, WA, 98195, USA
| | - Victor Omokehinde
- Department of Pathology, University of Washington, Seattle, WA, 98195, USA
| | - Corey Screws
- Department of Pathology, University of Washington, Seattle, WA, 98195, USA
| | - Esin Tunali
- Department of Pathology, University of Washington, Seattle, WA, 98195, USA
| | - Rachael K Tran
- Department of Pathology, University of Washington, Seattle, WA, 98195, USA
| | - Luz Valdez
- Department of Pathology, University of Washington, Seattle, WA, 98195, USA
| | - Edward Yang
- Department of Pathology, University of Washington, Seattle, WA, 98195, USA
| | - Scott R Kennedy
- Department of Pathology, University of Washington, Seattle, WA, 98195, USA
| | - Alan J Herr
- Department of Pathology, University of Washington, Seattle, WA, 98195, USA
| | - Matt Kaeberlein
- Department of Pathology, University of Washington, Seattle, WA, 98195, USA
| | - Brian M Wasko
- Department of Biology and Biotechnology, University of Houston-Clear Lake, Houston, TX, 77058, USA.
| |
Collapse
|
22
|
Gupta M, Outten CE. Iron-sulfur cluster signaling: The common thread in fungal iron regulation. Curr Opin Chem Biol 2020; 55:189-201. [PMID: 32234663 DOI: 10.1016/j.cbpa.2020.02.008] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Revised: 02/02/2020] [Accepted: 02/20/2020] [Indexed: 02/07/2023]
Abstract
Iron homeostasis in fungi involves balancing iron uptake and storage with iron utilization to achieve adequate, nontoxic levels of this essential nutrient. Extensive work in the nonpathogenic yeast Saccharomyces cerevisiae and Schizosaccharomyces pombe has uncovered unique iron regulation networks for each organism that control iron metabolism via distinct molecular mechanisms. However, common themes have emerged from these studies. The activities of all fungal iron-sensing transcription factors characterized to date are regulated via iron-sulfur cluster signaling. Furthermore, glutaredoxins often play a key role in relaying the intracellular iron status to these DNA-binding proteins. Recent work with fungal pathogens, including Candida and Aspergillus species and Cryptococcus neoformans, has revealed novel iron regulation mechanisms, yet similar roles for iron-sulfur clusters and glutaredoxins in iron signaling have been confirmed. This review will focus on these recent discoveries regarding iron regulation pathways in both pathogenic and nonpathogenic fungi.
Collapse
Affiliation(s)
- Malini Gupta
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, SC, USA 29208
| | - Caryn E Outten
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, SC, USA 29208.
| |
Collapse
|
23
|
Li L, Bertram S, Kaplan J, Jia X, Ward DM. The mitochondrial iron exporter genes MMT1 and MMT2 in yeast are transcriptionally regulated by Aft1 and Yap1. J Biol Chem 2020; 295:1716-1726. [PMID: 31896574 PMCID: PMC7008362 DOI: 10.1074/jbc.ra119.011154] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Revised: 12/30/2019] [Indexed: 12/12/2022] Open
Abstract
Budding yeast (Saccharomyces cerevisiae) responds to low cytosolic iron by up-regulating the expression of iron import genes; iron import can reflect iron transport into the cytosol or mitochondria. Mmt1 and Mmt2 are nuclearly encoded mitochondrial proteins that export iron from the mitochondria into the cytosol. Here we report that MMT1 and MMT2 expression is transcriptionally regulated by two pathways: the low-iron-sensing transcription factor Aft1 and the oxidant-sensing transcription factor Yap1. We determined that MMT1 and MMT2 expression is increased under low-iron conditions and decreased when mitochondrial iron import is increased through overexpression of the high-affinity mitochondrial iron importer Mrs3. Moreover, loss of iron-sulfur cluster synthesis induced expression of MMT1 and MMT2 We show that exposure to the oxidant H2O2 induced MMT1 expression but not MMT2 expression and identified the transcription factor Yap1 as being involved in oxidant-mediated MMT1 expression. We defined Aft1- and Yap1-dependent transcriptional sites in the MMT1 promoter that are necessary for low-iron- or oxidant-mediated MMT1 expression. We also found that the MMT2 promoter contains domains that are important for regulating its expression under low-iron conditions, including an upstream region that appears to partially repress expression under low-iron conditions. Our findings reveal that MMT1 and MMT2 are induced under low-iron conditions and that the low-iron regulator Aft1 is required for this induction. We further uncover an Aft1-binding site in the MMT1 promoter sufficient for inducing MMT1 transcription and identify an MMT2 promoter region required for low iron induction.
Collapse
Affiliation(s)
- Liangtao Li
- Department of Pathology, Division of Microbiology and Immunology, University of Utah School of Medicine, Salt Lake City, Utah 84132
| | - Sophie Bertram
- Department of Pathology, Division of Microbiology and Immunology, University of Utah School of Medicine, Salt Lake City, Utah 84132
| | - Jerry Kaplan
- Department of Pathology, Division of Microbiology and Immunology, University of Utah School of Medicine, Salt Lake City, Utah 84132
| | - Xuan Jia
- Department of Pathology, Division of Microbiology and Immunology, University of Utah School of Medicine, Salt Lake City, Utah 84132
| | - Diane M Ward
- Department of Pathology, Division of Microbiology and Immunology, University of Utah School of Medicine, Salt Lake City, Utah 84132.
| |
Collapse
|
24
|
Hughes CE, Coody TK, Jeong MY, Berg JA, Winge DR, Hughes AL. Cysteine Toxicity Drives Age-Related Mitochondrial Decline by Altering Iron Homeostasis. Cell 2020; 180:296-310.e18. [PMID: 31978346 PMCID: PMC7164368 DOI: 10.1016/j.cell.2019.12.035] [Citation(s) in RCA: 112] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2019] [Revised: 11/06/2019] [Accepted: 12/23/2019] [Indexed: 12/21/2022]
Abstract
Mitochondria and lysosomes are functionally linked, and their interdependent decline is a hallmark of aging and disease. Despite the long-standing connection between these organelles, the function(s) of lysosomes required to sustain mitochondrial health remains unclear. Here, working in yeast, we show that the lysosome-like vacuole maintains mitochondrial respiration by spatially compartmentalizing amino acids. Defects in vacuole function result in a breakdown in intracellular amino acid homeostasis, which drives age-related mitochondrial decline. Among amino acids, we find that cysteine is most toxic for mitochondria and show that elevated non-vacuolar cysteine impairs mitochondrial respiration by limiting intracellular iron availability through an oxidant-based mechanism. Cysteine depletion or iron supplementation restores mitochondrial health in vacuole-impaired cells and prevents mitochondrial decline during aging. These results demonstrate that cysteine toxicity is a major driver of age-related mitochondrial deterioration and identify vacuolar amino acid compartmentation as a cellular strategy to minimize amino acid toxicity.
Collapse
Affiliation(s)
- Casey E Hughes
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Troy K Coody
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Mi-Young Jeong
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT 84112, USA; Department of Medicine, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Jordan A Berg
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Dennis R Winge
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT 84112, USA; Department of Medicine, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Adam L Hughes
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT 84112, USA.
| |
Collapse
|
25
|
Su Y, Chen J, Huang Y. Disruption of ppr3, ppr4, ppr6 or ppr10 induces flocculation and filamentous growth in Schizosaccharomyces pombe. FEMS Microbiol Lett 2019; 365:5033677. [PMID: 29878109 DOI: 10.1093/femsle/fny141] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2018] [Accepted: 06/05/2018] [Indexed: 11/14/2022] Open
Abstract
Pentatricopeptide repeat (PPR) proteins are major players in mitochondrial and chloroplast RNA metabolism, which is essential for normal organellar function. The fission yeast Schizosaccharomyces pombe has 10 PPR proteins. We have previously reported that loss of ppr3, ppr4, ppr6 or ppr10 perturbs iron homeostasis leading to accumulation of reactive oxygen species and apoptotic cell death. In the present study, we show that loss of ppr3, ppr4, ppr6 or ppr10 can cause non-sexual flocculation and filamentous growth of cells. Furthermore, expression of a number of genes encoding cell-surface flocculins and cell wall-remodeling enzymes are induced in these ppr-deletion mutants. We also show that Δppr10 cells, and, to a lesser extent, Δppr4 and Δppr6 cells, exhibited increased tolerance to H2O2 toxicity compared with the wild-type strain. Finally, we found that overexpression of genes involved in iron uptake and/or iron homeostasis could cause the flocculation of wild-type cells. Our findings suggest that an elevated level of intracellular iron in the mutant caused by loss of ppr3, ppr4, ppr6 or ppr10 may result in flocculation and filamentous growth in S. pombe.
Collapse
Affiliation(s)
- Yang Su
- Jiangsu Key Laboratory for Microbes and Functional Genetics, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China
| | - Jie Chen
- Jiangsu Key Laboratory for Microbes and Functional Genetics, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China
| | - Ying Huang
- Jiangsu Key Laboratory for Microbes and Functional Genetics, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China
| |
Collapse
|
26
|
Li H, Outten CE. The conserved CDC motif in the yeast iron regulator Aft2 mediates iron-sulfur cluster exchange and protein-protein interactions with Grx3 and Bol2. J Biol Inorg Chem 2019; 24:809-815. [PMID: 31493153 DOI: 10.1007/s00775-019-01705-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Accepted: 08/20/2019] [Indexed: 10/26/2022]
Abstract
The Saccharomyces cerevisiae transcriptional activator Aft1 and its paralog Aft2 respond to iron deficiency by upregulating expression of proteins required for iron uptake at the plasma membrane, vacuolar iron transport, and mitochondrial iron metabolism, with the net result of mobilizing iron from extracellular sources and intracellular stores. Conversely, when iron levels are sufficient, Aft1 and Aft2 interact with the cytosolic glutaredoxins Grx3 and Grx4 and the BolA protein Bol2, which promote Aft1/2 dissociation from DNA and subsequent export from the nucleus. Previous studies unveiled the molecular mechanism for iron-dependent inhibition of Aft1/2 activity, demonstrating that the [2Fe-2S]-bridged Grx3-Bol2 heterodimer transfers a cluster to Aft2, driving Aft2 dimerization and dissociation from DNA. Here, we provide further insight into the regulation mechanism by investigating the roles of conserved cysteines in Aft2 in iron-sulfur cluster binding and interaction with [2Fe-2S]-Grx3-Bol2. Using size exclusion chromatography and circular dichroism spectroscopy, these studies reveal that both cysteines in the conserved Aft2 Cys-Asp-Cys motif are essential for Aft2 dimerization via [2Fe-2S] cluster binding, while only one cysteine is required for interaction with the [2Fe-2S]-Grx3-Bol2 complex. Taken together, these results provide novel insight into the molecular details of iron-sulfur cluster transfer from Grx3-Bol2 to Aft2 which likely occurs through a ligand exchange mechanism. Loss of either cysteine in the Aft2 iron-sulfur binding site may disrupt this ligand-exchange process leading to the isolation of a trapped Aft2-Grx3-Bol2 intermediate, while the replacement of both cysteines abrogates both the iron-sulfur cluster exchange and the protein-protein interactions between Aft2 and Grx3-Bol2.
Collapse
Affiliation(s)
- Haoran Li
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, SC, 29208, USA.,Kymera Therapeutics, Cambridge, MA, 02139, USA
| | - Caryn E Outten
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, SC, 29208, USA.
| |
Collapse
|
27
|
Ramos-Alonso L, Wittmaack N, Mulet I, Martínez-Garay CA, Fita-Torró J, Lozano MJ, Romero AM, García-Ferris C, Martínez-Pastor MT, Puig S. Molecular strategies to increase yeast iron accumulation and resistance. Metallomics 2019; 10:1245-1256. [PMID: 30137082 DOI: 10.1039/c8mt00124c] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
All eukaryotic organisms rely on iron as an essential micronutrient for life because it participates as a redox-active cofactor in multiple biological processes. However, excess iron can generate reactive oxygen species that damage cellular macromolecules. The low solubility of ferric iron under physiological conditions increases the prevalence of iron deficiency anemia. A common strategy to treat iron deficiency consists of dietary iron supplementation. The baker's yeast Saccharomyces cerevisiae is used as a model eukaryotic organism, but also as a feed supplement. In response to iron deficiency, the yeast Aft1 transcription factor activates cellular iron acquisition. However, when constitutively active, Aft1 inhibits growth probably due to iron toxicity. In this report, we have studied the consequences of using hyperactive AFT1 alleles, including AFT1-1UP, to increase yeast iron accumulation. We first characterized the iron sensitivity of cells expressing different constitutively active AFT1 alleles. We rescued the high iron sensitivity conferred by the AFT1 alleles by deleting the sphingolipid signaling kinase YPK1. We observed that the deletion of YPK1 exerts different effects on iron accumulation depending on the AFT1 allele and the environmental iron. Moreover, we determined that the impairment of the high-affinity iron transport system partially rescues the high iron toxicity of AFT1-1UP-expressing cells. Finally, we observed that AFT1-1UP inhibits oxygen consumption through activation of the RNA-binding protein Cth2. Deletion of CTH2 partially rescues the AFT1-1UP negative respiratory effect. Collectively, these results contribute to understand how the Aft1 transcription factor functions and the multiple consequences derived from its constitutive activation.
Collapse
Affiliation(s)
- Lucía Ramos-Alonso
- Departamento de Biotecnología, Instituto de Agroquímica y Tecnología de Alimentos (IATA), Consejo Superior de Investigaciones Científicas (CSIC), Paterna, Valencia, Spain.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
28
|
Ror S, Panwar SL. Sef1-Regulated Iron Regulon Responds to Mitochondria-Dependent Iron-Sulfur Cluster Biosynthesis in Candida albicans. Front Microbiol 2019; 10:1528. [PMID: 31354649 PMCID: PMC6630100 DOI: 10.3389/fmicb.2019.01528] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Accepted: 06/18/2019] [Indexed: 11/13/2022] Open
Abstract
Iron homeostasis mechanisms allow the prime commensal-pathogen Candida albicans to cope with the profound shift in iron levels in the mammalian host. The regulators, Sef1 and Sfu1 influence activation and repression of genes required for iron uptake and acquisition by inducing the expression of iron regulon genes in iron-deplete conditions and inactivating them in iron-replete condition. Our study for the first time shows that C. albicans coordinates the activation of the iron regulon with the mitochondrial use of iron for Fe–S cluster biosynthesis, a cellular process that is connected to cellular iron metabolism. We took advantage of a mutant defective in mitochondrial biogenesis (fzo1Δ/Δ) to assess the aforesaid link as this mutant exhibited sustained expression of the Sef1 iron regulon, signifying an iron-starved state in the mutant. Our analysis demonstrates that mitochondrion is pivotal for regulation of Fe–S cluster synthesis such that the disruption of this cellular process in fzo1Δ/Δ cells lead to excessive mitochondrial iron accumulation and reduced activity of the Fe–S cluster-containing enzyme aconitase. Sef1 responds to defective Fe–S cluster synthesis by regulated changes in its subcellular localization; it was retained in the nucleus resulting in the induced expression of the iron regulon. We predict that the mitochondrial Fe–S assembly generates a molecule that is critical for ensuring iron-responsive transcriptional activation of the Sef1 regulon. All told, our data marks Fe–S biogenesis as a mechanism that meshes cellular iron procurement with mitochondrial iron metabolism resulting in regulating the Sef1 regulon in C. albicans.
Collapse
Affiliation(s)
- Shivani Ror
- Yeast Molecular Genetics Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
| | - Sneh Lata Panwar
- Yeast Molecular Genetics Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
| |
Collapse
|
29
|
Do E, Park S, Li MH, Wang JM, Ding C, Kronstad JW, Jung WH. The mitochondrial ABC transporter Atm1 plays a role in iron metabolism and virulence in the human fungal pathogen Cryptococcus neoformans. Med Mycol 2019; 56:458-468. [PMID: 29420779 DOI: 10.1093/mmy/myx073] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Accepted: 08/17/2017] [Indexed: 12/19/2022] Open
Abstract
Iron-sulfur clusters (ISC) are indispensable cofactors for essential enzymes in various cellular processes. In the model yeast Saccharomyces cerevisiae, the precursor of ISCs is exported from mitochondria via a mitochondrial ABC transporter Atm1 and used for cytosolic and nuclear ISC protein assembly. Although iron homeostasis has been implicated in the virulence of the human fungal pathogen Cryptococcus neoformans, the key components of the ISC biosynthesis pathway need to be fully elucidated. In the current study, a homolog of S. cerevisiae Atm1 was identified in C. neoformans, and its function was characterized. We constructed C. neoformans mutants lacking ATM1 and found that deletion of ATM1 affected mitochondrial functions. Furthermore, we observed diminished activity of the cytosolic ISC-containing protein Leu1 and the heme-containing protein catalase in the atm1 mutant. These results suggested that Atm1 is required for the biosynthesis of ISCs in the cytoplasm as well as heme metabolism in C. neoformans. In addition, the atm1 mutants were avirulent in a murine model of cryptococcosis. Overall, our results demonstrated that Atm1 plays a critical role in iron metabolism and virulence for C. neoformans.
Collapse
Affiliation(s)
- Eunsoo Do
- Department of Systems Biotechnology, Chung-Ang University, Anseong 17546, Korea
| | - Seho Park
- Department of Systems Biotechnology, Chung-Ang University, Anseong 17546, Korea
| | - Ming-Hui Li
- College of Life and Health Sciences, Northeastern University, Shenyang, Liaoning 110015, China
| | - Jia-Mei Wang
- College of Life and Health Sciences, Northeastern University, Shenyang, Liaoning 110015, China
| | - Chen Ding
- College of Life and Health Sciences, Northeastern University, Shenyang, Liaoning 110015, China
| | - James W Kronstad
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Won Hee Jung
- Department of Systems Biotechnology, Chung-Ang University, Anseong 17546, Korea
| |
Collapse
|
30
|
Connecting iron regulation and mitochondrial function in Cryptococcus neoformans. Curr Opin Microbiol 2019; 52:7-13. [PMID: 31085406 DOI: 10.1016/j.mib.2019.04.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Revised: 04/04/2019] [Accepted: 04/05/2019] [Indexed: 12/13/2022]
Abstract
Iron acquisition is essential for the proliferation of microorganisms, and human pathogens such as the fungus Cryptococcus neoformans must use sophisticated uptake mechanisms to overcome host iron sequestration. Iron is of particular interest for C. neoformans because its availability is an important cue for the elaboration of virulence factors. In fungi, extracellular iron is taken up through high affinity, low affinity, siderophore-mediated, and heme uptake pathways, and the details of these mechanisms are under active investigation in C. neoformans. Following uptake, iron is transported to intracellular organelles including mitochondria where it is used in heme biosynthesis and the synthesis of iron-sulfur (Fe-S) cluster precursors. One Fe-S cluster binding protein of note is the monothiol glutaredoxin Grx4 which has emerged as a master regulator of iron sensing in C. neoformans and other fungi through its influence on the expression of proteins for iron uptake or use. The activity of Grx4 likely occurs through interactions with Fe-S clusters and transcription factors known to control expression of the iron-related functions. Although the extent to which Grx4 controls the iron regulatory network is still being investigated in C. neoformans, it is remarkable that it also influences the expression of many genes encoding mitochondrial functions. Coupled with recent studies linking mitochondrial morphology and electron transport to virulence factor elaboration, there is an emerging appreciation of mitochondria as central players in cryptococcal disease.
Collapse
|
31
|
Devaux F, Thiébaut A. The regulation of iron homeostasis in the fungal human pathogen Candida glabrata. MICROBIOLOGY-SGM 2019; 165:1041-1060. [PMID: 31050635 DOI: 10.1099/mic.0.000807] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Iron is an essential element to most microorganisms, yet an excess of iron is toxic. Hence, living cells have to maintain a tight balance between iron uptake and iron consumption and storage. The control of intracellular iron concentrations is particularly challenging for pathogens because mammalian organisms have evolved sophisticated high-affinity systems to sequester iron from microbes and because iron availability fluctuates among the different host niches. In this review, we present the current understanding of iron homeostasis and its regulation in the fungal pathogen Candida glabrata. This yeast is an emerging pathogen which has become the second leading cause of candidemia, a life-threatening invasive mycosis. C. glabrata is relatively poorly studied compared to the closely related model yeast Saccharomyces cerevisiae or to the pathogenic yeast Candida albicans. Still, several research groups have started to identify the actors of C. glabrata iron homeostasis and its transcriptional and post-transcriptional regulation. These studies have revealed interesting particularities of C. glabrata and have shed new light on the evolution of fungal iron homeostasis.
Collapse
Affiliation(s)
- Frédéric Devaux
- Sorbonne Université, CNRS, Institut de Biologie Paris-Seine, Laboratory of Computational and Quantitative Biology, F-75005, Paris, France
| | - Antonin Thiébaut
- Sorbonne Université, CNRS, Institut de Biologie Paris-Seine, Laboratory of Computational and Quantitative Biology, F-75005, Paris, France
| |
Collapse
|
32
|
Dakik P, Medkour Y, Mohammad K, Titorenko VI. Mechanisms Through Which Some Mitochondria-Generated Metabolites Act as Second Messengers That Are Essential Contributors to the Aging Process in Eukaryotes Across Phyla. Front Physiol 2019; 10:461. [PMID: 31057428 PMCID: PMC6482166 DOI: 10.3389/fphys.2019.00461] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Accepted: 04/02/2019] [Indexed: 12/21/2022] Open
Abstract
Recent studies have revealed that some low-molecular weight molecules produced in mitochondria are essential contributing factors to aging and aging-associated pathologies in evolutionarily distant eukaryotes. These molecules are intermediates or products of certain metabolic reactions that are activated in mitochondria in response to specific changes in the nutrient, stress, proliferation, or age status of the cell. After being released from mitochondria, these metabolites directly or indirectly change activities of a distinct set of protein sensors that reside in various cellular locations outside of mitochondria. Because these protein sensors control the efficiencies of some pro- or anti-aging cellular processes, such changes in their activities allow to create a pro- or anti-aging cellular pattern. Thus, mitochondria can function as signaling platforms that respond to certain changes in cell stress and physiology by remodeling their metabolism and releasing a specific set of metabolites known as "mitobolites." These mitobolites then define the pace of cellular and organismal aging because they regulate some longevity-defining processes taking place outside of mitochondria. In this review, we discuss recent progress in understanding mechanisms underlying the ability of mitochondria to function as such signaling platforms in aging and aging-associated diseases.
Collapse
|
33
|
Maio N, Kim KS, Holmes-Hampton G, Singh A, Rouault TA. Dimeric ferrochelatase bridges ABCB7 and ABCB10 homodimers in an architecturally defined molecular complex required for heme biosynthesis. Haematologica 2019; 104:1756-1767. [PMID: 30765471 PMCID: PMC6717564 DOI: 10.3324/haematol.2018.214320] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Accepted: 02/07/2019] [Indexed: 01/23/2023] Open
Abstract
Loss-of-function mutations in the ATP-binding cassette (ABC) transporter of the inner mitochondrial membrane, ABCB7, cause X-linked sideroblastic anemia with ataxia, a phenotype that remains largely unexplained by the proposed role of ABCB7 in exporting a special sulfur species for use in cytosolic iron-sulfur (Fe-S) cluster biogenesis. Here, we generated inducible ABCB7-knockdown cell lines to examine the time-dependent consequences of loss of ABCB7. We found that knockdown of ABCB7 led to significant loss of mitochondrial Fe-S proteins, which preceded the development of milder defects in cytosolic Fe-S enzymes. In erythroid cells, loss of ABCB7 altered cellular iron distribution and caused mitochondrial iron overload due to activation of iron regulatory proteins 1 and 2 in the cytosol and to upregulation of the mitochondrial iron importer, mitoferrin-1. Despite the exceptionally large amount of iron imported into mitochondria, erythroid cells lacking ABCB7 showed a profound hemoglobinization defect and underwent apoptosis triggered by oxidative stress. In ABCB7-depleted cells, defective heme biosynthesis resulted from translational repression of ALAS2 by iron regulatory proteins and from decreased stability of the terminal enzyme ferrochelatase. By combining chemical crosslinking, tandem mass spectrometry and mutational analyses, we characterized a complex formed of ferrochelatase, ABCB7 and ABCB10, and mapped the interfaces of interactions of its components. A dimeric ferrochelatase physically bridged ABCB7 and ABCB10 homodimers by binding near the nucleotide-binding domains of each ABC transporter. Our studies not only underscore the importance of ABCB7 for mitochondrial Fe-S biogenesis and iron homeostasis, but also provide the biochemical characterization of a multiprotein complex required for heme biosynthesis.
Collapse
Affiliation(s)
- Nunziata Maio
- Molecular Medicine Branch, 'Eunice Kennedy Shriver' National Institute of Child Health and Human Development, Bethesda, MD, USA
| | - Ki Soon Kim
- Molecular Medicine Branch, 'Eunice Kennedy Shriver' National Institute of Child Health and Human Development, Bethesda, MD, USA
| | - Gregory Holmes-Hampton
- Molecular Medicine Branch, 'Eunice Kennedy Shriver' National Institute of Child Health and Human Development, Bethesda, MD, USA
| | - Anamika Singh
- Molecular Medicine Branch, 'Eunice Kennedy Shriver' National Institute of Child Health and Human Development, Bethesda, MD, USA
| | - Tracey A Rouault
- Molecular Medicine Branch, 'Eunice Kennedy Shriver' National Institute of Child Health and Human Development, Bethesda, MD, USA
| |
Collapse
|
34
|
Depletion of thiol reducing capacity impairs cytosolic but not mitochondrial iron-sulfur protein assembly machineries. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2019; 1866:240-251. [DOI: 10.1016/j.bbamcr.2018.11.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2018] [Revised: 11/01/2018] [Accepted: 11/06/2018] [Indexed: 02/07/2023]
|
35
|
Shang J, Wu L, Yang Y, Li Y, Liu Z, Huang Y. Overexpression of Schizosaccharomyces pombe tRNA 3′-end processing enzyme Trz2 leads to an increased cellular iron level and apoptotic cell death. Fungal Genet Biol 2019; 122:11-20. [DOI: 10.1016/j.fgb.2018.10.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2017] [Revised: 10/10/2018] [Accepted: 10/23/2018] [Indexed: 01/18/2023]
|
36
|
Misslinger M, Lechner BE, Bacher K, Haas H. Iron-sensing is governed by mitochondrial, not by cytosolic iron-sulfur cluster biogenesis in Aspergillus fumigatus. Metallomics 2018; 10:1687-1700. [PMID: 30395137 PMCID: PMC6250123 DOI: 10.1039/c8mt00263k] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Accepted: 10/09/2018] [Indexed: 12/13/2022]
Abstract
Microorganisms have to adapt their metabolism to the requirements of their ecological niche to avoid iron shortage as well as iron toxicity. Therefore, mechanisms have been evolved to tightly regulate iron uptake, consumption, and detoxification, which depend on sensing the cellular iron status. In the facultative anaerobic yeast Saccharomyces cerevisiae, iron-sensing depends on mitochondrial (ISC) but not cytosolic iron-sulfur cluster assembly (CIA), while in mammals further processing of an ISC product via CIA is required for sensing of the cellular iron state. To address the question of how the obligatory aerobic mold Aspergillus fumigatus senses the cellular iron state, mutant strains allowing the downregulation of ISC and CIA were generated. These studies revealed that: (i) Nfs1 (Afu3g14240) and Nbp35 (Afu2g15960), which are involved in ISC and CIA, respectively, are essential for growth; (ii) a decrease in ISC (Nfs1 depletion) but not CIA (Nbp35 depletion) results in a transcriptional iron starvation response, (iii) a decrease in, ISC as well as CIA, increases the chelatable iron pool, accompanied by increased iron toxicity and increased susceptibility to oxidative stress and phleomycin. In agreement with ISC being essential for iron-sensing, a decrease in mitochondrial iron import by deletion of the mitochondrial iron importer MrsA resulted in an iron starvation response. Taken together, these data underline that iron-sensing in A. fumigatus depends on ISC but not CIA. Moreover, depletion of the glutathione pool via generating a mutant lacking γ-glutamylcysteine synthase, GshA (Afu3g13900), caused an iron starvation response, underlining a crucial role of glutathione in iron-sensing in A. fumigatus.
Collapse
Affiliation(s)
- Matthias Misslinger
- Division of Molecular Biology, Biocenter
, Medical University of Innsbruck
,
Innrain 80
, 6020 Innsbruck
, Austria
.
| | - Beatrix E. Lechner
- Division of Molecular Biology, Biocenter
, Medical University of Innsbruck
,
Innrain 80
, 6020 Innsbruck
, Austria
.
| | - Katharina Bacher
- Division of Molecular Biology, Biocenter
, Medical University of Innsbruck
,
Innrain 80
, 6020 Innsbruck
, Austria
.
| | - Hubertus Haas
- Division of Molecular Biology, Biocenter
, Medical University of Innsbruck
,
Innrain 80
, 6020 Innsbruck
, Austria
.
| |
Collapse
|
37
|
Martins TS, Costa V, Pereira C. Signaling pathways governing iron homeostasis in budding yeast. Mol Microbiol 2018; 109:422-432. [DOI: 10.1111/mmi.14009] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/13/2018] [Indexed: 12/13/2022]
Affiliation(s)
- Telma S. Martins
- I3S-Instituto de Investigação e Inovação em Saúde; Universidade do Porto; Porto Portugal
- IBMC-Instituto de Biologia Molecular e Celular; Universidade do Porto; Porto Portugal
| | - Vítor Costa
- I3S-Instituto de Investigação e Inovação em Saúde; Universidade do Porto; Porto Portugal
- IBMC-Instituto de Biologia Molecular e Celular; Universidade do Porto; Porto Portugal
- Departamento de Biologia Molecular; Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto; Porto Portugal
| | - Clara Pereira
- I3S-Instituto de Investigação e Inovação em Saúde; Universidade do Porto; Porto Portugal
- IBMC-Instituto de Biologia Molecular e Celular; Universidade do Porto; Porto Portugal
- Departamento de Biologia Molecular; Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto; Porto Portugal
| |
Collapse
|
38
|
The Gcn2-eIF2α pathway connects iron and amino acid homeostasis in Saccharomyces cerevisiae. Biochem J 2018; 475:1523-1534. [PMID: 29626156 DOI: 10.1042/bcj20170871] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Revised: 04/01/2018] [Accepted: 04/03/2018] [Indexed: 01/02/2023]
Abstract
In eukaryotic cells, amino acid biosynthesis is feedback-inhibited by amino acids through inhibition of the conserved protein kinase Gcn2. This decreases phosphorylation of initiation factor eIF2α, resulting in general activation of translation but inhibition of translation of mRNA for transcription factor (TF) Gcn4 in yeast or ATF4 in mammals. These TFs are positive regulators of amino acid biosynthetic genes. As several enzymes of amino acid biosynthesis contain iron-sulfur clusters (ISCs) and iron excess is toxic, iron and amino acid homeostasis should be co-ordinated. Working with the yeast Saccharomyces cerevisiae, we found that amino acid supplementation down-regulates expression of genes for iron uptake and decreases intracellular iron content. This cross-regulation requires Aft1, the major TF activated by iron scarcity, as well as Gcn2 and phosphorylatable eIF2α but not Gcn4. A mutant with constitutive activity of Gcn2 (GCN2c ) shows less repression of iron transport genes by amino acids and increased nuclear localization of Aft1 in an iron-poor medium, and increases iron content in this medium. As Aft1 is activated by depletion of mitochondrial ISCs, it is plausible that the Gcn2-eIF2α pathway inhibits the formation of these complexes. Accordingly, the GCN2c mutant has strongly reduced activity of succinate dehydrogenase, an iron-sulfur mitochondrial enzyme, and is unable to grow in media with very low iron or with galactose instead of glucose, conditions where formation of ISCs is specially needed. This mechanism adjusts the uptake of iron to the needs of amino acid biosynthesis and expands the list of Gcn4-independent activities of the Gcn2-eIF2α regulatory system.
Collapse
|
39
|
Gaspar‐Cordeiro A, Marques Caetano S, Amaral C, Rodrigues‐Pousada C, Pimentel C. Ace1 prevents intracellular copper accumulation by regulating Fet3 expression and thereby restricting Aft1 activity. FEBS J 2018; 285:1861-1872. [DOI: 10.1111/febs.14450] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Revised: 02/16/2018] [Accepted: 03/26/2018] [Indexed: 12/31/2022]
Affiliation(s)
- Ana Gaspar‐Cordeiro
- Instituto de Tecnologia Química e Biológica António Xavier Universidade Nova de Lisboa Oeiras Portugal
| | - Soraia Marques Caetano
- Instituto de Tecnologia Química e Biológica António Xavier Universidade Nova de Lisboa Oeiras Portugal
| | - Catarina Amaral
- Instituto de Tecnologia Química e Biológica António Xavier Universidade Nova de Lisboa Oeiras Portugal
| | | | - Catarina Pimentel
- Instituto de Tecnologia Química e Biológica António Xavier Universidade Nova de Lisboa Oeiras Portugal
| |
Collapse
|
40
|
Peña-Diaz P, Lukeš J. Fe-S cluster assembly in the supergroup Excavata. J Biol Inorg Chem 2018; 23:521-541. [PMID: 29623424 PMCID: PMC6006210 DOI: 10.1007/s00775-018-1556-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Accepted: 03/29/2018] [Indexed: 12/21/2022]
Abstract
The majority of established model organisms belong to the supergroup Opisthokonta, which includes yeasts and animals. While enlightening, this focus has neglected protists, organisms that represent the bulk of eukaryotic diversity and are often regarded as primitive eukaryotes. One of these is the “supergroup” Excavata, which comprises unicellular flagellates of diverse lifestyles and contains species of medical importance, such as Trichomonas, Giardia, Naegleria, Trypanosoma and Leishmania. Excavata exhibits a continuum in mitochondrial forms, ranging from classical aerobic, cristae-bearing mitochondria to mitochondria-related organelles, such as hydrogenosomes and mitosomes, to the extreme case of a complete absence of the organelle. All forms of mitochondria house a machinery for the assembly of Fe–S clusters, ancient cofactors required in various biochemical activities needed to sustain every extant cell. In this review, we survey what is known about the Fe–S cluster assembly in the supergroup Excavata. We aim to bring attention to the diversity found in this group, reflected in gene losses and gains that have shaped the Fe–S cluster biogenesis pathways.
Collapse
Affiliation(s)
- Priscila Peña-Diaz
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České Budějovice (Budweis), Czech Republic.
| | - Julius Lukeš
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České Budějovice (Budweis), Czech Republic
- Faculty of Sciences, University of South Bohemia, České Budějovice (Budweis), Czech Republic
| |
Collapse
|
41
|
Cardenas-Rodriguez M, Chatzi A, Tokatlidis K. Iron-sulfur clusters: from metals through mitochondria biogenesis to disease. J Biol Inorg Chem 2018; 23:509-520. [PMID: 29511832 PMCID: PMC6006200 DOI: 10.1007/s00775-018-1548-6] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2017] [Accepted: 02/22/2018] [Indexed: 01/12/2023]
Abstract
Iron–sulfur clusters are ubiquitous inorganic co-factors that contribute to a wide range of cell pathways including the maintenance of DNA integrity, regulation of gene expression and protein translation, energy production, and antiviral response. Specifically, the iron–sulfur cluster biogenesis pathways include several proteins dedicated to the maturation of apoproteins in different cell compartments. Given the complexity of the biogenesis process itself, the iron–sulfur research area constitutes a very challenging and interesting field with still many unaddressed questions. Mutations or malfunctions affecting the iron–sulfur biogenesis machinery have been linked with an increasing amount of disorders such as Friedreich’s ataxia and various cardiomyopathies. This review aims to recap the recent discoveries both in the yeast and human iron–sulfur cluster arena, covering recent discoveries from chemistry to disease.
Collapse
Affiliation(s)
- Mauricio Cardenas-Rodriguez
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Afroditi Chatzi
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Kostas Tokatlidis
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 8QQ, UK.
| |
Collapse
|
42
|
Gerwien F, Skrahina V, Kasper L, Hube B, Brunke S. Metals in fungal virulence. FEMS Microbiol Rev 2018; 42:4562650. [PMID: 29069482 PMCID: PMC5812535 DOI: 10.1093/femsre/fux050] [Citation(s) in RCA: 142] [Impact Index Per Article: 23.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Accepted: 10/19/2017] [Indexed: 12/25/2022] Open
Abstract
Metals are essential for life, and they play a central role in the struggle between infecting microbes and their hosts. In fact, an important aspect of microbial pathogenesis is the 'nutritional immunity', in which metals are actively restricted (or, in an extended definition of the term, locally enriched) by the host to hinder microbial growth and virulence. Consequently, fungi have evolved often complex regulatory networks, uptake and detoxification systems for essential metals such as iron, zinc, copper, nickel and manganese. These systems often differ fundamentally from their bacterial counterparts, but even within the fungal pathogens we can find common and unique solutions to maintain metal homeostasis. Thus, we here compare the common and species-specific mechanisms used for different metals among different fungal species-focusing on important human pathogens such as Candida albicans, Aspergillus fumigatus or Cryptococcus neoformans, but also looking at model fungi such as Saccharomyces cerevisiae or A. nidulans as well-studied examples for the underlying principles. These direct comparisons of our current knowledge reveal that we have a good understanding how model fungal pathogens take up iron or zinc, but that much is still to learn about other metals and specific adaptations of individual species-not the least to exploit this knowledge for new antifungal strategies.
Collapse
Affiliation(s)
- Franziska Gerwien
- Department Microbial Pathogenicity Mechanisms, Leibniz Institute for Natural Product Research and Infection Biology– Hans Knoell Institute, 07745 Jena, Germany
| | - Volha Skrahina
- Department Microbial Pathogenicity Mechanisms, Leibniz Institute for Natural Product Research and Infection Biology– Hans Knoell Institute, 07745 Jena, Germany
| | - Lydia Kasper
- Department Microbial Pathogenicity Mechanisms, Leibniz Institute for Natural Product Research and Infection Biology– Hans Knoell Institute, 07745 Jena, Germany
| | - Bernhard Hube
- Department Microbial Pathogenicity Mechanisms, Leibniz Institute for Natural Product Research and Infection Biology– Hans Knoell Institute, 07745 Jena, Germany
| | - Sascha Brunke
- Department Microbial Pathogenicity Mechanisms, Leibniz Institute for Natural Product Research and Infection Biology– Hans Knoell Institute, 07745 Jena, Germany
| |
Collapse
|
43
|
Abstract
SIGNIFICANCE Glutathione (GSH) is the most abundant cellular low-molecular-weight thiol in the majority of organisms in all kingdoms of life. Therefore, functions of GSH and disturbed regulation of its concentration are associated with numerous physiological and pathological situations. Recent Advances: The function of GSH as redox buffer or antioxidant is increasingly being questioned. New functions, especially functions connected to the cellular iron homeostasis, were elucidated. Via the formation of iron complexes, GSH is an important player in all aspects of iron metabolism: sensing and regulation of iron levels, iron trafficking, and biosynthesis of iron cofactors. The variety of GSH coordinated iron complexes and their functions with a special focus on FeS-glutaredoxins are summarized in this review. Interestingly, GSH analogues that function as major low-molecular-weight thiols in organisms lacking GSH resemble the functions in iron homeostasis. CRITICAL ISSUES Since these iron-related functions are most likely also connected to thiol redox chemistry, it is difficult to distinguish between mechanisms related to either redox or iron metabolisms. FUTURE DIRECTIONS The ability of GSH to coordinate iron in different complexes with or without proteins needs further investigation. The discovery of new Fe-GSH complexes and their physiological functions will significantly advance our understanding of cellular iron homeostasis. Antioxid. Redox Signal. 27, 1235-1251.
Collapse
Affiliation(s)
- Carsten Berndt
- 1 Department of Neurology, Medical Faculty, Life Science Center , Heinrich-Heine-Universität, Düsseldorf, Germany
| | - Christopher Horst Lillig
- 2 Institute for Medical Biochemistry and Molecular Biology, University Medicine Greifswald , Greifswald, Germany
| |
Collapse
|
44
|
Garcia-Santamarina S, Uzarska MA, Festa RA, Lill R, Thiele DJ. Cryptococcus neoformans Iron-Sulfur Protein Biogenesis Machinery Is a Novel Layer of Protection against Cu Stress. mBio 2017; 8:e01742-17. [PMID: 29089435 PMCID: PMC5666163 DOI: 10.1128/mbio.01742-17] [Citation(s) in RCA: 35] [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: 09/21/2017] [Accepted: 10/03/2017] [Indexed: 11/20/2022] Open
Abstract
Copper (Cu) ions serve as catalytic cofactors to drive key biochemical processes, and yet Cu levels that exceed cellular homeostatic control capacity are toxic. The underlying mechanisms for Cu toxicity are poorly understood. During pulmonary infection by the fungal pathogen Cryptococcus neoformans, host alveolar macrophages compartmentalize Cu to the phagosome, and the ability to detoxify Cu is critical for its survival and virulence. Here, we report that iron-sulfur (Fe-S) clusters are critical targets of Cu toxicity in both Saccharomyces cerevisiae and C. neoformans in a manner that depends on the accessibility of Cu to the Fe-S cofactor. To respond to this Cu-dependent Fe-S stress, C. neoformans induces the transcription of mitochondrial ABC transporter Atm1, which functions in cytosolic-nuclear Fe-S protein biogenesis in response to Cu and in a manner dependent on the Cu metalloregulatory transcription factor Cuf1. As Atm1 functions in exporting an Fe-S precursor from the mitochondrial matrix to the cytosol, C. neoformans cells depleted for Atm1 are sensitive to Cu even while the Cu-detoxifying metallothionein proteins are highly expressed. We provide evidence for a previously unrecognized microbial defense mechanism to deal with Cu toxicity, and we highlight the importance for C. neoformans of having several distinct mechanisms for coping with Cu toxicity which together could contribute to the success of this microbe as an opportunistic human fungal pathogen.IMPORTANCEC. neoformans is an opportunistic pathogen that causes lethal meningitis in over 650,000 people annually. The severity of C. neoformans infections is further compounded by the use of toxic or poorly effective systemic antifungal agents as well as by the difficulty of diagnosis. Cu is a natural potent antimicrobial agent that is compartmentalized within the macrophage phagosome and used by innate immune cells to neutralize microbial pathogens. While the Cu detoxification machinery of C. neoformans is essential for virulence, little is known about the mechanisms by which Cu kills fungi. Here we report that Fe-S cluster-containing proteins, including members of the Fe-S protein biogenesis machinery itself, are critical targets of Cu toxicity and therefore that this biosynthetic process provides an important layer of defense against high Cu levels. Given the role of Cu ionophores as antimicrobials, understanding how Cu is toxic to microorganisms could lead to the development of effective, broad-spectrum antimicrobials. Moreover, understanding Cu toxicity could provide additional insights into the pathophysiology of human diseases of Cu overload such as Wilson's disease.
Collapse
Affiliation(s)
| | - Marta A Uzarska
- Institut für Zytobiologie & Zytopathologie, Philipps-Universität, Marburg, Germany
| | - Richard A Festa
- Duke University School of Medicine, Durham, North Carolina, USA
| | - Roland Lill
- Institut für Zytobiologie & Zytopathologie, Philipps-Universität, Marburg, Germany
- LOEWE Zentrum für Synthetische Mikrobiologie SynMikro, Marburg, Germany
| | - Dennis J Thiele
- Duke University School of Medicine, Durham, North Carolina, USA
- Department of Pharmacology and Cancer Biology, Department of Biochemistry, Duke University School of Medicine, Durham, North Carolina, USA
- Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, North Carolina, USA
| |
Collapse
|
45
|
Vallières C, Holland SL, Avery SV. Mitochondrial Ferredoxin Determines Vulnerability of Cells to Copper Excess. Cell Chem Biol 2017; 24:1228-1237.e3. [PMID: 28867595 PMCID: PMC5654725 DOI: 10.1016/j.chembiol.2017.08.005] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Revised: 03/02/2017] [Accepted: 08/01/2017] [Indexed: 01/17/2023]
Abstract
The essential micronutrient copper is tightly regulated in organisms, as environmental exposure or homeostasis defects can cause toxicity and neurodegenerative disease. The principal target(s) of copper toxicity have not been pinpointed, but one key effect is impaired supply of iron-sulfur (FeS) clusters to the essential protein Rli1 (ABCE1). Here, to find upstream FeS biosynthesis/delivery protein(s) responsible for this, we compared copper sensitivity of yeast-overexpressing candidate targets. Overexpression of the mitochondrial ferredoxin Yah1 produced copper hyper-resistance. 55Fe turnover assays revealed that FeS integrity of Yah1 was particularly vulnerable to copper among the test proteins. Furthermore, destabilization of the FeS domain of Yah1 produced copper hypersensitivity, and YAH1 overexpression rescued Rli1 dysfunction. This copper-resistance function was conserved in the human ferredoxin, Fdx2. The data indicate that the essential mitochondrial ferredoxin is an important copper target, determining a tipping point where plentiful copper supply becomes excessive. This knowledge could help in tackling copper-related diseases.
Collapse
Affiliation(s)
- Cindy Vallières
- School of Life Sciences, University of Nottingham, University Park, Nottingham NG7 2RD, UK
| | - Sara L Holland
- School of Life Sciences, University of Nottingham, University Park, Nottingham NG7 2RD, UK
| | - Simon V Avery
- School of Life Sciences, University of Nottingham, University Park, Nottingham NG7 2RD, UK.
| |
Collapse
|
46
|
Xue Y, Schmollinger S, Attar N, Campos OA, Vogelauer M, Carey MF, Merchant SS, Kurdistani SK. Endoplasmic reticulum-mitochondria junction is required for iron homeostasis. J Biol Chem 2017. [PMID: 28637866 DOI: 10.1074/jbc.m117.784249] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The endoplasmic reticulum (ER)-mitochondria encounter structure (ERMES) is a protein complex that physically tethers the two organelles to each other and creates the physical basis for communication between them. ERMES functions in lipid exchange between the ER and mitochondria, protein import into mitochondria, and maintenance of mitochondrial morphology and genome. Here, we report that ERMES is also required for iron homeostasis. Loss of ERMES components activates an Aft1-dependent iron deficiency response even in iron-replete conditions, leading to accumulation of excess iron inside the cell. This function is independent of known ERMES roles in calcium regulation, phospholipid biosynthesis, or effects on mitochondrial morphology. A mutation in the vacuolar protein sorting 13 (VPS13) gene that rescues the glycolytic phenotype of ERMES mutants suppresses the iron deficiency response and iron accumulation. Our findings reveal that proper communication between the ER and mitochondria is required for appropriate maintenance of cellular iron levels.
Collapse
Affiliation(s)
- Yong Xue
- From the Department of Biological Chemistry.,Jiangsu Key Laboratory of Marine Pharmaceutical Compound Screening, Huaihai Institute of Technology, Lianyungang 222005, China
| | - Stefan Schmollinger
- Institute for Genomics and Proteomics, Department of Chemistry and Biochemistry, UCLA, Los Angeles, California 90095 and
| | - Narsis Attar
- From the Department of Biological Chemistry.,Molecular Biology Institute, and
| | - Oscar A Campos
- From the Department of Biological Chemistry.,Molecular Biology Institute, and
| | | | - Michael F Carey
- From the Department of Biological Chemistry.,Molecular Biology Institute, and
| | - Sabeeha S Merchant
- Institute for Genomics and Proteomics, Department of Chemistry and Biochemistry, UCLA, Los Angeles, California 90095 and
| | - Siavash K Kurdistani
- From the Department of Biological Chemistry, .,Molecular Biology Institute, and.,Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, David Geffen School of Medicine, and
| |
Collapse
|
47
|
Mechanisms of iron sensing and regulation in the yeast Saccharomyces cerevisiae. World J Microbiol Biotechnol 2017; 33:75. [DOI: 10.1007/s11274-017-2215-8] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Accepted: 01/18/2017] [Indexed: 01/11/2023]
|
48
|
Central roles of iron in the regulation of oxidative stress in the yeast Saccharomyces cerevisiae. Curr Genet 2017; 63:895-907. [DOI: 10.1007/s00294-017-0689-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Revised: 02/24/2017] [Accepted: 02/26/2017] [Indexed: 12/21/2022]
|
49
|
Pujol-Carrion N, Torre-Ruiz MADL. Physical interaction between the MAPK Slt2 of the PKC1-MAPK pathway and Grx3/Grx4 glutaredoxins is required for the oxidative stress response in budding yeast. Free Radic Biol Med 2017; 103:107-120. [PMID: 28007574 DOI: 10.1016/j.freeradbiomed.2016.12.023] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Revised: 12/02/2016] [Accepted: 12/18/2016] [Indexed: 01/20/2023]
Abstract
This study demonstrates that both monothiol glutaredoxins Grx3 and Grx4 physically interact with the MAPK Slt2 forming a complex involved in the cellular response to oxidative stress. The simultaneous absence of Grx3 and Grx4 provokes a serious impairment in cell viability, Slt2 activation and Rlm1 transcription in response to oxidative stress. Both in vivo and in vitro results clearly show that Slt2 can independently bind either Grx3 or Grx4 proteins. Our results suggest that Slt2 form iron/sulphur bridged clusters with Grx3 and Grx4. For the assembly of this complex, cysteines of the active site of each Grx3/4 glutaredoxins, glutathione and specific cysteine residues from Slt2 provide the ligands. One of the ligands of Slt2 is required for its dimerisation upon oxidative treatment and iron repletion. These interactions are relevant for the oxidative response, given that mutants in the cysteine ligands identified in the complex show a severe impairment of both cell viability and Slt2 phosphorylation upon oxidative stress. Grx4 is the relevant glutaredoxin that regulates Slt2 phosphorylation under oxidative conditions precluding cell survival. Our studies contribute to extend the functions of both monothiol glutaredoxins to the regulation of a MAPK in the context of the oxidative stress response.
Collapse
Affiliation(s)
- Nuria Pujol-Carrion
- Department of Basic Medical Sciences, IRB-Lleida. University of Lleida, Av. Alcalde Rovira Roure no 80, 25198 Lleida, Spain
| | - Maria Angeles de la Torre-Ruiz
- Department of Basic Medical Sciences, IRB-Lleida. University of Lleida, Av. Alcalde Rovira Roure no 80, 25198 Lleida, Spain.
| |
Collapse
|
50
|
Pang CNI, Lai YW, Campbell LT, Chen SCA, Carter DA, Wilkins MR. Transcriptome and network analyses in Saccharomyces cerevisiae reveal that amphotericin B and lactoferrin synergy disrupt metal homeostasis and stress response. Sci Rep 2017; 7:40232. [PMID: 28079179 PMCID: PMC5228129 DOI: 10.1038/srep40232] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Accepted: 12/02/2016] [Indexed: 12/16/2022] Open
Abstract
Invasive fungal infections are difficult to treat. The few available antifungal drugs have problems with toxicity or efficacy, and resistance is increasing. To overcome these challenges, existing therapies may be enhanced by synergistic combination with another agent. Previously, we found amphotericin B (AMB) and the iron chelator, lactoferrin (LF), were synergistic against a range of different fungal pathogens. This study investigates the mechanism of AMB-LF synergy, using RNA-seq and network analyses. AMB treatment resulted in increased expression of genes involved in iron homeostasis and ATP synthesis. Unexpectedly, AMB-LF treatment did not lead to increased expression of iron and zinc homeostasis genes. However, genes involved in adaptive response to zinc deficiency and oxidative stress had decreased expression. The clustering of co-expressed genes and network analysis revealed that many iron and zinc homeostasis genes are targets of transcription factors Aft1p and Zap1p. The aft1Δ and zap1Δ mutants were hypersensitive to AMB and H2O2, suggesting they are key regulators of the drug response. Mechanistically, AMB-LF synergy could involve AMB affecting the integrity of the cell wall and membrane, permitting LF to disrupt intracellular processes. We suggest that Zap1p- and Aft1p-binding molecules could be combined with existing antifungals to serve as synergistic treatments.
Collapse
Affiliation(s)
- Chi Nam Ignatius Pang
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Kensington, New South Wales, Australia
| | - Yu-Wen Lai
- School of Life and Environmental Sciences, University of Sydney, Sydney, New South Wales, Australia
| | - Leona T Campbell
- School of Life and Environmental Sciences, University of Sydney, Sydney, New South Wales, Australia
| | - Sharon C-A Chen
- Marie Bashir Institute for Infectious Diseases and Biosecurity, University of Sydney, Sydney, NSW, Australia.,Centre for Infectious Diseases and Microbiology, Institute of Clinical Pathology and Medical Research, Westmead Hospital, Sydney Medical School, University of Sydney, Westmead, NSW, Australia
| | - Dee A Carter
- School of Life and Environmental Sciences, University of Sydney, Sydney, New South Wales, Australia.,Marie Bashir Institute for Infectious Diseases and Biosecurity, University of Sydney, Sydney, NSW, Australia
| | - Marc R Wilkins
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Kensington, New South Wales, Australia
| |
Collapse
|