1
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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.
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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
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2
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Higdon AL, Won NH, Brar GA. Truncated protein isoforms generate diversity of protein localization and function in yeast. Cell Syst 2024; 15:388-408.e4. [PMID: 38636458 PMCID: PMC11075746 DOI: 10.1016/j.cels.2024.03.005] [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: 06/23/2023] [Revised: 01/21/2024] [Accepted: 03/20/2024] [Indexed: 04/20/2024]
Abstract
Genome-wide measurement of ribosome occupancy on mRNAs has enabled empirical identification of translated regions, but high-confidence detection of coding regions that overlap annotated coding regions has remained challenging. Here, we report a sensitive and robust algorithm that revealed the translation of 388 N-terminally truncated proteins in budding yeast-more than 30-fold more than previously known. We extensively experimentally validated them and defined two classes. The first class lacks large portions of the annotated protein and tends to be produced from a truncated transcript. We show that two such cases, Yap5truncation and Pus1truncation, have condition-specific regulation and distinct functions from their respective annotated isoforms. The second class of truncated protein isoforms lacks only a small region of the annotated protein and is less likely to be produced from an alternative transcript isoform. Many display different subcellular localizations than their annotated counterpart, representing a common strategy for dual localization of otherwise functionally identical proteins. A record of this paper's transparent peer review process is included in the supplemental information.
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Affiliation(s)
- Andrea L Higdon
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA; Center for Computational Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Nathan H Won
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Gloria A Brar
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA; Center for Computational Biology, University of California, Berkeley, Berkeley, CA 94720, USA.
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3
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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.
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Affiliation(s)
- Paul A Lindahl
- Departments of Chemistry and of Biochemistry and Biophysics, Texas A&M University, College Station, TX, USA.
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4
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Pijuan J, Moreno DF, Yahya G, Moisa M, Ul Haq I, Krukiewicz K, Mosbah R, Metwally K, Cavalu S. Regulatory and pathogenic mechanisms in response to iron deficiency and excess in fungi. Microb Biotechnol 2023; 16:2053-2071. [PMID: 37804207 PMCID: PMC10616654 DOI: 10.1111/1751-7915.14346] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Revised: 09/14/2023] [Accepted: 09/19/2023] [Indexed: 10/09/2023] Open
Abstract
Iron is an essential element for all eukaryote organisms because of its redox properties, which are important for many biological processes such as DNA synthesis, mitochondrial respiration, oxygen transport, lipid, and carbon metabolism. For this reason, living organisms have developed different strategies and mechanisms to optimally regulate iron acquisition, transport, storage, and uptake in different environmental responses. Moreover, iron plays an essential role during microbial infections. Saccharomyces cerevisiae has been of key importance for decrypting iron homeostasis and regulation mechanisms in eukaryotes. Specifically, the transcription factors Aft1/Aft2 and Yap5 regulate the expression of genes to control iron metabolism in response to its deficiency or excess, adapting to the cell's iron requirements and its availability in the environment. We also review which iron-related virulence factors have the most common fungal human pathogens (Aspergillus fumigatus, Cryptococcus neoformans, and Candida albicans). These factors are essential for adaptation in different host niches during pathogenesis, including different fungal-specific iron-uptake mechanisms. While being necessary for virulence, they provide hope for developing novel antifungal treatments, which are currently scarce and usually toxic for patients. In this review, we provide a compilation of the current knowledge about the metabolic response to iron deficiency and excess in fungi.
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Affiliation(s)
- Jordi Pijuan
- Laboratory of Neurogenetics and Molecular MedicineInstitut de Recerca Sant Joan de DéuBarcelonaSpain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), ISCIIIMadridSpain
| | - David F. Moreno
- Department of Molecular Cellular and Developmental BiologyYale UniversityNew HavenConnecticutUSA
- Systems Biology InstituteYale UniversityWest HavenConnecticutUSA
- Institut de Génétique et de Biologie Moléculaire et CellulaireIllkirchFrance
| | - Galal Yahya
- Department of Microbiology and Immunology, Faculty of PharmacyZagazig UniversityAl SharqiaEgypt
| | - Mihaela Moisa
- Faculty of Medicine and PharmacyUniversity of OradeaOradeaRomania
| | - Ihtisham Ul Haq
- Department of Physical Chemistry and Polymers TechnologySilesian University of TechnologyGliwicePoland
- Programa de Pós‐graduação em Inovação TecnológicaUniversidade Federal de Minas GeraisBelo HorizonteBrazil
| | - Katarzyna Krukiewicz
- Department of Physical Chemistry and Polymers TechnologySilesian University of TechnologyGliwicePoland
- Centre for Organic and Nanohybrid ElectronicsSilesian University of TechnologyGliwicePoland
| | - Rasha Mosbah
- Infection Control UnitHospitals of Zagazig UniversityZagazigEgypt
| | - Kamel Metwally
- Department of Medicinal Chemistry, Faculty of PharmacyUniversity of TabukTabukSaudi Arabia
- Department of Pharmaceutical Medicinal Chemistry, Faculty of PharmacyZagazig UniversityZagazigEgypt
| | - Simona Cavalu
- Faculty of Medicine and PharmacyUniversity of OradeaOradeaRomania
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5
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Van Genechten W, Vergauwen R, Van Dijck P. The intricate link between iron, mitochondria and azoles in Candida species. FEBS J 2023. [PMID: 37846606 DOI: 10.1111/febs.16977] [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] [Received: 05/21/2023] [Revised: 09/19/2023] [Accepted: 10/13/2023] [Indexed: 10/18/2023]
Abstract
Invasive fungal infections are rapidly increasing, and the opportunistic pathogenic Candida species are the fourth most common cause of nosocomial systemic infections. The current antifungal classes, of which azoles are the most widely used, all have shortcomings. Azoles are generally considered fungistatic rather than fungicidal, they do not actively kill fungal cells and therefore resistance against azoles can be rapidly acquired. Combination therapies with azoles provide an interesting therapeutic outlook and agents limiting iron are excellent candidates. We summarize how iron is acquired by the host and transported towards both storage and iron-utilizing organelles. We indicate whether these pathways alter azole susceptibility and/or tolerance, to finally link these transport mechanisms to mitochondrial iron availability. In this review, we highlight putative novel intracellular iron shuffling mechanisms and indicate that mitochondrial iron dynamics in relation to azole treatment and iron limitation is a significant knowledge gap.
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Affiliation(s)
- Wouter Van Genechten
- Laboratory of Molecular Cell Biology, Department of Biology, Institute of Botany and Microbiology, KU Leuven, Belgium
| | - Rudy Vergauwen
- Laboratory of Molecular Cell Biology, Department of Biology, Institute of Botany and Microbiology, KU Leuven, Belgium
| | - Patrick Van Dijck
- Laboratory of Molecular Cell Biology, Department of Biology, Institute of Botany and Microbiology, KU Leuven, Belgium
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6
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Higdon AL, Won NH, Brar GA. Truncated protein isoforms generate diversity of protein localization and function in yeast. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.13.548938. [PMID: 37503254 PMCID: PMC10369987 DOI: 10.1101/2023.07.13.548938] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
Genome-wide measurements of ribosome occupancy on mRNA transcripts have enabled global empirical identification of translated regions. These approaches have revealed an unexpected diversity of protein products, but high-confidence identification of new coding regions that entirely overlap annotated coding regions - including those that encode truncated protein isoforms - has remained challenging. Here, we develop a sensitive and robust algorithm focused on identifying N-terminally truncated proteins genome-wide, identifying 388 truncated protein isoforms, a more than 30-fold increase in the number known in budding yeast. We perform extensive experimental validation of these truncated proteins and define two general classes. The first set lack large portions of the annotated protein sequence and tend to be produced from a truncated transcript. We show two such cases, Yap5 truncation and Pus1 truncation , to have condition-specific regulation and functions that appear distinct from their respective annotated isoforms. The second set of N-terminally truncated proteins lack only a small region of the annotated protein and are less likely to be regulated by an alternative transcript isoform. Many localize to different subcellular compartments than their annotated counterpart, representing a common strategy for achieving dual localization of otherwise functionally identical proteins.
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7
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Analysis of Pneumocystis Transcription Factor Evolution and Implications for Biology and Lifestyle. mBio 2023; 14:e0271122. [PMID: 36651897 PMCID: PMC9973273 DOI: 10.1128/mbio.02711-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Pneumocystis jirovecii kills hundreds of thousands of immunocompromised patients each year. Yet many aspects of the biology of this obligate pathogen remain obscure because it is not possible to culture the fungus in vitro independently of its host. Consequently, our understanding of Pneumocystis pathobiology is heavily reliant upon bioinformatic inferences. We have exploited a powerful combination of genomic and phylogenetic approaches to examine the evolution of transcription factors in Pneumocystis species. We selected protein families (Pfam families) that correspond to transcriptional regulators and used bioinformatic approaches to compare these families in the seven Pneumocystis species that have been sequenced to date with those from other yeasts, other human and plant pathogens, and other obligate parasites. Some Pfam families of transcription factors have undergone significant reduction during their evolution in the Pneumocystis genus, and other Pfam families have been lost or appear to be in the process of being lost. Meanwhile, other transcription factor families have been retained in Pneumocystis species, and some even appear to have undergone expansion. On this basis, Pneumocystis species seem to have retained transcriptional regulators that control chromosome maintenance, ribosomal gene regulation, RNA processing and modification, and respiration. Meanwhile, regulators that promote the assimilation of alternative carbon sources, amino acid, lipid, and sterol biosynthesis, and iron sensing and homeostasis appear to have been lost. Our analyses of transcription factor retention, loss, and gain provide important insights into the biology and lifestyle of Pneumocystis. IMPORTANCE Pneumocystis jirovecii is a major fungal pathogen of humans that infects healthy individuals, colonizing the lungs of infants. In immunocompromised and transplant patients, this fungus causes life-threatening pneumonia, and these Pneumocystis infections remain among the most common and serious infections in HIV/AIDS patients. Yet we remain remarkably ignorant about the biology and epidemiology of Pneumocystis due to the inability to culture this fungus in vitro. Our analyses of transcription factor retentions, losses, and gains in sequenced Pneumocystis species provide valuable new views of their specialized biology, suggesting the retention of many metabolic and stress regulators and the loss of others that are essential in free-living fungi. Given the lack of in vitro culture methods for Pneumocystis, this powerful bioinformatic approach has advanced our understanding of the lifestyle of P. jirovecii and the nature of its dependence on the host for survival.
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8
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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.
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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
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9
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Lindahl PA, Vali SW. Mössbauer-based molecular-level decomposition of the Saccharomyces cerevisiae ironome, and preliminary characterization of isolated nuclei. Metallomics 2022; 14:mfac080. [PMID: 36214417 PMCID: PMC9624242 DOI: 10.1093/mtomcs/mfac080] [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: 06/22/2022] [Accepted: 09/23/2022] [Indexed: 11/25/2022]
Abstract
One hundred proteins in Saccharomyces cerevisiae are known to contain iron. These proteins are found mainly in mitochondria, cytosol, nuclei, endoplasmic reticula, and vacuoles. Cells also contain non-proteinaceous low-molecular-mass labile iron pools (LFePs). How each molecular iron species interacts on the cellular or systems' level is underdeveloped as doing so would require considering the entire iron content of the cell-the ironome. In this paper, Mössbauer (MB) spectroscopy was used to probe the ironome of yeast. MB spectra of whole cells and isolated organelles were predicted by summing the spectral contribution of each iron-containing species in the cell. Simulations required input from published proteomics and microscopy data, as well as from previous spectroscopic and redox characterization of individual iron-containing proteins. Composite simulations were compared to experimentally determined spectra. Simulated MB spectra of non-proteinaceous iron pools in the cell were assumed to account for major differences between simulated and experimental spectra of whole cells and isolated mitochondria and vacuoles. Nuclei were predicted to contain ∼30 μM iron, mostly in the form of [Fe4S4] clusters. This was experimentally confirmed by isolating nuclei from 57Fe-enriched cells and obtaining the first MB spectra of the organelle. This study provides the first semi-quantitative estimate of all concentrations of iron-containing proteins and non-proteinaceous species in yeast, as well as a novel approach to spectroscopically characterizing LFePs.
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Affiliation(s)
- Paul A Lindahl
- Department of Chemistry, Texas A&M University, College Station, TX,USA
- Department of Biochemistry and Biophysics, Texas A&M University, College Station TX,USA
| | - Shaik Waseem Vali
- Department of Chemistry, Texas A&M University, College Station, TX,USA
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10
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Fontenot CR, Ding H. Ferric uptake regulators (Fur) from Vibrio cholerae and Helicobacter pylori bind a [2Fe-2S] cluster in response to elevation of intracellular free iron content. Biometals 2022; 35:591-600. [PMID: 35353296 DOI: 10.1007/s10534-022-00390-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Accepted: 03/14/2022] [Indexed: 11/28/2022]
Abstract
Intracellular iron homeostasis in bacteria is primarily regulated by ferric uptake regulator (Fur). Since its discovery, Fur has been assumed to bind ferrous iron and regulate expression of target genes. However, the iron-bound Fur has never been isolated from any bacteria. In previous studies, we have shown that Escherichia coli Fur and Haemophilus influenzae Fur bind a [2Fe-2S] cluster via the conserved Cys-93 and Cys-96 when expressed in the E. coli mutant cells in which intracellular free iron content is elevated. Here we report that Fur homologs from Vibrio cholerae and Helicobacter pylori which contain Cys-93 and Cys-96 can also bind a [2Fe-2S] cluster. On the other hand, Fur homolog from Magnetospirillum gryphiswaldense MSR-1 which has no cysteine residues fails to bind any [2Fe-2S] clusters. Interestingly, different Fur proteins with the conserved Cys-93 and Cys-96 have distinct binding activities for the [2Fe-2S] cluster, with H. influenzae Fur having the highest, followed by E. coli Fur, V. cholera Fur, and H. pylori Fur. Binding of the [2Fe-2S] cluster in the Fur proteins is significantly decreased when expressed in wild-type E. coli cells, indicating that binding of the [2Fe-2S] clusters in Fur proteins is regulated by the levels of intracellular free iron content. Finally, unlike the [2Fe-2S] clusters in E. coli ferredoxin, the [2Fe-2S] clusters in the Fur proteins are not stable and quickly release ferrous iron when the clusters are reduced, suggesting that Fur may undergo reversible binding of the [2Fe-2S] cluster in response to intracellular free iron content in bacteria.
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Affiliation(s)
- Chelsey R Fontenot
- Department of Biological Sciences Building, Louisiana State University, Baton Rouge, LA, 70803, USA
| | - Huangen Ding
- Department of Biological Sciences Building, Louisiana State University, Baton Rouge, LA, 70803, USA.
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11
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Delaveau T, Thiébaut A, Benchouaia M, Merhej J, Devaux F. Yap5 Competes With Hap4 for the Regulation of Iron Homeostasis Genes in the Human Pathogen Candida glabrata. Front Cell Infect Microbiol 2021; 11:731988. [PMID: 34900750 PMCID: PMC8662346 DOI: 10.3389/fcimb.2021.731988] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Accepted: 11/10/2021] [Indexed: 11/18/2022] Open
Abstract
The CCAAT-binding complex (CBC) is a conserved heterotrimeric transcription factor which, in fungi, requires additional regulatory subunits to act on transcription. In the pathogenic yeast Candida glabrata, CBC has a dual role. Together with the Hap4 regulatory subunit, it activates the expression of genes involved in respiration upon growth with non-fermentable carbon sources, while its association with the Yap5 regulatory subunit is required for the activation of iron tolerance genes in response to iron excess. In the present work, we investigated further the interplay between CBC, Hap4 and Yap5. We showed that Yap5 regulation requires a specific Yap Response Element in the promoter of its target gene GRX4 and that the presence of Yap5 considerably strengthens the binding of CBC to the promoters of iron tolerance genes. Chromatin immunoprecipitation (ChIP) and transcriptome experiments showed that Hap4 can also bind these promoters but has no impact on the expression of those genes when Yap5 is present. In the absence of Yap5 however, GRX4 is constitutively regulated by Hap4, similarly to the genes involved in respiration. Our results suggest that the distinction between the two types of CBC targets in C. glabrata is mainly due to the dependency of Yap5 for very specific DNA sequences and to the competition between Hap4 and Yap5 at the promoter of the iron tolerance genes.
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Affiliation(s)
- Thierry Delaveau
- Sorbonne Université, CNRS, Institut de biologie Paris-Seine (IBPS), UMR 7238, Laboratoire de Biologie Computationnelle et Quantitative, Paris, France
| | - Antonin Thiébaut
- Sorbonne Université, CNRS, Institut de biologie Paris-Seine (IBPS), UMR 7238, Laboratoire de Biologie Computationnelle et Quantitative, Paris, France
| | - Médine Benchouaia
- Sorbonne Université, CNRS, Institut de biologie Paris-Seine (IBPS), UMR 7238, Laboratoire de Biologie Computationnelle et Quantitative, Paris, France
| | - Jawad Merhej
- Sorbonne Université, CNRS, Institut de biologie Paris-Seine (IBPS), UMR 7238, Laboratoire de Biologie Computationnelle et Quantitative, Paris, France
| | - Frédéric Devaux
- Sorbonne Université, CNRS, Institut de biologie Paris-Seine (IBPS), UMR 7238, Laboratoire de Biologie Computationnelle et Quantitative, Paris, France
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12
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Sorribes-Dauden R, Martínez-Pastor MT, Puig S. Expression of a Truncated Yeast Ccc1 Vacuolar Transporter Increases the Accumulation of Endogenous Iron. Genes (Basel) 2021; 12:genes12081120. [PMID: 34440294 PMCID: PMC8391176 DOI: 10.3390/genes12081120] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Revised: 07/12/2021] [Accepted: 07/15/2021] [Indexed: 01/13/2023] Open
Abstract
Iron is an essential micronutrient for all eukaryotic organisms because it participates as a redox cofactor in multiple metabolic processes. Iron bioavailability is highly restricted due to the low solubility of its oxidized form, frequently leading to iron deficiency anemia. The baker’s yeast Saccharomyces cerevisiae is used as a model organism for iron homeostasis studies, but also as a food supplement and fermentative microorganism in the food industry. Yeast cells use the vacuolar Ccc1 transporter to detoxify and store excess iron in the vacuoles. Here, we modulate CCC1 expression and properties to increase iron extraction from the environment. We show that constitutive expression of full-length CCC1 is toxic, whereas deletion of its cytosolic amino-terminal (Nt) domain (NtΔCCC1) rescues this phenotype. Toxicity is exacerbated in cells lacking AFT1 transcription factor. Further characterization of NtΔCcc1 protein suggests that it is a partially functional protein. Western blot analyses indicate that deletion of Ccc1 Nt domain does not significantly alter GFP-Ccc1 protein stability. A functional full-length GFP-Ccc1 protein localized to particular regions of the vacuolar membrane, whereas GFP-NtΔCcc1 protein was evenly distributed throughout this endogenous membrane. Interestingly, expression of NtΔCCC1 increased the accumulation of endogenous iron in cells cultivated under iron-sufficient conditions, a strategy that could be used to extract iron from media that are not rich in iron.
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Affiliation(s)
- Raquel Sorribes-Dauden
- Departamento de Bioquímica y Biología Molecular, Universitat de València, Doctor Moliner 50, 46100 Burjassot, Valencia, Spain;
| | - María Teresa Martínez-Pastor
- Departamento de Bioquímica y Biología Molecular, Universitat de València, Doctor Moliner 50, 46100 Burjassot, Valencia, Spain;
- Correspondence: (M.T.M.-P.); (S.P.)
| | - Sergi Puig
- Departamento de Biotecnología, Instituto de Agroquímica y Tecnología de Alimentos (IATA), Consejo Superior de Investigaciones Científicas (CSIC), Agustín Escardino 7, 46980 Paterna, Valencia, Spain
- Correspondence: (M.T.M.-P.); (S.P.)
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13
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Mühlenhoff U, Braymer JJ, Christ S, Rietzschel N, Uzarska MA, Weiler BD, Lill R. Glutaredoxins and iron-sulfur protein biogenesis at the interface of redox biology and iron metabolism. Biol Chem 2021; 401:1407-1428. [PMID: 33031050 DOI: 10.1515/hsz-2020-0237] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Accepted: 09/21/2020] [Indexed: 11/15/2022]
Abstract
The physiological roles of the intracellular iron and redox regulatory systems are intimately linked. Iron is an essential trace element for most organisms, yet elevated cellular iron levels are a potent generator and amplifier of reactive oxygen species and redox stress. Proteins binding iron or iron-sulfur (Fe/S) clusters, are particularly sensitive to oxidative damage and require protection from the cellular oxidative stress protection systems. In addition, key components of these systems, most prominently glutathione and monothiol glutaredoxins are involved in the biogenesis of cellular Fe/S proteins. In this review, we address the biochemical role of glutathione and glutaredoxins in cellular Fe/S protein assembly in eukaryotic cells. We also summarize the recent developments in the role of cytosolic glutaredoxins in iron metabolism, in particular the regulation of fungal iron homeostasis. Finally, we discuss recent insights into the interplay of the cellular thiol redox balance and oxygen with that of Fe/S protein biogenesis in eukaryotes.
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Affiliation(s)
- Ulrich Mühlenhoff
- Institut für Zytobiologie, Philipps-Universität Marburg, Robert-Koch-Str. 6, D-35032Marburg, Germany.,SYNMIKRO Center for Synthetic Microbiology, Philipps-Universität Marburg, Hans-Meerwein-Str., D-35043Marburg, Germany
| | - Joseph J Braymer
- Institut für Zytobiologie, Philipps-Universität Marburg, Robert-Koch-Str. 6, D-35032Marburg, Germany.,SYNMIKRO Center for Synthetic Microbiology, Philipps-Universität Marburg, Hans-Meerwein-Str., D-35043Marburg, Germany
| | - Stefan Christ
- Institut für Zytobiologie, Philipps-Universität Marburg, Robert-Koch-Str. 6, D-35032Marburg, Germany
| | - Nicole Rietzschel
- Institut für Zytobiologie, Philipps-Universität Marburg, Robert-Koch-Str. 6, D-35032Marburg, Germany
| | - Marta A Uzarska
- Institut für Zytobiologie, Philipps-Universität Marburg, Robert-Koch-Str. 6, D-35032Marburg, Germany.,Intercollegiate Faculty of Biotechnology, University of Gdansk, Abrahama 58, 80-307Gdansk, Poland
| | - Benjamin D Weiler
- Institut für Zytobiologie, Philipps-Universität Marburg, Robert-Koch-Str. 6, D-35032Marburg, Germany
| | - Roland Lill
- Institut für Zytobiologie, Philipps-Universität Marburg, Robert-Koch-Str. 6, D-35032Marburg, Germany.,SYNMIKRO Center for Synthetic Microbiology, Philipps-Universität Marburg, Hans-Meerwein-Str., D-35043Marburg, Germany
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14
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An Internal Promoter Drives the Expression of a Truncated Form of CCC1 Capable of Protecting Yeast from Iron Toxicity. Microorganisms 2021; 9:microorganisms9061337. [PMID: 34203091 PMCID: PMC8235630 DOI: 10.3390/microorganisms9061337] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Revised: 06/11/2021] [Accepted: 06/15/2021] [Indexed: 11/17/2022] Open
Abstract
In yeast, iron storage and detoxification depend on the Ccc1 transporter that mediates iron accumulation in vacuoles. While deletion of the CCC1 gene renders cells unable to survive under iron overload conditions, the deletion of its previously identified regulators only partially affects survival, indicating that the mechanisms controlling iron storage and detoxification in yeast are still far from well understood. This work reveals that CCC1 is equipped with a complex transcriptional structure comprising several regulatory regions. One of these is located inside the coding sequence of the gene and drives the expression of a short transcript encoding an N-terminally truncated protein, designated as s-Ccc1. s-Ccc1, though less efficiently than Ccc1, is able to promote metal accumulation in the vacuole, protecting cells against iron toxicity. While the expression of the s-Ccc1 appears to be repressed in the normal genomic context, our current data clearly demonstrates that it is functional and has the capacity to play a role under iron overload conditions.
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15
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Sorribes-Dauden R, Peris D, Martínez-Pastor MT, Puig S. Structure and function of the vacuolar Ccc1/VIT1 family of iron transporters and its regulation in fungi. Comput Struct Biotechnol J 2020; 18:3712-3722. [PMID: 33304466 PMCID: PMC7714665 DOI: 10.1016/j.csbj.2020.10.044] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Revised: 10/28/2020] [Accepted: 10/31/2020] [Indexed: 02/06/2023] Open
Abstract
Iron is an essential micronutrient for most living beings since it participates as a redox active cofactor in many biological processes including cellular respiration, lipid biosynthesis, DNA replication and repair, and ribosome biogenesis and recycling. However, when present in excess, iron can participate in Fenton reactions and generate reactive oxygen species that damage cells at the level of proteins, lipids and nucleic acids. Organisms have developed different molecular strategies to protect themselves against the harmful effects of high concentrations of iron. In the case of fungi and plants, detoxification mainly occurs by importing cytosolic iron into the vacuole through the Ccc1/VIT1 iron transporter. New sequenced genomes and bioinformatic tools are facilitating the functional characterization, evolution and ecological relevance of metabolic pathways and homeostatic networks across the Tree of Life. Sequence analysis shows that Ccc1/VIT1 homologs are widely distributed among organisms with the exception of animals. The recent elucidation of the crystal structure of a Ccc1/VIT1 plant ortholog has enabled the identification of both conserved and species-specific motifs required for its metal transport mechanism. Moreover, recent studies in the yeast Saccharomyces cerevisiae have also revealed that multiple transcription factors including Yap5 and Msn2/Msn4 contribute to the expression of CCC1 in high-iron conditions. Interestingly, Malaysian S. cerevisiae strains express a partially functional Ccc1 protein that renders them sensitive to iron. Different regulatory mechanisms have been described for non-Saccharomycetaceae Ccc1 homologs. The characterization of Ccc1/VIT1 proteins is of high interest in the development of biofortified crops and the protection against microbial-derived diseases.
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Key Words
- BLOSUM, BLOcks SUbstitution Matrix
- CBC, CCAAT-binding core complex
- CRD, Cysteine-rich domain
- CS, Consistency score
- Ccc1
- Cg, Candida glabrata
- Eg, Eucalyptus grandis
- Fe, Iron
- Fungi
- H, Helix
- Hap, Heme activator protein
- ISC, Iron-sulfur luster
- Iron detoxification
- Iron regulation
- Iron transport
- MAFFT, Multiple Alignment using Fast Fourier Transform
- MBD, Metal-binding domain
- ML, Maximum-likelihood
- NRAMP, Natural Resistance-Associated Macrophage Protein
- Plants
- ROS, Reactive oxygen species
- TMD, Transmembrane domain
- VIT, Vacuolar iron transporter
- VIT1
- VTL, Vacuolar iron transporter-like
- Vacuole
- YRE, Yap response elements
- Yeast
- bZIP, basic leucine-zipper
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Affiliation(s)
- Raquel Sorribes-Dauden
- Departamento de Bioquímica y Biología Molecular, Universitat de València, Burjassot, Valencia, Spain
| | - David Peris
- Departamento de Biotecnología, Instituto de Agroquímica y Tecnología de Alimentos (IATA), Consejo Superior de Investigaciones Científicas (CSIC), Paterna, Valencia, Spain
| | | | - Sergi Puig
- Departamento de Biotecnología, Instituto de Agroquímica y Tecnología de Alimentos (IATA), Consejo Superior de Investigaciones Científicas (CSIC), Paterna, Valencia, Spain
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16
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Lill R. Do FeS clusters rule bacterial iron regulation? J Biol Chem 2020; 295:15464-15465. [PMID: 33188081 DOI: 10.1074/jbc.h120.016190] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
For decades, the bacterial ferric uptake regulator (Fur) has been thought to respond to ferrous iron to transcriptionally regulate genes required for balancing iron uptake, storage, and utilization. Because iron binding to Fur has never been confirmed in vivo, the physiological iron-sensing mechanism remains an open question. Fontenot et al. now show that Fur purified from Escherichia coli binds an all-Cys-coordinated [2Fe-2S] cluster. This finding opens the exciting possibility that Fur may join numerous well-studied bacterial, fungal, and mammalian proteins that use FeS clusters for cellular iron regulation.
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Affiliation(s)
- Roland Lill
- Institut für Zytobiologie, Philipps-Universität Marburg, Marburg, Germany; SYNMIKRO Center for Synthetic Microbiology, Philipps-Universität Marburg, Marburg, Germany.
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17
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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.
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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.
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18
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Fontenot CR, Tasnim H, Valdes KA, Popescu CV, Ding H. Ferric uptake regulator (Fur) reversibly binds a [2Fe-2S] cluster to sense intracellular iron homeostasis in Escherichia coli. J Biol Chem 2020; 295:15454-15463. [PMID: 32928958 DOI: 10.1074/jbc.ra120.014814] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Revised: 09/04/2020] [Indexed: 12/19/2022] Open
Abstract
The ferric uptake regulator (Fur) is a global transcription factor that regulates intracellular iron homeostasis in bacteria. The current hypothesis states that when the intracellular "free" iron concentration is elevated, Fur binds ferrous iron, and the iron-bound Fur represses the genes encoding for iron uptake systems and stimulates the genes encoding for iron storage proteins. However, the "iron-bound" Fur has never been isolated from any bacteria. Here we report that the Escherichia coli Fur has a bright red color when expressed in E. coli mutant cells containing an elevated intracellular free iron content because of deletion of the iron-sulfur cluster assembly proteins IscA and SufA. The acid-labile iron and sulfide content analyses in conjunction with the EPR and Mössbauer spectroscopy measurements and the site-directed mutagenesis studies show that the red Fur protein binds a [2Fe-2S] cluster via conserved cysteine residues. The occupancy of the [2Fe-2S] cluster in Fur protein is ∼31% in the E. coli iscA/sufA mutant cells and is decreased to ∼4% in WT E. coli cells. Depletion of the intracellular free iron content using the membrane-permeable iron chelator 2,2´-dipyridyl effectively removes the [2Fe-2S] cluster from Fur in E. coli cells, suggesting that Fur senses the intracellular free iron content via reversible binding of a [2Fe-2S] cluster. The binding of the [2Fe-2S] cluster in Fur appears to be highly conserved, because the Fur homolog from Hemophilus influenzae expressed in E. coli cells also reversibly binds a [2Fe-2S] cluster to sense intracellular iron homeostasis.
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Affiliation(s)
- Chelsey R Fontenot
- Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana, USA
| | - Homyra Tasnim
- Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana, USA
| | - Kathryn A Valdes
- Department of Chemistry, University of St. Thomas, St. Paul, Minnesota, USA
| | - Codrina V Popescu
- Department of Chemistry, University of St. Thomas, St. Paul, Minnesota, USA
| | - Huangen Ding
- Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana, USA.
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19
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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.
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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
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20
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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.
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Affiliation(s)
| | - Sergi Puig
- Departamento de Biotecnología, Instituto de Agroquímica y Tecnología de Alimentos (IATA), Consejo Superior de Investigaciones Científicas (CSIC), Paterna, Valencia, Spain.
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21
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Furukawa T, Scheven MT, Misslinger M, Zhao C, Hoefgen S, Gsaller F, Lau J, Jöchl C, Donaldson I, Valiante V, Brakhage AA, Bromley MJ, Haas H, Hortschansky P. The fungal CCAAT-binding complex and HapX display highly variable but evolutionary conserved synergetic promoter-specific DNA recognition. Nucleic Acids Res 2020; 48:3567-3590. [PMID: 32086516 PMCID: PMC7144946 DOI: 10.1093/nar/gkaa109] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Revised: 02/07/2020] [Accepted: 02/18/2020] [Indexed: 12/13/2022] Open
Abstract
To sustain iron homeostasis, microorganisms have evolved fine-tuned mechanisms for uptake, storage and detoxification of the essential metal iron. In the human pathogen Aspergillus fumigatus, the fungal-specific bZIP-type transcription factor HapX coordinates adaption to both iron starvation and iron excess and is thereby crucial for virulence. Previous studies indicated that a HapX homodimer interacts with the CCAAT-binding complex (CBC) to cooperatively bind bipartite DNA motifs; however, the mode of HapX-DNA recognition had not been resolved. Here, combination of in vivo (genetics and ChIP-seq), in vitro (surface plasmon resonance) and phylogenetic analyses identified an astonishing plasticity of CBC:HapX:DNA interaction. DNA motifs recognized by the CBC:HapX protein complex comprise a bipartite DNA binding site 5′-CSAATN12RWT-3′ and an additional 5′-TKAN-3′ motif positioned 11–23 bp downstream of the CCAAT motif, i.e. occasionally overlapping the 3′-end of the bipartite binding site. Phylogenetic comparison taking advantage of 20 resolved Aspergillus species genomes revealed that DNA recognition by the CBC:HapX complex shows promoter-specific cross-species conservation rather than regulon-specific conservation. Moreover, we show that CBC:HapX interaction is absolutely required for all known functions of HapX. The plasticity of the CBC:HapX:DNA interaction permits fine tuning of CBC:HapX binding specificities that could support adaptation of pathogens to their host niches.
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Affiliation(s)
- Takanori Furukawa
- Manchester Fungal Infection Group, Institute of Inflammation and Repair, University of Manchester, Manchester M13 9PL, UK
| | - Mareike Thea Scheven
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology (HKI), Jena D-07745, Germany
| | - Matthias Misslinger
- Division of Molecular Biology/Biocenter, Innsbruck Medical University, Innsbruck, A-6020, Austria
| | - Can Zhao
- Manchester Fungal Infection Group, Institute of Inflammation and Repair, University of Manchester, Manchester M13 9PL, UK
| | - Sandra Hoefgen
- Leibniz Research Group Biobricks of Microbial Natural Product Syntheses, Leibniz Institute for Natural Product Research and Infection Biology (HKI), Jena D-07745, Germany
| | - Fabio Gsaller
- Division of Molecular Biology/Biocenter, Innsbruck Medical University, Innsbruck, A-6020, Austria
| | - Jeffrey Lau
- Manchester Fungal Infection Group, Institute of Inflammation and Repair, University of Manchester, Manchester M13 9PL, UK
| | - Christoph Jöchl
- Division of Molecular Biology/Biocenter, Innsbruck Medical University, Innsbruck, A-6020, Austria
| | - Ian Donaldson
- Manchester Fungal Infection Group, Institute of Inflammation and Repair, University of Manchester, Manchester M13 9PL, UK
| | - Vito Valiante
- Leibniz Research Group Biobricks of Microbial Natural Product Syntheses, Leibniz Institute for Natural Product Research and Infection Biology (HKI), Jena D-07745, Germany.,Friedrich Schiller University Jena, Jena D-07745, Germany
| | - Axel A Brakhage
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology (HKI), Jena D-07745, Germany.,Friedrich Schiller University Jena, Jena D-07745, Germany
| | - Michael J Bromley
- Manchester Fungal Infection Group, Institute of Inflammation and Repair, University of Manchester, Manchester M13 9PL, UK
| | - Hubertus Haas
- Division of Molecular Biology/Biocenter, Innsbruck Medical University, Innsbruck, A-6020, Austria
| | - Peter Hortschansky
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology (HKI), Jena D-07745, Germany
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22
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A Transcriptional Regulatory Map of Iron Homeostasis Reveals a New Control Circuit for Capsule Formation in Cryptococcus neoformans. Genetics 2020; 215:1171-1189. [PMID: 32580959 DOI: 10.1534/genetics.120.303270] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2020] [Accepted: 06/18/2020] [Indexed: 11/18/2022] Open
Abstract
Iron is essential for the growth of the human fungal pathogen Cryptococcus neoformans within the vertebrate host, and iron sensing contributes to the elaboration of key virulence factors, including the formation of the polysaccharide capsule. C. neoformans employs sophisticated iron acquisition and utilization systems governed by the transcription factors Cir1 and HapX. However, the details of the transcriptional regulatory networks that are governed by these transcription factors and connections to virulence remain to be defined. Here, we used chromatin immunoprecipitation followed by next-generation sequencing (ChIP-seq) and transcriptome analysis (RNA-seq) to identify genes directly regulated by Cir1 and/or HapX in response to iron availability. Overall, 40 and 100 genes were directly regulated by Cir1, and 171 and 12 genes were directly regulated by HapX, under iron-limited and replete conditions, respectively. More specifically, we found that Cir1 directly controls the expression of genes required for iron acquisition and metabolism, and indirectly governs capsule formation by regulating specific protein kinases, a regulatory connection not previously revealed. HapX regulates the genes responsible for iron-dependent pathways, particularly under iron-depleted conditions. By analyzing target genes directly bound by Cir1 and HapX, we predicted the binding motifs for the transcription factors and verified that the purified proteins bind these motifs in vitro Furthermore, several direct target genes were coordinately and reciprocally regulated by Cir1 and HapX, suggesting that these transcription factors play conserved roles in the response to iron availability. In addition, biochemical analyses revealed that Cir1 and HapX are iron-containing proteins, implying that the regulatory networks of Cir1 and HapX may be influenced by the incorporation of iron into these proteins. Taken together, our identification of the genome-wide transcriptional networks provides a detailed understanding of the iron-related regulatory landscape, establishes a new connection between Cir1 and kinases that regulate capsule, and underpins genetic and biochemical analyses that reveal iron-sensing mechanisms for Cir1 and HapX in C. neoformans.
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23
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Zhang ZM, Zhuang M, Wang BT, Jin L, Jin FJ. Identification and characterization of a DevR-interacting protein in Aspergillus oryzae. Fungal Biol 2020; 124:155-163. [PMID: 32220376 DOI: 10.1016/j.funbio.2020.01.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Revised: 01/08/2020] [Accepted: 01/08/2020] [Indexed: 11/24/2022]
Abstract
The basic helix-loop-helix (bHLH) proteins belong to a superfamily of transcription factors. Recent research has shown that the bHLH transcription factor DevR is involved in both sexual and asexual development as well as conidial melanin production in Aspergillus species. Our previous research also found that DevR significantly influences polysaccharide metabolism in Aspergillus oryzae. In this study, to further explore the function of DevR, its interaction proteins were screened by a yeast two-hybrid assay. An A. oryzae cDNA library was transformed into the Y187 strain by using the SMART technique and the homologous recombination method, and then hybridized with a constructed DevR bait plasmid introducing strain to obtain positive clones. Through sequencing analysis, the potential interaction proteins of DevR were determined. Among them, an AO090701000363 gene-encoding protein (named DipA), which was predicted to be a basic leucine zipper (bZIP) transcription factor, was a possible candidate. Phenotypic analysis indicated that overexpression of the AodipA may significantly suppress growth of the strain. Additionally, although no obvious change in the growth rate was found, the deletion of AodipA resulted in thicker hyphae morphology relative to the control. Comparative proteomic analysis further indicated that DipA was potentially involved in the regulation of cell wall integrity, carbon utilization, acetate catabolic process and other biological processes. Partial similarity of the phenotype to that of DevR suggested a correlation between them and implied that the DipA has a function partially similar to that of DevR.
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Affiliation(s)
- Zhi-Min Zhang
- Co-Innovation Center for Sustainable Forestry in Southern China, College of Biology and the Environment, Nanjing Forestry University, 159 Longpan Road, Nanjing 210037, China
| | - Miao Zhuang
- Co-Innovation Center for Sustainable Forestry in Southern China, College of Biology and the Environment, Nanjing Forestry University, 159 Longpan Road, Nanjing 210037, China
| | - Bao-Teng Wang
- Co-Innovation Center for Sustainable Forestry in Southern China, College of Biology and the Environment, Nanjing Forestry University, 159 Longpan Road, Nanjing 210037, China
| | - Long Jin
- Co-Innovation Center for Sustainable Forestry in Southern China, College of Biology and the Environment, Nanjing Forestry University, 159 Longpan Road, Nanjing 210037, China
| | - Feng-Jie Jin
- Co-Innovation Center for Sustainable Forestry in Southern China, College of Biology and the Environment, Nanjing Forestry University, 159 Longpan Road, Nanjing 210037, China.
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24
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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.
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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.
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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.
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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.
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26
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Lindahl PA. A comprehensive mechanistic model of iron metabolism in Saccharomyces cerevisiae. Metallomics 2019; 11:1779-1799. [PMID: 31531508 DOI: 10.1039/c9mt00199a] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The ironome of budding yeast (circa 2019) consists of approximately 139 proteins and 5 nonproteinaceous species. These proteins were grouped according to location in the cell, type of iron center(s), and cellular function. The resulting 27 groups were used, along with an additional 13 nonprotein components, to develop a mesoscale mechanistic model that describes the import, trafficking, metallation, and regulation of iron within growing yeast cells. The model was designed to be simultaneously mutually autocatalytic and mutually autoinhibitory - a property called autocatinhibitory that should be most realistic for simulating cellular biochemical processes. The model was assessed at the systems' level. General conclusions are presented, including a new perspective on understanding regulatory mechanisms in cellular systems. Some unsettled issues are described. This model, once fully developed, has the potential to mimic the phenotype (at a coarse-grain level) of all iron-related genetic mutations in this simple and well-studied eukaryote.
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Affiliation(s)
- Paul A Lindahl
- Departments of Chemistry and of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843-3255, USA.
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27
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The monothiol glutaredoxin GrxD is essential for sensing iron starvation in Aspergillus fumigatus. PLoS Genet 2019; 15:e1008379. [PMID: 31525190 PMCID: PMC6762210 DOI: 10.1371/journal.pgen.1008379] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Revised: 09/26/2019] [Accepted: 08/20/2019] [Indexed: 01/17/2023] Open
Abstract
Efficient adaptation to iron starvation is an essential virulence determinant of the most common human mold pathogen, Aspergillus fumigatus. Here, we demonstrate that the cytosolic monothiol glutaredoxin GrxD plays an essential role in iron sensing in this fungus. Our studies revealed that (i) GrxD is essential for growth; (ii) expression of the encoding gene, grxD, is repressed by the transcription factor SreA in iron replete conditions and upregulated during iron starvation; (iii) during iron starvation but not iron sufficiency, GrxD displays predominant nuclear localization; (iv) downregulation of grxD expression results in de-repression of genes involved in iron-dependent pathways and repression of genes involved in iron acquisition during iron starvation, but did not significantly affect these genes during iron sufficiency; (v) GrxD displays protein-protein interaction with components of the cytosolic iron-sulfur cluster biosynthetic machinery, indicating a role in this process, and with the transcription factors SreA and HapX, which mediate iron regulation of iron acquisition and iron-dependent pathways; (vi) UV-Vis spectra of recombinant HapX or the complex of HapX and GrxD indicate coordination of iron-sulfur clusters; (vii) the cysteine required for iron-sulfur cluster coordination in GrxD is in vitro dispensable for interaction with HapX; and (viii) there is a GrxD-independent mechanism for sensing iron sufficiency by HapX; (ix) inactivation of SreA suppresses the lethal effect caused by GrxD inactivation. Taken together, this study demonstrates that GrxD is crucial for iron homeostasis in A. fumigatus. Aspergillus fumigatus is a ubiquitous saprophytic mold and the major causative pathogen causing life-threatening aspergillosis. To improve therapy, there is an urgent need for a better understanding of the fungal physiology. We have previously shown that adaptation to iron starvation is an essential virulence attribute of A. fumigatus. In the present study, we characterized the mechanism employed by A. fumigatus to sense the cellular iron status, which is essential for iron homeostasis. We demonstrate that the transcription factors SreA and HapX, which coordinate iron acquisition, iron consumption and iron detoxification require physical interaction with the monothiol glutaredoxin GrxD to sense iron starvation. Moreover, we show that there is a GrxD-independent mechanism for sensing excess of iron.
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Mendoza-Cózatl DG, Gokul A, Carelse MF, Jobe TO, Long TA, Keyster M. Keep talking: crosstalk between iron and sulfur networks fine-tunes growth and development to promote survival under iron limitation. JOURNAL OF EXPERIMENTAL BOTANY 2019; 70:4197-4210. [PMID: 31231775 DOI: 10.1093/jxb/erz290] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Accepted: 06/08/2019] [Indexed: 05/21/2023]
Abstract
Plants are capable of synthesizing all the molecules necessary to complete their life cycle from minerals, water, and light. This plasticity, however, comes at a high energetic cost and therefore plants need to regulate their economy and allocate resources accordingly. Iron-sulfur (Fe-S) clusters are at the center of photosynthesis, respiration, amino acid, and DNA metabolism. Fe-S clusters are extraordinary catalysts, but their main components (Fe2+ and S2-) are highly reactive and potentially toxic. To prevent toxicity, plants have evolved mechanisms to regulate the uptake, storage, and assimilation of Fe and S. Recent advances have been made in understanding the cellular economy of Fe and S metabolism individually, and growing evidence suggests that there is dynamic crosstalk between Fe and S networks. In this review, we summarize and discuss recent literature on Fe sensing, allocation, use efficiency, and, when pertinent, its relationship to S metabolism. Our future perspectives include a discussion about the open questions and challenges ahead and how the plant nutrition field can come together to approach these questions in a cohesive and more efficient way.
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Affiliation(s)
- David G Mendoza-Cózatl
- Division of Plant Sciences, C.S. Bond Life Sciences Center, University of Missouri, Columbia, MO, USA
| | - Arun Gokul
- Environmental Biotechnology Laboratory, Department of Biotechnology, University of the Western Cape, Bellville, South Africa
| | - Mogamat F Carelse
- Environmental Biotechnology Laboratory, Department of Biotechnology, University of the Western Cape, Bellville, South Africa
| | - Timothy O Jobe
- Botanical Institute and Cluster of Excellence on Plant Sciences (CEPLAS), University of Cologne, Cologne, Germany
| | - Terri A Long
- Plant and Microbial Biology, North Carolina State University, Raleigh, NC, USA
| | - Marshall Keyster
- Environmental Biotechnology Laboratory, Department of Biotechnology, University of the Western Cape, Bellville, South Africa
- DST-NRF Centre of Excellence in Food Security, University of the Western Cape, Bellville, South Africa
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Rodrigues-Pousada C, Devaux F, Caetano SM, Pimentel C, da Silva S, Cordeiro AC, Amaral C. Yeast AP-1 like transcription factors (Yap) and stress response: a current overview. MICROBIAL CELL 2019; 6:267-285. [PMID: 31172012 PMCID: PMC6545440 DOI: 10.15698/mic2019.06.679] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Yeast adaptation to stress has been extensively studied. It involves large reprogramming of genome expression operated by many, more or less specific, transcription factors. Here, we review our current knowledge on the function of the eight Yap transcription factors (Yap1 to Yap8) in Saccharomyces cerevisiae, which were shown to be involved in various stress responses. More precisely, Yap1 is activated under oxidative stress, Yap2/Cad1 under cadmium, Yap4/Cin5 and Yap6 under osmotic shock, Yap5 under iron overload and Yap8/Arr1 by arsenic compounds. Yap3 and Yap7 seem to be involved in hydroquinone and nitrosative stresses, respectively. The data presented in this article illustrate how much knowledge on the function of these Yap transcription factors is advanced. The evolution of the Yap family and its roles in various pathogenic and non-pathogenic fungal species is discussed in the last section.
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Affiliation(s)
- Claudina Rodrigues-Pousada
- Instituto de Tecnologia Química e Biológica Anónio Xavier, Universidade Nova de Lisboa, Avenida da República, EAN, Oeiras 2781-901, Oeiras, Portugal
| | - Frédéric Devaux
- Sorbonne Université, CNRS, Institut de Biologie Paris-Seine, Laboratory of Computational and Quantitative Biology, F-75005, Paris, France
| | - Soraia M Caetano
- Instituto de Tecnologia Química e Biológica Anónio Xavier, Universidade Nova de Lisboa, Avenida da República, EAN, Oeiras 2781-901, Oeiras, Portugal
| | - Catarina Pimentel
- Instituto de Tecnologia Química e Biológica Anónio Xavier, Universidade Nova de Lisboa, Avenida da República, EAN, Oeiras 2781-901, Oeiras, Portugal
| | - Sofia da Silva
- Instituto de Tecnologia Química e Biológica Anónio Xavier, Universidade Nova de Lisboa, Avenida da República, EAN, Oeiras 2781-901, Oeiras, Portugal
| | - Ana Carolina Cordeiro
- Instituto de Tecnologia Química e Biológica Anónio Xavier, Universidade Nova de Lisboa, Avenida da República, EAN, Oeiras 2781-901, Oeiras, Portugal
| | - Catarina Amaral
- Instituto de Tecnologia Química e Biológica Anónio Xavier, Universidade Nova de Lisboa, Avenida da República, EAN, Oeiras 2781-901, Oeiras, Portugal
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30
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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.
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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
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31
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Pandey AK, Pain J, Dancis A, Pain D. Mitochondria export iron-sulfur and sulfur intermediates to the cytoplasm for iron-sulfur cluster assembly and tRNA thiolation in yeast. J Biol Chem 2019; 294:9489-9502. [PMID: 31040179 DOI: 10.1074/jbc.ra119.008600] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2019] [Revised: 04/26/2019] [Indexed: 12/28/2022] Open
Abstract
Iron-sulfur clusters are essential cofactors of proteins. In eukaryotes, iron-sulfur cluster biogenesis requires a mitochondrial iron-sulfur cluster machinery (ISC) and a cytoplasmic iron-sulfur protein assembly machinery (CIA). Here we used mitochondria and cytoplasm isolated from yeast cells, and [35S]cysteine to detect cytoplasmic Fe-35S cluster assembly on a purified apoprotein substrate. We showed that mitochondria generate an intermediate, called (Fe-S)int, needed for cytoplasmic iron-sulfur cluster assembly. The mitochondrial biosynthesis of (Fe-S)int required ISC components such as Nfs1 cysteine desulfurase, Isu1/2 scaffold, and Ssq1 chaperone. Mitochondria then exported (Fe-S)int via the Atm1 transporter in the inner membrane, and we detected (Fe-S)int in active form. When (Fe-S)int was added to cytoplasm, CIA utilized it for iron-sulfur cluster assembly without any further help from the mitochondria. We found that both iron and sulfur for cytoplasmic iron-sulfur cluster assembly originate from the mitochondria, revealing a surprising and novel mitochondrial role. Mitochondrial (Fe-S)int export was most efficient in the presence of cytoplasm containing an apoprotein substrate, suggesting that mitochondria respond to the cytoplasmic demand for iron-sulfur cluster synthesis. Of note, the (Fe-S)int is distinct from the sulfur intermediate called Sint, which is also made and exported by mitochondria but is instead used for cytoplasmic tRNA thiolation. In summary, our findings establish a direct and vital role of mitochondria in cytoplasmic iron-sulfur cluster assembly in yeast cells.
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Affiliation(s)
- Ashutosh K Pandey
- From the Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School, Rutgers University, Newark, New Jersey 07103 and
| | - Jayashree Pain
- From the Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School, Rutgers University, Newark, New Jersey 07103 and
| | - Andrew Dancis
- the Department of Medicine, Division of Hematology-Oncology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Debkumar Pain
- From the Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School, Rutgers University, Newark, New Jersey 07103 and
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Rey P, Taupin-Broggini M, Couturier J, Vignols F, Rouhier N. Is There a Role for Glutaredoxins and BOLAs in the Perception of the Cellular Iron Status in Plants? FRONTIERS IN PLANT SCIENCE 2019; 10:712. [PMID: 31231405 PMCID: PMC6558291 DOI: 10.3389/fpls.2019.00712] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Accepted: 05/14/2019] [Indexed: 05/12/2023]
Abstract
Glutaredoxins (GRXs) have at least three major identified functions. In apoforms, they exhibit oxidoreductase activity controlling notably protein glutathionylation/deglutathionylation. In holoforms, i.e., iron-sulfur (Fe-S) cluster-bridging forms, they act as maturation factors for the biogenesis of Fe-S proteins or as regulators of iron homeostasis contributing directly or indirectly to the sensing of cellular iron status and/or distribution. The latter functions seem intimately connected with the capacity of specific GRXs to form [2Fe-2S] cluster-bridging homodimeric or heterodimeric complexes with BOLA proteins. In yeast species, both proteins modulate the localization and/or activity of transcription factors regulating genes coding for proteins involved in iron uptake and intracellular sequestration in response notably to iron deficiency. Whereas vertebrate GRX and BOLA isoforms may display similar functions, the involved partner proteins are different. We perform here a critical evaluation of the results supporting the implication of both protein families in similar signaling pathways in plants and provide ideas and experimental strategies to delineate further their functions.
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Affiliation(s)
- Pascal Rey
- Plant Protective Proteins Team, CEA, CNRS, BIAM, Aix-Marseille University, Saint-Paul-lez-Durance, France
| | - Maël Taupin-Broggini
- Biochimie et Physiologie Moléculaire des Plantes, CNRS/INRA/Université de Montpellier/SupAgro, Montpellier, France
| | | | - Florence Vignols
- Biochimie et Physiologie Moléculaire des Plantes, CNRS/INRA/Université de Montpellier/SupAgro, Montpellier, France
| | - Nicolas Rouhier
- Université de Lorraine, INRA, IAM, Nancy, France
- *Correspondence: Nicolas Rouhier,
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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.
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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
.
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34
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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
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Zhang Y, Xu Z. miR-93 enhances cell proliferation by directly targeting CDKN1A in nasopharyngeal carcinoma. Oncol Lett 2017; 15:1723-1727. [PMID: 29434867 PMCID: PMC5774441 DOI: 10.3892/ol.2017.7492] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2017] [Accepted: 11/16/2017] [Indexed: 12/21/2022] Open
Abstract
Nasopharyngeal carcinoma (NPC) is an epithelial malignancy of the head and neck with the highest incidence rate in southern China. The aim of the present study was to understand the molecular mechanisms that underlie the progression of NPC. The relative expression of miR-93 and CDKN1A was detected by the reverse-transcription quantitative PCR. Western blot analysis was applied to detect the protein levels of genes. Luciferase activity report was applied to verify the target of miRNA. Cell growth was assayed by using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. miR-93 was upregulated in NPC tissues and cell lines compared with normal samples. Re-expression of miR-93 promoted cell growth in vitro as determined by the MTT assay. CDKN1A was identified by luciferase reporter as a direct target of miR-93. Its expression was downregulated by miR-93. Furthermore, the results showed that the expression of miR-93 was inversely correlated with the expression of CDKN1A protein. miR-93 enhanced cell proliferation in NPC by directly targeting CDKN1A. It is suggested that miR-93/CDKN1A axis may present a new target for the treatment of NPC.
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Affiliation(s)
- Yingyao Zhang
- Department of Otorhinolaryngology Head and Neck Surgery, Yidu Central Hospital of Weifang, Weifang, Shandong 262500, P.R. China
| | - Zhina Xu
- Department of Otorhinolaryngology Head and Neck Surgery, Yidu Central Hospital of Weifang, Weifang, Shandong 262500, P.R. China
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Li L, Ward DM. Iron toxicity in yeast: transcriptional regulation of the vacuolar iron importer Ccc1. Curr Genet 2017; 64:413-416. [PMID: 29043483 DOI: 10.1007/s00294-017-0767-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Revised: 10/11/2017] [Accepted: 10/13/2017] [Indexed: 11/27/2022]
Abstract
All eukaryotes require the transition metal, iron, a redox active element that is an essential cofactor in many metabolic pathways, as well as an oxygen carrier. Iron can also react to generate oxygen radicals such as hydroxyl radicals and superoxide anions, which are highly toxic to cells. Therefore, organisms have developed intricate mechanisms to acquire iron as well as to protect themselves from the toxic effects of excess iron. In fungi and plants, iron is stored in the vacuole as a protective mechanism against iron toxicity. Iron storage in the vacuole is mediated predominantly by the vacuolar metal importer Ccc1 in yeast and the homologous transporter VIT1 in plants. Transcription of yeast CCC1 expression is tightly controlled primarily by the transcription factor Yap5, which sits on the CCC1 promoter and activates transcription through the binding of Fe-S clusters. A second mechanism that regulates CCC1 transcription is through the Snf1 signaling pathway involved in low-glucose sensing. Snf1 activates stress transcription factors Msn2 and Msn4 to mediate CCC1 transcription. Transcriptional regulation by Yap5 and Snf1 are completely independent and provide for a graded response in Ccc1 expression. The identification of multiple independent transcriptional pathways that regulate the levels of Ccc1 under high iron conditions accentuates the importance of protecting cells from the toxic effects of high iron.
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Affiliation(s)
- Liangtao Li
- Division of Microbiology and Immunology, Department of Pathology, School of Medicine, University of Utah, Salt Lake City, UT, 84132-2501, USA
| | - Diane M Ward
- Division of Microbiology and Immunology, Department of Pathology, School of Medicine, University of Utah, Salt Lake City, UT, 84132-2501, USA.
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Li L, Kaplan J, Ward DM. The glucose sensor Snf1 and the transcription factors Msn2 and Msn4 regulate transcription of the vacuolar iron importer gene CCC1 and iron resistance in yeast. J Biol Chem 2017; 292:15577-15586. [PMID: 28760824 DOI: 10.1074/jbc.m117.802504] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2017] [Revised: 07/21/2017] [Indexed: 12/30/2022] Open
Abstract
The budding yeast Saccharomyces cerevisiae stores iron in the vacuole, which is a major resistance mechanism against iron toxicity. One key protein involved in vacuolar iron storage is the iron importer Ccc1, which facilitates iron entry into the vacuole. Transcription of the CCC1 gene is largely regulated by the binding of iron-sulfur clusters to the activator domain of the transcriptional activator Yap5. Additional evidence, however, suggests that Yap5-independent transcriptional activation of CCC1 also contributes to iron resistance. Here, we demonstrate that components of the signaling pathway involving the low-glucose sensor Snf1 regulate CCC1 transcription and iron resistance. We found that SNF1 deletion acts synergistically with YAP5 deletion to regulate CCC1 transcription and iron resistance. A kinase-dead mutation of Snf1 lowered iron resistance as did deletion of SNF4, which encodes a partner protein of Snf1. Deletion of all three alternative partners of Snf1 encoded by SIT1, SIT2, and GAL83 decreased both CCC1 transcription and iron resistance. The Snf1 complex is known to activate the general stress transcription factors Msn2 and Msn4. We show that Msn2 and Msn4 contribute to Snf1-mediated CCC1 transcription. Of note, SNF1 deletion in combination with MSN2 and MSN4 deletion resulted in additive effects on CCC1 transcription, suggesting that other activators contribute to the regulation of CCC1 transcription. In conclusion, we show that yeast have developed multiple transcriptional mechanisms to regulate Ccc1 expression and to protect against high cytosolic iron toxicity.
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Affiliation(s)
- Liangtao Li
- From the Department of Pathology, Division of Microbiology and Immunology, School of Medicine, University of Utah, Salt Lake City, Utah 84132-2501
| | - Jerry Kaplan
- From the Department of Pathology, Division of Microbiology and Immunology, School of Medicine, University of Utah, Salt Lake City, Utah 84132-2501
| | - Diane M Ward
- From the Department of Pathology, Division of Microbiology and Immunology, School of Medicine, University of Utah, Salt Lake City, Utah 84132-2501
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The CCAAT-Binding Complex Controls Respiratory Gene Expression and Iron Homeostasis in Candida Glabrata. Sci Rep 2017; 7:3531. [PMID: 28615656 PMCID: PMC5471220 DOI: 10.1038/s41598-017-03750-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Accepted: 04/20/2017] [Indexed: 12/04/2022] Open
Abstract
The CCAAT-binding complex (CBC) is a heterotrimeric transcription factor which is widely conserved in eukaryotes. In the model yeast S. cerevisiae, CBC positively controls the expression of respiratory pathway genes. This role involves interactions with the regulatory subunit Hap4. In many pathogenic fungi, CBC interacts with the HapX regulatory subunit to control iron homeostasis. HapX is a bZIP protein which only shares with Hap4 the Hap4Like domain (Hap4L) required for its interaction with CBC. Here, we show that CBC has a dual role in the pathogenic yeast C. glabrata. It is required, along with Hap4, for the constitutive expression of respiratory genes and it is also essential for the iron stress response, which is mediated by the Yap5 bZIP transcription factor. Interestingly, Yap5 contains a vestigial Hap4L domain. The mutagenesis of this domain severely reduced Yap5 binding to its targets and compromised its interaction with Hap5. Hence, Yap5, like HapX in other species, acts as a CBC regulatory subunit in the regulation of iron stress response. This work reveals new aspects of iron homeostasis in C. glabrata and of the evolution of the role of CBC and Hap4L-bZIP proteins in this process.
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Eisenberg-Bord M, Schuldiner M. Mitochatting - If only we could be a fly on the cell wall. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2017; 1864:1469-1480. [PMID: 28433686 DOI: 10.1016/j.bbamcr.2017.04.012] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 01/07/2017] [Revised: 04/12/2017] [Accepted: 04/18/2017] [Indexed: 12/24/2022]
Abstract
Mitochondria, cellular metabolic hubs, perform many essential processes and are required for the production of metabolites such as ATP, iron-sulfur clusters, heme, amino acids and nucleotides. To fulfill their multiple roles, mitochondria must communicate with all other organelles to exchange small molecules, ions and lipids. Since mitochondria are largely excluded from vesicular trafficking routes, they heavily rely on membrane contact sites. Contact sites are areas of close proximity between organelles that allow efficient transfer of molecules, saving the need for slow and untargeted diffusion through the cytosol. More globally, multiple metabolic pathways require coordination between mitochondria and additional organelles and mitochondrial activity affects all other cellular entities and vice versa. Therefore, uncovering the different means of mitochondrial communication will allow us a better understanding of mitochondria and may illuminate disease processes that occur in the absence of proper cross-talk. In this review we focus on how mitochondria interact with all other organelles and emphasize how this communication is essential for mitochondrial and cellular homeostasis. This article is part of a Special Issue entitled: Membrane Contact Sites edited by Christian Ungermann and Benoit Kornmann.
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Affiliation(s)
- Michal Eisenberg-Bord
- Department of Molecular Genetics, Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Maya Schuldiner
- Department of Molecular Genetics, Weizmann Institute of Science, 7610001 Rehovot, Israel.
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40
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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]
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41
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Hortschansky P, Haas H, Huber EM, Groll M, Brakhage AA. The CCAAT-binding complex (CBC) in Aspergillus species. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2016; 1860:560-570. [PMID: 27939757 DOI: 10.1016/j.bbagrm.2016.11.008] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Revised: 11/25/2016] [Accepted: 11/26/2016] [Indexed: 11/30/2022]
Abstract
BACKGROUND The CCAAT binding complex (CBC), consisting of a heterotrimeric core structure, is highly conserved in eukaryotes and constitutes an important general transcriptional regulator. Scope of the review. In this review we discuss the scientific history and the current state of knowledge of the multiple gene regulatory functions, protein motifs and structure of the CBC in fungi with a special focus on Aspergillus species. Major conclusions and general significance. Initially identified as a transcriptional activator of respiration in Saccharomyces cerevisiae, in other fungal species the CBC was found to be involved in highly diverse pathways, but a general rationale for its involvement was missing. Subsequently, the CBC was found to sense reactive oxygen species through oxidative modifications of cysteine residues in order to mediate redox regulation. Moreover, via interaction with the iron-sensing bZIP transcription factor HapX, the CBC was shown to mediate adaptation to both iron starvation and iron excess. Due to the control of various pathways in primary and secondary metabolism the CBC is of crucial importance for fungal virulence in both animal and plant hosts as well as antifungal resistance. Consequently, CBC-mediated control affects biological processes that are of high interest in biotechnology, agriculture and infection medicine. This article is part of a Special Issue entitled: Nuclear Factor Y in Development and Disease, edited by Prof. Roberto Mantovani.
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Affiliation(s)
- Peter Hortschansky
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology (HKI), Beutenbergstr. 11a, D-07745, Jena, Germany
| | - Hubertus Haas
- Division of Molecular Biology, Biocenter, Medical University of Innsbruck, Innrain 80-82, A6020 Innsbruck, Austria
| | - Eva M Huber
- Center for Integrated Protein Science Munich at the Department Chemistry, Technische Universität München, Lichtenbergstr. 4, D-85748, Garching, Germany
| | - Michael Groll
- Center for Integrated Protein Science Munich at the Department Chemistry, Technische Universität München, Lichtenbergstr. 4, D-85748, Garching, Germany
| | - Axel A Brakhage
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology (HKI), Beutenbergstr. 11a, D-07745, Jena, Germany; Department of Microbiology and Molecular Biology, Friedrich Schiller University (FSU), D-07745 Jena, Germany.
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A Novel Hybrid Iron Regulation Network Combines Features from Pathogenic and Nonpathogenic Yeasts. mBio 2016; 7:mBio.01782-16. [PMID: 27795405 PMCID: PMC5082906 DOI: 10.1128/mbio.01782-16] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Iron is an essential micronutrient for both pathogens and their hosts, which restrict iron availability during infections in an effort to prevent microbial growth. Successful human pathogens like the yeast Candida glabrata have thus developed effective iron acquisition strategies. Their regulation has been investigated well for some pathogenic fungi and in the model organism Saccharomyces cerevisiae, which employs an evolutionarily derived system. Here, we show that C. glabrata uses a regulation network largely consisting of components of the S. cerevisiae regulon but also of elements of other pathogenic fungi. Specifically, similarly to baker's yeast, Aft1 is the main positive regulator under iron starvation conditions, while Cth2 degrades mRNAs encoding iron-requiring enzymes. However, unlike the case with S. cerevisiae, a Sef1 ortholog is required for full growth under iron limitation conditions, making C. glabrata an evolutionary intermediate to SEF1-dependent fungal pathogens. Therefore, C. glabrata has evolved an iron homeostasis system which seems to be unique within the pathogenic fungi. IMPORTANCE The fungus Candida glabrata represents an evolutionarily close relative of the well-studied and benign baker's yeast and model organism Saccharomyces cerevisiae On the other hand, C. glabrata is an important opportunistic human pathogen causing both superficial and systemic infections. The ability to acquire trace metals, in particular, iron, and to tightly regulate this process during infection is considered an important virulence attribute of a variety of pathogens. Importantly, S. cerevisiae uses a highly derivative regulatory system distinct from those of other fungi. Until now, the regulatory mechanism of iron homeostasis in C. glabrata has been mostly unknown. Our study revealed a hybrid iron regulation network that is unique to C. glabrata and is placed at an evolutionary midpoint between those of S. cerevisiae and related fungal pathogens. We thereby show that, in the host, even a successful human pathogen can rely largely on a strategy normally found in nonpathogenic fungi from a terrestrial environment.
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Merhej J, Thiebaut A, Blugeon C, Pouch J, Ali Chaouche MEA, Camadro JM, Le Crom S, Lelandais G, Devaux F. A Network of Paralogous Stress Response Transcription Factors in the Human Pathogen Candida glabrata. Front Microbiol 2016; 7:645. [PMID: 27242683 PMCID: PMC4860858 DOI: 10.3389/fmicb.2016.00645] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2016] [Accepted: 04/18/2016] [Indexed: 01/15/2023] Open
Abstract
The yeast Candida glabrata has become the second cause of systemic candidemia in humans. However, relatively few genome-wide studies have been conducted in this organism and our knowledge of its transcriptional regulatory network is quite limited. In the present work, we combined genome-wide chromatin immunoprecipitation (ChIP-seq), transcriptome analyses, and DNA binding motif predictions to describe the regulatory interactions of the seven Yap (Yeast AP1) transcription factors of C. glabrata. We described a transcriptional network containing 255 regulatory interactions and 309 potential target genes. We predicted with high confidence the preferred DNA binding sites for 5 of the 7 CgYaps and showed a strong conservation of the Yap DNA binding properties between S. cerevisiae and C. glabrata. We provided reliable functional annotation for 3 of the 7 Yaps and identified for Yap1 and Yap5 a core regulon which is conserved in S. cerevisiae, C. glabrata, and C. albicans. We uncovered new roles for CgYap7 in the regulation of iron-sulfur cluster biogenesis, for CgYap1 in the regulation of heme biosynthesis and for CgYap5 in the repression of GRX4 in response to iron starvation. These transcription factors define an interconnected transcriptional network at the cross-roads between redox homeostasis, oxygen consumption, and iron metabolism.
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Affiliation(s)
- Jawad Merhej
- Laboratoire de Biologie Computationnelle et Quantitative, Centre National de la Recherche Scientifique, Institut de Biologie Paris-Seine, UMR 7238, Sorbonne Universités, Université Pierre et Marie Curie Paris, France
| | - Antonin Thiebaut
- Laboratoire de Biologie Computationnelle et Quantitative, Centre National de la Recherche Scientifique, Institut de Biologie Paris-Seine, UMR 7238, Sorbonne Universités, Université Pierre et Marie Curie Paris, France
| | - Corinne Blugeon
- École Normale Supérieure, Paris Sciences et Lettres Research University, Centre National de la Recherche Scientifique, Institut National de la Santé et de la Recherche Médicale, Institut de Biologie de l'École Normale Supérieure, Plateforme Génomique Paris, France
| | - Juliette Pouch
- École Normale Supérieure, Paris Sciences et Lettres Research University, Centre National de la Recherche Scientifique, Institut National de la Santé et de la Recherche Médicale, Institut de Biologie de l'École Normale Supérieure, Plateforme Génomique Paris, France
| | - Mohammed El Amine Ali Chaouche
- École Normale Supérieure, Paris Sciences et Lettres Research University, Centre National de la Recherche Scientifique, Institut National de la Santé et de la Recherche Médicale, Institut de Biologie de l'École Normale Supérieure, Plateforme Génomique Paris, France
| | - Jean-Michel Camadro
- Centre National de la Recherche Scientifique, UMR 7592, Institut Jacques Monod, Université Paris Diderot, Sorbonne Paris Cité Paris, France
| | - Stéphane Le Crom
- Évolution, Centre National de la Recherche Scientifique, Institut de Biologie Paris-Seine, UMR 7138, Sorbonne Universités, Université Pierre et Marie Curie Paris, France
| | - Gaëlle Lelandais
- Centre National de la Recherche Scientifique, UMR 7592, Institut Jacques Monod, Université Paris Diderot, Sorbonne Paris Cité Paris, France
| | - Frédéric Devaux
- Laboratoire de Biologie Computationnelle et Quantitative, Centre National de la Recherche Scientifique, Institut de Biologie Paris-Seine, UMR 7238, Sorbonne Universités, Université Pierre et Marie Curie Paris, France
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44
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Wofford JD, Lindahl PA. Mitochondrial Iron-Sulfur Cluster Activity and Cytosolic Iron Regulate Iron Traffic in Saccharomyces cerevisiae. J Biol Chem 2015; 290:26968-26977. [PMID: 26306041 PMCID: PMC4646409 DOI: 10.1074/jbc.m115.676668] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Revised: 08/17/2015] [Indexed: 11/06/2022] Open
Abstract
An ordinary differential equation-based mathematical model was developed to describe trafficking and regulation of iron in growing fermenting budding yeast. Accordingly, environmental iron enters the cytosol and moves into mitochondria and vacuoles. Dilution caused by increasing cell volume is included. Four sites are regulated, including those in which iron is imported into the cytosol, mitochondria, and vacuoles, and the site at which vacuolar Fe(II) is oxidized to Fe(III). The objective of this study was to determine whether cytosolic iron (Fecyt) and/or a putative sulfur-based product of iron-sulfur cluster (ISC) activity was/were being sensed in regulation. The model assumes that the matrix of healthy mitochondria is anaerobic, and that in ISC mutants, O2 diffuses into the matrix where it reacts with nonheme high spin Fe(II) ions, oxidizing them to nanoparticles and generating reactive oxygen species. This reactivity causes a further decline in ISC/heme biosynthesis, which ultimately gives rise to the diseased state. The ordinary differential equations that define this model were numerically integrated, and concentrations of each component were plotted versus the concentration of iron in the growth medium and versus the rate of ISC/heme biosynthesis. Model parameters were optimized by fitting simulations to literature data. The model variant that assumed that both Fecyt and ISC biosynthesis activity were sensed in regulation mimicked observed behavior best. Such "dual sensing" probably arises in real cells because regulation involves assembly of an ISC on a cytosolic protein using Fecyt and a sulfur species generated in mitochondria during ISC biosynthesis and exported into the cytosol.
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Affiliation(s)
- Joshua D Wofford
- Departments of Chemistry, Texas A & M University, College Station, Texas 77843
| | - Paul A Lindahl
- Departments of Chemistry, Texas A & M University, College Station, Texas 77843; Departments of Chemistry, Biochemistry and Biophysics, Texas A & M University, College Station, Texas 77843.
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Wang H, Nair VS, Holland AA, Capolicchio S, Jessen HJ, Johnson MK, Shears SB. Asp1 from Schizosaccharomyces pombe binds a [2Fe-2S](2+) cluster which inhibits inositol pyrophosphate 1-phosphatase activity. Biochemistry 2015; 54:6462-74. [PMID: 26422458 DOI: 10.1021/acs.biochem.5b00532] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Iron-sulfur (Fe-S) clusters are widely distributed protein cofactors that are vital to cellular biochemistry and the maintenance of bioenergetic homeostasis, but to our knowledge, they have never been identified in any phosphatase. Here, we describe an iron-sulfur cluster in Asp1, a dual-function kinase/phosphatase that regulates cell morphogenesis in Schizosaccharomyces pombe. Full-length Asp1, and its phosphatase domain (Asp1(371-920)), were each heterologously expressed in Escherichia coli. The phosphatase activity is exquisitely specific: it hydrolyzes the 1-diphosphate from just two members of the inositol pyrophosphate (PP-InsP) signaling family, namely, 1-InsP7 and 1,5-InsP8. We demonstrate that Asp1 does not hydrolyze either InsP6, 2-InsP7, 3-InsP7, 4-InsP7, 5-InsP7, 6-InsP7, or 3,5-InsP8. We also recorded 1-phosphatase activity in a human homologue of Asp1, hPPIP5K1, which was heterologously expressed in Drosophila S3 cells with a biotinylated N-terminal tag, and then isolated from cell lysates with avidin beads. Purified, recombinant Asp1(371-920) contained iron and acid-labile sulfide, but the stoichiometry (0.8 atoms of each per protein molecule) indicates incomplete iron-sulfur cluster assembly. We reconstituted the Fe-S cluster in vitro under anaerobic conditions, which increased the stoichiometry to approximately 2 atoms of iron and acid-labile sulfide per Asp1 molecule. The presence of a [2Fe-2S](2+) cluster in Asp1(371-920) was demonstrated by UV-visible absorption, resonance Raman spectroscopy, and electron paramagnetic resonance spectroscopy. We determined that this [2Fe-2S](2+) cluster is unlikely to participate in redox chemistry, since it rapidly degraded upon reduction by dithionite. Biochemical and mutagenic studies demonstrated that the [2Fe-2S](2+) cluster substantially inhibits the phosphatase activity of Asp1, thereby increasing its net kinase activity.
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Affiliation(s)
- Huanchen Wang
- Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, National Institutes of Health , 101 T. W. Alexander Drive, Research Triangle Park, North Carolina 27709, United States
| | - Vasudha S Nair
- Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, National Institutes of Health , 101 T. W. Alexander Drive, Research Triangle Park, North Carolina 27709, United States
| | - Ashley A Holland
- Department of Chemistry and Center for Metalloenzyme Studies, University of Georgia , Athens, Georgia 30602, United States
| | - Samanta Capolicchio
- Department of Chemistry, University of Zurich (UZH) , Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Henning J Jessen
- Department of Chemistry, University of Zurich (UZH) , Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Michael K Johnson
- Department of Chemistry and Center for Metalloenzyme Studies, University of Georgia , Athens, Georgia 30602, United States
| | - Stephen B Shears
- Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, National Institutes of Health , 101 T. W. Alexander Drive, Research Triangle Park, North Carolina 27709, United States
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Cellular sensing and transport of metal ions: implications in micronutrient homeostasis. J Nutr Biochem 2015; 26:1103-15. [PMID: 26342943 DOI: 10.1016/j.jnutbio.2015.08.002] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Revised: 07/23/2015] [Accepted: 08/04/2015] [Indexed: 12/15/2022]
Abstract
Micronutrients include the transition metal ions zinc, copper and iron. These metals are essential for life as they serve as cofactors for many different proteins. On the other hand, they can also be toxic to cell growth when in excess. As a consequence, all organisms require mechanisms to tightly regulate the levels of these metal ions. In eukaryotes, one of the primary ways in which metal levels are regulated is through changes in expression of genes required for metal uptake, compartmentalization, storage and export. By tightly regulating the expression of these genes, each organism is able to balance metal levels despite fluctuations in the diet or extracellular environment. The goal of this review is to provide an overview of how gene expression can be controlled at a transcriptional, posttranscriptional and posttranslational level in response to metal ions in lower and higher eukaryotes. Specifically, I review what is known about how these metalloregulatory factors sense fluctuations in metal ion levels and how changes in gene expression maintain nutrient homeostasis.
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47
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Compartmentalization of iron between mitochondria and the cytosol and its regulation. Eur J Cell Biol 2015; 94:292-308. [DOI: 10.1016/j.ejcb.2015.05.003] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
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48
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Merhej J, Delaveau T, Guitard J, Palancade B, Hennequin C, Garcia M, Lelandais G, Devaux F. Yap7 is a transcriptional repressor of nitric oxide oxidase in yeasts, which arose from neofunctionalization after whole genome duplication. Mol Microbiol 2015; 96:951-72. [DOI: 10.1111/mmi.12983] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/24/2015] [Indexed: 11/27/2022]
Affiliation(s)
- Jawad Merhej
- Sorbonne Universités, UPMC Univ. Paris 06, Institut de Biologie Paris Seine UMR 7238; Laboratoire de biologie computationnelle et quantitative; F-75006 Paris France
- CNRS, UMR 7238; Laboratoire de biologie computationnelle et quantitative; F-75006 Paris France
| | - Thierry Delaveau
- Sorbonne Universités, UPMC Univ. Paris 06, Institut de Biologie Paris Seine UMR 7238; Laboratoire de biologie computationnelle et quantitative; F-75006 Paris France
- CNRS, UMR 7238; Laboratoire de biologie computationnelle et quantitative; F-75006 Paris France
| | - Juliette Guitard
- Sorbonne Universités, UPMC Univ Paris 06, CR7; Centre d'Immunologie et des Maladies Infectieuses (CIMI-Paris); 91 Bd de l'hôpital F-75013 Paris France
- Inserm; U1135; CIMI-Paris; 91 Bd de l'hôpital F-75013 Paris France
- Assistance Publique-Hôpitaux de Paris, Hôpital St Antoine; Service de Parasitologie-Mycologie; F-75012 Paris France
- CNRS; ERL 8255; CIMI-Paris; 91 Bd de l'hôpital F-75013 Paris France
| | - Benoit Palancade
- Institut Jacques Monod, CNRS, UMR 7592, Univ Paris Diderot; Sorbonne Paris Cité; F-75205 Paris France
| | - Christophe Hennequin
- Sorbonne Universités, UPMC Univ Paris 06, CR7; Centre d'Immunologie et des Maladies Infectieuses (CIMI-Paris); 91 Bd de l'hôpital F-75013 Paris France
- Inserm; U1135; CIMI-Paris; 91 Bd de l'hôpital F-75013 Paris France
- Assistance Publique-Hôpitaux de Paris, Hôpital St Antoine; Service de Parasitologie-Mycologie; F-75012 Paris France
- CNRS; ERL 8255; CIMI-Paris; 91 Bd de l'hôpital F-75013 Paris France
| | - Mathilde Garcia
- Sorbonne Universités, UPMC Univ. Paris 06, Institut de Biologie Paris Seine UMR 7238; Laboratoire de biologie computationnelle et quantitative; F-75006 Paris France
- CNRS, UMR 7238; Laboratoire de biologie computationnelle et quantitative; F-75006 Paris France
| | - Gaëlle Lelandais
- Institut Jacques Monod, CNRS, UMR 7592, Univ Paris Diderot; Sorbonne Paris Cité; F-75205 Paris France
| | - Frédéric Devaux
- Sorbonne Universités, UPMC Univ. Paris 06, Institut de Biologie Paris Seine UMR 7238; Laboratoire de biologie computationnelle et quantitative; F-75006 Paris France
- CNRS, UMR 7238; Laboratoire de biologie computationnelle et quantitative; F-75006 Paris France
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