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Li S, He J, Wu Q, Gou J, Wang D, Niu X. Gene fusion and functional diversification of P450 genes facilitate thermophilic fungal adaptation to temperature change. Mycology 2024; 15:485-505. [PMID: 39247895 PMCID: PMC11376295 DOI: 10.1080/21501203.2024.2324993] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Accepted: 02/22/2024] [Indexed: 09/10/2024] Open
Abstract
Thermomyces dupontii harbors two P450 paralogs (P450S and P450L) in the gene cluster for the biosynthesis of prenylated indole alkaloids (PIAs) and correponding iron chelators with P450L assigned as one protein containing a CYP like domain fused with a FAD-binding domain-containing oxidoreductase. Genetic manipulation and metabolic profile analysis indicated both P450S and P450L were involved in transforming simple PIAs to their corresponding iron chelators. Moreover, P450S is responsible for bolstering simple PIAs to complex PIAs, and P450L for reinforcing conjugating unsaturated systems in complex PIAs. Chemical investigation led to isolation and characterization of novel complex PIA metabolites with more oxidations. P450L also contributed to forming the third iron-chelating core in iron chelators. A series of iron bioassays and infrastructure analysis revealed that lack of these P450 genes caused strongly elevated Fe3+ levels but attenuated Fe2+ levels, together with abnormal mitochondria in mycelia and lipid droplets and vacuoles in conidia. Phenotype analysis revealed that P450S and P450L facilitated fungal colony pigments, conidial formation and germination via bolstering conidiophores and cell walls in response to temperature reduction.
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Affiliation(s)
- Shuhong Li
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, School of Life Sciences, Key Laboratory for Microbial Resources of the Ministry of Education, Yunnan University, Kunming, China
| | - Jiangbo He
- Kunming Key Laboratory of Respiratory Disease, Kunming University, Kunming, China
| | - Qunfu Wu
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, School of Life Sciences, Key Laboratory for Microbial Resources of the Ministry of Education, Yunnan University, Kunming, China
| | - Jianghui Gou
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, School of Life Sciences, Key Laboratory for Microbial Resources of the Ministry of Education, Yunnan University, Kunming, China
| | - Donglou Wang
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, School of Life Sciences, Key Laboratory for Microbial Resources of the Ministry of Education, Yunnan University, Kunming, China
| | - Xuemei Niu
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, School of Life Sciences, Key Laboratory for Microbial Resources of the Ministry of Education, Yunnan University, Kunming, China
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2
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Sandalio LM, Espinosa J, Shabala S, León J, Romero-Puertas MC. Reactive oxygen species- and nitric oxide-dependent regulation of ion and metal homeostasis in plants. JOURNAL OF EXPERIMENTAL BOTANY 2023; 74:5970-5988. [PMID: 37668424 PMCID: PMC10575707 DOI: 10.1093/jxb/erad349] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Accepted: 09/04/2023] [Indexed: 09/06/2023]
Abstract
Deterioration and impoverishment of soil, caused by environmental pollution and climate change, result in reduced crop productivity. To adapt to hostile soils, plants have developed a complex network of factors involved in stress sensing, signal transduction, and adaptive responses. The chemical properties of reactive oxygen species (ROS) and reactive nitrogen species (RNS) allow them to participate in integrating the perception of external signals by fine-tuning protein redox regulation and signal transduction, triggering specific gene expression. Here, we update and summarize progress in understanding the mechanistic basis of ROS and RNS production at the subcellular level in plants and their role in the regulation of ion channels/transporters at both transcriptional and post-translational levels. We have also carried out an in silico analysis of different redox-dependent modifications of ion channels/transporters and identified cysteine and tyrosine targets of nitric oxide in metal transporters. Further, we summarize possible ROS- and RNS-dependent sensors involved in metal stress sensing, such as kinases and phosphatases, as well as some ROS/RNS-regulated transcription factors that could be involved in metal homeostasis. Understanding ROS- and RNS-dependent signaling events is crucial to designing new strategies to fortify crops and improve plant tolerance of nutritional imbalance and metal toxicity.
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Affiliation(s)
- Luisa M Sandalio
- Stress, Development and Signaling in Plants, Estación Experimental del Zaidín, Granada, Spain
| | - Jesús Espinosa
- Stress, Development and Signaling in Plants, Estación Experimental del Zaidín, Granada, Spain
| | - Sergey Shabala
- School of Biological Science, University of Western Australia, Crawley, WA 6009, Australia
- International Research Centre for Environmental Membrane Biology, Foshan University, Foshan, China
| | - José León
- Institute of Plant Molecular and Cellular Biology (CSIC-UPV), Valencia, Spain
| | - María C Romero-Puertas
- Stress, Development and Signaling in Plants, Estación Experimental del Zaidín, Granada, Spain
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3
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Aghabi D, Sloan M, Gill G, Hartmann E, Antipova O, Dou Z, Guerra AJ, Carruthers VB, Harding CR. The vacuolar iron transporter mediates iron detoxification in Toxoplasma gondii. Nat Commun 2023; 14:3659. [PMID: 37339985 PMCID: PMC10281983 DOI: 10.1038/s41467-023-39436-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Accepted: 06/13/2023] [Indexed: 06/22/2023] Open
Abstract
Iron is essential to cells as a cofactor in enzymes of respiration and replication, however without correct storage, iron leads to the formation of dangerous oxygen radicals. In yeast and plants, iron is transported into a membrane-bound vacuole by the vacuolar iron transporter (VIT). This transporter is conserved in the apicomplexan family of obligate intracellular parasites, including in Toxoplasma gondii. Here, we assess the role of VIT and iron storage in T. gondii. By deleting VIT, we find a slight growth defect in vitro, and iron hypersensitivity, confirming its essential role in parasite iron detoxification, which can be rescued by scavenging of oxygen radicals. We show VIT expression is regulated by iron at transcript and protein levels, and by altering VIT localization. In the absence of VIT, T. gondii responds by altering expression of iron metabolism genes and by increasing antioxidant protein catalase activity. We also show that iron detoxification has an important role both in parasite survival within macrophages and in virulence in a mouse model. Together, by demonstrating a critical role for VIT during iron detoxification in T. gondii, we reveal the importance of iron storage in the parasite and provide the first insight into the machinery involved.
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Affiliation(s)
- Dana Aghabi
- Wellcome Centre of Integrative Parasitology, School of Infection and Immunity, University of Glasgow, Glasgow, UK
| | - Megan Sloan
- Wellcome Centre of Integrative Parasitology, School of Infection and Immunity, University of Glasgow, Glasgow, UK
| | - Grace Gill
- Wellcome Centre of Integrative Parasitology, School of Infection and Immunity, University of Glasgow, Glasgow, UK
| | - Elena Hartmann
- Wellcome Centre of Integrative Parasitology, School of Infection and Immunity, University of Glasgow, Glasgow, UK
| | - Olga Antipova
- X-Ray Sciences Division, Advanced Photon Source, Argonne National Laboratory, Argonne, IL, USA
| | - Zhicheng Dou
- Department of Biological Sciences, Clemson University, Clemson, SC, USA
| | - Alfredo J Guerra
- Department of Microbiology and Immunology, University of Michigan, Ann Arbor, MI, USA
- Cayman Chemical Company, Ann Arbor, MI, USA
| | - Vern B Carruthers
- Department of Microbiology and Immunology, University of Michigan, Ann Arbor, MI, USA
| | - Clare R Harding
- Wellcome Centre of Integrative Parasitology, School of Infection and Immunity, University of Glasgow, Glasgow, UK.
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4
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XUE P, SÁNCHEZ-LEÓN E, DAMOO D, HU G, JUNG WH, KRONSTAD JW. Heme sensing and trafficking in fungi. FUNGAL BIOL REV 2023; 43:100286. [PMID: 37781717 PMCID: PMC10540271 DOI: 10.1016/j.fbr.2022.09.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Fungal pathogens cause life-threatening diseases in humans, and the increasing prevalence of these diseases emphasizes the need for new targets for therapeutic intervention. Nutrient acquisition during infection is a promising target, and recent studies highlight the contributions of endomembrane trafficking, mitochondria, and vacuoles in the sensing and acquisition of heme by fungi. These studies have been facilitated by genetically encoded biosensors and other tools to quantitate heme in subcellular compartments and to investigate the dynamics of trafficking in living cells. In particular, the applications of biosensors in fungi have been extended beyond the detection of metabolites, cofactors, pH, and redox status to include the detection of heme. Here, we focus on studies that make use of biosensors to examine mechanisms of heme uptake and degradation, with guidance from the model fungus Saccharomyces cerevisiae and an emphasis on the pathogenic fungi Candida albicans and Cryptococcus neoformans that threaten human health. These studies emphasize a role for endocytosis in heme uptake, and highlight membrane contact sites involving mitochondria, the endoplasmic reticulum and vacuoles as mediators of intracellular iron and heme trafficking.
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Affiliation(s)
- Peng XUE
- Michael Smith Laboratories, Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Eddy SÁNCHEZ-LEÓN
- Michael Smith Laboratories, Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Djihane DAMOO
- Michael Smith Laboratories, Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Guanggan HU
- Michael Smith Laboratories, Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Won Hee JUNG
- Department of Systems Biotechnology, Chung-Ang University, Anseong 17546, Korea
| | - James W. KRONSTAD
- Michael Smith Laboratories, Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada
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5
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Zhao B, He D, Gao S, Zhang Y, Wang L. Hypothetical protein FoDbp40 influences the growth and virulence of Fusarium oxysporum by regulating the expression of isocitrate lyase. Front Microbiol 2022; 13:1050637. [DOI: 10.3389/fmicb.2022.1050637] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Accepted: 11/04/2022] [Indexed: 11/29/2022] Open
Abstract
Fungal growth is closely related to virulence. Finding the key genes and pathways that regulate growth can help elucidate the regulatory mechanisms of fungal growth and virulence in efforts to locate new drug targets. Fusarium oxysporum is an important plant pathogen and human opportunistic pathogen that has research value in agricultural and medicinal fields. A mutant of F. oxysporum with reduced growth was obtained by Agrobacterium tumefaciens-mediated transformation, the transferred DNA (T-DNA) interrupted gene in this mutant coded a hypothetical protein that we named FoDbp40. FoDbp40 has an unknown function, but we chose to explore its possible functions as it may play a role in fungal growth regulatory mechanisms. Results showed that F. oxysporum growth and virulence decreased after FoDbp40 deletion. FOXG_05529 (NCBI Gene ID, isocitrate lyase, ICL) was identified as a key gene that involved in the reduced growth of this mutant. Deletion of FoDbp40 results in a decrease of more than 80% in ICL expression and activity, succinate level, and energy level, plus a decrease in phosphorylated mammalian target of rapamycin level and an increase in phosphorylated 5′-adenosine monophosphate activated protein kinase level. In summary, our study found that the FoDbp40 regulates the expression of ICL at a transcriptional level and affects energy levels and downstream related pathways, thereby regulating the growth and virulence of F. oxysporum.
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Sorribes-Dauden R, Jordá T, Peris D, Martínez-Pastor MT, Puig S. Adaptation of Saccharomyces Species to High-Iron Conditions. Int J Mol Sci 2022; 23:13965. [PMID: 36430442 PMCID: PMC9693265 DOI: 10.3390/ijms232213965] [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: 10/07/2022] [Revised: 11/06/2022] [Accepted: 11/09/2022] [Indexed: 11/16/2022] Open
Abstract
Iron is an indispensable element that participates as an essential cofactor in multiple biological processes. However, when present in excess, iron can engage in redox reactions that generate reactive oxygen species that damage cells at multiple levels. In this report, we characterized the response of budding yeast species from the Saccharomyces genus to elevated environmental iron concentrations. We have observed that S. cerevisiae strains are more resistant to high-iron concentrations than Saccharomyces non-cerevisiae species. Liquid growth assays showed that species evolutionarily closer to S. cerevisiae, such as S. paradoxus, S. jurei, S. mikatae, and S. arboricola, were more resistant to high-iron levels than the more distant species S. eubayanus and S. uvarum. Remarkably, S. kudriavzevii strains were especially iron sensitive. Growth assays in solid media suggested that S. cerevisiae and S. paradoxus were more resistant to the oxidative stress caused by elevated iron concentrations. When comparing iron accumulation and sensitivity, different patterns were observed. As previously described for S. cerevisiae, S. uvarum and particular strains of S. kudriavzevii and S. paradoxus became more sensitive to iron while accumulating more intracellular iron levels. However, no remarkable changes in intracellular iron accumulation were observed for the remainder of species. These results indicate that different mechanisms of response to elevated iron concentrations exist in the different species of the genus Saccharomyces.
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Affiliation(s)
- Raquel Sorribes-Dauden
- Departamento de Bioquímica y Biología Molecular, Universitat de València, Doctor Moliner 50, 46100 Burjassot, Spain
- Departamento de Biotecnología, Instituto de Agroquímica y Tecnología de Alimentos (IATA), Consejo Superior de Investigaciones Científicas (CSIC), Agustín Escardino 7, 46980 Paterna, Spain
| | - Tania Jordá
- Departamento de Biotecnología, Instituto de Agroquímica y Tecnología de Alimentos (IATA), Consejo Superior de Investigaciones Científicas (CSIC), Agustín Escardino 7, 46980 Paterna, Spain
| | - David Peris
- Departamento de Biotecnología, Instituto de Agroquímica y Tecnología de Alimentos (IATA), Consejo Superior de Investigaciones Científicas (CSIC), Agustín Escardino 7, 46980 Paterna, Spain
- Section for Genetics and Evolutionary Biology, Department of Biosciences, University of Oslo, Blindernveien 31, 0371 Oslo, Norway
| | - María Teresa Martínez-Pastor
- Departamento de Bioquímica y Biología Molecular, Universitat de València, Doctor Moliner 50, 46100 Burjassot, Spain
| | - Sergi Puig
- Departamento de Biotecnología, Instituto de Agroquímica y Tecnología de Alimentos (IATA), Consejo Superior de Investigaciones Científicas (CSIC), Agustín Escardino 7, 46980 Paterna, Spain
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7
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Aminopeptidases trim Xaa-Pro proteins, initiating their degradation by the Pro/N-degron pathway. Proc Natl Acad Sci U S A 2021; 118:2115430118. [PMID: 34663735 DOI: 10.1073/pnas.2115430118] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/12/2021] [Indexed: 12/26/2022] Open
Abstract
N-degron pathways are proteolytic systems that recognize proteins bearing N-terminal (Nt) degradation signals (degrons) called N-degrons. Our previous work identified Gid4 as a recognition component (N-recognin) of the Saccharomyces cerevisiae proteolytic system termed the proline (Pro)/N-degron pathway. Gid4 is a subunit of the oligomeric glucose-induced degradation (GID) ubiquitin ligase. Gid4 targets proteins through the binding to their Nt-Pro residue. Gid4 is also required for degradation of Nt-Xaa-Pro (Xaa is any amino acid residue) proteins such as Nt-[Ala-Pro]-Aro10 and Nt-[Ser-Pro]-Pck1, with Pro at position 2. Here, we show that specific aminopeptidases function as components of the Pro/N-degron pathway by removing Nt-Ala or Nt-Ser and yielding Nt-Pro, which can be recognized by Gid4-GID. Nt-Ala is removed by the previously uncharacterized aminopeptidase Fra1. The enzymatic activity of Fra1 is shown to be essential for the GID-dependent degradation of Nt-[Ala-Pro]-Aro10. Fra1 can also trim Nt-[Ala-Pro-Pro-Pro] (stopping immediately before the last Pro) and thereby can target for degradation a protein bearing this Nt sequence. Nt-Ser is removed largely by the mitochondrial/cytosolic/nuclear aminopeptidase Icp55. These advances are relevant to eukaryotes from fungi to animals and plants, as Fra1, Icp55, and the GID ubiquitin ligase are conserved in evolution. In addition to discovering the mechanism of targeting of Xaa-Pro proteins, these insights have also expanded the diversity of substrates of the Pro/N-degron pathway.
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8
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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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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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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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A Cytoplasmic Heme Sensor Illuminates the Impacts of Mitochondrial and Vacuolar Functions and Oxidative Stress on Heme-Iron Homeostasis in Cryptococcus neoformans. mBio 2020; 11:mBio.00986-20. [PMID: 32723917 PMCID: PMC7387795 DOI: 10.1128/mbio.00986-20] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Invasive fungal diseases are increasing in frequency, and new drug targets and antifungal drugs are needed to bolster therapy. The mechanisms by which pathogens obtain critical nutrients such as iron from heme during host colonization represent a promising target for therapy. In this study, we employed a fluorescent heme sensor to investigate heme homeostasis in Cryptococcus neoformans. We demonstrated that endocytosis is a key aspect of heme acquisition and that vacuolar and mitochondrial functions are important in regulating the pool of available heme in cells. Stress generated by oxidative conditions impacts the heme pool, as do the drugs artemisinin and metformin; these drugs have heme-related activities and are in clinical use for malaria and diabetes, respectively. Overall, our study provides insights into mechanisms of fungal heme acquisition and demonstrates the utility of the heme sensor for drug characterization in support of new therapies for fungal diseases. Pathogens must compete with hosts to acquire sufficient iron for proliferation during pathogenesis. The pathogenic fungus Cryptococcus neoformans is capable of acquiring iron from heme, the most abundant source in vertebrate hosts, although the mechanisms of heme sensing and acquisition are not entirely understood. In this study, we adopted a chromosomally encoded heme sensor developed for Saccharomyces cerevisiae to examine cytosolic heme levels in C. neoformans using fluorescence microscopy, fluorimetry, and flow cytometry. We validated the responsiveness of the sensor upon treatment with exogenous hemin, during proliferation in macrophages, and in strains defective for endocytosis. We then used the sensor to show that vacuolar and mitochondrial dysregulation and oxidative stress reduced the labile heme pool in the cytosol. Importantly, the sensor provided a tool to further demonstrate that the drugs artemisinin and metformin have heme-related activities and the potential to be repurposed for antifungal therapy. Overall, this study provides insights into heme sensing by C. neoformans and establishes a powerful tool to further investigate mechanisms of heme-iron acquisition in the context of fungal pathogenesis.
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12
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Aspergillus fumigatus Mitochondrial Acetyl Coenzyme A Acetyltransferase as an Antifungal Target. Appl Environ Microbiol 2020; 86:AEM.02986-19. [PMID: 32005728 PMCID: PMC7082573 DOI: 10.1128/aem.02986-19] [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: 12/21/2019] [Accepted: 01/15/2020] [Indexed: 12/27/2022] Open
Abstract
Ergosterol plays an important role in maintaining cell membrane sterol homeostasis in fungi, and as such, it is considered an effective target in antifungal chemotherapy. In yeast, the enzyme acetyl-coenzyme A (CoA) acetyltransferase (ERG10) catalyzes the Claisen condensation of two acetyl-CoA molecules to acetoacetyl-CoA in the ergosterol biosynthesis pathway and is reported as being critical for cell viability. Using yeast ERG10 for alignment, two orthologues, AfERG10A (AFUB_000550) and AfERG10B (AFUB_083570), were discovered in the opportunistic fungal pathogen Aspergillus fumigatus Despite the essentiality of AfERG10B having been previously validated, the biological function of AfERG10A remains unclear. In this study, we have characterized recombinant AfERG10A as a functional acetyl-CoA acetyltransferase catalyzing both synthetic and degradative reactions. Unexpectedly, AfERG10A localizes to the mitochondria in A. fumigatus, as shown by C-terminal green fluorescent protein (GFP) tag fusion. Both knockout and inducible promoter strategies demonstrate that Aferg10A is essential for the survival of A. fumigatus The reduced expression of Aferg10A leads to severe morphological defects and increased susceptibility to oxidative and cell wall stresses. Although the catalytic mechanism of acetyl-CoA acetyltransferase family is highly conserved, the crystal structure of AfERG10A and its complex with CoA are solved, revealing four substitutions within the CoA binding site that are different from human orthologues. Taken together, our combination of genetic and structural studies demonstrates that mitochondrial AfERG10A is essential for A. fumigatus cell viability and could be a potential drug target to feed the antifungal drug development pipeline.IMPORTANCE A growing number of people worldwide are suffering from invasive aspergillosis caused by the human opportunistic fungal pathogen A. fumigatus Current therapeutic options rely on a limited repertoire of antifungals. Ergosterol is an essential component of the fungal cell membrane as well as a target of current antifungals. Approximately 20 enzymes are involved in ergosterol biosynthesis, of which acetyl-CoA acetyltransferase (ACAT) is the first enzyme. Two ACATs in A. fumigatus are AfErg10A and AfErg10B. However, the biological function of AfErg10A is yet to be investigated. In this study, we showed that AfErg10A is localized in the mitochondria and is essential for A. fumigatus survival and morphological development. In combination with structural studies, we validated AfErg10A as a potential drug target that will facilitate the development of novel antifungals and improve the efficiency of existing drugs.
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Mitochondrial dysfunctions trigger the calcium signaling-dependent fungal multidrug resistance. Proc Natl Acad Sci U S A 2019; 117:1711-1721. [PMID: 31811023 DOI: 10.1073/pnas.1911560116] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Drug resistance in fungal pathogens has risen steadily over the past decades due to long-term azole therapy or triazole usage in agriculture. Modification of the drug target protein to prevent drug binding is a major recognized route to induce drug resistance. However, mechanisms for nondrug target-induced resistance remain only loosely defined. Here, we explore the molecular mechanisms of multidrug resistance resulted from an efficient adaptation strategy for survival in drug environments in the human pathogen Aspergillus fumigatus We show that mutants conferring multidrug resistance are linked with mitochondrial dysfunction induced by defects in heme A biosynthesis. Comparison of the gene expression profiles between the drug-resistant mutants and the parental wild-type strain shows that multidrug-resistant transporters, chitin synthases, and calcium-signaling-related genes are significantly up-regulated, while scavenging mitochondrial reactive oxygen species (ROS)-related genes are significantly down-regulated. The up-regulated-expression genes share consensus calcium-dependent serine threonine phosphatase-dependent response elements (the binding sites of calcium-signaling transcription factor CrzA). Accordingly, drug-resistant mutants show enhanced cytosolic Ca2+ transients and persistent nuclear localization of CrzA. In comparison, calcium chelators significantly restore drug susceptibility and increase azole efficacy either in laboratory-derived or in clinic-isolated A. fumigatus strains. Thus, the mitochondrial dysfunction as a fitness cost can trigger calcium signaling and, therefore, globally up-regulate a series of embedding calcineurin-dependent-response-element genes, leading to antifungal resistance. These findings illuminate how fitness cost affects drug resistance and suggest that disruption of calcium signaling might be a promising therapeutic strategy to fight against nondrug target-induced drug resistance.
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14
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Moore MJ, Wofford JD, Dancis A, Lindahl PA. Recovery of mrs3Δmrs4Δ Saccharomyces cerevisiae Cells under Iron-Sufficient Conditions and the Role of Fe 580. Biochemistry 2018; 57:672-683. [PMID: 29228768 PMCID: PMC6468996 DOI: 10.1021/acs.biochem.7b01034] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Mrs3 and Mrs4 are mitochondrial inner membrane proteins that deliver an unidentified cytosolic iron species into the matrix for use in iron-sulfur cluster (ISC) and heme biosynthesis. The Mrs3/4 double-deletion strain (ΔΔ) grew slowly in iron-deficient glycerol/ethanol medium but recovered to wild-type (WT) rates in iron-sufficient medium. ΔΔ cells grown under both iron-deficient and iron-sufficient respiring conditions acquired large amounts of iron relative to WT cells, indicating iron homeostatic dysregulation regardless of nutrient iron status. Biophysical spectroscopy (including Mössbauer, electron paramagnetic resonance, and electronic absorption) and bioanalytical methods (liquid chromatography with online inductively coupled plasma mass spectrometry detection) were used to characterize these phenotypes. Anaerobically isolated mitochondria contained a labile iron pool composed of a nonheme high-spin FeII complex with primarily O and N donor ligands, called Fe580. Fe580 likely serves as feedstock for ISC and heme biosynthesis. Mitochondria from respiring ΔΔ cells grown under iron-deficient conditions were devoid of Fe580, ISCs, and hemes; most iron was present as FeIII nanoparticles. O2 likely penetrates the matrix of slow-growing poorly respiring iron-deficient ΔΔ cells and reacts with Fe580 to form nanoparticles, thereby inhibiting ISC and heme biosynthesis. Mitochondria from iron-sufficient ΔΔ cells contained ISCs, hemes, and Fe580 at concentrations comparable to those of WT mitochondria. The matrix of these mutant cells was probably sufficiently anaerobic to protect Fe580 from degradation by O2. An ∼1100 Da manganese complex, an ∼1200 Da zinc complex, and an ∼5000 Da copper species were also present in ΔΔ and WT mitochondrial flow-through solutions. No lower-mass copper complex was evident.
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Affiliation(s)
- Michael J. Moore
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Joshua D. Wofford
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Andrew Dancis
- Department of Medicine, Division of Hematology-Oncology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Paul A. Lindahl
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843, United States
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15
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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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16
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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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17
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Eid R, Arab NTT, Greenwood MT. Iron mediated toxicity and programmed cell death: A review and a re-examination of existing paradigms. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2016; 1864:399-430. [PMID: 27939167 DOI: 10.1016/j.bbamcr.2016.12.002] [Citation(s) in RCA: 165] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Revised: 11/08/2016] [Accepted: 12/04/2016] [Indexed: 12/11/2022]
Abstract
Iron is an essential micronutrient that is problematic for biological systems since it is toxic as it generates free radicals by interconverting between ferrous (Fe2+) and ferric (Fe3+) forms. Additionally, even though iron is abundant, it is largely insoluble so cells must treat biologically available iron as a valuable commodity. Thus elaborate mechanisms have evolved to absorb, re-cycle and store iron while minimizing toxicity. Focusing on rarely encountered situations, most of the existing literature suggests that iron toxicity is common. A more nuanced examination clearly demonstrates that existing regulatory processes are more than adequate to limit the toxicity of iron even in response to iron overload. Only under pathological or artificially harsh situations of exposure to excess iron does it become problematic. Here we review iron metabolism and its toxicity as well as the literature demonstrating that intracellular iron is not toxic but a stress responsive programmed cell death-inducing second messenger.
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Affiliation(s)
- Rawan Eid
- Department of Chemistry and Chemical Engineering, Royal Military College of Canada, Kingston, Ontario, Canada
| | - Nagla T T Arab
- Department of Chemistry and Chemical Engineering, Royal Military College of Canada, Kingston, Ontario, Canada
| | - Michael T Greenwood
- Department of Chemistry and Chemical Engineering, Royal Military College of Canada, Kingston, Ontario, Canada.
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18
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Long N, Xu X, Qian H, Zhang S, Lu L. A Putative Mitochondrial Iron Transporter MrsA in Aspergillus fumigatus Plays Important Roles in Azole-, Oxidative Stress Responses and Virulence. Front Microbiol 2016; 7:716. [PMID: 27433157 PMCID: PMC4922219 DOI: 10.3389/fmicb.2016.00716] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Accepted: 04/29/2016] [Indexed: 11/25/2022] Open
Abstract
Iron is an essential nutrient and enzyme co-factor required for a wide range of cellular processes, especially for the function of mitochondria. For the opportunistic fungal pathogen Aspergillus fumigatus, the ability to obtain iron is required for growth and virulence during the infection process. However, knowledge of how mitochondria are involved in iron regulation is still limited. Here, we show that a mitochondrial iron transporter, MrsA, a homolog of yeast Mrs4p, is critical for adaptation to iron-limited or iron-excess conditions in A. fumigatus. Deletion of mrsA leads to disruption of iron homeostasis with a decreased sreA expression, resulted in activated reductive iron assimilation (RIA) and siderophore-mediated iron acquisition (SIA). Furthermore, deletion of mrsA induces hypersusceptibility to azole and oxidative stresses. An assay for cellular ROS content in ΔmrsA combined with rescue from the mrsA-defective phenotype by the antioxidant reagent L-ascorbic acid indicates that the increased sensitivity of ΔmrsA to the azole itraconazole and to oxidative stress is mainly the result of abnormal ROS accumulation. Moreover, site-directed mutation experiments verified that three conserved histidine residues related to iron transport in MrsA are required for responses to oxidative and azole stresses. Importantly, ΔmrsA causes significant attenuation of virulence in an immunocompromised murine model of aspergillosis. Collectively, our results show that the putative mitochondrial iron transporter MrsA plays important roles in azole- and oxidative-stress responses and virulence by regulating the balance of cellular iron in A. fumigatus.
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Affiliation(s)
- Nanbiao Long
- Jiangsu Key Laboratory for Microbes and Functional Genomics, Jiangsu Engineering and Technology Research Center for Microbiology, College of Life Sciences, Nanjing Normal University Nanjing, China
| | - Xiaoling Xu
- Jiangsu Key Laboratory for Microbes and Functional Genomics, Jiangsu Engineering and Technology Research Center for Microbiology, College of Life Sciences, Nanjing Normal University Nanjing, China
| | - Hui Qian
- Jiangsu Key Laboratory for Microbes and Functional Genomics, Jiangsu Engineering and Technology Research Center for Microbiology, College of Life Sciences, Nanjing Normal University Nanjing, China
| | - Shizhu Zhang
- Jiangsu Key Laboratory for Microbes and Functional Genomics, Jiangsu Engineering and Technology Research Center for Microbiology, College of Life Sciences, Nanjing Normal University Nanjing, China
| | - Ling Lu
- Jiangsu Key Laboratory for Microbes and Functional Genomics, Jiangsu Engineering and Technology Research Center for Microbiology, College of Life Sciences, Nanjing Normal University Nanjing, China
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19
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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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20
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Petryk N, Zhou YF, Sybirna K, Mucchielli MH, Guiard B, Bao WG, Stasyk OV, Stasyk OG, Krasovska OS, Budin K, Reymond N, Imbeaud S, Coudouel S, Delacroix H, Sibirny A, Bolotin-Fukuhara M. Functional study of the Hap4-like genes suggests that the key regulators of carbon metabolism HAP4 and oxidative stress response YAP1 in yeast diverged from a common ancestor. PLoS One 2014; 9:e112263. [PMID: 25479159 PMCID: PMC4257542 DOI: 10.1371/journal.pone.0112263] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2014] [Accepted: 10/06/2014] [Indexed: 12/05/2022] Open
Abstract
The transcriptional regulator HAP4, induced by respiratory substrates, is involved in the balance between fermentation and respiration in S. cerevisiae. We identified putative orthologues of the Hap4 protein in all ascomycetes, based only on a conserved sixteen amino acid-long motif. In addition to this motif, some of these proteins contain a DNA-binding motif of the bZIP type, while being nonetheless globally highly divergent. The genome of the yeast Hansenula polymorpha contains two HAP4-like genes encoding the protein HpHap4-A which, like ScHap4, is devoid of a bZIP motif, and HpHap4-B which contains it. This species has been chosen for a detailed examination of their respective properties. Based mostly on global gene expression studies performed in the S. cerevisiae HAP4 disruption mutant (ScΔhap4), we show here that HpHap4-A is functionally equivalent to ScHap4, whereas HpHap4-B is not. Moreover HpHAP4-B is able to complement the H2O2 hypersensitivity of the ScYap1 deletant, YAP1 being, in S. cerevisiae, the main regulator of oxidative stress. Finally, a transcriptomic analysis performed in the ScΔyap1 strain overexpressing HpHAP4-B shows that HpHap4-B acts both on oxidative stress response and carbohydrate metabolism in a manner different from both ScYap1 and ScHap4. Deletion of these two genes in their natural host, H. polymorpha, confirms that HpHAP4-A participates in the control of the fermentation/respiration balance, while HpHAP4-B is involved in oxidative stress since its deletion leads to hypersensitivity to H2O2. These data, placed in an evolutionary context, raise new questions concerning the evolution of the HAP4 transcriptional regulation function and suggest that Yap1 and Hap4 have diverged from a unique regulatory protein in the fungal ancestor.
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Affiliation(s)
- Nataliya Petryk
- Institut de Génétique et Microbiologie, IFR Génome 115, Université Paris-Sud and CNRS, Orsay, France
- Institute of Cell Biology, National Academy of Sciences, Lviv, Ukraine
- Centre de Génétique Moléculaire, CNRS, Gif sur Yvette, France
| | - You-Fang Zhou
- Institut de Génétique et Microbiologie, IFR Génome 115, Université Paris-Sud and CNRS, Orsay, France
| | - Kateryna Sybirna
- Institut de Génétique et Microbiologie, IFR Génome 115, Université Paris-Sud and CNRS, Orsay, France
| | - Marie-Hélène Mucchielli
- Gif/Orsay DNA MicroArray Platform, Gif sur Yvette, France
- Centre de Génétique Moléculaire, CNRS, Gif sur Yvette, France
| | - Bernard Guiard
- Centre de Génétique Moléculaire, CNRS, Gif sur Yvette, France
| | - Wei-Guo Bao
- Institut de Génétique et Microbiologie, IFR Génome 115, Université Paris-Sud and CNRS, Orsay, France
| | - Oleh V. Stasyk
- Institute of Cell Biology, National Academy of Sciences, Lviv, Ukraine
| | - Olena G. Stasyk
- Institute of Cell Biology, National Academy of Sciences, Lviv, Ukraine
- Department of Biochemistry, Ivan Franko Lviv National University, Lviv, Ukraine
| | | | - Karine Budin
- Institut de Génétique et Microbiologie, IFR Génome 115, Université Paris-Sud and CNRS, Orsay, France
- Gif/Orsay DNA MicroArray Platform, Gif sur Yvette, France
| | - Nancie Reymond
- Gif/Orsay DNA MicroArray Platform, Gif sur Yvette, France
- Centre de Génétique Moléculaire, CNRS, Gif sur Yvette, France
| | | | | | - Hervé Delacroix
- Gif/Orsay DNA MicroArray Platform, Gif sur Yvette, France
- Centre de Génétique Moléculaire, CNRS, Gif sur Yvette, France
| | - Andriy Sibirny
- Institute of Cell Biology, National Academy of Sciences, Lviv, Ukraine
- University of Rzeszow, Rzeszow, Poland
| | - Monique Bolotin-Fukuhara
- Institut de Génétique et Microbiologie, IFR Génome 115, Université Paris-Sud and CNRS, Orsay, France
- * E-mail:
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21
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Li L, Miao R, Jia X, Ward DM, Kaplan J. Expression of the yeast cation diffusion facilitators Mmt1 and Mmt2 affects mitochondrial and cellular iron homeostasis: evidence for mitochondrial iron export. J Biol Chem 2014; 289:17132-41. [PMID: 24798331 DOI: 10.1074/jbc.m114.574723] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mmt1 and Mmt2 are highly homologous yeast members of the cation diffusion facilitator transporter family localized to mitochondria. Overexpression of MMT1/2 led to changes in cellular metal homeostasis (increased iron sensitivity, decreased cobalt sensitivity, increased sensitivity to copper), oxidant generation, and increased sensitivity to H2O2. The phenotypes due to overexpression of MMT1&2 were similar to that seen in cells with deletions in MRS3 and MRS4, genes that encode the mitochondrial iron importers. Overexpression of MMT1&2 resulted in induction of the low iron transcriptional response, similar to that seen in Δmrs3Δmr4 cells. This low iron transcriptional response was suppressed by deletion of CCC1, the gene that encodes the vacuolar iron importer. Measurement of the activity of the iron-dependent gentisate 1,2-dioxygenase from Pseudaminobacter salicylatoxidans expressed in yeast cytosol, showed that changes in Mmt1/2 levels affected cytosol iron concentration even in the absence of Ccc1. Overexpression of MMT1 resulted in increased cytosolic iron whereas deletion of MMT1/MMT2 led to decreased cytosolic iron. These results support the hypothesis that Mmt1/2 function as mitochondrial iron exporters.
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Affiliation(s)
- Liangtao Li
- From the Department of Pathology, School of Medicine, University of Utah, Salt Lake City, Utah 84132
| | - Ren Miao
- From the Department of Pathology, School of Medicine, University of Utah, Salt Lake City, Utah 84132
| | - Xuan Jia
- From the Department of Pathology, School of Medicine, University of Utah, Salt Lake City, Utah 84132
| | - Diane M Ward
- From the Department of Pathology, School of Medicine, University of Utah, Salt Lake City, Utah 84132
| | - Jerry Kaplan
- From the Department of Pathology, School of Medicine, University of Utah, Salt Lake City, Utah 84132
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22
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Cockrell A, McCormick SP, Moore MJ, Chakrabarti M, Lindahl PA. Mössbauer, EPR, and modeling study of iron trafficking and regulation in Δccc1 and CCC1-up Saccharomyces cerevisiae. Biochemistry 2014; 53:2926-40. [PMID: 24785783 PMCID: PMC4025571 DOI: 10.1021/bi500002n] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
![]()
Strains lacking and overexpressing
the vacuolar iron (Fe) importer CCC1 were characterized
using Mössbauer and EPR spectroscopies.
Vacuolar Fe import is impeded in Δccc1 cells
and enhanced in CCC1-up cells, causing vacuolar Fe
in these strains to decline and accumulate, respectively, relative
to WT cells. Cytosolic Fe levels should behave oppositely. The Fe
content of Δccc1 cells grown under low-Fe conditions
was similar to that in WT cells. Most Fe was mitochondrial with some
nonheme high spin (NHHS) FeII present. Δccc1 cells grown with increasing Fe concentration in the medium contained
less total Fe, less vacuolar HS FeIII, and more NHHS FeII than in comparable WT cells. As the Fe concentration in
the growth medium increased, the concentration of HS FeIII in Δccc1 cells increased to just 60% of WT
levels, while NHHS FeII increased to twice WT levels, suggesting
that the NHHS FeII was cytosolic. Δccc1 cells suffered more oxidative damage than WT cells, suggesting that
the accumulated NHHS FeII promoted Fenton chemistry. The
Fe concentration in CCC1-up cells was higher than
in WT cells; the extra Fe was present as NHHS FeII and
FeIII and as FeIII oxyhydroxide nanoparticles.
These cells contained less mitochondrial Fe and exhibited less ROS
damage than Δccc1 cells. CCC1-up cells were adenine-deficient on minimal medium; supplementing with
adenine caused a decline of NHHS FeII suggesting that some
of the NHHS FeII that accumulated in these cells was associated
with adenine deficiency rather than the overexpression of CCC1. A mathematical model was developed that simulated
changes in Fe distributions. Simulations suggested that only a modest
proportion of the observed NHHS FeII in both strains was
the cytosolic form of Fe that is sensed by the Fe import regulatory
system. The remainder is probably generated by the reduction of the
vacuolar NHHS FeIII species.
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Affiliation(s)
- Allison Cockrell
- Department of Biochemistry and Biophysics, Texas A&M University , College Station, Texas 77843-2128, United States
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23
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Xu N, Dong Y, Cheng X, Yu Q, Qian K, Mao J, Jia C, Ding X, Zhang B, Chen Y, Zhang B, Xing L, Li M. Cellular iron homeostasis mediated by the Mrs4–Ccc1–Smf3 pathway is essential for mitochondrial function, morphogenesis and virulence in Candida albicans. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1843:629-39. [DOI: 10.1016/j.bbamcr.2013.12.009] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Revised: 12/11/2013] [Accepted: 12/13/2013] [Indexed: 11/29/2022]
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Molin M, Demir AB. Linking Peroxiredoxin and Vacuolar-ATPase Functions in Calorie Restriction-Mediated Life Span Extension. Int J Cell Biol 2014; 2014:913071. [PMID: 24639875 PMCID: PMC3930189 DOI: 10.1155/2014/913071] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2013] [Revised: 11/11/2013] [Accepted: 12/15/2013] [Indexed: 01/09/2023] Open
Abstract
Calorie restriction (CR) is an intervention extending the life spans of many organisms. The mechanisms underlying CR-dependent retardation of aging are still poorly understood. Despite mechanisms involving conserved nutrient signaling pathways proposed, few target processes that can account for CR-mediated longevity have so far been identified. Recently, both peroxiredoxins and vacuolar-ATPases were reported to control CR-mediated retardation of aging downstream of conserved nutrient signaling pathways. In this review, we focus on peroxiredoxin-mediated stress-defence and vacuolar-ATPase regulated acidification and pinpoint common denominators between the two mechanisms proposed for how CR extends life span. Both the activities of peroxiredoxins and vacuolar-ATPases are stimulated upon CR through reduced activities in conserved nutrient signaling pathways and both seem to stimulate cellular resistance to peroxide-stress. However, whereas vacuolar-ATPases have recently been suggested to control both Ras-cAMP-PKA- and TORC1-mediated nutrient signaling, neither the physiological benefits of a proposed role for peroxiredoxins in H2O2-signaling nor downstream targets regulated are known. Both peroxiredoxins and vacuolar-ATPases do, however, impinge on mitochondrial iron-metabolism and further characterization of their impact on iron homeostasis and peroxide-resistance might therefore increase our understanding of the beneficial effects of CR on aging and age-related diseases.
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Affiliation(s)
- Mikael Molin
- Department of Chemistry and Molecular Biology, University of Gothenburg, Medicinaregatan 9C, 413 90 Gothenburg, Sweden
| | - Ayse Banu Demir
- Department of Chemistry and Molecular Biology, University of Gothenburg, Medicinaregatan 9C, 413 90 Gothenburg, Sweden
- Department of Molecular Biology and Genetics, Izmir Institute of Technology, 35430 Urla, Izmir, Turkey
- Department of Oncology, Institute of Oncology, Dokuz Eylul University, 35340 Inciralti, Izmir, Turkey
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The MAP kinase Slt2 is involved in vacuolar function and actin remodeling in Saccharomyces cerevisiae mutants affected by endogenous oxidative stress. Appl Environ Microbiol 2013; 79:6459-71. [PMID: 23956390 DOI: 10.1128/aem.01692-13] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Oxidative stress causes transient actin cytoskeleton depolarization and also provokes vacuole fragmentation in wild-type cells. Under conditions of oxidative stress induced by hydrogen peroxide, the Slt2 protein is required to repolarize the actin cytoskeleton and to promote vacuole fusion. In this study, we show that grx3 grx4 and grx5 mutants are cellular models of endogenous oxidative stress. This stress is the result of alterations in iron homeostasis that lead to impairment of vacuolar function and also to disorganization of the actin cytoskeleton. Slt2 overexpression suppresses defects in vacuolar function and actin cytoskeleton organization in the grx3 grx4 mutant. Slt2 exerts this effect independently of the intracellular levels of reactive oxygen species (ROS) and of iron homeostasis. The deletion of SLT2 in the grx3 grx4 mutant results in synthetic lethality related to vacuolar function with substantial vacuole fragmentation. The observation that both Vps4 and Vps73 (two proteins related to vacuole sorting) suppress vacuole fragmentation and actin depolarization in the grx3 grx4 slt2 triple mutant strengthens the hypothesis that Slt2 plays a role in vacuole homeostasis related to actin dynamics. Here we show that in sod1, grx5, and grx3 grx4 slt2 mutants, all of which are affected by chronic oxidative stress, the overexpression of Slt2 favors vacuole fusion through a mechanism dependent on an active actin cytoskeleton.
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Diab HI, Kane PM. Loss of vacuolar H+-ATPase (V-ATPase) activity in yeast generates an iron deprivation signal that is moderated by induction of the peroxiredoxin TSA2. J Biol Chem 2013; 288:11366-77. [PMID: 23457300 DOI: 10.1074/jbc.m112.419259] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Vacuolar H(+)-ATPases (V-ATPases) acidify intracellular organelles and help to regulate overall cellular pH. Yeast vma mutants lack V-ATPase activity and allow exploration of connections between cellular pH, iron, and redox homeostasis common to all eukaryotes. A previous microarray study in a vma mutant demonstrated up-regulation of multiple iron uptake genes under control of Aft1p (the iron regulon) and only one antioxidant gene, the peroxiredoxin TSA2 (Milgrom, E., Diab, H., Middleton, F., and Kane, P. M. (2007) Loss of vacuolar proton-translocating ATPase activity in yeast results in chronic oxidative stress. J. Biol. Chem. 282, 7125-7136). Fluorescent biosensors placing GFP under transcriptional control of either an Aft1-dependent promoter (P(FIT2)-GFP) or the TSA2 promoter (P(TSA2)-GFP) were constructed to monitor transcriptional signaling. Both biosensors were up-regulated in the vma2Δ mutant, and acute V-ATPase inhibition with concanamycin A induced coordinate up-regulation from both promoters. PTSA2-GFP induction was Yap1p-dependent, indicating an oxidative stress signal. Total cell iron measurements indicate that the vma2Δ mutant is iron-replete, despite up-regulation of the iron regulon. Acetic acid up-regulated P(FIT2)-GFP expression in wild-type cells, suggesting that loss of pH control contributes to an iron deficiency signal in the mutant. Iron supplementation significantly decreased P(FIT2)-GFP expression and, surprisingly, restored P(TSA2)-GFP to wild-type levels. A tsa2Δ mutation induced both nuclear localization of Aft1p and P(FIT2)-GFP expression. The data suggest a novel function for Tsa2p as a negative regulator of Aft1p-driven transcription, which is induced in V-ATPase mutants to limit transcription of the iron regulon. This represents a new mechanism bridging the antioxidant and iron-regulatory pathways that is intimately linked to pH homeostasis.
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Affiliation(s)
- Heba I Diab
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, New York 13210, USA
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Abstract
This chapter is focused on the iron metallome in eukaryotes at the cellular and subcellular level, including properties, utilization in metalloproteins, trafficking, storage, and regulation of these processes. Studies in the model eukaryote Saccharomyces cerevisiae and mammalian cells will be highlighted. The discussion of iron properties will center on the speciation and localization of intracellular iron as well as the cellular and molecular mechanisms for coping with both low iron bioavailability and iron toxicity. The section on iron metalloproteins will emphasize heme, iron-sulfur cluster, and non-heme iron centers, particularly their cellular roles and mechanisms of assembly. The section on iron uptake, trafficking, and storage will compare methods used by yeast and mammalian cells to import iron, how this iron is brought into various organelles, and types of iron storage proteins. Regulation of these processes will be compared between yeast and mammalian cells at the transcriptional, post-transcriptional, and post-translational levels.
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Affiliation(s)
- Adrienne C. Dlouhy
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, SC 29208, USA
| | - Caryn E. Outten
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, SC 29208, USA
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28
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Ycf1p attenuates basal level oxidative stress response in Saccharomyces cerevisiae. FEBS Lett 2012; 586:847-53. [PMID: 22449970 DOI: 10.1016/j.febslet.2012.02.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2011] [Revised: 02/06/2012] [Accepted: 02/08/2012] [Indexed: 11/22/2022]
Abstract
Ycf1p function is regulated by casein kinase 2α, Cka1p, via phosphorylation of Ser251. Cka1p-mediated phosphorylation of Ycf1p is attenuated in response to high salt stress. Previous results from our lab suggest a role for Ycf1p in cellular resistance to salt stress. Here, we show that Ycf1p plays an important role in cellular resistance to salt stress by maintaining the cellular redox balance via glutathione recycling. Our results suggest that during acute salt stress increased Sod1p, Sod2p and Ctt1p activity is the main compensatory for the loss in Ycf1p function that results from reduced Ycf1p-dependent recycling of cellular GSH levels.
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Rim2, a pyrimidine nucleotide exchanger, is needed for iron utilization in mitochondria. Biochem J 2011; 440:137-46. [PMID: 21777202 DOI: 10.1042/bj20111036] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Mitochondria transport and utilize iron for the synthesis of haem and Fe-S clusters. Although many proteins are known to be involved in these processes, additional proteins are likely to participate. To test this hypothesis, in the present study we used a genetic screen looking for yeast mutants that are synthetically lethal with the mitochondrial iron carriers Mrs3 and Mrs4. Several genes were identified, including an isolate mutated for Yfh1, the yeast frataxin homologue. All such triple mutants were complemented by increased expression of Rim2, another mitochondrial carrier protein. Rim2 overexpression was able to enhance haem and Fe-S cluster synthesis in wild-type or Δmrs3/Δmrs4 backgrounds. Conversely Rim2 depletion impaired haem and Fe-S cluster synthesis in wild-type or Δmrs3/Δmrs4 backgrounds, indicating a unique requirement for this mitochondrial transporter for these processes. Rim2 was previously shown to mediate pyrimidine exchange in and out of vesicles. In the present study we found that isolated mitochondria lacking Rim2 exhibited concordant iron defects and pyrimidine transport defects, although the connection between these two functions is not explained. When organellar membranes were ruptured to bypass iron transport, haem synthesis from added iron and porphyrin was still markedly deficient in Rim2-depleted mitochondrial lysate. The results indicate that Rim2 is a pyrimidine exchanger with an additional unique function in promoting mitochondrial iron utilization.
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Li L, Jia X, Ward DM, Kaplan J. Yap5 protein-regulated transcription of the TYW1 gene protects yeast from high iron toxicity. J Biol Chem 2011; 286:38488-38497. [PMID: 21917924 DOI: 10.1074/jbc.m111.286666] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The budding yeast Saccharomyces cerevisiae responds to high cytosolic iron by inducing Yap5-mediated transcription. We identified genes regulated by Yap5 in response to iron and show that one of the genes induced is TYW1, which encodes an iron-sulfur cluster enzyme that participates in the synthesis of wybutosine-modified tRNA. Strains deleted for TYW1 do not show a phenotype in standard yeast medium. In contrast, overexpression of TYW1 results in decreased cell growth and induction of the iron regulon, leading to increased expression of the high affinity iron transporters. We identified a minimal domain of S. cerevisiae Tyw1 that is sufficient to induce the iron regulon. CCC1, a vacuolar iron importer, is a Yap5-regulated gene, and deletion of either CCC1 or YAP5 resulted in high iron sensitivity. Deletion of TYW1 in a Δccc1 strain led to increased iron sensitivity. The increased iron sensitivity of Δccc1Δtyw1 could be suppressed by overexpression of iron-sulfur cluster enzymes. We conclude that the Yap5-mediated induction of TYW1 provides protection from high iron toxicity by the consumption of free cytosolic iron through the formation of protein-bound iron-sulfur clusters.
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Affiliation(s)
- Liangtao Li
- Department of Pathology, School of Medicine, University of Utah, Salt Lake City, Utah 84132
| | - Xuan Jia
- Department of Pathology, School of Medicine, University of Utah, Salt Lake City, Utah 84132
| | - Diane M Ward
- Department of Pathology, School of Medicine, University of Utah, Salt Lake City, Utah 84132
| | - Jerry Kaplan
- Department of Pathology, School of Medicine, University of Utah, Salt Lake City, Utah 84132.
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31
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The rice mitochondrial iron transporter is essential for plant growth. Nat Commun 2011; 2:322. [PMID: 21610725 PMCID: PMC3113228 DOI: 10.1038/ncomms1326] [Citation(s) in RCA: 113] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2011] [Accepted: 04/26/2011] [Indexed: 11/18/2022] Open
Abstract
In plants, iron (Fe) is essential for mitochondrial electron transport, heme, and Fe-Sulphur (Fe-S) cluster synthesis; however, plant mitochondrial Fe transporters have not been identified. Here we show, identify and characterize the rice mitochondrial Fe transporter (MIT). Based on a transfer DNA library screen, we identified a rice line showing symptoms of Fe deficiency while accumulating high shoot levels of Fe. Homozygous knockout of MIT in this line resulted in a lethal phenotype. MIT localized to the mitochondria and complemented the growth of Δmrs3Δmrs4 yeast defective in mitochondrial Fe transport. The growth of MIT-knockdown (mit-2) plants was also significantly impaired despite abundant Fe accumulation. Further, the decrease in the activity of the mitochondrial and cytosolic Fe-S enzyme, aconitase, indicated that Fe-S cluster synthesis is affected in mit-2 plants. These results indicate that MIT is a mitochondrial Fe transporter essential for rice growth and development. Increasing the nutritional content of plant crops and the identification of iron transporters in rice would facilitate the improvement of rice varieties. In this study, the authors identify a mitochondrial iron transporter in rice — MIT — and suggest that this gene is important for rice growth and development.
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Lindahl PA, Holmes-Hampton GP. Biophysical probes of iron metabolism in cells and organelles. Curr Opin Chem Biol 2011; 15:342-6. [PMID: 21282072 DOI: 10.1016/j.cbpa.2011.01.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2010] [Revised: 01/04/2011] [Accepted: 01/05/2011] [Indexed: 10/18/2022]
Abstract
In living systems, iron is found in many different structures, including Fe/S clusters, hemes and nonheme centers, and magnetically interacting aggregates. Understanding Fe metabolism and trafficking will require biophysical spectroscopic tools that can evaluate the types of Fe centers within entire cells and isolated organelles. Mössbauer spectroscopy will play an important role in such analyses, as it has perhaps the best combination of resolution, sensitivity, coverage, and quantifying abilities. Other spectroscopic techniques, with particular strengths, will be used in combination with Mössbauer, and results will be integrated to assess the 'ironome' of such complex samples. This integrative biophysical approach is illustrated by a discussion of iron trafficking in yeast cells.
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Affiliation(s)
- Paul A Lindahl
- Department of Chemistry, Texas A&M University, College Station, TX 77843-3255, USA.
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Lin H, Li L, Jia X, Ward DM, Kaplan J. Genetic and biochemical analysis of high iron toxicity in yeast: iron toxicity is due to the accumulation of cytosolic iron and occurs under both aerobic and anaerobic conditions. J Biol Chem 2010; 286:3851-62. [PMID: 21115478 DOI: 10.1074/jbc.m110.190959] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Iron storage in yeast requires the activity of the vacuolar iron transporter Ccc1. Yeast with an intact CCC1 are resistant to iron toxicity, but deletion of CCC1 renders yeast susceptible to iron toxicity. We used genetic and biochemical analysis to identify suppressors of high iron toxicity in Δccc1 cells to probe the mechanism of high iron toxicity. All genes identified as suppressors of high iron toxicity in aerobically grown Δccc1 cells encode organelle iron transporters including mitochondrial iron transporters MRS3, MRS4, and RIM2. Overexpression of MRS3 suppressed high iron toxicity by decreasing cytosolic iron through mitochondrial iron accumulation. Under anaerobic conditions, Δccc1 cells were still sensitive to high iron toxicity, but overexpression of MRS3 did not suppress iron toxicity and did not result in mitochondrial iron accumulation. We conclude that Mrs3/Mrs4 can sequester iron within mitochondria under aerobic conditions but not anaerobic conditions. We show that iron toxicity in Δccc1 cells occurred under both aerobic and anaerobic conditions. Microarray analysis showed no evidence of oxidative damage under anaerobic conditions, suggesting that iron toxicity may not be solely due to oxidative damage. Deletion of TSA1, which encodes a peroxiredoxin, exacerbated iron toxicity in Δccc1 cells under both aerobic and anaerobic conditions, suggesting a unique role for Tsa1 in iron toxicity.
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Affiliation(s)
- Huilan Lin
- Department of Pharmacology, School of Medicine, University of California at San Diego, La Jolla, California 92093, USA
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34
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Current awareness on yeast. Yeast 2010. [DOI: 10.1002/yea.1721] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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