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Clúa J, Montpetit J, Jimenez-Sandoval P, Naumann C, Santiago J, Poirier Y. A CYBDOM protein impacts iron homeostasis and primary root growth under phosphate deficiency in Arabidopsis. Nat Commun 2024; 15:423. [PMID: 38212368 PMCID: PMC10784552 DOI: 10.1038/s41467-023-43911-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Accepted: 11/23/2023] [Indexed: 01/13/2024] Open
Abstract
Arabidopsis primary root growth response to phosphate (Pi) deficiency is mainly controlled by changes in apoplastic iron (Fe). Upon Pi deficiency, apoplastic Fe deposition in the root apical meristem activates pathways leading to the arrest of meristem maintenance and inhibition of cell elongation. Here, we report that a member of the uncharacterized cytochrome b561 and DOMON domain (CYBDOM) protein family, named CRR, promotes iron reduction in an ascorbate-dependent manner and controls apoplastic iron deposition. Under low Pi, the crr mutant shows an enhanced reduction of primary root growth associated with increased apoplastic Fe in the root meristem and a reduction in meristematic cell division. Conversely, CRR overexpression abolishes apoplastic Fe deposition rendering primary root growth insensitive to low Pi. The crr single mutant and crr hyp1 double mutant, harboring a null allele in another member of the CYDOM family, shows increased tolerance to high-Fe stress upon germination and seedling growth. Conversely, CRR overexpression is associated with increased uptake and translocation of Fe to the shoot and results in plants highly sensitive to Fe excess. Our results identify a ferric reductase implicated in Fe homeostasis and developmental responses to abiotic stress, and reveal a biological role for CYBDOM proteins in plants.
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Affiliation(s)
- Joaquín Clúa
- Department of Plant Molecular Biology, Biophore Building, University of Lausanne, 1015, Lausanne, Switzerland
| | - Jonatan Montpetit
- Department of Plant Molecular Biology, Biophore Building, University of Lausanne, 1015, Lausanne, Switzerland
| | - Pedro Jimenez-Sandoval
- Department of Plant Molecular Biology, Biophore Building, University of Lausanne, 1015, Lausanne, Switzerland
| | - Christin Naumann
- Department of Molecular Signal Processing, Leibniz Institute of Plant Biochemistry, Weinberg 3, 06120, Halle, Germany
| | - Julia Santiago
- Department of Plant Molecular Biology, Biophore Building, University of Lausanne, 1015, Lausanne, Switzerland
| | - Yves Poirier
- Department of Plant Molecular Biology, Biophore Building, University of Lausanne, 1015, Lausanne, Switzerland.
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2
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Nurmalasari NPD, Winans MJ, Perroz K, Bovard VR, Anderson R, Smith S, Gallagher JEG. Toxicity and assimilation of cellulosic copper nanoparticles require α-arrestins in S. cerevisiae. Metallomics 2023; 15:mfad011. [PMID: 36841230 PMCID: PMC10022662 DOI: 10.1093/mtomcs/mfad011] [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: 12/20/2022] [Accepted: 02/24/2023] [Indexed: 02/27/2023]
Abstract
The increased use of antimicrobial compounds such as copper into nanoparticles changes how living cells interact with these novel materials. The increased use of antimicrobial nanomaterials combats infectious disease and food spoilage. Fungal infections are particularly difficult to treat because of the few druggable targets, and Saccharomyces cerevisiae provides an insightful model organism to test these new materials. However, because of the novel characteristics of these materials, it is unclear how these materials interact with living cells and if resistance to copper-based nanomaterials could occur. Copper nanoparticles built on carboxymethylcellulose microfibril strands with copper (CMC-Cu) are a promising nanomaterial when imported into yeast cells and induce cell death. The α-arrestins are cargo adaptors that select which molecules are imported into eukaryotic cells. We screened α-arrestins mutants and identified Aly2, Rim8, and Rog3 α-arrestins, which are necessary for the internalization of CMC-Cu nanoparticles. Internal reactive oxygen species in these mutants were lower and corresponded to the increased viability in the presence of CMC-Cu. Using lattice light-sheet microscopy on live cells, we determined that CMC-Cu were imported into yeast within 30 min of exposure. Initially, the cytoplasmic pH decreased but returned to basal level 90 min later. However, there was heterogeneity in response to CMC-Cu exposure, which could be due to the heterogeneity of the particles or differences in the metabolic states within the population. When yeast were exposed to sublethal concentrations of CMC-Cu no resistance occurred. Internalization of CMC-Cu increases the potency of these antimicrobial nanomaterials and is likely key to preventing fungi from evolving resistance.
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Affiliation(s)
- Ni Putu Dewi Nurmalasari
- Department of Nanoscience & Biomedical Engineering, South Dakota School of Mines and Technology, Rapid City, SD, USA
| | - Matthew J Winans
- Department of Biology, West Virginia University, Morgantown, WV, USA
| | - Katelyn Perroz
- Department of Biology, West Virginia University, Morgantown, WV, USA
| | - Victoria R Bovard
- Department of Biology, West Virginia University, Morgantown, WV, USA
| | - Robert Anderson
- Department of Nanoscience & Biomedical Engineering, South Dakota School of Mines and Technology, Rapid City, SD, USA
| | - Steve Smith
- Department of Nanoscience & Biomedical Engineering, South Dakota School of Mines and Technology, Rapid City, SD, USA
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3
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Sun J, Xu S, Du Y, Yu K, Jiang Y, Weng H, Yuan W. Accumulation and Enrichment of Trace Elements by Yeast Cells and Their Applications: A Critical Review. Microorganisms 2022; 10:1746. [PMID: 36144348 PMCID: PMC9504137 DOI: 10.3390/microorganisms10091746] [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: 07/21/2022] [Revised: 08/26/2022] [Accepted: 08/27/2022] [Indexed: 11/24/2022] Open
Abstract
Maintaining the homeostasis balance of trace elements is crucial for the health of organisms. Human health is threatened by diseases caused by a lack of trace elements. Saccharomyces cerevisiae has a wide and close relationship with human daily life and industrial applications. It can not only be used as fermentation products and single-cell proteins, but also as a trace elements supplement that is widely used in food, feed, and medicine. Trace-element-enriched yeast, viz., chromium-, iron-, zinc-, and selenium-enriched yeast, as an impactful microelements supplement, is more efficient, more environmentally friendly, and safer than its inorganic and organic counterparts. Over the last few decades, genetic engineering has been developing large-scaled genetic re-design and reconstruction in yeast. It is hoped that engineered yeast will include a higher concentration of trace elements. In this review, we compare the common supplement forms of several key trace elements. The mechanisms of detoxification and transport of trace elements in yeast are also reviewed thoroughly. Moreover, genes involved in the transport and detoxification of trace elements are summarized. A feasible way of metabolic engineering transformation of S. cerevisiae to produce trace-element-enriched yeast is examined. In addition, the economy, safety, and environmental protection of the engineered yeast are explored, and the future research direction of yeast enriched in trace elements is discussed.
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Affiliation(s)
- Jie Sun
- Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou 310014, China
| | - Shiyi Xu
- Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou 310014, China
| | - Yongbao Du
- Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou 310014, China
| | - Kechen Yu
- Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou 310014, China
| | - Yi Jiang
- Hangzhou Se-easy Biotechnology Co., Ltd., Hangzhou 311100, China
| | - Hao Weng
- Hangzhou Se-easy Biotechnology Co., Ltd., Hangzhou 311100, China
| | - Wei Yuan
- Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou 310014, China
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4
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Robinson JR, Isikhuemhen OS, Anike FN. Fungal-Metal Interactions: A Review of Toxicity and Homeostasis. J Fungi (Basel) 2021; 7:225. [PMID: 33803838 PMCID: PMC8003315 DOI: 10.3390/jof7030225] [Citation(s) in RCA: 69] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Revised: 03/15/2021] [Accepted: 03/17/2021] [Indexed: 12/18/2022] Open
Abstract
Metal nanoparticles used as antifungals have increased the occurrence of fungal-metal interactions. However, there is a lack of knowledge about how these interactions cause genomic and physiological changes, which can produce fungal superbugs. Despite interest in these interactions, there is limited understanding of resistance mechanisms in most fungi studied until now. We highlight the current knowledge of fungal homeostasis of zinc, copper, iron, manganese, and silver to comprehensively examine associated mechanisms of resistance. Such mechanisms have been widely studied in Saccharomyces cerevisiae, but limited reports exist in filamentous fungi, though they are frequently the subject of nanoparticle biosynthesis and targets of antifungal metals. In most cases, microarray analyses uncovered resistance mechanisms as a response to metal exposure. In yeast, metal resistance is mainly due to the down-regulation of metal ion importers, utilization of metallothionein and metallothionein-like structures, and ion sequestration to the vacuole. In contrast, metal resistance in filamentous fungi heavily relies upon cellular ion export. However, there are instances of resistance that utilized vacuole sequestration, ion metallothionein, and chelator binding, deleting a metal ion importer, and ion storage in hyphal cell walls. In general, resistance to zinc, copper, iron, and manganese is extensively reported in yeast and partially known in filamentous fungi; and silver resistance lacks comprehensive understanding in both.
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Affiliation(s)
| | - Omoanghe S. Isikhuemhen
- Department of Natural Resources and Environmental Design, North Carolina Agricultural and Technical State University, 1601 East Market Street, Greensboro, NC 27411, USA; (J.R.R.); (F.N.A.)
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5
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Adaptive Laboratory Evolution and Reverse Engineering of Single-Vitamin Prototrophies in Saccharomyces cerevisiae. Appl Environ Microbiol 2020; 86:AEM.00388-20. [PMID: 32303542 PMCID: PMC7267190 DOI: 10.1128/aem.00388-20] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Accepted: 04/11/2020] [Indexed: 01/28/2023] Open
Abstract
Many strains of Saccharomyces cerevisiae, a popular platform organism in industrial biotechnology, carry the genetic information required for synthesis of biotin, thiamine, pyridoxine, para-aminobenzoic acid, pantothenic acid, nicotinic acid, and inositol. However, omission of these B vitamins typically leads to suboptimal growth. This study demonstrates that, for each individual B vitamin, it is possible to achieve fast vitamin-independent growth by adaptive laboratory evolution (ALE). Identification of mutations responsible for these fast-growing phenotypes by whole-genome sequencing and reverse engineering showed that, for each compound, a small number of mutations sufficed to achieve fast growth in its absence. These results form an important first step toward development of S. cerevisiae strains that exhibit fast growth on inexpensive, fully supplemented mineral media that only require complementation with a carbon source, thereby reducing costs, complexity, and contamination risks in industrial yeast fermentation processes. Quantitative physiological studies on Saccharomyces cerevisiae commonly use synthetic media (SM) that contain a set of water-soluble growth factors that, based on their roles in human nutrition, are referred to as B vitamins. Previous work demonstrated that in S. cerevisiae CEN.PK113-7D, requirements for biotin were eliminated by laboratory evolution. In the present study, this laboratory strain was shown to exhibit suboptimal specific growth rates when either inositol, nicotinic acid, pyridoxine, pantothenic acid, para-aminobenzoic acid (pABA), or thiamine was omitted from SM. Subsequently, this strain was evolved in parallel serial-transfer experiments for fast aerobic growth on glucose in the absence of individual B vitamins. In all evolution lines, specific growth rates reached at least 90% of the growth rate observed in SM supplemented with a complete B vitamin mixture. Fast growth was already observed after a few transfers on SM without myo-inositol, nicotinic acid, or pABA. Reaching similar results in SM lacking thiamine, pyridoxine, or pantothenate required more than 300 generations of selective growth. The genomes of evolved single-colony isolates were resequenced, and for each B vitamin, a subset of non-synonymous mutations associated with fast vitamin-independent growth was selected. These mutations were introduced in a non-evolved reference strain using CRISPR/Cas9-based genome editing. For each B vitamin, the introduction of a small number of mutations sufficed to achieve a substantially increased specific growth rate in non-supplemented SM that represented at least 87% of the specific growth rate observed in fully supplemented complete SM. IMPORTANCE Many strains of Saccharomyces cerevisiae, a popular platform organism in industrial biotechnology, carry the genetic information required for synthesis of biotin, thiamine, pyridoxine, para-aminobenzoic acid, pantothenic acid, nicotinic acid, and inositol. However, omission of these B vitamins typically leads to suboptimal growth. This study demonstrates that, for each individual B vitamin, it is possible to achieve fast vitamin-independent growth by adaptive laboratory evolution (ALE). Identification of mutations responsible for these fast-growing phenotypes by whole-genome sequencing and reverse engineering showed that, for each compound, a small number of mutations sufficed to achieve fast growth in its absence. These results form an important first step toward development of S. cerevisiae strains that exhibit fast growth on inexpensive, fully supplemented mineral media that only require complementation with a carbon source, thereby reducing costs, complexity, and contamination risks in industrial yeast fermentation processes.
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6
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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: 17] [Impact Index Per Article: 2.8] [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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7
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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: 3.2] [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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8
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Dikicioglu D, Oliver SG. Extension of the yeast metabolic model to include iron metabolism and its use to estimate global levels of iron-recruiting enzyme abundance from cofactor requirements. Biotechnol Bioeng 2019; 116:610-621. [PMID: 30578666 PMCID: PMC6492170 DOI: 10.1002/bit.26905] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Revised: 11/21/2018] [Accepted: 12/20/2018] [Indexed: 12/15/2022]
Abstract
Metabolic networks adapt to changes in their environment by modulating the activity of their enzymes and transporters; often by changing their abundance. Understanding such quantitative changes can shed light onto how metabolic adaptation works, or how it can fail and lead to a metabolically dysfunctional state. We propose a strategy to quantify metabolic protein requirements for cofactor‐utilising enzymes and transporters through constraint‐based modelling. The first eukaryotic genome‐scale metabolic model to comprehensively represent iron metabolism was constructed, extending the most recent community model of the Saccharomyces cerevisiae metabolic network. Partial functional impairment of the genes involved in the maturation of iron‐sulphur (Fe‐S) proteins was investigated employing the model and the in silico analysis revealed extensive rewiring of the fluxes in response to this functional impairment, despite its marginal phenotypic effect. The optimal turnover rate of enzymes bearing ion cofactors can be determined via this novel approach; yeast metabolism, at steady state, was determined to employ a constant turnover of its iron‐recruiting enzyme at a rate of 3.02 × 10
−11 mmol·(g biomass)
−1·h
−1.
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Affiliation(s)
- Duygu Dikicioglu
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, UK.,Cambridge Systems Biology Centre, University of Cambridge, Cambridge, UK
| | - Stephen G Oliver
- Cambridge Systems Biology Centre, University of Cambridge, Cambridge, UK.,Department of Biochemistry, University of Cambridge, Cambridge, UK
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Gaspar‐Cordeiro A, Marques Caetano S, Amaral C, Rodrigues‐Pousada C, Pimentel C. Ace1 prevents intracellular copper accumulation by regulating Fet3 expression and thereby restricting Aft1 activity. FEBS J 2018; 285:1861-1872. [DOI: 10.1111/febs.14450] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Revised: 02/16/2018] [Accepted: 03/26/2018] [Indexed: 12/31/2022]
Affiliation(s)
- Ana Gaspar‐Cordeiro
- Instituto de Tecnologia Química e Biológica António Xavier Universidade Nova de Lisboa Oeiras Portugal
| | - Soraia Marques Caetano
- Instituto de Tecnologia Química e Biológica António Xavier Universidade Nova de Lisboa Oeiras Portugal
| | - Catarina Amaral
- Instituto de Tecnologia Química e Biológica António Xavier Universidade Nova de Lisboa Oeiras Portugal
| | | | - Catarina Pimentel
- Instituto de Tecnologia Química e Biológica António Xavier Universidade Nova de Lisboa Oeiras Portugal
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Abstract
Transmembrane NADPH oxidase (NOX) enzymes have been so far only characterized in eukaryotes. In most of these organisms, they reduce molecular oxygen to superoxide and, depending on the presence of additional domains, are called NOX or dual oxidases (DUOX). Reactive oxygen species (ROS), including superoxide, have been traditionally considered accidental toxic by-products of aerobic metabolism. However, during the last decade it has become evident that both O2•− and H2O2 are key players in complex signaling networks and defense. A well-studied example is the production of O2•− during the bactericidal respiratory burst of phagocytes; this production is catalyzed by NOX2. Here, we devised and applied a novel algorithm to search for additional NOX genes in genomic databases. This procedure allowed us to discover approximately 23% new sequences from bacteria (in relation to the number of NOX-related sequences identified by the authors) that we have added to the existing eukaryotic NOX family and have used to build an expanded phylogenetic tree. We cloned and overexpressed the identified nox gene from Streptococcus pneumoniae and confirmed that it codes for an NADPH oxidase. The membrane of the S. pneumoniae NOX protein (SpNOX) shares many properties with its eukaryotic counterparts, such as affinity for NADPH and flavin adenine dinucleotide, superoxide dismutase and diphenylene iodonium inhibition, cyanide resistance, oxygen consumption, and superoxide production. Traditionally, NOX enzymes in eukaryotes are related to functions linked to multicellularity. Thus, the discovery of a large family of NOX-related enzymes in the bacterial world brings up fascinating questions regarding their role in this new biological context. NADPH oxidase (NOX) enzymes have not yet been reported in bacteria. Here, we carried out computational and experimental studies to provide the first characterization of a prokaryotic NOX. Out of 996 prokaryotic proteins showing NOX signatures, we initially selected, cloned, and overexpressed four of them. Subsequently, and based on preliminary testing, we concentrated our efforts on Streptococcus SpNOX, which shares many biochemical characteristics with NOX2, the referent model of NOX enzymes. Our work makes possible, for the first time, the study of pure forms of this important family of enzymes, allowing for biophysical and molecular characterization in an unprecedented way. Similar advances regarding other membrane protein families have led to new structures, further mechanistic studies, and the improvement of inhibitors. In addition, biological functions of these newly described bacterial enzymes will be certainly discovered in the near future.
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Raya-Díaz S, Sánchez-Rodríguez AR, Segura-Fernández JM, del Campillo MDC, Quesada-Moraga E. Entomopathogenic fungi-based mechanisms for improved Fe nutrition in sorghum plants grown on calcareous substrates. PLoS One 2017; 12:e0185903. [PMID: 28982140 PMCID: PMC5628914 DOI: 10.1371/journal.pone.0185903] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Accepted: 09/21/2017] [Indexed: 11/30/2022] Open
Abstract
Although entomopathogenic fungi (EPF) are best known for their ability to protect crops against insect pests, they may have other beneficial effects on their host plants. These effects, which include promoting plant growth and conferring resistance against abiotic stresses, have been examined in recent years to acquire a better understanding of them. The primary purposes of the present study were (i) to ascertain in vitro whether three different strains of EPF (viz., Metarhizium, Beauveria and Isaria) would increase the Fe bioavailability in calcareous or non-calcareous media containing various Fe sources (ferrihydrite, hematite and goethite) and (ii) to assess the influence of the EPF inoculation method (seed dressing, soil treatment or leaf spraying) on the extent of the endophytic colonization of sorghum and the improvement in the Fe nutrition of pot-grown sorghum plants on an artificial calcareous substrate. All the EPFs studied were found to increase the Fe availability during the in vitro assay. The most efficient EPF was M. brunneum EAMa 01/58-Su, which lowered the pH of the calcareous medium, suggesting that it used a different strategy (organic acid release) than the other two fungi that raised the pH of the non-calcareous medium. The three methods used to inoculate sorghum plants with B. bassiana and M. brunneum in the pot experiment led to differences in re-isolation from plant tissues and in the plant height. These three inoculation methods increased the leaf chlorophyll content of young leaves when the Fe deficiency symptoms were most apparent in the control plants (without fungal inoculation) as well as the Fe content of the above-ground biomass in the plants at the end of the experiment. The total root lengths and fine roots were also increased in response to fungal applications with the three inoculation methods. However, the soil treatment was the most efficient method; thus, its effect on the leaf chlorophyll content was the most persistent, and the effects on the total root length and fine roots were the most apparent. In conclusion, EPF improved the Fe nutrition of the sorghum plants, but their effects depended on the inoculation method.
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Affiliation(s)
- Silvia Raya-Díaz
- Departamento de Ciencias y Recursos Agrícolas y Forestales, Universidad de Córdoba, ETSIAM, Córdoba, Spain
| | | | | | | | - Enrique Quesada-Moraga
- Departamento de Ciencias y Recursos Agrícolas y Forestales, Universidad de Córdoba, ETSIAM, Córdoba, Spain
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12
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Gerwien F, Safyan A, Wisgott S, Brunke S, Kasper L, Hube B. The Fungal Pathogen Candida glabrata Does Not Depend on Surface Ferric Reductases for Iron Acquisition. Front Microbiol 2017. [PMID: 28642757 PMCID: PMC5463049 DOI: 10.3389/fmicb.2017.01055] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Iron acquisition is a crucial virulence determinant for many bacteria and fungi, including the opportunistic fungal pathogens Candida albicans and C. glabrata. While the diverse strategies used by C. albicans for obtaining iron from the host are well-described, much less is known about the acquisition of this micronutrient from host sources by C. glabrata – a distant relative of C. albicans with closer evolutionary ties to Saccharomyces cerevisiae, which nonetheless causes severe clinical symptoms in humans. Here we show that C. glabrata is much more restricted than C. albicans in using host iron sources, lacking, for example, the ability to grow on transferrin and hemin/hemoglobin. Instead, C. glabrata is able to use ferritin and non-protein-bound iron (FeCl3) as iron sources in a pH-dependent manner. As in other fungal pathogens, iron-dependent growth requires the reductive high affinity (HA) iron uptake system. Typically highly conserved, this uptake mechanism normally relies on initial ferric reduction by cell-surface ferric reductases. The C. glabrata genome contains only three such putative ferric reductases, which were found to be dispensable for iron-dependent growth. In addition and in contrast to C. albicans and S. cerevisiae, we also detected no surface ferric reductase activity in C. glabrata. Instead, extracellular ferric reduction was found in this and the two other fungal species, which was largely dependent on an excreted low-molecular weight, non-protein ferric reductant. We therefore propose an iron acquisition strategy of C. glabrata which differs from other pathogenic fungi, such as C. albicans, in that it depends on a limited set of host iron sources and that it lacks the need for surface ferric reductases. Extracellular ferric reduction by a secreted molecule possibly compensates for the loss of surface ferric reductase activity in the HA iron uptake system.
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Affiliation(s)
- Franziska Gerwien
- Department of Microbial Pathogenicity Mechanisms, Leibniz Institute for Natural Product Research and Infection Biology - Hans Knoell InstituteJena, Germany
| | - Abu Safyan
- Department of Microbial Pathogenicity Mechanisms, Leibniz Institute for Natural Product Research and Infection Biology - Hans Knoell InstituteJena, Germany
| | - Stephanie Wisgott
- Department of Microbial Pathogenicity Mechanisms, Leibniz Institute for Natural Product Research and Infection Biology - Hans Knoell InstituteJena, Germany
| | - Sascha Brunke
- Department of Microbial Pathogenicity Mechanisms, Leibniz Institute for Natural Product Research and Infection Biology - Hans Knoell InstituteJena, Germany
| | - Lydia Kasper
- Department of Microbial Pathogenicity Mechanisms, Leibniz Institute for Natural Product Research and Infection Biology - Hans Knoell InstituteJena, Germany
| | - Bernhard Hube
- Department of Microbial Pathogenicity Mechanisms, Leibniz Institute for Natural Product Research and Infection Biology - Hans Knoell InstituteJena, Germany.,Department of Microbial Pathogenicity Mechanisms, Friedrich Schiller UniversityJena, Germany.,Center for Sepsis Control and Care, University HospitalJena, Germany
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13
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Cadiou JL, Pichat S, Bondanese VP, Soulard A, Fujii T, Albarède F, Oger P. Copper transporters are responsible for copper isotopic fractionation in eukaryotic cells. Sci Rep 2017; 7:44533. [PMID: 28303916 PMCID: PMC5356015 DOI: 10.1038/srep44533] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Accepted: 02/06/2017] [Indexed: 12/14/2022] Open
Abstract
Copper isotopic composition is altered in cancerous compared to healthy tissues. However, the rationale for this difference is yet unknown. As a model of Cu isotopic fractionation, we monitored Cu uptake in Saccharomyces cerevisiae, whose Cu import is similar to human. Wild type cells are enriched in 63Cu relative to 65Cu. Likewise, 63Cu isotope enrichment in cells without high-affinity Cu transporters is of slightly lower magnitude. In cells with compromised Cu reductase activity, however, no isotope fractionation is observed and when Cu is provided solely in reduced form for this strain, copper is enriched in 63Cu like in the case of the wild type. Our results demonstrate that Cu isotope fractionation is generated by membrane importers and that its amplitude is modulated by Cu reduction. Based on ab initio calculations, we propose that the fractionation may be due to Cu binding with sulfur-rich amino acids: methionine and cysteine. In hepatocellular carcinoma (HCC), lower expression of the STEAP3 copper reductase and heavy Cu isotope enrichment have been reported for the tumor mass, relative to the surrounding tissue. Our study suggests that copper isotope fractionation observed in HCC could be due to lower reductase activity in the tumor.
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Affiliation(s)
- Jean-Loup Cadiou
- Univ Lyon, ENS de Lyon, Université Claude Bernard Lyon 1, CNRS, UMR 5276, Lyon, France
| | - Sylvain Pichat
- Univ Lyon, ENS de Lyon, Université Claude Bernard Lyon 1, CNRS, UMR 5276, Lyon, France
| | - Victor P. Bondanese
- Univ Lyon, ENS de Lyon, Université Claude Bernard Lyon 1, CNRS, UMR 5276, Lyon, France
| | - Alexandre Soulard
- Univ Lyon, Université Claude Bernard Lyon 1, INSA-Lyon, CNRS, UMR5240, Villeurbanne, France
| | - Toshiyuki Fujii
- Division of Sustainable Energy and Environmental Engineering, Graduate School of Engineering, Osaka University, Osaka, Japan
| | - Francis Albarède
- Univ Lyon, ENS de Lyon, Université Claude Bernard Lyon 1, CNRS, UMR 5276, Lyon, France
| | - Philippe Oger
- Univ Lyon, ENS de Lyon, Université Claude Bernard Lyon 1, CNRS, UMR 5276, Lyon, France
- Univ Lyon, Université Claude Bernard Lyon 1, INSA-Lyon, CNRS, UMR5240, Villeurbanne, France
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14
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Luck AN, Yuan X, Voronin D, Slatko BE, Hamza I, Foster JM. Heme acquisition in the parasitic filarial nematode Brugia malayi. FASEB J 2016; 30:3501-3514. [PMID: 27363426 PMCID: PMC5024691 DOI: 10.1096/fj.201600603r] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Accepted: 06/21/2016] [Indexed: 11/11/2022]
Abstract
Nematodes lack a heme biosynthetic pathway and must acquire heme from exogenous sources. Given the indispensable role of heme, this auxotrophy may be exploited to develop drugs that interfere with heme uptake in parasites. Although multiple heme-responsive genes (HRGs) have been characterized within the free-living nematode Caenorhabditis elegans, we have undertaken the first study of heme transport in Brugia malayi, a causative agent of lymphatic filariasis. Through functional assays in yeast, as well as heme analog, RNAi, and transcriptomic experiments, we have shown that the heme transporter B. malayi HRG-1 (BmHRG-1) is indeed functional in B. malayi In addition, BmHRG-1 localizes both to the endocytic compartments and cell membrane when expressed in yeast cells. Transcriptomic sequencing revealed that BmHRG-1, BmHRG-2, and BmMRP-5 (all orthologs of HRGs in C. elegans) are down-regulated in heme-treated B. malayi, as compared to non-heme-treated control worms. Likely because of short gene lengths, multiple exons, other HRGs in B. malayi (BmHRG-3-6) remain unidentified. Although the precise mechanisms of heme homeostasis in a nematode with the ability to acquire heme remains unknown, this study clearly demonstrates that the filarial nematode B. malayi is capable of transporting exogenous heme.-Luck, A. N., Yuan, X., Voronin, D., Slatko, B. E., Hamza, I., Foster, J. M. Heme acquisition in the parasitic filarial nematode Brugia malayi.
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Affiliation(s)
- Ashley N Luck
- New England BioLabs, Incorporated, Genome Biology Division, Ipswich, Massachusetts, USA
| | - Xiaojing Yuan
- Department of Animal and Avian Sciences, University of Maryland, College Park, Maryland, USA; Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland, USA; and
| | - Denis Voronin
- New York Blood Center, Lindsley F. Kimball Research Institute, New York, New York, USA
| | - Barton E Slatko
- New England BioLabs, Incorporated, Genome Biology Division, Ipswich, Massachusetts, USA
| | - Iqbal Hamza
- Department of Animal and Avian Sciences, University of Maryland, College Park, Maryland, USA; Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland, USA; and
| | - Jeremy M Foster
- New England BioLabs, Incorporated, Genome Biology Division, Ipswich, Massachusetts, USA;
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15
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Identification of ferrichrome- and ferrioxamine B-mediated iron uptake by Aspergillus fumigatus. Biochem J 2016; 473:1203-13. [DOI: 10.1042/bcj20160066] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Accepted: 02/26/2016] [Indexed: 11/17/2022]
Abstract
Aspergillus fumigatus is an opportunistic fungal pathogen for immunocompromised patients, and genes involved in siderophore metabolism have been identified as virulence factors. Recently, we identified the membrane transporters sit1 and sit2, which are putative virulence factors of A. fumigatus; sit1 and sit2 are homologous to yeast Sit1, and sit1 and sit2 gene expression was up-regulated after iron depletion. When expressed heterologously in Saccharomyces cerevisiae, sit1 and sit2 were localized to the plasma membrane; sit1 efficiently complemented ferrichrome (FC) and ferrioxamine B (FOB) uptake in yeast cells, whereas sit2 complemented only FC uptake. Deletion of sit1 resulted in a decrease in FOB and FC uptake, and deletion of sit2 resulted in a decrease in FC uptake in A. fumigatus. It is of interest that a sit1 and sit2 double-deletion mutant resulted in a synergistic decrease in FC uptake activity. Both sit1 and sit2 were localized to the plasma membrane in A. fumigatus. The expression levels of the sit1 and sit2 genes were dependent on hapX under low-but not high-iron conditions. Furthermore, mirB, and sidA gene expression was up-regulated and sreA expression down-regulated when sit1 and sit2 were deleted. Although sit1 and sit2 failed to affect mouse survival rate, these genes affected conidial killing activity. Taken together, our results suggest that sit1 and sit2 are siderophore transporters and putative virulence factors localized to the plasma membrane.
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16
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Acetylated Deoxynivalenol Generates Differences of Gene Expression that Discriminate Trichothecene Toxicity. Toxins (Basel) 2016; 8:42. [PMID: 26861396 PMCID: PMC4773795 DOI: 10.3390/toxins8020042] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Accepted: 02/03/2016] [Indexed: 01/06/2023] Open
Abstract
Deoxynivalenol (DON), which is a toxic secondary metabolite generated by Fusarium species, is synthesized through two separate acetylation pathways. Both acetylation derivatives, 3-acetyl-DON (3ADON) and 15-acetyl-DON (15ADON), also contaminate grain and corn widely. These derivatives are deacetylated via a variety of processes after ingestion, so it has been suggested that they have the same toxicity as DON. However, in the intestinal entry region such as the duodenum, the derivatives might come into contact with intestinal epithelium cells because metabolism by microflora or import into the body has not progressed. Therefore, the differences of toxicity between DON and these derivatives need to be investigated. Here, we observed gene expression changes in the yeast pdr5Δ mutant strain under concentration-dependent mycotoxin exposure conditions. 15ADON exposure induced significant gene expression changes and DON exposure generally had a similar but smaller effect. However, the glucose transporter genes HXT2 and HXT4 showed converse trends. 3ADON also induced a different expression trend in these genes than DON and 15ADON. These differences in gene expression suggest that DON and its derivatives have different effects on cells.
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17
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Kang CM, Kang S, Park YS, Yun CW. Physical interaction between Sit1 and Aft1 upregulates FOB uptake activity by inhibiting protein degradation of Sit1 in Saccharomyces cerevisiae. FEMS Yeast Res 2015; 15:fov080. [PMID: 26323600 DOI: 10.1093/femsyr/fov080] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/06/2015] [Indexed: 11/15/2022] Open
Abstract
Previously, we reported that Aft1 regulates Sit1 by modulating the ubiquitination of Sit1 in Saccharomyces cerevisiae. Here, we report the function of the physical interaction between Sit1 and Aft1 in ferrioxamine B (FOB) uptake. The interaction between Sit1 and Aft1 induced protein localization of Sit1 to the plasma membrane, and more Sit1 was detected in the plasma membrane when Sit1 and Aft1 were coexpressed compared with Sit1 expression alone. The MSN5-deletion mutant, which failed to translocate Aft1 to the cytosolic compartment, showed lower FOB uptake activity than the wild type. However, higher free iron uptake activity was detected in the MSN5-deletion mutant. Furthermore, the strain transformed with AFT1-1(up) plasmid, which failed to regulate Aft1 via iron concentration and accumulated Aft1 in the nucleus, showed lower FOB uptake activity. The Aft1 Y179F mutant, which contained a tyrosine residue that was changed to phenylalanine, failed to interact physically with Sit1 and showed more degradation of the Sit1 and, ultimately, lower FOB uptake activity. Additionally, we found that MG132 and PMSF, which are inhibitors of proteasomes and serine proteases, respectively, increased the Sit1 protein level. Taken together, these results suggest that the protein-protein interaction between Sit1 and Aft1 is an important factor in the FOB uptake activity of Sit1.
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Affiliation(s)
- Chang-Min Kang
- School of Life Sciences and Biotechnology, Korea University, Anam-dong, Sungbuk-gu, Seoul 136-701, Republic of Korea
| | - Suzie Kang
- School of Life Sciences and Biotechnology, Korea University, Anam-dong, Sungbuk-gu, Seoul 136-701, Republic of Korea
| | - Yong-Sung Park
- School of Life Sciences and Biotechnology, Korea University, Anam-dong, Sungbuk-gu, Seoul 136-701, Republic of Korea
| | - Cheol-Won Yun
- School of Life Sciences and Biotechnology, Korea University, Anam-dong, Sungbuk-gu, Seoul 136-701, Republic of Korea
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18
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Yeast protective response to arsenate involves the repression of the high affinity iron uptake system. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2013; 1833:997-1005. [PMID: 23295455 DOI: 10.1016/j.bbamcr.2012.12.018] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2012] [Revised: 12/19/2012] [Accepted: 12/23/2012] [Indexed: 11/20/2022]
Abstract
Arsenic is a double-edge sword. On the one hand it is powerful carcinogen and on the other it is used therapeutically to treat acute promyelocytic leukemia. Here we report that arsenic activates the iron responsive transcription factor, Aft1, as a consequence of a defective high-affinity iron uptake mediated by Fet3 and Ftr1, whose mRNAs are drastically decreased upon arsenic exposure. Moreover, arsenic causes the internalization and degradation of Fet3. Most importantly, fet3ftr1 mutant exhibits increased arsenic resistance and decreased arsenic accumulation over the wild-type suggesting that Fet3 plays a role in arsenic toxicity. Finally we provide data suggesting that arsenic also disrupts iron uptake in mammals and the link between Fet3, arsenic and iron, can be relevant to clinical applications.
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19
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Blaby-Haas CE, Merchant SS. The ins and outs of algal metal transport. BIOCHIMICA ET BIOPHYSICA ACTA 2012; 1823:1531-52. [PMID: 22569643 PMCID: PMC3408858 DOI: 10.1016/j.bbamcr.2012.04.010] [Citation(s) in RCA: 134] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2012] [Revised: 04/20/2012] [Accepted: 04/23/2012] [Indexed: 10/28/2022]
Abstract
Metal transporters are a central component in the interaction of algae with their environment. They represent the first line of defense to cellular perturbations in metal concentration, and by analyzing algal metal transporter repertoires, we gain insight into a fundamental aspect of algal biology. The ability of individual algae to thrive in environments with unique geochemistry, compared to non-algal species commonly used as reference organisms for metal homeostasis, provides an opportunity to broaden our understanding of biological metal requirements, preferences and trafficking. Chlamydomonas reinhardtii is the best developed reference organism for the study of algal biology, especially with respect to metal metabolism; however, the diversity of algal niches necessitates a comparative genomic analysis of all sequenced algal genomes. A comparison between known and putative proteins in animals, plants, fungi and algae using protein similarity networks has revealed the presence of novel metal metabolism components in Chlamydomonas including new iron and copper transporters. This analysis also supports the concept that, in terms of metal metabolism, algae from similar niches are more related to one another than to algae from the same phylogenetic clade. This article is part of a Special Issue entitled: Cell Biology of Metals.
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20
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Iron and neurodegeneration: from cellular homeostasis to disease. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2012; 2012:128647. [PMID: 22701145 PMCID: PMC3369498 DOI: 10.1155/2012/128647] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/10/2012] [Revised: 03/21/2012] [Accepted: 04/05/2012] [Indexed: 01/04/2023]
Abstract
Accumulation of iron (Fe) is often detected in the brains of people suffering from neurodegenerative diseases. High Fe concentrations have been consistently observed in Parkinson's, Alzheimer's, and Huntington's diseases; however, it is not clear whether this Fe contributes to the progression of these diseases. Other conditions, such as Friedreich's ataxia or neuroferritinopathy are associated with genetic factors that cause Fe misregulation. Consequently, excessive intracellular Fe increases oxidative stress, which leads to neuronal dysfunction and death. The characterization of the mechanisms involved in the misregulation of Fe in the brain is crucial to understand the pathology of the neurodegenerative disorders and develop new therapeutic strategies. Saccharomyces cerevisiae, as the best understood eukaryotic organism, has already begun to play a role in the neurological disorders; thus it could perhaps become a valuable tool also to study the metalloneurobiology.
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21
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Identification of the molecular mechanisms underlying the cytotoxic action of a potent platinum metallointercalator. J Chem Biol 2011; 5:51-61. [PMID: 23226166 DOI: 10.1007/s12154-011-0070-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2011] [Accepted: 11/22/2011] [Indexed: 10/15/2022] Open
Abstract
UNLABELLED Platinum-based DNA metallointercalators are structurally different from the covalent DNA binders such as cisplatin and its derivatives but have potent in vitro activity in cancer cell lines. However, limited understanding of their molecular mechanisms of cytotoxic action greatly hinders their further development as anticancer agents. In this study, a lead platinum-based metallointercalator, [(5,6-dimethyl-1,10-phenanthroline) (1S,2S-diaminocyclohexane)platinum(II)](2+) (56MESS) was found to be 163-fold more active than cisplatin in a cisplatin-resistant cancer cell line. By using transcriptomics in a eukaryotic model organism, yeast Saccharomyces cerevisiae, we identified 93 genes that changed their expressions significantly upon exposure of 56MESS in comparison to untreated controls (p ≤ 0.05). Bioinformatic analysis of these genes demonstrated that iron and copper metabolism, sulfur-containing amino acids and stress response were involved in the cytotoxicity of 56MESS. Follow-up experiments showed that the iron and copper concentrations were much lower in 56MESS-treated cells compared to controls as measured by inductively coupled plasma optical emission spectrometry. Deletion mutants of the key genes in the iron and copper metabolism pathway and glutathione synthesis were sensitive to 56MESS. Taken together, the study demonstrated that the cytotoxic action of 56MESS is mediated by its ability to disrupt iron and copper metabolism, suppress the biosynthesis of sulfur-containing amino acids and attenuate cellular defence capacity. As these mechanisms are in clear contrast to the DNA binding mechanism for cisplatin and its derivative, 56MESS may be able to overcome cisplatin-resistant cancers. These findings have provided basis to further develop the platinum-based metallointercalators as anticancer agents. ELECTRONIC SUPPLEMENTARY MATERIAL The online version of this article (doi:10.1007/s12154-011-0070-x) contains supplementary material, which is available to authorized users.
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22
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Botta G, Turn CS, Quintyne NJ, Kirchman PA. Increased iron supplied through Fet3p results in replicative life span extension of Saccharomyces cerevisiae under conditions requiring respiratory metabolism. Exp Gerontol 2011; 46:827-32. [PMID: 21798334 DOI: 10.1016/j.exger.2011.07.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2011] [Revised: 07/07/2011] [Accepted: 07/11/2011] [Indexed: 01/05/2023]
Abstract
We have previously shown that copper supplementation extends the replicative life span of Saccharomyces cerevisiae when grown under conditions forcing cells to respire. We now show that copper's effect on life span is through Fet3p, a copper containing enzyme responsible for high affinity transport of iron into yeast cells. Life span extensions can also be obtained by supplementing the growth medium with 1mM ferric chloride. Extension by high iron levels is still dependent on the presence of Fet3p. Life span extension by iron or copper requires growth on media containing glycerol as the sole carbon source, which forces yeast to respire. Yeast grown on glucose containing media supplemented with iron show no extension of life span. The iron associated with cells grown in media supplemented with copper or iron is 1.4-1.8 times that of cells grown without copper or iron supplementation. As with copper supplementation, iron supplementation partially rescues the life span of superoxide dismutase mutants. Cells grown with copper supplementation display decreased production of superoxide as measured by dihydroethidium staining.
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Affiliation(s)
- Gabriela Botta
- Department of Biological Sciences, Florida Atlantic University, Boca Raton, FL 33431, United States.
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23
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Bleackley MR, Macgillivray RTA. Transition metal homeostasis: from yeast to human disease. Biometals 2011; 24:785-809. [PMID: 21479832 DOI: 10.1007/s10534-011-9451-4] [Citation(s) in RCA: 169] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2011] [Accepted: 03/28/2011] [Indexed: 12/16/2022]
Abstract
Transition metal ions are essential nutrients to all forms of life. Iron, copper, zinc, manganese, cobalt and nickel all have unique chemical and physical properties that make them attractive molecules for use in biological systems. Many of these same properties that allow these metals to provide essential biochemical activities and structural motifs to a multitude of proteins including enzymes and other cellular constituents also lead to a potential for cytotoxicity. Organisms have been required to evolve a number of systems for the efficient uptake, intracellular transport, protein loading and storage of metal ions to ensure that the needs of the cells can be met while minimizing the associated toxic effects. Disruptions in the cellular systems for handling transition metals are observed as a number of diseases ranging from hemochromatosis and anemias to neurodegenerative disorders including Alzheimer's and Parkinson's disease. The yeast Saccharomyces cerevisiae has proved useful as a model organism for the investigation of these processes and many of the genes and biological systems that function in yeast metal homeostasis are conserved throughout eukaryotes to humans. This review focuses on the biological roles of iron, copper, zinc, manganese, nickel and cobalt, the homeostatic mechanisms that function in S. cerevisiae and the human diseases in which these metals have been implicated.
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Affiliation(s)
- Mark R Bleackley
- Department of Biochemistry and Molecular Biology, Centre for Blood Research, Life Sciences Institute, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC, V6T1Z3, Canada
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24
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Hilty J, George Smulian A, Newman SL. Histoplasma capsulatum utilizes siderophores for intracellular iron acquisition in macrophages. Med Mycol 2011; 49:633-42. [PMID: 21341981 DOI: 10.3109/13693786.2011.558930] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Histoplasma capsulatum is a dimorphic fungal pathogen that survives and replicates within macrophages (MΦ). Studies in human and murine MΦ demonstrate that the intracellular growth of H. capsulatum yeasts is exquisitely sensitive to the availability of iron. As H. capsulatum produces hydroxamate siderophores, we sought to determine if siderophores were required for intracellular survival in MΦ, and in a murine model of pulmonary histoplasmosis. The expression of SID1 (coding for L-ornithine-N(5)-monooxygenase) was silenced by RNA interference (RNAi) in H. capsulatum strain G217B, and abolished by gene targeting in strain G186AR. G217B SID1-silenced yeasts grew normally in rich medium, did not synthesize siderophores, and were unable to grow on apotransferrin-chelated medium. Their intracellular growth in human and murine MΦ was significantly decreased compared to wild type (WT) yeasts, but growth was restored to WT levels by the addition of exogenous iron, or restoration of SID1 expression. Similar results were obtained with G186AR Δsid1 yeasts. Compared to WT yeasts, G217B SID1-silenced yeasts demonstrated in C57BL/6 mice significantly reduced growth in the lungs and spleens seven days after infection, and 40% of the mice given a normally lethal inoculum of G217B SID1-silenced yeasts survived. These experiments demonstrate that: (1) SID1 expression is required for siderophore biosynthesis by H. capsulatum strain G217B, (2) SID1 expression is required for optimum intracellular growth in MΦ, and (3) inhibition of SID1 expression in vivo reduces the virulence of H. capsulatum yeasts.
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Affiliation(s)
- Jeremy Hilty
- Department of Internal Medicine, Division of Infectious Diseases, University of Cincinnati College of Medicine, Cincinnati, OH 45267-0560, USA
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25
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Sharma PK, Mittal N, Deswal S, Roy N. Calorie restriction up-regulates iron and copper transport genes in Saccharomyces cerevisiae. MOLECULAR BIOSYSTEMS 2010; 7:394-402. [PMID: 21031176 DOI: 10.1039/c0mb00084a] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Calorie restriction (CR) is a non genetic intervention, known to confer longevity benefits across the various phyla from unicellular yeast to mammals. CR also invokes homeostatic responses similar to stress, however the sequence of molecular events leading to longevity is still illusive. In this study, we analysed the whole genome gene expression profile in response to CR, mutations mimicking CR, heat shock and H(2)O(2) from a gene ontology perspective. Our analysis revealed that mitochondrion is a common hub in the gene expression programme under these conditions and the electron transport chain (ETC) is a major player. Consequently the genes involved in the metal ion transport were also significantly up-regulated. We confirmed the results of the in silico analysis using quantitative real time PCR which showed up-regulation of genes involved in respiration and transport of iron and copper. The promoter activity of one of the representative genes, FET3, was also found to be higher upon calorie restriction. Altogether, our results indicate that upon calorie restriction the levels of iron and copper fall in cells, which elicits a transcriptional response up-regulating the genes involved in their uptake to maintain cellular homeostasis.
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Affiliation(s)
- Praveen Kumar Sharma
- Department of Biotechnology, National Institute of Pharmaceutical Education and Research, Sector 67, S A S Nagar, Punjab, 160062, India
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26
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Grissa I, Bidard F, Grognet P, Grossetete S, Silar P. The Nox/Ferric reductase/Ferric reductase-like families of Eumycetes. Fungal Biol 2010; 114:766-77. [DOI: 10.1016/j.funbio.2010.07.002] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2010] [Revised: 07/05/2010] [Accepted: 07/06/2010] [Indexed: 02/07/2023]
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27
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Pereira M, Bailão AM, Parente JA, Borges CL, Salem-Izacc SM, Soares CMDA. Preferential transcription of Paracoccidioides brasiliensis genes: host niche and time-dependent expression. Mem Inst Oswaldo Cruz 2009; 104:486-91. [PMID: 19547877 DOI: 10.1590/s0074-02762009000300015] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2008] [Accepted: 03/10/2009] [Indexed: 11/22/2022] Open
Abstract
Paracoccidioides brasiliensis causes infection through inhalation by the host of airborne propagules from the mycelium phase of the fungus. This fungus reaches the lungs, differentiates into the yeast form and is then disseminated to virtually all parts of the body. Here we review the identification of differentially-expressed genes in host-interaction conditions. These genes were identified by analyzing expressed sequence tags (ESTs) from P. brasiliensis cDNA libraries. The P. brasiliensis was recovered from infected mouse liver as well as from fungal yeast cells incubated in human blood and plasma, mimicking fungal dissemination to organs and tissues and sites of infection with inflammation, respectively. In addition, ESTs from a cDNA library of P. brasiliensis mycelium undergoing the transition to yeast were previously analyzed. Together, these studies reveal significant changes in the expression of a number of genes of potential importance in the host-fungus interaction. In addition, the unique and divergent representation of transcripts when the cDNA libraries are compared suggests differential gene expression in response to specific niches in the host. This analysis of gene expression patterns provides details about host-pathogen interactions and peculiarities of sites within the host.
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Affiliation(s)
- Maristela Pereira
- Laboratório de Biologia Molecular, Instituto de Ciências Biológicas, Universidade Federal de Goiás, Goiânia, GO, Brasil
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28
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A novel function of Aft1 in regulating ferrioxamine B uptake: Aft1 modulates Arn3 ubiquitination in Saccharomyces cerevisiae. Biochem J 2009; 422:181-91. [PMID: 19469713 DOI: 10.1042/bj20082399] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Aft1 is a transcriptional activator in Saccharomyces cerevisiae that responds to iron availability and regulates the expression of genes in the iron regulon, such as FET3, FTR1 and the ARN family. Using a two-hybrid screen, we found that Aft1 physically interacts with the FOB (ferrioxamine B) transporter Arn3. This interaction modulates the ability of Arn3 to take up FOB. The interaction between Arn3 and Aft1 was confirmed by beta-galactosidase, co-immunoprecipitation and SPR (surface plasmon resonance) assays. Truncated Aft1 had a stronger interaction with Arn3 and caused a higher FOB-uptake activity than full-length Aft1. Interestingly, only full-length Aft1 induced the correct localization of Arn3 in response to FOB. Furthermore, we found Aft1 affected Arn3 ubiquitination. These results suggest that Aft1 interacts with Arn3 and may regulate the ubiquitination of Arn3 in the cytosolic compartment.
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29
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Sedláček V, van Spanning RJM, Kučera I. Ferric reductase A is essential for effective iron acquisition in Paracoccus denitrificans. MICROBIOLOGY-SGM 2009; 155:1294-1301. [PMID: 19332830 DOI: 10.1099/mic.0.022715-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Based on N-terminal sequences obtained from the purified cytoplasmic ferric reductases FerA and FerB, their corresponding genes were identified in the published genome sequence of Paracoccus denitrificans Pd1222. The ferA and ferB genes were cloned and individually inactivated by insertion of a kanamycin resistance marker, and then returned to P. denitrificans for exchange with their wild-type copies. The resulting ferA and ferB mutant strains showed normal growth in brain heart infusion broth. Unlike the ferB mutant, the strain lacking FerA did not grow on succinate minimal medium with ferric 2,3-dihydroxybenzoate as the iron source, and grew only poorly in the presence of ferric sulfate, chloride, citrate, NTA, EDTA and EGTA. Moreover, the ferA mutant strain was unable to produce catechols, which are normally detectable in supernatants from iron-limited wild-type cultures. Complementation of the ferA mutation using a derivative of the conjugative broad-host-range plasmid pEG400 that contained the whole ferA gene and its putative promoter region largely restored the wild-type phenotype. Partial, though significant, restoration could also be achieved with 1 mM chorismate added to the growth medium. The purified FerA protein acted as an NADH : FMN oxidoreductase and catalysed the FMN-mediated reductive release of iron from the ferric complex of parabactin, the major catecholate siderophore of P. denitrificans. The deduced amino acid sequence of the FerA protein has closest similarity to flavin reductases that form part of the flavin-dependent two-component monooxygenases. Taken together, our results demonstrate an essential role of reduced flavins in the utilization of exogenous ferric iron. These flavins not only provide the electrons for Fe(III) reduction but most probably also affect the rate of siderophore production.
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Affiliation(s)
- Vojtěch Sedláček
- Department of Biochemistry, Faculty of Science, Masaryk University, Czech Republic, CZ-611 37 Brno, Czech Republic
| | - Rob J M van Spanning
- Department of Molecular Cell Physiology, Faculty of Earth and Life Science, VU University Amsterdam, NL-1081 HV Amsterdam, The Netherlands
| | - Igor Kučera
- Department of Biochemistry, Faculty of Science, Masaryk University, Czech Republic, CZ-611 37 Brno, Czech Republic
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Overexpression of amyloid precursor protein increases copper content in HEK293 cells. Biochem Biophys Res Commun 2009; 382:740-4. [DOI: 10.1016/j.bbrc.2009.03.096] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2009] [Accepted: 03/18/2009] [Indexed: 11/17/2022]
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Sugui JA, Kim HS, Zarember KA, Chang YC, Gallin JI, Nierman WC, Kwon-Chung KJ. Genes differentially expressed in conidia and hyphae of Aspergillus fumigatus upon exposure to human neutrophils. PLoS One 2008; 3:e2655. [PMID: 18648542 PMCID: PMC2481287 DOI: 10.1371/journal.pone.0002655] [Citation(s) in RCA: 97] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2008] [Accepted: 06/02/2008] [Indexed: 01/30/2023] Open
Abstract
BACKGROUND Aspergillus fumigatus is the most common etiologic agent of invasive aspergillosis in immunocompromised patients. Several studies have addressed the mechanism involved in host defense but only few have investigated the pathogen's response to attack by the host cells. To our knowledge, this is the first study that investigates the genes differentially expressed in conidia vs hyphae of A. fumigatus in response to neutrophils from healthy donors as well as from those with chronic granulomatous disease (CGD) which are defective in the production of reactive oxygen species. METHODOLOGY/PRINCIPAL FINDINGS Transcriptional profiles of conidia and hyphae exposed to neutrophils, either from normal donors or from CGD patients, were obtained by using the genome-wide microarray. Upon exposure to either normal or CGD neutrophils, 244 genes were up-regulated in conidia but not in hyphae. Several of these genes are involved in the degradation of fatty acids, peroxisome function and the glyoxylate cycle which suggests that conidia exposed to neutrophils reprogram their metabolism to adjust to the host environment. In addition, the mRNA levels of four genes encoding proteins putatively involved in iron/copper assimilation were found to be higher in conidia and hyphae exposed to normal neutrophils compared to those exposed to CGD neutrophils. Deletants in several of the differentially expressed genes showed phenotypes related to the proposed functions, i.e. deletants of genes involved in fatty acid catabolism showed defective growth on fatty acids and the deletants of iron/copper assimilation showed higher sensitivity to the oxidative agent menadione. None of these deletants, however, showed reduced resistance to neutrophil attack. CONCLUSION This work reveals the complex response of the fungus to leukocytes, one of the major host factors involved in antifungal defense, and identifies fungal genes that may be involved in establishing or prolonging infections in humans.
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Affiliation(s)
- Janyce A. Sugui
- Laboratory of Clinical Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - H. Stanley Kim
- Department of Medicine, College of Medicine, Korea University, Anam-Dong, Seongbuk-Gu, Seoul, Korea
| | - Kol A. Zarember
- Laboratory of Host Defenses, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Yun C. Chang
- Laboratory of Clinical Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - John I. Gallin
- Laboratory of Host Defenses, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Willian C. Nierman
- J. Craig Venter Institute, Rockville, Maryland, United States of America
| | - Kyung J. Kwon-Chung
- Laboratory of Clinical Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
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Naumenko EA, Naumov AV, Suvorova ES, Gerlach R, Ziganshin AM, Lozhkin AP, Silkin NI, Naumova RP. Participation of oxygen in the bacterial transformation of 2,4,6-trinitrotoluene. BIOCHEMISTRY (MOSCOW) 2008; 73:463-9. [PMID: 18457577 DOI: 10.1134/s0006297908040123] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The exposure of Bacillus cereus ZS18 cell suspensions to 2,4,6-trinitrotoluene (TNT) in the absence of other oxidizable substrates increases oxygen uptake, exceeding the basal level of respiration of the bacterium 1.5- and 2-fold with 50 and 100 mg/liter of TNT, respectively. The interaction of both living and to less extent dead bacterial cells with TNT results in the accumulation of superoxide anion (O2*-) in the extracellular medium, which was revealed by the EPR spectroscopy. The accumulation of O2*- decreased by 50-70% in the presence of Cu,Zn-superoxide dismutase of animal origin. In the presence of living bacterial cells, the level of TNT decreased progressively, yielding hydroxylaminodinitrotoluenes together with O2*-. In the presence of heat-killed cells, a moderate decrease in TNT was observed, and the appearance of O2*- was not accompanied by the production of any detectable TNT metabolites. Chelating agents inhibited the transformation of TNT and decreased the formation of O2*-. The demonstrated generation of O2*- during the interaction of TNT with K4[Fe(CN)6] together with the observed effects of chelating agents suggest the participation of iron in the one-electron reduction of TNT and the functioning of an extracellular redox cycle with the involvement of molecular oxygen.
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Weissman Z, Shemer R, Conibear E, Kornitzer D. An endocytic mechanism for haemoglobin-iron acquisition in Candida albicans. Mol Microbiol 2008; 69:201-17. [PMID: 18466294 DOI: 10.1111/j.1365-2958.2008.06277.x] [Citation(s) in RCA: 106] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The fungal pathogen Candida albicans is able to utilize haemin and haemoglobin as iron sources. Haem-iron utilization is facilitated by Rbt5, an extracellular, glycosylphophatidylinositol (GPI)-anchored, haemin- and haemoglobin-binding protein. Here, we show that Rbt5 and its close homologue Rbt51 are short-lived plasma membrane proteins, degradation of which depends on vacuolar activity. Rbt5 facilitates the rapid endocytosis of haemoglobin into the C. albicans vacuole. We relied on recapitulation of the Rbt51-dependent haem-iron utilization in Saccharomyces cerevisiae to identify mutants defective in haemoglobin utilization. Homologues of representative mutants in S. cerevisiae were deleted in C. albicans and tested for haemoglobin-iron utilization and haemoglobin uptake. These mutants define a novel endocytosis-mediated haemoglobin utilization mechanism that depends on acidification of the lumen of the late secretory pathway, on a type I myosin and on the activity of the ESCRT pathway.
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Affiliation(s)
- Ziva Weissman
- Department of Molecular Microbiology, Technion-B. Rappaport Faculty of Medicine, and the Rappaport Institute for Research in the Medical Sciences, Haifa 31096, Israel
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Haas H, Eisendle M, Turgeon BG. Siderophores in fungal physiology and virulence. ANNUAL REVIEW OF PHYTOPATHOLOGY 2008; 46:149-87. [PMID: 18680426 DOI: 10.1146/annurev.phyto.45.062806.094338] [Citation(s) in RCA: 326] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Maintaining the appropriate balance of iron between deficiency and toxicity requires fine-tuned control of systems for iron uptake and storage. Both among fungal species and within a single species, different systems for acquisition, storage, and regulation of iron are present. Here we discuss the most recent findings on the mechanisms involved in maintaining iron homeostasis with a focus on siderophores, low-molecular-mass iron chelators, employed for iron uptake and storage. Recently siderophores have been found to be crucial for pathogenicity of animal, as well as plant-pathogenic fungi and for maintenance of plant-fungal symbioses.
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Affiliation(s)
- Hubertus Haas
- Division of Molecular Biology/Biocenter, Innsbruck Medical University, A-6020 Innsbruck, Austria.
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Froissard M, Belgareh-Touzé N, Dias M, Buisson N, Camadro JM, Haguenauer-Tsapis R, Lesuisse E. Trafficking of siderophore transporters in Saccharomyces cerevisiae and intracellular fate of ferrioxamine B conjugates. Traffic 2007; 8:1601-16. [PMID: 17714436 PMCID: PMC2171038 DOI: 10.1111/j.1600-0854.2007.00627.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We have studied the intracellular trafficking of Sit1 [ferrioxamine B (FOB) transporter] and Enb1 (enterobactin transporter) in Saccharomyces cerevisiae using green fluorescent protein (GFP) fusion proteins. Enb1 was constitutively targeted to the plasma membrane. Sit1 was essentially targeted to the vacuolar degradation pathway when synthesized in the absence of substrate. Massive plasma membrane sorting of Sit1 was induced by various siderophore substrates of Sit1, and by coprogen, which is not a substrate of Sit1. Thus, different siderophore transporters use different regulated trafficking processes. We also studied the fate of Sit1-mediated internalized siderophores. Ferrioxamine B was recovered in isolated vacuolar fractions, where it could be detected spectrophotometrically. Ferrioxamine B coupled to an inhibitor of mitochondrial protoporphyrinogen oxidase (acifluorfen) could not reach its target unless the cells were disrupted, confirming the tight compartmentalization of siderophores within cells. Ferrioxamine B coupled to a fluorescent moiety, FOB-nitrobenz-2-oxa-1,3-diazole, used as a Sit1-dependent iron source, accumulated in the vacuolar lumen even in mutants displaying a steady-state accumulation of Sit1 at the plasma membrane or in endosomal compartments. Thus, the fates of siderophore transporters and siderophores diverge early in the trafficking process.
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Affiliation(s)
- Marine Froissard
- Laboratoire Trafic intracellulaire des protéines dans la levure, Département de biologie Cellulaire, Institut Jacques MonodUnité Mixte de Recherche 7592 CNRS-Universités Paris 6 et 7, France
| | - Naïma Belgareh-Touzé
- Laboratoire Trafic intracellulaire des protéines dans la levure, Département de biologie Cellulaire, Institut Jacques MonodUnité Mixte de Recherche 7592 CNRS-Universités Paris 6 et 7, France
| | - Marylène Dias
- Chimie, Ingénierie Moléculaire et Matériaux d’Angers (CIMMA)Unité Mixte de Recherche 6200 CNRS, Université d’Angers, France
| | - Nicole Buisson
- Laboratoire Trafic intracellulaire des protéines dans la levure, Département de biologie Cellulaire, Institut Jacques MonodUnité Mixte de Recherche 7592 CNRS-Universités Paris 6 et 7, France
| | - Jean-Michel Camadro
- Laboratoire d’Ingénierie des Protéines et Contrôle Métabolique, Département de Biologie des Génomes, Institut Jacques MonodUnité Mixte de Recherche 7592 CNRS-Universités Paris 6 et 7, France
| | - Rosine Haguenauer-Tsapis
- Laboratoire Trafic intracellulaire des protéines dans la levure, Département de biologie Cellulaire, Institut Jacques MonodUnité Mixte de Recherche 7592 CNRS-Universités Paris 6 et 7, France
| | - Emmanuel Lesuisse
- Laboratoire d’Ingénierie des Protéines et Contrôle Métabolique, Département de Biologie des Génomes, Institut Jacques MonodUnité Mixte de Recherche 7592 CNRS-Universités Paris 6 et 7, France
- Emmanuel Lesuisse,
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Greenshields DL, Liu G, Feng J, Selvaraj G, Wei Y. The siderophore biosynthetic gene SID1, but not the ferroxidase gene FET3, is required for full Fusarium graminearum virulence. MOLECULAR PLANT PATHOLOGY 2007; 8:411-21. [PMID: 20507510 DOI: 10.1111/j.1364-3703.2007.00401.x] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
To acquire iron from plant hosts, fungal pathogens have evolved at least two pathways for iron uptake. One system is hinged on the secretion and subsequent uptake of low-molecular-weight iron chelators termed siderophores, while the other uses cell-surface reductases to solubilize ferric iron by reducing it to ferrous iron for uptake. We identified five iron uptake-related genes from the head blight pathogen Fusarium graminearum and showed that they were transcribed in response to iron limitation. To examine the relative contribution of the reductive and siderophore pathways of iron uptake, we created mutants disrupted at the ferroxidase gene FET3 (Deltafet3) or the siderophore biosynthetic gene SID1 (Deltasid1). The Deltafet3 mutants produced wild-type amounts of siderophores and grew at the same rate as the wild-type under iron limitation, but accumulated high levels of free intracellular iron. The Deltasid1 mutants did not produce siderophores and grew slowly under low iron conditions. Transcription of the iron uptake-related genes was induced in the Deltasid1 mutant regardless of the growth medium iron content, whereas these genes were transcribed normally in the Deltafet3 mutant. Finally, the Deltasid1 mutants could infect single, inoculated spikelets, but were unable to spread from spikelet-to-spikelet through the rachises of wheat spikes, while the Deltafet3 mutants behaved as wild-type throughout infection. Together, our data suggest that siderophore-mediated iron uptake is the major pathway of cellular iron uptake and is required for full virulence in F. graminearum.
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Affiliation(s)
- David L Greenshields
- Department of Biology, University of Saskatchewan, 112 Science Place, Saskatoon, SK S7N 5E2, Canada
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Rees EM, Thiele DJ. Identification of a Vacuole-associated Metalloreductase and Its Role in Ctr2-mediated Intracellular Copper Mobilization. J Biol Chem 2007; 282:21629-38. [PMID: 17553781 DOI: 10.1074/jbc.m703397200] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Copper is an essential trace metal whose biological utility is derived from its ability to cycle between oxidized Cu(II) and reduced Cu(I). Ctr1 is a high affinity plasma membrane copper permease, conserved from yeast to humans, that mediates the physiological uptake of Cu(I) from the extracellular environment. In the baker's yeast Saccharomyces cerevisiae, extracellular Cu(II) is reduced to Cu(I) via the action of the cell surface metalloreductase Fre1, similar to the human gp91(phox) subunit of the NADPH oxidase complex, which utilizes heme and flavins to catalyze electron transfer. The S. cerevisiae Ctr2 protein is structurally similar to Ctr1, localizes to the vacuole membrane, and mobilizes vacuolar copper stores to the cytosol via a mechanism that is not well understood. Here we show that Ctr2-1, a mutant form of Ctr2 that mislocalizes to the plasma membrane, requires the Fre1 plasma membrane metalloreductase for Cu(I) import. The conserved methionine residues that are essential for Ctr1 function at the plasma membrane are also essential for Ctr2-1-mediated Cu(I) uptake. We demonstrate that Fre6, a member of the yeast Fre1 metalloreductase protein family, resides on the vacuole membrane and functions in Ctr2-mediated vacuolar copper export, and cells lacking Fre6 phenocopy the Cu-deficient growth defect of ctr2Delta cells. Furthermore, both CTR2 and FRE6 mRNA levels are regulated by iron availability. Taken together these studies suggest that copper movement across intracellular membranes is mechanistically similar to that at the plasma membrane. This work provides a model for communication between the extracellular Cu(I) uptake and the intracellular Cu(I) mobilization machinery.
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Affiliation(s)
- Erin M Rees
- Department of Pharmacology and Cancer Biology and Sarah W Stedman Nutrition and Metabolism Center, Duke University Medical Center, Durham, NC 27710, USA
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Labbé S, Pelletier B, Mercier A. Iron homeostasis in the fission yeast Schizosaccharomyces pombe. Biometals 2007; 20:523-537. [PMID: 17211681 DOI: 10.1007/s10534-006-9056-5] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2006] [Accepted: 11/28/2006] [Indexed: 01/22/2023]
Abstract
Schizosaccharomyces pombe has acquisition processes for iron, an essential nutrient. One pathway consists to produce, excrete, and capture siderophore-iron complexes. A second pathway requires enzymatic reduction of ferric iron at the cell surface prior to uptake by a permease-oxidase complex. Genes encoding proteins involved in iron assimilation are transcriptionally regulated as a function of iron availability. Under high iron conditions, the GATA-type regulator Fep1 represses the expression of iron uptake genes. The repressor function of Fep1 requires the presence of the Tup11 or Tup12 transcriptional co-repressor. Under low iron conditions, two regulatory mechanisms occur. First, the iron transport genes are highly induced. Second, there is a transcription factor cascade implicating the heteromeric CCAAT-binding complex that turns off a set of genes encoding iron-utilizing proteins, presumably to avoid a futile expenditure of energy in producing iron-using proteins that lack the necessary cofactor to function. Thus, collectively, these regulatory responses to variations in iron concentrations ensure that iron is present within cells for essential biochemical reactions, yet prevent the accumulation of iron or iron-using proteins to deleterious levels.
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Affiliation(s)
- Simon Labbé
- Département de Biochimie, Faculté de médecine, Université de Sherbrooke, 3001 12e Ave Nord, Sherbrooke, QC, Canada J1H 5N4.
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Bérczi A, Su D, Asard H. An Arabidopsis cytochrome b561 with trans-membrane ferrireductase capability. FEBS Lett 2007; 581:1505-8. [PMID: 17376442 DOI: 10.1016/j.febslet.2007.03.006] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2007] [Revised: 02/20/2007] [Accepted: 03/02/2007] [Indexed: 11/26/2022]
Abstract
Ascorbate-reducible cytochromes b561 (Cyts-b561) are a class of intrinsic trans-membrane proteins. Tonoplast Cyt-b561 (TCytb), one of the four Cyt-b561 isoforms in Arabidopsis was localized to the tonoplast. We demonstrate here that the optical spectra, EPR spectra and redox potentials of recombinant TCytb are similar to those of the well characterized bovine chromaffin granule Cyt-b561. We provide evidence for the reduction of ferric-chelates by the reduced TCytb. It is also shown that TCytb is capable of trans-membrane electron transport from intracellular ascorbate to extracellular ferric-chelates in yeast cells.
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Affiliation(s)
- Alajos Bérczi
- Institute of Biophysics, Biological Research Center, Hungarian Academy of Sciences, PO Box 521, H-6701 Szeged, Hungary.
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Eichhorn H, Lessing F, Winterberg B, Schirawski J, Kämper J, Müller P, Kahmann R. A ferroxidation/permeation iron uptake system is required for virulence in Ustilago maydis. THE PLANT CELL 2006; 18:3332-45. [PMID: 17138696 PMCID: PMC1693961 DOI: 10.1105/tpc.106.043588] [Citation(s) in RCA: 135] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2006] [Revised: 10/18/2006] [Accepted: 11/02/2006] [Indexed: 05/12/2023]
Abstract
In the smut fungus Ustilago maydis, a tightly regulated cAMP signaling cascade is necessary for pathogenic development. Transcriptome analysis using whole genome microarrays set up to identify putative target genes of the protein kinase A catalytic subunit Adr1 revealed nine genes with putative functions in two high-affinity iron uptake systems. These genes locate to three gene clusters on different chromosomes and include the previously identified complementing siderophore auxotroph genes sid1 and sid2 involved in siderophore biosynthesis. Transcription of all nine genes plus three additional genes associated with the gene clusters was also coregulated by iron through the Urbs1 transcription factor. Two components of a high-affinity iron uptake system were characterized in more detail: fer2, encoding a high-affinity iron permease; and fer1, encoding an iron multicopper oxidase. Fer2 localized to the plasma membrane and complemented an ftr1 mutant of Saccharomyces cerevisiae lacking a high-affinity iron permease. During pathogenic development, fer2 expression was confined to the phase of hyphal proliferation inside the plant. fer2 as well as fer1 deletion mutants were strongly affected in virulence. These data highlight the importance of the high-affinity iron uptake system via an iron permease and a multicopper oxidase for biotrophic development in the U. maydis/maize (Zea mays) pathosystem.
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Affiliation(s)
- Heiko Eichhorn
- Max Planck Institute for Terrestrial Microbiology, D-35043 Marburg, Germany
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Abstract
Cytochromes b(561) are a family of transmembrane proteins found in most eukaryotic cells. Three evolutionarily closely related mammalian cytochromes b(561) (chromaffin granule cytochrome b, duodenal cytochrome b, and lysosomal cytochrome b) were expressed in a Saccharomyces cerevisiaeDeltafre1Deltafre2 mutant, which lacks almost all of its plasma membrane ferrireductase activity, to study their ability to reduce ferric iron (Fe(3+)). The expression of each of these cytochromes b(561) was able to rescue the growth defect of the Deltafre1Deltafre2 mutant cells in iron-deficient conditions, suggesting their involvement in iron metabolism. Plasma membrane ferrireductase activities were measured using intact yeast cells. Each cytochrome b(561) showed significant FeCN and Fe(3+)-EDTA reductase activities that were dependent on the presence of intracellular ascorbate. Site-directed mutagenesis of lysosomal cytochrome b was conducted to identify amino acids that are indispensable for its activity. Among more than 20 conserved or partially conserved amino acids that were investigated, mutations of four His residues (H47, H83, H117 and H156), one Tyr (Y66) and one Arg (R67) completely abrogated the FeCN reductase activity, whereas mutations of Arg (R149), Phe (F44), Ser (S115), Trp (W119), Glu (E196), and Gln (Q131) affected the ferrireductase activity to some degree. These mutations may affect the heme coordination, ascorbate binding, and/or ferric substrate binding. Possible roles of these residues in lysosomal cytochrome b are discussed. This study demonstrates the ascorbate-dependent transmembrane ferrireductase activities of members of the mammalian cytochrome b(561) family of proteins.
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Affiliation(s)
- Dan Su
- Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, NE, USA
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Knight SAB, Dancis A. Reduction of 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide inner salt (XTT) is dependent on CaFRE10 ferric reductase for Candida albicans grown in unbuffered media. MICROBIOLOGY-SGM 2006; 152:2301-2308. [PMID: 16849796 DOI: 10.1099/mic.0.28843-0] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The reduction of 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide inner salt (XTT) and other tetrazolium salts is widely used as an assay for bacterial, fungal and mammalian cell viability, but the genes encoding the reductase activities have not been defined. Here, it was shown that XTT and plasma membrane ferric reductase activities were 10-40-fold greater in Candida albicans than in Saccharomyces cerevisiae. XTT reductase activity was induced fivefold in C. albicans grown in low-iron conditions compared with iron-replete conditions, and for cells grown in unbuffered (pH 4.0-4.4) medium, XTT reductase activity was largely dependent on CaFRE10. XTT reductase activity of C. albicans grown in medium buffered to pH 6.8 was independent of CaFRE10 but, nonetheless, was upregulated in cells deprived of iron. Reduction of 2-(4,5-dimethyl-2-thiazolyl)-3,5-diphenyl-2H-tetrazolium bromide (MTT), a membrane-permeable tetrazolium salt, occurred at an intracellular location and was independent of CaFRE10. However, MTT activity was induced by iron deprivation in C. albicans but not in S. cerevisiae. C. albicans possessed multiple iron- and pH-regulated reductase activities capable of reducing tetrazolium salts, but, when grown in unbuffered medium, CaFRE10 was required for XTT reductase activity.
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Affiliation(s)
- Simon A B Knight
- University of Pennsylvania School of Medicine, Department of Medicine, Division of Hematology/Oncology, 730 BRB II/III, 421 Curie Boulevard, Philadelphia, PA 19104-6160, USA
| | - Andrew Dancis
- University of Pennsylvania School of Medicine, Department of Medicine, Division of Hematology/Oncology, 730 BRB II/III, 421 Curie Boulevard, Philadelphia, PA 19104-6160, USA
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Laliberté J, Labbé S. Mechanisms of copper loading on the Schizosaccharomyces pombe copper amine oxidase 1 expressed in Saccharomyces cerevisiae. MICROBIOLOGY (READING, ENGLAND) 2006; 152:2819-2830. [PMID: 16946276 DOI: 10.1099/mic.0.28998-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Copper amine oxidases (CAOs) are found in almost every living kingdom. Although Saccharomyces cerevisiae is one of the few yeast species that lacks an endogenous CAO, heterologous gene expression of CAOs from other organisms produces a functional enzyme. To begin to characterize their function and mechanisms of copper acquisition, two putative cao(+) genes from Schizosaccharomyces pombe were expressed in S. cerevisiae. Expression of spao1(+) resulted in the production of an active enzyme capable of catalysing the oxidative deamination of primary amines. On the other hand, expression of spao2(+) failed to produce an active CAO. Using a functional spao1(+)-GFP fusion allele, the SPAO1 protein was localized in the cytosol. Under copper-limiting conditions, yeast cells harbouring deletions of the MAC1, CTR1 and CTR3 genes were defective in amine oxidase activity. Likewise, atx1Delta null cells exhibited no CAO activity, while ccc2Delta mutant cells exhibited decreased levels of amine oxidase activity, and mutations in cox17Delta and ccs1Delta did not cause any defects in this activity. Copper-deprived S. cerevisiae cells expressing spao1(+) required a functional atx1(+) gene for growth on minimal medium containing ethylamine as the sole nitrogen source. Under these conditions, the inability of the atx1Delta cells to utilize ethylamine correlated with the lack of SPAO1 activity, in spite of the efficient expression of the protein. Cells carrying a disrupted ccc2Delta allele exhibited only weak growth on ethylamine medium containing a copper chelator. The results of these studies reveal that expression of the heterologous spao1(+) gene in S. cerevisiae is required for its growth in medium containing ethylamine as the sole nitrogen source, and that expression of an active Schiz. pombe SPAO1 protein in S. cerevisiae depends on the acquisition of copper through the high-affinity copper transporters Ctr1 and Ctr3, and the copper chaperone Atx1.
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Affiliation(s)
- Julie Laliberté
- Département de Biochimie, Université de Sherbrooke, 3001 12e Avenue Nord, Sherbrooke, Québec J1H 5N4, Canada
| | - Simon Labbé
- Département de Biochimie, Université de Sherbrooke, 3001 12e Avenue Nord, Sherbrooke, Québec J1H 5N4, Canada
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Kaplan J, McVey Ward D, Crisp RJ, Philpott CC. Iron-dependent metabolic remodeling in S. cerevisiae. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2006; 1763:646-51. [PMID: 16697062 DOI: 10.1016/j.bbamcr.2006.03.008] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2006] [Revised: 03/28/2006] [Accepted: 03/29/2006] [Indexed: 10/24/2022]
Abstract
All eukaryotes require iron although iron is not readily bioavailable. Organisms expend much effort in acquiring iron and in response have evolved multiple mechanisms to acquire iron. Because iron is essential, organisms prioritize the iron use when iron is limiting; iron-sparing enzymes or metabolic pathways are utilized at the expense of iron-rich enzymes. A large percentage of cellular iron containing proteins is devoted to oxygen binding or metabolism, therefore, changes in oxygen availability affect iron usage. Transcriptional and post-transcriptional mechanisms have been shown to affect the concentration of iron-containing proteins under iron or oxygen limiting conditions. In this review, we describe how the budding yeast Saccharomyces cerevisiae utilizes multiple mechanisms to optimize iron usage under iron limiting conditions.
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Affiliation(s)
- Jerry Kaplan
- Department of Pathology, School of Medicine University of Utah, Salt Lake City, UT 84132-2501, USA.
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Philpott CC. Iron uptake in fungi: a system for every source. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2006; 1763:636-45. [PMID: 16806534 DOI: 10.1016/j.bbamcr.2006.05.008] [Citation(s) in RCA: 178] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2005] [Revised: 05/08/2006] [Accepted: 05/10/2006] [Indexed: 10/24/2022]
Abstract
Fungi have a remarkable capacity to take up iron when present in any of a wide variety of forms, which include free iron ions, low-affinity iron chelates, siderophore-iron chelates, transferrin, heme, and hemoglobin. Appropriately, these unicellular eukaryotes express a variety of iron uptake systems, some of which are unique to fungi and some of which are present in plants and animals, as well. The reductive system of uptake relies upon the external reduction of ferric salts, chelates, and proteins prior to uptake by a high-affinity, ferrous-specific, oxidase/permease complex. This system recognizes a broad range of substrates. The non-reductive system exhibits specificity for siderophore-iron chelates, and transporters of this system exhibit multiple substrate-dependent intracellular trafficking events.
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Affiliation(s)
- Caroline C Philpott
- Liver Disease Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA.
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Curry BJ, Holt JE, McLaughlin EA, Aitken RJ. Characterization of structure and expression of the Dzip1 gene in the rat and mouse. Genomics 2006; 87:275-85. [PMID: 16368222 DOI: 10.1016/j.ygeno.2005.10.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2005] [Revised: 10/12/2005] [Accepted: 10/21/2005] [Indexed: 11/28/2022]
Abstract
A transcript encoding a rat homologue of DZIP1 (DAZ-interacting protein) was isolated from testis RNA. Like human DZIP1, it contains a C(2)H(2) zinc finger domain. A predicted mouse homologue of DZIP1 was found in the GenBank database. Genome analysis indicated that while DZIP1 and mouse Dzip1 contain 22 and 20 exons, respectively, the rat sequence was intronless, confirmed by PCR on genomic DNA. This rat Dzip1 sequence is homologous to mouse Dzip1 exons 1-6 and DZIP1 exons 5-9. As this rat sequence was shorter than DZIP1 it was designated rat Dzip1S. The rat genome also contained a further predicted homologue of DZIP1 displaying conserved linkage homology with mouse Dzip1 and DZIP1. This sequence, if expressed, is the true rat homologue of DZIP1, designated rat Dzip1. Rat Dzip1S mRNA was present in all tissues examined by qualitative RT-RCR, and in situ hybridization of rat testis confirmed that expression of rat Dzip1S mRNA was confined to the spermatogenic lineage, specifically premeiotic spermatogonia.
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Affiliation(s)
- Benjamin J Curry
- Reproductive Science Group, Discipline of Biological Science, School of Environmental and Life Sciences, University of Newcastle, Callaghan, NSW 2308, Australia
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Kimura A, Ohashi K, Naganuma A. Cisplatin upregulatesSaccharomyces cerevisiae genes involved in iron homeostasis through activation of the iron insufficiency-responsive transcription factor Aft1. J Cell Physiol 2006; 210:378-84. [PMID: 17096368 DOI: 10.1002/jcp.20845] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The response of Saccharomyces cerevisiae to cisplatin was investigated by examining variations in gene expression using cDNA microarrays and confirming the results by reverse transcription polymerase chain reaction (RT-PCR). The mRNA levels of 14 proteins involved in iron homeostasis were shown to be increased by cisplatin. Interestingly, the expression of all 14 genes is known to be regulated by Aft1, a transcription factor activated in response to iron insufficiency. The promoter of one of these genes, FET3, has been relatively well studied, so we performed a reporter assay using the FET3 promoter and showed that an Aft1 binding site in the promoter region is indispensable for induction of transcription by cisplatin. The active domain of Aft1 necessary for activation of the FET3 promoter by cisplatin is identical to the one required for activation by bathophenanthroline sulfonate, an inhibitor of cellular iron uptake. Furthermore, we found that cisplatin inhibits the uptake of (55)Fe(II) into yeast cells. These findings suggest that cisplatin activates Aft1 through the inhibition of iron uptake into the cells, after which the expression of Aft1 target genes involved in iron uptake might be induced.
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Affiliation(s)
- Akiko Kimura
- Laboratory of Molecular and Biochemical Toxicology, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Japan
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van Bakel H, Strengman E, Wijmenga C, Holstege FCP. Gene expression profiling and phenotype analyses ofS. cerevisiaein response to changing copper reveals six genes with new roles in copper and iron metabolism. Physiol Genomics 2005; 22:356-67. [PMID: 15886332 DOI: 10.1152/physiolgenomics.00055.2005] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Exhaustive microarray time course analyses of Saccharomyces cerevisiae during copper starvation and copper excess reveal new aspects of metal-induced gene regulation. Aside from identifying targets of established copper- and iron-responsive transcription factors, we find that genes encoding mitochondrial proteins are downregulated and that copper-independent iron transport genes are preferentially upregulated, both during prolonged copper deprivation. The experiments also suggest the presence of a small regulatory iron pool that links copper and iron responses. One hundred twenty-eight genes with putative roles in metal metabolism were further investigated by several systematic phenotype screens. Of the novel phenotypes uncovered, hsp12-Δ and arn1-Δ display increased sensitivity to copper, cyc1-Δ and crr1-Δ show resistance to high copper, vma13-Δ exhibits increased sensitivity to iron deprivation, and pep12-Δ results in reduced growth in high copper and low iron. Besides revealing new components of eukaryotic metal trafficking pathways, the results underscore the previously determined intimate links between iron and copper metabolism and mitochondrial and vacuolar function in metal trafficking. The analyses further suggest that copper starvation can specifically lead to downregulation of respiratory function to preserve iron and copper for other cellular processes.
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Affiliation(s)
- Harm van Bakel
- Complex Genetics Group, Division of Biomedical Genetics-Department of Medical Genetics, University Medical Center Utrecht, The Netherlands
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Kim Y, Lampert SM, Philpott CC. A receptor domain controls the intracellular sorting of the ferrichrome transporter, ARN1. EMBO J 2005; 24:952-62. [PMID: 15719020 PMCID: PMC554128 DOI: 10.1038/sj.emboj.7600579] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2004] [Accepted: 01/20/2005] [Indexed: 11/09/2022] Open
Abstract
The Saccharomyces cerevisiae transporter Arn1p takes up the ferric-siderophore ferrichrome, and extracellular ferrichrome dramatically influences the intracellular trafficking of Arn1p. In the absence of ferrichrome, Arn1p sorts directly to the endosomal compartment. At low concentrations of ferrichrome, Arn1p stably relocalizes to the plasma membrane, yet little to no uptake of ferrichrome occurs at these low concentrations. At higher concentrations of ferrichrome, Arn1p cycles between the plasma membrane and endosome. Arn1p contains two binding sites for ferrichrome: one site has an affinity similar to the K(T) for transport, but the second site has a much higher affinity. Here we report that this high-affinity binding site lies within a unique extracytosolic, carboxyl-terminal domain. Mutations within this domain lead to loss of ferrichrome binding and uptake activities and missorting of Arn1p, including a failure to relocalize to the plasma membrane in the presence of ferrichrome. Mutation of phenylalanine residues in the cytosolic tail of Arn1p also lead to missorting, but without defects in ferrichrome binding. We propose that the carboxyl terminus of Arn1p contains a receptor domain that controls the intracellular trafficking of the transporter.
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Affiliation(s)
- Youngwoo Kim
- Liver Diseases Branch, National Institutes of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Sarah M Lampert
- Liver Diseases Branch, National Institutes of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Caroline C Philpott
- Liver Diseases Branch, National Institutes of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
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Eapen S, D'Souza SF. Prospects of genetic engineering of plants for phytoremediation of toxic metals. Biotechnol Adv 2005; 23:97-114. [PMID: 15694122 DOI: 10.1016/j.biotechadv.2004.10.001] [Citation(s) in RCA: 158] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/04/2004] [Indexed: 11/26/2022]
Abstract
Bioremediation is gaining a lot of importance in recent times as an alternate technology for removal of elemental pollutants in soil and water, which require effective methods of decontamination. Phytoremediation--the use of green plants to remove, contain or render harmless environmental pollutants--may offer an effective, environmentally nondestructive and cheap remediation method. The use of genetic engineering to modify plants for metal uptake, transport and sequestration may open up new avenues for enhancing efficiency of phytoremediation. Metal chelator, metal transporter, metallothionein (MT), and phytochelatin (PC) genes have been transferred to plants for improved metal uptake and sequestration. Transgenic plants, which detoxify/accumulate cadmium, lead, mercury, arsenic and selenium have been developed. A better understanding of the mechanisms of rhizosphere interaction, uptake, transport and sequestration of metals in hyperaccumulator plants will lead to designing novel transgenic plants with improved remediation traits. As more genes related to metal metabolism are discovered, facilitated by the genome sequencing projects, new vistas will be opened up for development of efficient transgenic plants for phytoremediation.
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Affiliation(s)
- Susan Eapen
- Nuclear Agriculture and Biotechnology Division, Bhabha Atomic Research Centre, Mumbai-40085, India.
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