1
|
Dietl AM, Misslinger M, Aguiar MM, Ivashov V, Teis D, Pfister J, Decristoforo C, Hermann M, Sullivan SM, Smith LR, Haas H. The Siderophore Transporter Sit1 Determines Susceptibility to the Antifungal VL-2397. Antimicrob Agents Chemother 2019; 63:e00807-19. [PMID: 31405865 PMCID: PMC6761561 DOI: 10.1128/aac.00807-19] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Accepted: 07/18/2019] [Indexed: 01/07/2023] Open
Abstract
VL-2397 (previously termed ASP2397) is an antifungal, aluminum-chelating cyclic hexapeptide with a structure analogous to that of ferrichrome-type siderophores, whereby replacement of aluminum by iron was shown to decrease the antifungal activity of this compound. Here, we found that inactivation of an importer for ferrichrome-type siderophores, termed Sit1, renders Aspergillus fumigatus resistant to VL-2397. Moreover, expression of the endogenous sit1 gene under the control of a xylose-inducible promoter (to uncouple sit1 expression from iron repression) combined with C-terminal tagging with a fluorescent protein demonstrated localization of Sit1 in the plasma membrane and xylose-dependent VL-2397 susceptibility. This underlines that Sit1-mediated uptake is essential for VL-2397 susceptibility. Under xylose-induced sit1 expression, VL-2397 also retained antifungal activity after replacing aluminum with iron, which demonstrates that VL-2397 bears antifungal activity independent of cellular aluminum importation. Analysis of sit1 expression indicated that the reduced antifungal activity of the iron-chelated VL-2397 is caused by downregulation of sit1 expression by the imported iron. Furthermore, we demonstrate that defects in iron homeostatic mechanisms modulate the activity of VL-2397. In contrast to A. fumigatus and Candida glabrata, Saccharomyces cerevisiae displays intrinsic resistance to VL-2397 antifungal activity. However, expression of sit1 from A. fumigatus, or its homologue from C. glabrata, resulted in susceptibility to VL-2397, which suggests that the intrinsic resistance of S. cerevisiae is based on lack of uptake and that A. fumigatus, C. glabrata, and S. cerevisiae share an intracellular target for VL-2397.
Collapse
Affiliation(s)
- Anna-Maria Dietl
- Division of Molecular Biology, Biocenter, Medical University of Innsbruck, Innsbruck, Austria
| | - Matthias Misslinger
- Division of Molecular Biology, Biocenter, Medical University of Innsbruck, Innsbruck, Austria
| | - Mario M Aguiar
- Division of Molecular Biology, Biocenter, Medical University of Innsbruck, Innsbruck, Austria
| | - Vasyl Ivashov
- Division Cell Biology, Biocenter, Medical University of Innsbruck, Innsbruck, Austria
| | - David Teis
- Division Cell Biology, Biocenter, Medical University of Innsbruck, Innsbruck, Austria
| | - Joachim Pfister
- Department of Nuclear Medicine, Medical University of Innsbruck, Innsbruck, Austria
| | - Clemens Decristoforo
- Department of Nuclear Medicine, Medical University of Innsbruck, Innsbruck, Austria
| | - Martin Hermann
- Department of Anesthesiology and Critical Care Medicine, Medical University of Innsbruck, Innsbruck, Austria
| | | | | | - Hubertus Haas
- Division of Molecular Biology, Biocenter, Medical University of Innsbruck, Innsbruck, Austria
| |
Collapse
|
2
|
Kojima T, Kunitake E, Ihara K, Kobayashi T, Nakano H. A Robust Analytical Pipeline for Genome-Wide Identification of the Genes Regulated by a Transcription Factor: Combinatorial Analysis Performed Using gSELEX-Seq and RNA-Seq. PLoS One 2016; 11:e0159011. [PMID: 27411092 PMCID: PMC4943734 DOI: 10.1371/journal.pone.0159011] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Accepted: 06/25/2016] [Indexed: 11/19/2022] Open
Abstract
For identifying the genes that are regulated by a transcription factor (TF), we have established an analytical pipeline that combines genomic systematic evolution of ligands by exponential enrichment (gSELEX)-Seq and RNA-Seq. Here, SELEX was used to select DNA fragments from an Aspergillus nidulans genomic library that bound specifically to AmyR, a TF from A. nidulans. High-throughput sequencing data were obtained for the DNAs enriched through the selection, following which various in silico analyses were performed. Mapping reads to the genome revealed the binding motifs including the canonical AmyR-binding motif, CGGN8CGG, as well as the candidate promoters controlled by AmyR. In parallel, differentially expressed genes related to AmyR were identified by using RNA-Seq analysis with samples from A. nidulans WT and amyR deletant. By obtaining the intersecting set of genes detected using both gSELEX-Seq and RNA-Seq, the genes directly regulated by AmyR in A. nidulans can be identified with high reliability. This analytical pipeline is a robust platform for comprehensive genome-wide identification of the genes that are regulated by a target TF.
Collapse
Affiliation(s)
- Takaaki Kojima
- Department of Bioengineering Sciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
- * E-mail: (TK); (HN)
| | - Emi Kunitake
- Department of Biological Mechanisms and Functions, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
| | - Kunio Ihara
- Center for Gene Research, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8602, Japan
| | - Tetsuo Kobayashi
- Department of Biological Mechanisms and Functions, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
| | - Hideo Nakano
- Department of Bioengineering Sciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
- * E-mail: (TK); (HN)
| |
Collapse
|
3
|
The lysine biosynthetic enzyme Lys4 influences iron metabolism, mitochondrial function and virulence in Cryptococcus neoformans. Biochem Biophys Res Commun 2016; 477:706-711. [PMID: 27353379 DOI: 10.1016/j.bbrc.2016.06.123] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Accepted: 06/24/2016] [Indexed: 12/17/2022]
Abstract
The lysine biosynthesis pathway via α-aminoadipate in fungi is considered an attractive target for antifungal drugs due to its absence in mammalian hosts. The iron-sulfur cluster-containing enzyme homoaconitase converts homocitrate to homoisocitrate in the lysine biosynthetic pathway, and is encoded by LYS4 in the model yeast Saccharomyces cerevisiae. In this study, we identified the ortholog of LYS4 in the human fungal pathogen, Cryptococcus neoformans, and found that LYS4 expression is regulated by iron levels and by the iron-related transcription factors Hap3 and HapX. Deletion of the LYS4 gene resulted in lysine auxotrophy suggesting that Lys4 is essential for lysine biosynthesis. Our study also revealed that lysine uptake was mediated by two amino acid permeases, Aap2 and Aap3, and influenced by nitrogen catabolite repression (NCR). Furthermore, the lys4 mutant showed increased sensitivity to oxidative stress, agents that challenge cell wall/membrane integrity, and azole antifungal drugs. We showed that these phenotypes were due in part to impaired mitochondrial function as a result of LYS4 deletion, which we propose disrupts iron homeostasis in the organelle. The combination of defects are consistent with our observation that the lys4 mutant was attenuated virulence in a mouse inhalation model of cryptococcosis.
Collapse
|
4
|
Wiemann P, Lechner BE, Baccile JA, Velk TA, Yin WB, Bok JW, Pakala S, Losada L, Nierman WC, Schroeder FC, Haas H, Keller NP. Perturbations in small molecule synthesis uncovers an iron-responsive secondary metabolite network in Aspergillus fumigatus. Front Microbiol 2014; 5:530. [PMID: 25386169 PMCID: PMC4208449 DOI: 10.3389/fmicb.2014.00530] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2014] [Accepted: 09/23/2014] [Indexed: 11/13/2022] Open
Abstract
Iron plays a critical role in survival and virulence of the opportunistic pathogen Aspergillus fumigatus. Two transcription factors, the GATA-factor SreA and the bZip-factor HapX oppositely monitor iron homeostasis with HapX activating iron acquisition pathways (e.g., siderophores) and shutting down iron consumptive pathways (and SreA) during iron starvation conditions whereas SreA negatively regulates HapX and corresponding pathways during iron sufficiency. Recently the non-ribosomal peptide, hexadehydroastechrome (HAS; a tryptophan-derived iron (III)-complex), has been found important in A. fumigatus virulence. We found that HAS overproduction caused an iron starvation phenotype, from alteration of siderophore pools to regulation of iron homeostasis gene expression including sreA. Moreover, we uncovered an iron dependent secondary metabolism network where both SreA and HapX oppositely regulate multiple other secondary metabolites including HAS. This circuitry links iron-acquisition and consumption pathways with secondary metabolism-thus placing HAS as part of a metabolic feedback circuitry designed to balance iron pools in the fungus and presenting iron availability as one environmental trigger of secondary metabolism.
Collapse
Affiliation(s)
- Philipp Wiemann
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison Madison, WI, USA
| | - Beatrix E Lechner
- Division of Molecular Biology/Biocenter, Innsbruck Medical University Innsbruck, Austria
| | - Joshua A Baccile
- Boyce Thompson Institute and Department of Chemistry and Chemical Biology, Cornell University Ithaca, NY, USA
| | - Thomas A Velk
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison Madison, WI, USA
| | - Wen-Bing Yin
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison Madison, WI, USA
| | - Jin Woo Bok
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison Madison, WI, USA
| | - Suman Pakala
- The J. Craig Venter Institute Rockville, MD, USA
| | | | | | - Frank C Schroeder
- Boyce Thompson Institute and Department of Chemistry and Chemical Biology, Cornell University Ithaca, NY, USA
| | - Hubertus Haas
- Division of Molecular Biology/Biocenter, Innsbruck Medical University Innsbruck, Austria
| | - Nancy P Keller
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison Madison, WI, USA ; Department of Bacteriology, University of Wisconsin-Madison Madison, WI, USA
| |
Collapse
|
5
|
Choi J, Détry N, Kim KT, Asiegbu FO, Valkonen JPT, Lee YH. fPoxDB: fungal peroxidase database for comparative genomics. BMC Microbiol 2014; 14:117. [PMID: 24885079 PMCID: PMC4029949 DOI: 10.1186/1471-2180-14-117] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2013] [Accepted: 04/24/2014] [Indexed: 01/01/2023] Open
Abstract
BACKGROUND Peroxidases are a group of oxidoreductases which mediate electron transfer from hydrogen peroxide (H2O2) and organic peroxide to various electron acceptors. They possess a broad spectrum of impact on industry and fungal biology. There are numerous industrial applications using peroxidases, such as to catalyse highly reactive pollutants and to breakdown lignin for recycling of carbon sources. Moreover, genes encoding peroxidases play important roles in fungal pathogenicity in both humans and plants. For better understanding of fungal peroxidases at the genome-level, a novel genomics platform is required. To this end, Fungal Peroxidase Database (fPoxDB; http://peroxidase.riceblast.snu.ac.kr/) has been developed to provide such a genomics platform for this important gene family. DESCRIPTION In order to identify and classify fungal peroxidases, 24 sequence profiles were built and applied on 331 genomes including 216 from fungi and Oomycetes. In addition, NoxR, which is known to regulate NADPH oxidases (NoxA and NoxB) in fungi, was also added to the pipeline. Collectively, 6,113 genes were predicted to encode 25 gene families, presenting well-separated distribution along the taxonomy. For instance, the genes encoding lignin peroxidase, manganese peroxidase, and versatile peroxidase were concentrated in the rot-causing basidiomycetes, reflecting their ligninolytic capability. As a genomics platform, fPoxDB provides diverse analysis resources, such as gene family predictions based on fungal sequence profiles, pre-computed results of eight bioinformatics programs, similarity search tools, a multiple sequence alignment tool, domain analysis functions, and taxonomic distribution summary, some of which are not available in the previously developed peroxidase resource. In addition, fPoxDB is interconnected with other family web systems, providing extended analysis opportunities. CONCLUSIONS fPoxDB is a fungi-oriented genomics platform for peroxidases. The sequence-based prediction and diverse analysis toolkits with easy-to-follow web interface offer a useful workbench to study comparative and evolutionary genomics of peroxidases in fungi.
Collapse
Affiliation(s)
- Jaeyoung Choi
- Fungal Bioinformatics Laboratory and Department of Agricultural Biotechnology, Seoul National University, Seoul 151-921, Korea
- Center for Fungal Pathogenesis, Seoul National University, Seoul 151-921, Korea
| | - Nicolas Détry
- Department of Forest Sciences, University of Helsinki, 00014 Helsinki, Finland
| | - Ki-Tae Kim
- Fungal Bioinformatics Laboratory and Department of Agricultural Biotechnology, Seoul National University, Seoul 151-921, Korea
| | - Fred O Asiegbu
- Department of Forest Sciences, University of Helsinki, 00014 Helsinki, Finland
| | - Jari PT Valkonen
- Department of Agricultural Sciences, University of Helsinki, 00014 Helsinki, Finland
| | - Yong-Hwan Lee
- Fungal Bioinformatics Laboratory and Department of Agricultural Biotechnology, Seoul National University, Seoul 151-921, Korea
- Center for Fungal Pathogenesis, Seoul National University, Seoul 151-921, Korea
- Department of Forest Sciences, University of Helsinki, 00014 Helsinki, Finland
- Department of Agricultural Sciences, University of Helsinki, 00014 Helsinki, Finland
- Center for Fungal Genetic Resources, Plant Genomics and Breeding Institute, and Research Institute for Agriculture and Life Sciences, Seoul National University, Seoul 151-921, Korea
| |
Collapse
|
6
|
Fazius F, Shelest E, Gebhardt P, Brock M. The fungal α-aminoadipate pathway for lysine biosynthesis requires two enzymes of the aconitase family for the isomerization of homocitrate to homoisocitrate. Mol Microbiol 2012; 86:1508-30. [PMID: 23106124 PMCID: PMC3556520 DOI: 10.1111/mmi.12076] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/15/2012] [Indexed: 11/30/2022]
Abstract
Fungi produce α-aminoadipate, a precursor for penicillin and lysine via the α-aminoadipate pathway. Despite the biotechnological importance of this pathway, the essential isomerization of homocitrate via homoaconitate to homoisocitrate has hardly been studied. Therefore, we analysed the role of homoaconitases and aconitases in this isomerization. Although we confirmed an essential contribution of homoaconitases from Saccharomyces cerevisiae and Aspergillus fumigatus, these enzymes only catalysed the interconversion between homoaconitate and homoisocitrate. In contrast, aconitases from fungi and the thermophilic bacterium Thermus thermophilus converted homocitrate to homoaconitate. Additionally, a single aconitase appears essential for energy metabolism, glutamate and lysine biosynthesis in respirating filamentous fungi, but not in the fermenting yeast S. cerevisiae that possesses two contributing aconitases. While yeast Aco1p is essential for the citric acid cycle and, thus, for glutamate synthesis, Aco2p specifically and exclusively contributes to lysine biosynthesis. In contrast, Aco2p homologues present in filamentous fungi were transcribed, but enzymatically inactive, revealed no altered phenotype when deleted and did not complement yeast aconitase mutants. From these results we conclude that the essential requirement of filamentous fungi for respiration versus the preference of yeasts for fermentation may have directed the evolution of aconitases contributing to energy metabolism and lysine biosynthesis.
Collapse
Affiliation(s)
- Felicitas Fazius
- Microbial Biochemistry and Physiology, Leibniz Institute for Natural Product Research and Infection Biology, Hans-Knoell-Institute, Beutenbergstr. 11a, 07745 Jena, Germany
| | | | | | | |
Collapse
|
7
|
López-Berges MS, Capilla J, Turrà D, Schafferer L, Matthijs S, Jöchl C, Cornelis P, Guarro J, Haas H, Di Pietro A. HapX-mediated iron homeostasis is essential for rhizosphere competence and virulence of the soilborne pathogen Fusarium oxysporum. THE PLANT CELL 2012; 24:3805-22. [PMID: 22968717 PMCID: PMC3480304 DOI: 10.1105/tpc.112.098624] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Soilborne fungal pathogens cause devastating yield losses and are highly persistent and difficult to control. During the infection process, these organisms must cope with limited availability of iron. Here we show that the bZIP protein HapX functions as a key regulator of iron homeostasis and virulence in the vascular wilt fungus Fusarium oxysporum. Deletion of hapX does not affect iron uptake but causes derepression of genes involved in iron-consuming pathways, leading to impaired growth under iron-depleted conditions. F. oxysporum strains lacking HapX are reduced in their capacity to invade and kill tomato (Solanum lycopersicum) plants and immunodepressed mice. The virulence defect of ΔhapX on tomato plants is exacerbated by coinoculation of roots with a biocontrol strain of Pseudomonas putida, but not with a siderophore-deficient mutant, indicating that HapX contributes to iron competition of F. oxysporum in the tomato rhizosphere. These results establish a conserved role for HapX-mediated iron homeostasis in fungal infection of plants and mammals.
Collapse
Affiliation(s)
- Manuel S. López-Berges
- Departamento de Genética, Universidad de Córdoba, 14071 Córdoba, Spain
- Campus de Excelencia Internacional Agroalimentario ceiA3, 14071 Córdoba, Spain
| | - Javier Capilla
- Unitat de Microbiologia, Facultat de Medicina i Ciències de la Salut, Institut d'Investigació Sanitària Pere Virgili, Universitat Rovira i Virgili, 43201 Reus, Spain
| | - David Turrà
- Departamento de Genética, Universidad de Córdoba, 14071 Córdoba, Spain
- Campus de Excelencia Internacional Agroalimentario ceiA3, 14071 Córdoba, Spain
| | - Lukas Schafferer
- Division of Molecular Biology/Biocenter, Innsbruck Medical University, 6020 Innsbruck, Austria
| | - Sandra Matthijs
- Institut de Recherches Microbiologiques Jean-Marie Wiame, 1070 Brussels, Belgium
| | - Christoph Jöchl
- Division of Molecular Biology/Biocenter, Innsbruck Medical University, 6020 Innsbruck, Austria
| | - Pierre Cornelis
- Department of Bioengineering Sciences, Research Group Microbiology, and Flanders Institute for Biotechnology, Department of Structural Biology, Vrije Universiteit Brussel, 1050 Brussels, Belgium
| | - Josep Guarro
- Unitat de Microbiologia, Facultat de Medicina i Ciències de la Salut, Institut d'Investigació Sanitària Pere Virgili, Universitat Rovira i Virgili, 43201 Reus, Spain
| | - Hubertus Haas
- Division of Molecular Biology/Biocenter, Innsbruck Medical University, 6020 Innsbruck, Austria
| | - Antonio Di Pietro
- Departamento de Genética, Universidad de Córdoba, 14071 Córdoba, Spain
- Campus de Excelencia Internacional Agroalimentario ceiA3, 14071 Córdoba, Spain
- Address correspondence to
| |
Collapse
|
8
|
Siderophore synthesis in Magnaporthe grisea is essential for vegetative growth, conidiation and resistance to oxidative stress. Fungal Genet Biol 2008; 46:321-32. [PMID: 19171198 DOI: 10.1016/j.fgb.2008.12.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2008] [Revised: 12/11/2008] [Accepted: 12/15/2008] [Indexed: 11/21/2022]
Abstract
The plant pathogenic fungus Magnaporthe grisea excretes siderophores of the coprogen-type for iron acquisition and uses ferricrocin for intracellular iron storage. In the present report we characterize mutants with defects in extracellular siderophore biosynthesis. Deletion of the M. grisea SSM2 gene, which encodes a non-ribosomal peptide synthetase, resulted in a loss of the production of all coprogens. The mutant strains had a reduced growth rate, produced fewer conidia and were more sensitive to oxidative stress. Ferricrocin production was not affected. Upon deletion of M. grisea OMO1, a gene predicted to encode an L-ornithine-N(5)-monooxygenase, no siderophores of any type were detected, the strain was aconidial, growth rate was reduced and sensitivity to oxidative stress was increased. Abundance of several proteins was affected in the mutants. The Deltassm2 and Deltaomo1 mutant phenotypes were complemented by supplementation of the medium with siderophores or reintroduction of the respective genes.
Collapse
|
9
|
Proteomic and transcriptomic analysis of Aspergillus fumigatus on exposure to amphotericin B. Antimicrob Agents Chemother 2008; 52:4220-7. [PMID: 18838595 DOI: 10.1128/aac.01431-07] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Amphotericin B (AMB) is the most widely used polyene antifungal drug for the treatment of systemic fungal infections, including invasive aspergillosis. It has been our aim to understand the molecular targets of AMB in Aspergillus fumigatus by genomic and proteomic approaches. In transcriptomic analysis, a total of 295 genes were found to be differentially expressed (165 upregulated and 130 downregulated), including many involving the ergosterol pathway, cell stress proteins, cell wall proteins, transport proteins, and hypothetical proteins. Proteomic profiles of A. fumigatus alone or A. fumigatus treated with AMB showed differential expression levels for 85 proteins (76 upregulated and 9 downregulated). Forty-eight of them were identified with high confidence and belonged to the above-mentioned categories. Differential expression levels for Rho-GDP dissociation inhibitor (Rho-GDI), secretory-pathway GDI, clathrin, Sec 31 (a subunit of the exocyst complex), and RAB GTPase Ypt51 in response to an antifungal drug are reported here for the first time and may represent a specific response of A. fumigatus to AMB. The expression of some of these genes was validated by real-time reverse transcription-PCR. The AMB responsive genes/proteins observed to be differentially expressed in A. fumigatus may be further explored for novel drug development.
Collapse
|
10
|
Schrettl M, Kim HS, Eisendle M, Kragl C, Nierman WC, Heinekamp T, Werner ER, Jacobsen I, Illmer P, Yi H, Brakhage AA, Haas H. SreA-mediated iron regulation in Aspergillus fumigatus. Mol Microbiol 2008; 70:27-43. [PMID: 18721228 PMCID: PMC2610380 DOI: 10.1111/j.1365-2958.2008.06376.x] [Citation(s) in RCA: 206] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Aspergillus fumigatus, the most common airborne fungal pathogen of humans, employs two high-affinity iron uptake systems: iron uptake mediated by the extracellular siderophore triacetylfusarinine C and reductive iron assimilation. Furthermore, A. fumigatus utilizes two intracellular siderophores, ferricrocin and hydroxyferricrocin, to store iron. Siderophore biosynthesis, which is essential for virulence, is repressed by iron. Here we show that this control is mediated by the GATA factor SreA. During iron-replete conditions, SreA deficiency partially derepressed synthesis of triacetylfusarinine C and uptake of iron resulting in increased cellular accumulation of both iron and ferricrocin. Genome-wide DNA microarray analysis identified 49 genes that are repressed by iron in an SreA-dependent manner. This gene set, termed SreA regulon, includes all known genes involved in iron acquisition, putative novel siderophore biosynthetic genes, and also genes not directly linked to iron metabolism. SreA deficiency also caused upregulation of iron-dependent and antioxidative pathways, probably due to the increased iron content and iron-mediated oxidative stress. Consistently, the sreA disruption mutant displayed increased sensitivity to iron, menadion and phleomycin but retained wild-type virulence in a mouse model. As all detrimental effects of sreA disruption are restricted to iron-replete conditions these data underscore that A. fumigatus faces iron-depleted conditions during infection.
Collapse
Affiliation(s)
- Markus Schrettl
- Divisions of Molecular Biology/Biocenter, Medical University Innsbruck, Fritz-Pregl-Str.3, A-6020 Innsbruck, Austria
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
11
|
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: 308] [Impact Index Per Article: 19.3] [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.
Collapse
Affiliation(s)
- Hubertus Haas
- Division of Molecular Biology/Biocenter, Innsbruck Medical University, A-6020 Innsbruck, Austria.
| | | | | |
Collapse
|
12
|
Hortschansky P, Eisendle M, Al-Abdallah Q, Schmidt AD, Bergmann S, Thön M, Kniemeyer O, Abt B, Seeber B, Werner ER, Kato M, Brakhage AA, Haas H. Interaction of HapX with the CCAAT-binding complex--a novel mechanism of gene regulation by iron. EMBO J 2007; 26:3157-68. [PMID: 17568774 PMCID: PMC1914100 DOI: 10.1038/sj.emboj.7601752] [Citation(s) in RCA: 183] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2006] [Accepted: 05/16/2007] [Indexed: 11/08/2022] Open
Abstract
Iron homeostasis requires subtle control systems, as iron is both essential and toxic. In Aspergillus nidulans, iron represses iron acquisition via the GATA factor SreA, and induces iron-dependent pathways at the transcriptional level, by a so far unknown mechanism. Here, we demonstrate that iron-dependent pathways (e.g., heme biosynthesis) are repressed during iron-depleted conditions by physical interaction of HapX with the CCAAT-binding core complex (CBC). Proteome analysis identified putative HapX targets. Mutual transcriptional control between hapX and sreA and synthetic lethality resulting from deletion of both regulatory genes indicate a tight interplay of these control systems. Expression of genes encoding CBC subunits was not influenced by iron availability, and their deletion was deleterious during iron-depleted and iron-replete conditions. Expression of hapX was repressed by iron and its deletion was deleterious during iron-depleted conditions only. These data indicate that the CBC has a general role and that HapX function is confined to iron-depleted conditions. Remarkably, CBC-mediated regulation has an inverse impact on the expression of the same gene set in A. nidulans, compared with Saccharomyces cerevisae.
Collapse
Affiliation(s)
- Peter Hortschansky
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology (HKI), and Friedrich-Schiller-University Jena, Jena, Germany
| | - Martin Eisendle
- Division of Molecular Biology, Biocenter, Innsbruck Medical University, Innsbruck, Austria
| | - Qusai Al-Abdallah
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology (HKI), and Friedrich-Schiller-University Jena, Jena, Germany
| | - André D Schmidt
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology (HKI), and Friedrich-Schiller-University Jena, Jena, Germany
| | - Sebastian Bergmann
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology (HKI), and Friedrich-Schiller-University Jena, Jena, Germany
| | - Marcel Thön
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology (HKI), and Friedrich-Schiller-University Jena, Jena, Germany
| | - Olaf Kniemeyer
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology (HKI), and Friedrich-Schiller-University Jena, Jena, Germany
| | - Beate Abt
- Division of Molecular Biology, Biocenter, Innsbruck Medical University, Innsbruck, Austria
| | - Birgit Seeber
- Division of Molecular Biology, Biocenter, Innsbruck Medical University, Innsbruck, Austria
| | - Ernst R Werner
- Division of Biological Chemistry, Biocenter, Innsbruck Medical University, Innsbruck, Austria
| | - Masashi Kato
- Department of Biological Mechanisms and Functions, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan
| | - Axel A Brakhage
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology (HKI), and Friedrich-Schiller-University Jena, Jena, Germany
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology (HKI), and Friedrich-Schiller-University Jena, Beutenbergstrasse 11a, 07745 Jena, Germany. Tel.: +49 3641 656601; Fax: +49 3641 656603; E-mail:
| | - Hubertus Haas
- Division of Molecular Biology, Biocenter, Innsbruck Medical University, Innsbruck, Austria
- Division of Molecular Biology, Biocenter, Innsbruck Medical University, Fritz-Pregl-Strasse 3, 6020 Innsbruck, Austria. Tel.: +43 512 9003 70205; Fax: +43 512 9003 73100; E-mail:
| |
Collapse
|
13
|
Eisendle M, Schrettl M, Kragl C, Müller D, Illmer P, Haas H. The intracellular siderophore ferricrocin is involved in iron storage, oxidative-stress resistance, germination, and sexual development in Aspergillus nidulans. EUKARYOTIC CELL 2006; 5:1596-603. [PMID: 17030991 PMCID: PMC1595343 DOI: 10.1128/ec.00057-06] [Citation(s) in RCA: 98] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Iron is required by most organisms, but an excess of this metal is potentially toxic. Consequently, uptake and intracellular storage of iron are tightly controlled. The filamentous fungus A. nidulans lacks the iron storage compound ferritin but possesses an intracellular siderophore, which is accumulated in a highly regulated manner as iron-free desferri-ferricrocin or iron-containing ferricrocin via transcriptional regulation of the nonribosomal peptide synthetase SidC. Biosynthesis of desferri-ferricrocin was low during iron-replete conditions but up-regulated by both iron starvation and intracellular iron excess, the latter caused by either a shift from iron-depleted to high-iron conditions or deregulation of iron uptake. Consequently, ferricrocin constituted only about 5% of the total iron content under iron-replete conditions but up to 64% during conditions of intracellular excess. In contrast, during iron starvation, desferri-ferricrocin was accumulated, which appears to represent a proactive strategy to prevent iron toxicity. Accumulation of the intracellular siderophore was also up-regulated by oxidative stress, which underscores the intertwining of iron metabolism and oxidative stress. Lack of the intracellular siderophore causes pleiotropic effects, as SidC deficiency results in (i) less-efficient utilization of iron, indicated by reduced growth under iron-depleted conditions and a higher iron demand under iron-replete conditions, (ii) delayed germination under iron-depleted conditions, (iii) increased sensitivity of conidia to oxidative stress, and (iv) elimination of cleistothecia formation in homothallic conditions.
Collapse
Affiliation(s)
- Martin Eisendle
- Division of Molecular Biology/Biocenter, Innsbruck Medical University, Fritz-Pregl-Str. 3, A-6020 Innsbruck, Austria
| | | | | | | | | | | |
Collapse
|
14
|
Missall TA, Lodge JK, McEwen JE. Mechanisms of resistance to oxidative and nitrosative stress: implications for fungal survival in mammalian hosts. EUKARYOTIC CELL 2005; 3:835-46. [PMID: 15302816 PMCID: PMC500878 DOI: 10.1128/ec.3.4.835-846.2004] [Citation(s) in RCA: 143] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- Tricia A Missall
- Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, 1402 S. Grand Blvd., St. Louis, MO 63104, USA
| | | | | |
Collapse
|
15
|
Lan CY, Rodarte G, Murillo LA, Jones T, Davis RW, Dungan J, Newport G, Agabian N. Regulatory networks affected by iron availability in Candida albicans. Mol Microbiol 2005; 53:1451-69. [PMID: 15387822 DOI: 10.1111/j.1365-2958.2004.04214.x] [Citation(s) in RCA: 208] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Iron, an essential element for almost every organism, serves as a regulatory signal for the expression of virulence determinants in many prokaryotic and eukaryotic pathogens. Using a custom Affymetrix GeneChip representing the entire Candida albicans genome, we examined the changes in genome-wide gene expression in this opportunistic pathogen as a function of alterations in environmental concentrations of iron. A total of 526 open reading frame (ORF) transcripts are more highly expressed when the levels of available iron are low, while 626 ORF transcripts are more highly expressed in high-iron conditions. The transcripts dominantly affected by iron concentration range from those associated with cell-surface properties to others which affect mitochondrial function, iron transport and virulence-related secreted hydrolases. Moreover gene expression as assayed in DNA microarrays confirms and extends reports of alterations in cell-surface antigens and drug sensitivity correlated with iron availability. To understand how these genes and pathways might be regulated, we isolated a gene designated SFU1 that encodes a homologue of the Ustilago maydis URBS1, a transcriptional repressor of siderophore uptake/biosynthesis. Comparisons between wild-type and SFU1-null mutant strains revealed 139 potential target genes of Sfu1p; many of which are iron-responsive. Together, these results not only expand our understanding of global iron regulation in C. albicans, but also provide insights into the potential role of iron availability in C. albicans virulence.
Collapse
Affiliation(s)
- Chung-Yu Lan
- Department of Stomatology, University of California, San Francisco, CA 94143, USA
| | | | | | | | | | | | | | | |
Collapse
|
16
|
Kwok E, Kosman D. Iron in yeast: Mechanisms involved in homeostasis. TOPICS IN CURRENT GENETICS 2005. [DOI: 10.1007/4735_92] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
|
17
|
Rutherford JC, Bird AJ. Metal-responsive transcription factors that regulate iron, zinc, and copper homeostasis in eukaryotic cells. EUKARYOTIC CELL 2004; 3:1-13. [PMID: 14871932 PMCID: PMC329510 DOI: 10.1128/ec.3.1.1-13.2004] [Citation(s) in RCA: 200] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
- Julian C Rutherford
- Division of Hematology, Department of Internal Medicine, University of Utah Health Sciences Center, Salt Lake City, Utah 84132, USA
| | | |
Collapse
|
18
|
Oberegger H, Eisendle M, Schrettl M, Graessle S, Haas H. 4'-phosphopantetheinyl transferase-encoding npgA is essential for siderophore biosynthesis in Aspergillus nidulans. Curr Genet 2003; 44:211-5. [PMID: 14508603 DOI: 10.1007/s00294-003-0434-z] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2003] [Revised: 06/27/2003] [Accepted: 07/15/2003] [Indexed: 11/25/2022]
Abstract
Aspergillus nidulans produces two major siderophores: it excretes triacetylfusarinine C to capture iron and contains ferricrocin as an intracellular iron-storage compound. Siderophore biosynthesis involves the enzymatic activity of nonribosomal peptide synthetases (NRPS). NRPS contain 4'-phosphopantetheine as an essential prosthetic group, which is attached by 4'-phosphopantetheinyl transferases. A. nidulans appears to possess at least one gene, npgA, encoding such an enzyme. Using a strain carrying a temperature-sensitive allele, cfwA2, we showed that NpgA is essential for biosynthesis of both the peptide bond-containing ferricrocin and the ester bond-containing triacetylfusarinene C. The cfwA2 strain was found to be iron-starved at the restrictive temperature during iron-replete conditions, consistent with the siderophore system being the major iron-uptake system-as we recently demonstrated. Northern analysis indicated that, in contrast to other genes which are involved in siderophore biosynthesis and uptake, expression of npgA is not controlled by the GATA-transcription factor SreA. It was shown previously that NpgA is required for biosynthesis of penicillin, pigment, and potentially lysine via the alpha-aminoadipate pathway. Supplementation with lysine plus triacetylfusarinine C restored normal growth of the cfwA2 strain at the restrictive temperature, suggesting that the growth defect of the mutant is mainly due to impaired biosynthesis of siderophores and lysine.
Collapse
Affiliation(s)
- Harald Oberegger
- Department of Molecular Biology, University of Innsbruck, Peter-Mayr-Strasse 4b, 6020 Innsbruck, Austria
| | | | | | | | | |
Collapse
|
19
|
Pelletier B, Beaudoin J, Philpott CC, Labbé S. Fep1 represses expression of the fission yeast Schizosaccharomyces pombe siderophore-iron transport system. Nucleic Acids Res 2003; 31:4332-44. [PMID: 12888492 PMCID: PMC169938 DOI: 10.1093/nar/gkg647] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2003] [Revised: 06/10/2003] [Accepted: 06/10/2003] [Indexed: 12/16/2022] Open
Abstract
When iron repletes, Schizosaccharomyces pombe cells repress transcription of genes encoding components involved in the reductive iron transport system. Fep1 mediates this transcriptional control by interacting specifically with GATA-type cis-acting elements. To further investigate the role that Fep1 plays in iron homeostasis, we searched for additional Fep1-regulated genes. We found that str1+ is subject to negative transcriptional regulation, which is exerted through binding of Fep1 to a single GATA element in the str1+ promoter. Introduction of str1+ into a Saccharomyces cerevisiae fet3Delta arn1-4Delta strain led to assimilation of iron from ferrichrome, revealing that Str1 functions as a siderophore-iron transporter in S.pombe. We also identified two additional target genes of Fep1, named str2+ and str3+. We demonstrate that the str1+, str2+ and str3+ genes share a common promoter element, 5'-(A/T)GATAA-3'. We found that the N-terminal 241 residue segment of Fep1 expressed in Escherichia coli specifically interacts with the 5'-(A/T)GATAA-3' element present in each of these promoters. Consistent with this, constitutive high level str1+, str2+ and str3+ gene expression was observed in a fep1Delta mutant strain. Taken together, these results demonstrate that Fep1 occupies a central role in coordinating transcriptional regulation of genes encoding components of the reductive and non-reductive iron transport systems in fission yeast.
Collapse
Affiliation(s)
- Benoit Pelletier
- Département de Biochimie, Université de Sherbrooke, Sherbrooke, Quebec J1H 5N4, Canada
| | | | | | | |
Collapse
|
20
|
Eisendle M, Oberegger H, Zadra I, Haas H. The siderophore system is essential for viability of Aspergillus nidulans: functional analysis of two genes encoding l-ornithine N 5-monooxygenase (sidA) and a non-ribosomal peptide synthetase (sidC). Mol Microbiol 2003; 49:359-75. [PMID: 12828635 DOI: 10.1046/j.1365-2958.2003.03586.x] [Citation(s) in RCA: 188] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The filamentous ascomycete A. nidulans produces two major siderophores: it excretes triacetylfusarinine C to capture iron and contains ferricrocin intracellularly. In this study we report the characterization of two siderophore biosynthetic genes, sidA encoding l-ornithine N(5)-monooxygenase and sidC encoding a non-ribosomal peptide synthetase respectively. Disruption of sidC eliminated synthesis of ferricrocin and deletion of sidA completely blocked siderophore biosynthesis. Siderophore-deficient strains were unable to grow, unless the growth medium was supplemented with siderophores, suggesting that the siderophore system is the major iron assimilatory system of A. nidulans during both iron depleted and iron-replete conditions. Partial restoration of the growth of siderophore-deficient mutants by high concentrations of Fe(2+) (but not Fe(3+)) indicates the presence of an additional ferrous transport system and the absence of an efficient reductive iron assmilatory system. Uptake studies demonstrated that TAFC-bound iron is transferred to cellular ferricrocin whereas ferricrocin is stored after uptake. The siderophore-deficient mutant was able to synthesize ferricrocin from triacetylfusarinine C. Ferricrocin-deficiency caused an increased intracellular labile iron pool, upregulation of antioxidative enzymes and elevated sensitivity to the redox cycler paraquat. This indicates that the lack of this cellular iron storage compound causes oxidative stress. Moreover, ferricrocin biosynthesis was found to be crucial for efficient conidiation.
Collapse
Affiliation(s)
- Martin Eisendle
- Department of Molecular Biology, University of Innsbruck, Fritz-Pregl-Str. 3, A-6020 Innsbruck, Austria
| | | | | | | |
Collapse
|
21
|
Haas H, Schoeser M, Lesuisse E, Ernst JF, Parson W, Abt B, Winkelmann G, Oberegger H. Characterization of the Aspergillus nidulans transporters for the siderophores enterobactin and triacetylfusarinine C. Biochem J 2003; 371:505-13. [PMID: 12487628 PMCID: PMC1223275 DOI: 10.1042/bj20021685] [Citation(s) in RCA: 100] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2002] [Revised: 12/12/2002] [Accepted: 12/17/2002] [Indexed: 11/17/2022]
Abstract
The filamentous ascomycete Aspergillus nidulans produces three major siderophores: fusigen, triacetylfusarinine C, and ferricrocin. Biosynthesis and uptake of iron from these siderophores, as well as from various heterologous siderophores, is repressed by iron and this regulation is mediated in part by the transcriptional repressor SREA. Recently we have characterized a putative siderophore-transporter-encoding gene ( mirA ). Here we present the characterization of two further SREA- and iron-regulated paralogues (mirB and mirC ), including the chromosomal localization and the complete exon/intron structure. Expression of mirA and mirB in a Saccharomyces cerevisiae strain, which lacks high affinity iron transport systems, showed that MIRA transports specifically the heterologous siderophore enterobactin and that MIRB transports exclusively the native siderophore triacetylfusarinine C. Construction and analysis of an A. nidulans mirA deletion mutant confirmed the substrate specificity of MIRA. Phylogenetic analysis of the available sequences suggests that the split of the species A. nidulans and S. cerevisiae predates the divergence of the paralogous Aspergillus siderophore transporters.
Collapse
Affiliation(s)
- Hubertus Haas
- Department of Molecular Biology, University of Innsbruck, Austria.
| | | | | | | | | | | | | | | |
Collapse
|