Discovery of highly reactive self-splicing group II introns within the mitochondrial genomes of human pathogenic fungi.

Fungal pathogens represent an expanding global health threat for which treatment options are limited. Self-splicing group II introns have emerged as promising drug targets, but their development has been limited by a lack of information on their distribution and architecture in pathogenic fungi. To meet this challenge, we developed a bioinformatic workflow for scanning sequence data to identify unique RNA structural signatures within group II introns. Using this approach, we discovered a set of ubiquitous introns within thermally dimorphic fungi (genera of Blastomyces, Coccidioides and Histoplasma). These introns are the most biochemically reactive group II introns ever reported, and they self-splice rapidly under near-physiological conditions without protein cofactors. Moreover, we demonstrated the small molecule targetability of these introns by showing that they can be inhibited by the FDA-approved drug mitoxantrone in vitro. Taken together, our results highlight the utility of structure-based informatic searches for identifying riboregulatory elements in pathogens, revealing a striking diversity of reactive self-splicing introns with great promise as antifungal drug targets.

Diversity of fungal pathogens associated with loquat and development of novel virulence scales.

Loquat [Eriobotrya japonica (Thunb.) Lindl.] is an important fruit crop in Pakistan; however, a constant decline in its production is noted due biotic and abiotic stresses, particularly disease infestation. Fungal pathogens are the major disease-causing agents; therefore, their identification is necessary for devising management options. This study explored Taxila, Wah-Cantt, Tret, Chatar, Murree, Kalar-Kahar, Choa-Saidan-Shah and Khan-Pur districts in the Punjab and Khyber Paktoon Khawa (KPK) provinces of Pakistan to explore the diversity of fungal pathogens associated with loquat. The samples were collected from these districts and their microscopic characterizations were accomplished for reliable identification. Alternaria alternata, Curvularia lunata, Lasiodiplodia theobromae, Aspergilus flavis, Botrytis cinerea, Chaetomium globosum, Pestalotiopsis mangiferae and Phomopsis sp. were the fungal pathogens infesting loquat in the study area. The isolates of A. alternata and C. lunata were isolated from leaf spots and fruit rot, while the isolates of L. theobromae were associated with twig dieback. The remaining pathogens were allied with fruit rot. The nucleotide evidence of internal transcribed spacer (ITS) regions (ITS1, 5.8S, and ITS2) were computed from all the pathogens and submitted in the database of National Center for Biotechnology Information (NCBI). For multigene analysis, beta-tubulin (BT) gene and glyceraldehyde 3-phosphate dehydrogenase (GAPDH) regions were explored for A. alternata and C. lunata isolates, respectively. The virulence scales of leaf spots, fruit rot, and twig dieback diseases of loquat were developed for the first time through this study. It is the first comprehensive study with morpho-molecular identification, and newly developed virulence scales of the fungal pathogens associated with loquat, which improves the understanding of these destructive diseases.

miRNA Mediated Regulation and Interaction between Plants and Pathogens.

Plants have evolved diverse molecular mechanisms that enable them to respond to a wide range of pathogens. It has become clear that microRNAs, a class of short single-stranded RNA molecules that regulate gene expression at the transcriptional or post-translational level, play a crucial role in coordinating plant-pathogen interactions. Specifically, miRNAs have been shown to be involved in the regulation of phytohormone signals, reactive oxygen species, and NBS-LRR gene expression, thereby modulating the arms race between hosts and pathogens. Adding another level of complexity, it has recently been shown that specific lncRNAs (ceRNAs) can act as decoys that interact with and modulate the activity of miRNAs. Here we review recent findings regarding the roles of miRNA in plant defense, with a focus on the regulatory modes of miRNAs and their possible applications in breeding pathogen-resistance plants including crops and trees. Special emphasis is placed on discussing the role of miRNA in the arms race between hosts and pathogens, and the interaction between disease-related miRNAs and lncRNAs.

Botrytis polygoni, a new species of the genus Botrytis infecting Polygonaceae in Gansu, China.

A new species, Botrytis polygoni, was isolated from several species of Polygonaceae in 2011 and 2012 in Tongwei County, Gansu Province, China. The species infects Fagopyrum esculentum, F. tataricum, and Fallopia convolvulus, causing brown leaf spots and large blotches with concentric rings in the field. Botrytis polygoni is morphologically characterized by conidia spherical, unicellular, hyaline to pale brown or brown, (10.2-)14.3-21.4(-23.5) µm; and sclerotia black, spherical to subspherical, allantoid, or irregular-shaped, 0.2-4.1 × 0.1-3.0 mm. Comparison of the nuc rDNA internal transcribed spacer region (ITS1-5.8S-ITS2) sequences confirmed its placement in the genus Botrytis. Phylogenetic analysis based on the protein-coding genes glyceraldehyde 3-phosphate dehydrogenase (G3PDH), heat shock protein 60 (HSP60), and DNA-dependent RNA polymerase subunit II (RPB2) showed that the new species is clustered close but separate from Botrytis pyriformis, which was distant from 37 other Botrytis species and 17 undescribed species. Pathogenicity tests showed that the new species has aggressive pathogenicity to four species of Polygonaceae, specifically Fag. tataricum, Fal. convolvulus, Polygonum sibiricum, and Pol. aviculare, weak pathogenicity to Vicia faba in the Fabaceae, and no pathogenicity to eight other tested plants: Amaranthus retroflexus, Cirsium arvense, Convolvulus arvensis, Kalanchoe blossfeldiana, Lagopsis supine, Mentha canadensis, Plantago asiatica, and Raphanus sativus.

New genus of trichomatous coelomycete on Myrcia fenzliana from the Brazilian Cerrado.

Megacoelomyces (type species: Megacoelomyces sanchezii), an ascomycete asexual morph infecting Myrcia fenzliana (Myrtaceae) from the Brazilian Cerrado, is described as a new genus in the Phaeosphaeriaceae (Pleosporales, Dothideomycetes, Ascomycota), based on multilocus phylogeny (three nuclear ribosomal DNA and two protein-coding genes) in addition to morphological (light and scanning electron microscopy) and ecological data.

Chromoblastomycosis in the Amazon region, Brazil, caused by Fonsecaea pedrosoi, Fonsecaea nubica, and Rhinocladiella similis: Clinicopathology, susceptibility, and molecular identification.

Chromoblastomycosis is a chronic subcutaneous disease caused by human contact with melanized fungi occurring mainly in tropical and subtropical zones worldwide. This study assessed 12 patients with chromoblastomycosis from Rondônia, Brazil, Amazon region. In sum, 83.3% were men, 41.6% were from Monte Negro city, median age was 52.9 years, and median time to disease progression was 12.2 years. Lesions were located on the lower limbs (75%), and verruciform was prevalent form (66.6%). After 3 years of treatment with itraconazole, two patients were considered cured. The etiological agents were identified by the molecular sequence of the ribosomal internal transcribed spacer ITS1, 5.8S, and ITS2 region and ß-tubulin genes. Eight strains were identified as Fonsecaea pedrosoi, two were F. nubica, and two were Rhinocladiella similis. The antifungal activity of five drugs was evaluated, and the most active drug was terbinafine (range minimal inhibitory concentration [MIC] 0.015-0.12 µg/ml), itraconazole (range MIC 0.03-0.5 µg/ml) and voriconazole (range MIC 0.06-0.5 µg/ml). The highest MIC was 5-fluorocytosine (range MIC 2-32 µg/ml), and amphotericin B (range MIC 0.25-2 µg/ml). In conclusion, the present study expanded the epidemiological disease database and described for the first time F. nubica and R. similis as chromoblastomycosis agents in the Brazilian Amazon region. Our results confirmed the importance of using molecular methods to identify the melanized fungi and stimulate the recognition of the disease in other places where no cases have been reported.

Comparison of aquatic hyphomycetes communities between lotic and lentic environments in the Atlantic rain forest of Pernambuco, Northeast Brazil.

Riparian forests are important to aquatic ecosystems and produce large quantities of organic matter that are recycled by the microbial community that includes microscopic fungi. The aim of this study was to unveil and compare the diversity of aquatic hyphomycetes associated to submerged leaf litter of tropical lotic and lentic environments in the Atlantic Forest of Northeast Brazil. Six sampling events were carried out in six points of two study areas: Biological Reserve "Mata da Chuva" (MC) and Environmental Protection Area "Lagoa da Mata" (LM), in Pernambuco, Brazil. Twenty three taxa of hyphomycetes were identified resulting in 87 occurrences. In the lake LM, 13 taxa of hyphomycetes were identified with 34 occurrences and in the MC (stream), 20 taxa with 53 occurrences. Ten species were common to both areas. Diversity indices and fungal biomass (ergosterol) were mostly higher in the lotic system. The fungal community analysis did not show any structure regarding sampling periods or sampling points within an area, however the two areas are different. Although the turbulence of the water is considered important for the development of these aquatic fungi, it is possible to find a diverse community of hyphomycetes and considerable fungal biomass in the lentic environment.

Molecular identification and antibacterial properties of an ericoid associated mycorrhizal fungus.

BACKGROUND: The quest for novel sources of antibacterial compounds have necessitated the inclusion of ericoid mycorrhizal fungi (ERM) commonly found within the root of ericaceous plants. Agar-well diffusion method was used to detect antibacterial activity and was followed by the microbroth diffusion method [minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC)]. RESULTS: The results of the phytochemical screening indicated that only alkaloids, flavonoids, phenols, saponins, cardiac glycosides and terpenoids were present, while steroids and tannins were absent. The MIC of the extracts ranged between 2 and 16 mg/mL, and the lowest MIC was obtained with Staphylococcus aureus. Also, the result of the MBC study indicated that the fungal extract was most active at concentrations of 2 and 4 mg/mL against Bacillus subtilis and S. aureus, respectively. CONCLUSIONS: This bioassay showed, for the first time, antibacterial activity of L. incrustata against some bacterial species. Subsequently, ERM fungi should be given attention when searching for antimicrobial agents because they could provide a solution to solve problems associated with conventional disease treatments (i.e. pathogenic microorganisms resistance).

Screening of bacterial endophytes as potential biocontrol agents against soybean diseases.

AIMS: This research was aimed at identifying and characterizing endophytic micro-organisms associated with soybean that have antimicrobial activity towards soybean pathogens. METHODS AND RESULTS: Soybean plants were collected from field trials in four locations of southern Brazil that were cultivated with conventional (C) and transgenic glyphosate-resistant (GR) soybeans. Endophytic bacteria isolated from roots, stems and leaves of soybeans were evaluated for their capacity to inhibit fungal and bacterial plant pathogens and 13 micro-organisms were identified with antagonistic activity. Approximately 230 bacteria were isolated and identified based on the 16S rRNA and rpoN gene sequences. Bacteria isolated from conventional and transgenic soybeans were significantly different not only in population diversity but also in their antagonistic capacity. Thirteen isolates showed in vitro antagonism against Sclerotinia sclerotiorum, Phomopsis sojae and Rhizoctonia solani. Bacillus sp. and Burkholderia sp. were the most effective isolates in controlling bacterial and fungal pathogens in vitro. Extracts and precipitates from culture supernatants of isolates showed different patterns of inhibitory activity on growth of fungal and bacterial pathogens. CONCLUSIONS: Bacillus sp. and Burkholderia sp. were the most effective isolates in controlling fungal pathogens in vitro, and the activity is mainly due to peptides. However, most of the studied bacteria showed the presence of antimicrobial compounds in the culture supernatant, either peptides, bacteriocins or secondary metabolites. SIGNIFICANCE AND IMPACT OF THE STUDY: These results could be significant to develop tools for the biological control of soybean diseases. The work brought to the identification of micro-organisms such as Bacillus sp. and Burkholderia sp. that have the potential to protect crops in order to enhance a sustainable management system of crops. Furthermore, the study provides the first evidences of the influence of management as well as the genetics of glyphosate-resistant soybean on the diversity of bacterial endophytes of soybean phytobiome.

Improvement of bilirubin oxidase productivity of Myrothecium verrucaria and studies on the enzyme overproduced by the mutant strain in the solid-state fermentation.

Bilirubin oxidase has applications in the health and environmental sectors. Hence, several attempts have been made to increase enzyme yields. However, improvements were not very high. We report here the development of a mutant strain of Myrothecium verrucaria by using UV-rays, which produced 28.8 times more enzyme compared with the parent and was higher than the yields reported in earlier submerged cultures. The mutant strain produced 35.6 times more enzyme than the parent in solid-state fermentation, which is better than that previously reported for a solid-state fermentation process. The specific activity of the enzyme produced by the mutant was higher than that of the parental enzyme. Bilirubin oxidase from both strains showed an optimum activity at pH 7 and 40°C. However, the time required to inactivate half of the initial enzyme activity at 60°C was much higher in the case of the enzyme obtained from the mutant compared with the parental enzyme. The improved thermostability of the enzyme from the mutant strain could be due to the point mutations induced during the UV irradiation, since there was no change in the mass of the enzyme compared with the parental enzyme. The bilirubin oxidase of the mutant strain degraded the bilirubin faster than the enzyme obtained from the parent under similar conditions. Faster activity of the enzyme obtained from the mutant strain could be due to its lower Km (79.4 µM) compared with that of the parental enzyme (184 µM). Hence, the mutant enzyme showed a better functionality and thermostability, which will be beneficial for industrial applications.

Molecular analyses uncover the phylogenetic placement of the lichenized hyphomycetous genus Cheiromycina.

The genus Cheiromycina is one of the few genera of lichenized hyphomycetes for which no sexual reproductive stages have been observed. The genus includes species from boreal to temperate regions of the Northern Hemisphere where it is found growing on bark or wood. Congeners in Cheiromycina are characterized by a noncorticate thallus, nearly immersed in the substrate and presenting powdery unpigmented sporodochia, and containing chlorococcoid photobionts. The relationships of members of Cheiromycina with other fungi are not known. Here we inferred the phylogenetic placement of Cheiromycina using three loci (nuSSU, nuLSU, and mtSSU) representing C. flabelliformis, the type species for the genus, C. petri, and C. reimeri. Our results revealed that the genus Cheiromycina is found within the family Malmideaceae (Lecanorales) where members formed a monophyletic clade sister to the genera Savoronala and Malmidea. This phylogenetic placement and the relationships of Cheiromycina with other lichenized hyphomycetous taxa are here discussed.

CRISPR system in filamentous fungi: Current achievements and future directions.

As eukaryotes, filamentous fungi share many features with humans, and they produce numerous active metabolites, some of which are toxic. Traditional genetic approaches are generally inefficient, but the clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 system that has been widely used for basic research on bacteria, mammals and plants offers a simple, fast, versatile technology for systemic research on filamentous fungi. In this review, we summarized the current knowledge on Cas9 and its variants, various selective markers used to screen positive clones, different ways used to detect off-target mutations, and different approaches used to express and transform the CRISPR complex. We also highlight several methods that improve the nuclease specificity and efficiency, and discuss current and potential applications of CRISPR/Cas9 system in filamentous fungi for pathogenesis decoding, confirmation of the gene and pathway, bioenergy process, drug discovery, and chromatin dynamics. We also describe how the synthetic gene circuit of CRISPR/Cas9 systems has been used in the response to various complex environmental signals to redirect metabolite flux and ensure continuous metabolite biosynthesis.

Codon optimization underpins generalist parasitism in fungi.

The range of hosts that parasites can infect is a key determinant of the emergence and spread of disease. Yet, the impact of host range variation on the evolution of parasite genomes remains unknown. Here, we show that codon optimization underlies genome adaptation in broad host range parasites. We found that the longer proteins encoded by broad host range fungi likely increase natural selection on codon optimization in these species. Accordingly, codon optimization correlates with host range across the fungal kingdom. At the species level, biased patterns of synonymous substitutions underpin increased codon optimization in a generalist but not a specialist fungal pathogen. Virulence genes were consistently enriched in highly codon-optimized genes of generalist but not specialist species. We conclude that codon optimization is related to the capacity of parasites to colonize multiple hosts. Our results link genome evolution and translational regulation to the long-term persistence of generalist parasitism.

Nomenclatural notes on Nadsoniella and the human opportunist black yeast genus Exophiala.

The opportunistic black yeast are particularly known through the genus Exophiala, characterised by annellidic budding cells. However, this phenotype is polyphyletic within the order Chaetothyriales. Seventeen generic names are available in the family Herpotrichiellaceae, one of which is Exophiala. Future taxonomy will be based on molecular phylogeny; each multi-species clade may qualify for one of these names. This paper focuses on the genus Nadsoniella, which is the oldest valid name in the Herpotrichiellaceae. Despite its exophiala-like phenotype, the type species of Nadsoniella clusters in the jeanselmei-clade, competing with the sympodial genus Rhinocladiella. In contrast, Exophiala competes with morphologically pronounced genera Thysanorea and Veronaea. Replacing the current phenotypic system for phylogenetic nomenclature requires highly stable phylogenies, which currently are not available.

Modeling dermatophytosis in reconstructed human epidermis: A new tool to study infection mechanisms and to test antifungal agents.

Dermatophytosis is a superficial fungal infection of keratinized structures that exhibits an increasing prevalence in humans and is thus requesting novel prophylactic strategies and therapies. However, precise mechanisms used by dermatophytes to adhere at the surface of the human epidermis and invade its stratum corneum are still incompletely identified, as well as the responses provided by the underlying living keratinocytes during the infection. We hereby report development of an in vitro model of human dermatophytosis through infection of reconstructed human epidermis (RHE) by arthroconidia of the anthropophilic Trichophyton rubrum species or of the zoophilic Microsporum canis and Arthroderma benhamiae species. By modulating density of arthroconidia in the inoculum and duration of exposure to such pathogens, fungal infection limited to the stratum corneum was obtained, mimicking severe but typical in vivo situation. Fungal elements in infected RHE were monitored over time by histochemical analysis using periodic-acid Schiff-staining or quantified by qPCR-detection of fungal genes inside RHE lysates. This model brings improvements to available ones, dedicated to better understand how dermatophytes and epidermis interact, as well as to evaluate preventive and therapeutic agents. Indeed, miconazole topically added to RHE was demonstrated to inhibit fungal infection in this model.

[Advances in the regulation of cephalosporin C biosynthesis - A review].

The beta-lactam antibiotic cephalosporin C is produced industrially by Acremonium chrysogenum. Its derivative 7-aminocephalosporanic acid (7-ACA) is the intermediate of most chemical modification cephalosporins that are the most frequently used antibiotics for the therapy of infectious diseases. Due to its importance, the biosynthetic pathway of cephalosporin C has been elucidated in Acremonium chrysogenum. To improve the yield of cephalosporin C and reduce the cost of production, recent studies have been focused on the sophisticated regulation of cephalosporin C biosynthesis. In this review, recent advances in cephalosporin C biosynthesis and regulation are summarized.

The Black Yeast Exophiala dermatitidis and Other Selected Opportunistic Human Fungal Pathogens Spread from Dishwashers to Kitchens.

We investigated the diversity and distribution of fungi in nine different sites inside 30 residential dishwashers. In total, 503 fungal strains were isolated, which belong to 10 genera and 84 species. Irrespective of the sampled site, 83% of the dishwashers were positive for fungi. The most frequent opportunistic pathogenic species were Exophiala dermatitidis, Candida parapsilosis sensu stricto, Exophiala phaeomuriformis, Fusarium dimerum, and the Saprochaete/Magnusiomyces clade. The black yeast E. dermatitidis was detected in 47% of the dishwashers, primarily at the dishwasher rubber seals, at up to 106 CFU/cm2; the other fungi detected were in the range of 102 to 105 CFU/cm2. The other most heavily contaminated dishwasher sites were side nozzles, doors and drains. Only F. dimerum was isolated from washed dishes, while dishwasher waste water contained E. dermatitidis, Exophiala oligosperma and Sarocladium killiense. Plumbing systems supplying water to household appliances represent the most probable route for contamination of dishwashers, as the fungi that represented the core dishwasher mycobiota were also detected in the tap water. Hot aerosols from dishwashers contained the human opportunistic yeast C. parapsilosis, Rhodotorula mucilaginosa and E. dermatitidis (as well as common air-borne genera such as Aspergillus, Penicillium, Trichoderma and Cladosporium). Comparison of fungal contamination of kitchens without and with dishwashers revealed that virtually all were contaminated with fungi. In both cases, the most contaminated sites were the kitchen drain and the dish drying rack. The most important difference was higher prevalence of black yeasts (E. dermatitidis in particular) in kitchens with dishwashers. In kitchens without dishwashers, C. parapsilosis strongly prevailed with negligible occurrence of E. dermatitidis. F. dimerum was isolated only from kitchens with dishwashers, while Saprochaete/Magnusiomyces isolates were only found within dishwashers. We conclude that dishwashers represent a reservoir of enriched opportunistic pathogenic species that can spread from the dishwasher into the indoor biome.

Seasonal and spatial variation of Deuteromycetes population in polluted cost of Kiaochow Bay.

Objective: To reveal the relationship between Deuteromycetes community and the environmental in Kiaochow Bay of the Yellow Sea. Methods: Using recorded pollution survey, we used molecular methods to study seasonal and spatial variation of Deuteromycetes community diversity in different polluted waters of Kiaochow Bay of the Yellow Sea, China. Results: Denaturing gradient gel electrophoresis fingerprints varied obviously among different sites of similar level of pollution. Moreover, sequence analysis of recovered dominant bands exhibited the existence of plenty of uncultivable fungi, among which Penicillium was the dominant genus. Furthermore, in heavily polluted estuary, there were abundant animal pathogens such as amoeba and Pythium as well as Deuteromycetes. These discoveries demonstrate that the Deuteromycetes community structure is closely related to marine environment, and are indicative of different level of marine contamination. Conclusion: The relationship between Deuteromycetes community and different level of pollution and seasons varied were closely related.

Especies oportunistas de importancia clínica de los géneros bipolaris shoemaker y curvularia boedijn: su caracterización bajo los nuevos criterios taxonómicos / Opportunistic species of clinical relevance in the bipolaris shoemaker & curvularia boedijn genera: its characterization under newest taxonomic criteria

Los géneros fúngicos Bipolaris y Curvularia,incluyen numerosas especies fitopatógenas,saprotrofas y algunas oportunistas emergentes enel ser humano como en otros animales. La distribuciónecológica de ambos taxas es cosmopolita enla gran mayoría de sus integrantes, encontrándosefrecuentemente en hojas, tallos y raíces de diferentespastos, en especial Poaceae, pero tambiénen una gran variedad de dicotiledoneas, aire y sueloen todos los continentes. Cochliobolus, Bipolarisy Curvularia integran un complejo de especiestaxonómicamente confuso, debido a los constantescambios en la nomenclatura de algunos de sus integrantesasexuales (Bipolaris y Curvularia), loscuales se han diferenciado principalmente en basea la morfología de sus conidios, situación a vecesmuy dificultosa debido a que en ambos génerosalgunas especies presentan similares característicasconidiales. Una cuidadosa identificación y unanominación precisa de las especies es crucial parael acceso a la información referente en la literaturamoderna, que gracias a la biología molecularha resuelto muchas de las dudas de la taxonomíabasada solo en el fenotipo.Las especies de ambos géneros (principalmenteCurvularia) pueden afectar a pacientesinmunocomprometidos e inmunocompetentes,en especial B. cynodontis, C. australiensis C.hawaiensis y C. spicifera, causando cuadros clínicosdiversos ya sea superficiales o profundos enmuchas áreas geográficas...

The fungal genera Bipolaris and Curvularia,include numerous plant pathogenic species,saprophitic and some emerging opportunistic inman and other animals. The ecological distributionof both taxa is cosmopolitan in the vast majority ofits members, often being in leaves, stems and rootsof different grasses, especially Poaceae, but also ina variety of dicotyledonous, air and soil on all continents. Cochliobolus, Bipolaris and Curvulariaintegrate a complex of species taxonomically confusingdue to the constant changes in the nomenclatureof some of its asexual members (Bipolarisand Curvularia), which are differentiated mainlybased on the morphology of its conidia, a situationsometimes very difficult because in both generaconidial of some species have similar characteristics. Careful identification and a precise nominationof species is crucial for access to informationconcerning in modern literature, actually thanks tomolecular biology has solved many of the doubtsof taxonomy based only on the phenotype.The species of both genera (mainly Curvularia)can affect immunocompetent or debilitatepatients, especially B. cynodontis, C. australiensis,C. hawaiensis and C.spicifera, causing varioussuperficial or systemic clinical cases in manygeographic areas...

Molecular basis of the regulation of iron homeostasis in fission and filamentous yeasts.

When iron load exceeds that needed by fission and filamentous yeasts, iron-regulatory GATA-type transcription factors repress genes encoding iron acquisition systems. In contrast, under iron starvation, optimization of cellular iron utilization is coordinated by a specialized regulatory subunit of the CCAAT-binding factor that fosters repression of genes encoding iron-using proteins. Despite these findings, there is still limited knowledge concerning the mechanisms by which these iron-responsive regulators respond to high- or low-iron availability. To provide a framework for understanding common and distinct properties of iron-dependent transcriptional regulators, a repertoire of their functional domains in different fungal species is presented here. In addition, discovery of interacting partners of these iron-responsive factors contributes to provide additional insight into their properties.