Adaptation to different types of environmental stress is a common part of life for today’s fungi. A deeper understanding of the organization, regulation and evolution of fungal stress response systems may lead to the development of novel antifungal drugs and technologies or the engineering of industrial strains with elevated stress tolerance. Here we present the Fungal Stress Response Database (http://internal.med.unideb.hu/fsrd) aimed to stimulate further research on stress biology of fungi. The database incorporates 1985 fungal stress response proteins with verified physiological function(s) and their orthologs identified and annotated in 28 species including human and plant pathogens, as well as important industrial fungi. The database will be extended continuously to cover other fully sequenced fungal species. Our database, as a starting point for future stress research, facilitates the analysis of literature data on stress and the identification of ortholog groups of stress response proteins in newly sequenced fungal genomes. Database URL:http://internal.med.unideb.hu/fsrd

The polyphyletic group of black fungi within the Ascomycota (Arthoniomycetes, Dothideomycetes, and Eurotiomycetes) is ubiquitous in natural and anthropogenic habitats. Partly because of their dark, melanin-based pigmentation, black fungi are resistant to stresses including UV- and ionizing-radiation, heat and desiccation, toxic metals, and organic pollutants. Consequently, they are amongst the most stunning extremophiles and poly-extreme-tolerant organisms on Earth. Even though ca. 60 black fungal genomes have been sequenced to date, [mostly in the family Herpotrichiellaceae (Eurotiomycetes)], the class Dothideomycetes that hosts the largest majority of extremophiles has only been sparsely sampled. By sequencing up to 92 species that will become reference genomes, the “Shed light in The daRk lineagES of the fungal tree of life” (STRES) project will cover a broad collection of black fungal diversity spread throughout the Fungal Tree of Life. Interestingly, the STRES project will focus on mostly unsampled genera that display different ecologies and life-styles (e.g., ant- and lichen-associated fungi, rock-inhabiting fungi, etc.). With a resequencing strategy of 10- to 15-fold depth coverage of up to ~550 strains, numerous new reference genomes will be established. To identify metabolites and functional processes, these new genomic resources will be enriched with metabolomics analyses coupled with transcriptomics experiments on selected species under various stress conditions (salinity, dryness, UV radiation, oligotrophy). The data acquired will serve as a reference and foundation for establishing an encyclopedic database for fungal metagenomics as well as the biology, evolution, and ecology of the fungi in extreme environments.

Yeast protein sequence-based homology search for glutathione (GSH) metabolic enzymes and GSH transporters demonstrated that Aspergillus nidulans has a robust GSH uptake and metabolic system with several paralogous genes. In wet laboratory experiments, two key genes of GSH metabolism, gcsA, and glrA, encoding γ-l-glutamyl-l-cysteine synthetase and glutathione reductase, respectively, were deleted. The gene gcsA was essential, and the ΔgcsA mutant required GSH supplementation at considerably higher concentration than the Saccharomyces cerevisiae gsh1 mutant (8–10 mmol l⁻¹ vs. 0.5 μmol l⁻¹). In addition to some functions known previously, both genes were important in the germination of conidiospores, and both gene deletion strains required the addition of extra GSH to reach wild-type germination rates in liquid cultures. Nevertheless, the supplementation of cultures with 10 mmol l⁻¹ GSH was toxic for the control and ΔglrA strains especially during vegetative growth, which should be considered in future development of high GSH-producer fungal strains. Importantly, the ΔglrA strain was characterized by increased sensitivity toward a wide spectrum of osmotic, cell wall integrity and antimycotic stress conditions in addition to previously reported temperature and oxidative stress sensitivities. These novel phenotypes underline the distinguished functions of GSH and GSH metabolic enzymes in the stress responses of fungi.

Indoleamine 2,3‐dioxygenase 1 (IDO1) is the rate‐limiting enzyme in tryptophan metabolism that plays a central role in immune regulation across a range of diseases, including cancer. Beyond its enzymatic role, IDO1 has a non‐enzymatic function that remains poorly understood. This study explores how phosphorylation of immunoreceptor tyrosine‐based inhibitory motifs (ITIMs) modulates IDO1's structural dynamics and functional states. Using molecular dynamics simulations and structural analysis, we show that phosphorylation acts as a molecular switch, inducing conformational changes that regulate heme‐binding, remodel specific loop regions, and govern protein–protein interactions with SHP1, SHP2, and SOCS3. Notably, Tyr249 phosphorylation inhibits enzymatic activity by compacting the heme‐binding pocket, creating steric hindrance that prevents cofactor binding. In contrast, Tyr111 phosphorylation enhances interactions with SHP1 or SHP2 proteins by embedding their C‐terminal regions into the heme‐binding pocket, also obstructing heme binding. Furthermore, Tyr249 phosphorylation promotes SOCS3 binding through the formation of a unique loop structure near the phosphorylation site. These findings provide a detailed mechanistic framework for understanding how ITIM phosphorylation orchestrates IDO1's functional transitions, effectively balancing its enzymatic and non‐enzymatic functions.

The importance of manganese superoxide dismutase (Mn-SOD), an evolutionarily ancient metalloenzyme that maintains the integrity and function of mitochondria, was studied in oxidative stress-treated Aspergillus fumigatus cultures. Deletion of the Mn-SOD gene (sodB) increased both the menadione sodium bisulfite (MSB)-elicited oxidative stress and the deferiprone (DFP)-induced iron limitation stress sensitivity of the strain. Moreover, DFP treatment enhanced the MSB sensitivity of both the gene deletion mutant and the reference strain. The lack of SodB also increased the susceptibility of conidia to killing by human macrophages. Concurring with the stress sensitivity data, RNS sequencing data also demonstrated that the deletion of sodB largely altered the MSB-induced oxidative stress response. The difference between the oxidative stress responses of the two strains manifested mainly in the intensity of the response. Importantly, upregulation of “Ribosome protein”, “Iron uptake”, and “Fe-S cluster assembly” genes, alterations in the transcription of “Fe-S cluster protein” genes, and downregulation of “Heme binding protein” genes under MSB stress were characteristic only for the ΔsodB gene deletion mutant. We assume that the elevated superoxide level generated by MSB treatment may have destroyed Fe-S cluster proteins of mitochondria in the absence of SodB. This intensified the resynthesis of Fe-S cluster proteins, which was accompanied with enhanced translation and iron acquisition, leading to increased DFP sensitivity.

Asexual sporulation (conidiogenesis) in filamentous fungi is a complex developmental process that requires precise coordination with primary metabolism and environmental stress responses. In the model fungus Aspergillus nidulans, we demonstrate that the bZIP-type transcription factor AtfA plays a central role in integrating conidiogenesis with the underlying metabolic and regulatory networks. Using combined ChIP-seq and RNA-seq analyses in wild-type, ∆atfA, and atfA-complemented strains under stress-free and oxidative stress (menadione) conditions, we identify a conserved AtfA binding motif and map its functional targets genome-wide. Our data reveal that AtfA binding to its target promoters is largely stress-independent, suggesting a preemptive regulatory mechanism in conidial development. AtfA directly binds to the promoters of genes involved in the MAPK signaling cascade, light-dependent sporulation, antioxidant defense, eisosome biogenesis, and the biosynthesis of trehalose and polyols—key metabolites supporting spore maturation and dormancy. Importantly, AtfA acts predominantly as a transcriptional activator, and its regulatory scope extends beyond stress adaptation to the orchestration of metabolic processes essential for spore integrity and germination. These findings position AtfA as a master integrator that synchronizes morphological development with metabolic preparedness during asexual reproduction in A. nidulans.