Non-antifungal medications administered during fungal infections drive drug tolerance and resistance in .

Fungal infections are increasingly concerning, particularly in immunocompromised patients. These patients often suffer from comorbidities and receive multiple, non-antifungal medications. The effects of these co-administered medications on fungal cells - and their potential to influence antifungal drug efficacy - are poorly understood.

The role of metabolism in shaping enzyme structures over 400 million years.

Advances in deep learning and AlphaFold2 have enabled the large-scale prediction of protein structures across species, opening avenues for studying protein function and evolution. Here we analyse 11,269 predicted and experimentally determined enzyme structures that catalyse 361 metabolic reactions across 225 pathways to investigate metabolic evolution over 400 million years in the Saccharomycotina subphylum. By linking sequence divergence in structurally conserved regions to a variety of metabolic properties of the enzymes, we reveal that metabolism shapes structural evolution across multiple scales, from species-wide metabolic specialization to network organization and the molecular properties of the enzymes.

The impact of phenotypic heterogeneity on fungal pathogenicity and drug resistance.

Phenotypic heterogeneity in genetically clonal populations facilitates cellular adaptation to adverse environmental conditions while enabling a return to the basal physiological state. It also plays a crucial role in pathogenicity and the acquisition of drug resistance in unicellular organisms and cancer cells, yet the exact contributing factors remain elusive. In this review, we outline the current state of understanding concerning the contribution of phenotypic heterogeneity to fungal pathogenesis and antifungal drug resistance.

Step-wise evolution of azole resistance through copy number variation followed by KSR1 loss of heterozygosity in Candida albicans.

Antimicrobial drug resistance poses a global health threat, requiring a deeper understanding of the evolutionary processes that lead to its emergence in pathogens. Complex evolutionary dynamics involve multiple mutations that can result in cooperative or competitive (clonal interference) effects. Candida albicans, a major fungal pathogen, displays high rates of copy number variation (CNV) and loss of heterozygosity (LOH).

Reshaping Echinocandin Antifungal Drugs To Circumvent Glucan Synthase Point-Mutation-Mediated Resistance.

Echinocandins are a class of antifungal drugs that inhibit the activity of the β-(1,3)-glucan synthase complex, which synthesizes fungal cell wall β-(1,3)-glucan. Echinocandin resistance is linked to mutations in the FKS gene, which encodes the catalytic subunit of the glucan synthase complex. We present a molecular-docking-based model that provides insight into how echinocandins interact with the target Fks protein: echinocandins form a ternary complex with both Fks and membrane lipids.

exhibits heterogeneous and adaptive cytoprotective responses to antifungal compounds.

an opportunistic human pathogen, poses a significant threat to human health and is associated with significant socio-economic burden. Current antifungal treatments fail, at least in part, because can initiate a strong drug tolerance response that allows some cells to grow at drug concentrations above their minimal inhibitory concentration. To better characterize this cytoprotective tolerance program at the molecular single-cell level, we used a nanoliter droplet-based transcriptomics platform to profile thousands of individual fungal cells and establish their subpopulation characteristics in the absence and presence of antifungal drugs.

The Metabolism of Susceptibility: Clearing the FoG Between Tolerance and Resistance in .

Purpose Of Review: Failure of antifungal treatment is alarmingly common in patients infected with isolates that test as susceptible in vitro. This means that clinical susceptibility tests have limited predictive value for treatment success. To guide the improvement of patient outcomes, we must understand the effects of environmental and metabolic states on drug responses.

Protocols for Measuring Tolerant and Heteroresistant Drug Responses of Pathogenic Yeasts.

The classic definition of antimicrobial susceptibility to antifungal drugs ignores the persistence of subpopulations that survive in the presence of a drug. Even in entirely clonal populations, small subpopulations of yeast can grow in the presence of a drug, sometimes up to extremely high drug concentrations, such that they may be clinically relevant. Identifying and quantifying the incidence with which these subpopulations arise is an essential step in understanding how pathogenic yeast, such as Candida species (i.

Antifungal Tolerance and Resistance Emerge at Distinct Drug Concentrations and Rely upon Different Aneuploid Chromosomes.

Antifungal drug tolerance is a response distinct from resistance, in which cells grow slowly above the MIC. Here, we found that the majority (69.2%) of 133 Candida albicans clinical isolates, including standard lab strain SC5314, exhibited temperature-enhanced tolerance at 37°C and 39°C, and were not tolerant at 30°C.

Fold-change of chromatin condensation in yeast is a conserved property.

During mitosis, chromatin is condensed and organized into mitotic chromosomes. Condensation is critical for genome stability and dynamics, yet the degree of condensation is significantly different between multicellular and single-cell eukaryotes. What is less clear is whether there is a minimum degree of chromosome condensation in unicellular eukaryotes.

The future of fungi: threats and opportunities.

The fungal kingdom represents an extraordinary diversity of organisms with profound impacts across animal, plant, and ecosystem health. Fungi simultaneously support life, by forming beneficial symbioses with plants and producing life-saving medicines, and bring death, by causing devastating diseases in humans, plants, and animals. With climate change, increased antimicrobial resistance, global trade, environmental degradation, and novel viruses altering the impact of fungi on health and disease, developing new approaches is now more crucial than ever to combat the threats posed by fungi and to harness their extraordinary potential for applications in human health, food supply, and environmental remediation.

The importance of antimicrobial resistance in medical mycology.

Prior to the SARS-CoV-2 pandemic, antibiotic resistance was listed as the major global health care priority. Some analyses, including the O'Neill report, have predicted that deaths due to drug-resistant bacterial infections may eclipse the total number of cancer deaths by 2050. Although fungal infections remain in the shadow of public awareness, total attributable annual deaths are similar to, or exceeds, global mortalities due to malaria, tuberculosis or HIV.

Regulation of heme utilization and homeostasis in Candida albicans.

Heme (iron-protoporphyrin IX) is an essential but potentially toxic cellular cofactor. While most organisms are heme prototrophs, many microorganisms can utilize environmental heme as iron source. The pathogenic yeast Candida albicans can utilize host heme in the iron-poor host environment, using an extracellular cascade of soluble and anchored hemophores, and plasma membrane ferric reductase-like proteins.

An orthologous gene coevolution network provides insight into eukaryotic cellular and genomic structure and function.

The evolutionary rates of functionally related genes often covary. We present a gene coevolution network inferred from examining nearly 3 million orthologous gene pairs from 332 budding yeast species spanning ~400 million years of evolution. Network modules provide insight into cellular and genomic structure and function.

Tackling the emerging threat of antifungal resistance to human health.

Invasive fungal infections pose an important threat to public health and are an under-recognized component of antimicrobial resistance, an emerging crisis worldwide. Across a period of profound global environmental change and expanding at-risk populations, human-infecting pathogenic fungi are evolving resistance to all licensed systemic antifungal drugs. In this Review, we highlight the main mechanisms of antifungal resistance and explore the similarities and differences between bacterial and fungal resistance to antimicrobial control.

Microbial communities form rich extracellular metabolomes that foster metabolic interactions and promote drug tolerance.

Microbial communities are composed of cells of varying metabolic capacity, and regularly include auxotrophs that lack essential metabolic pathways. Through analysis of auxotrophs for amino acid biosynthesis pathways in microbiome data derived from >12,000 natural microbial communities obtained as part of the Earth Microbiome Project (EMP), and study of auxotrophic-prototrophic interactions in self-establishing metabolically cooperating yeast communities (SeMeCos), we reveal a metabolically imprinted mechanism that links the presence of auxotrophs to an increase in metabolic interactions and gains in antimicrobial drug tolerance. As a consequence of the metabolic adaptations necessary to uptake specific metabolites, auxotrophs obtain altered metabolic flux distributions, export more metabolites and, in this way, enrich community environments in metabolites.

Aneuploidy Underlies Tolerance and Cross-Tolerance to Drugs in Candida parapsilosis.

species are the most common human fungal pathogens worldwide. Although C. albicans remains the predominant cause of candidiasis, infections caused by non-albicans species, including C.

Adaptation to Fluconazole via Aneuploidy Enables Cross-Adaptation to Amphotericin B and Flucytosine in Cryptococcus neoformans.

The high morbidity and mortality of cryptococcal meningitis is due to the limited range of therapeutic options: only three classes of antifungal drugs are available (polyenes [amphotericin B], azoles [fluconazole], and pyrimidine analogues [flucytosine]). Fluconazole is the most widely used antifungal drug in sub-Saharan Africa, where cryptococcal meningitis is a major cause of death in patients infected with HIV. In this study, we found that exposure to fluconazole, even for short times (48 h) at subinhibitory concentrations, drove rapid adaptation of Cryptococcus neoformans serotype A strain H99 via the acquisition of different aneuploid chromosomes.

Tunicamycin Potentiates Antifungal Drug Tolerance via Aneuploidy in Candida albicans.

How cells exposed to one stress are later able to better survive other types of stress is not well understood. In eukaryotic organisms, physiological and pathological stresses can disturb endoplasmic reticulum (ER) function, resulting in "ER stress." Here, we found that exposure to tunicamycin, an inducer of ER stress, resulted in the acquisition of a specific aneuploidy, chromosome 2 trisomy (Chr2x3), in Candida albicans.