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Genes Jul 2020Ergosterol is an essential component of fungal cell membranes that determines the fluidity, permeability and activity of membrane-associated proteins. Ergosterol... (Review)
Review
Ergosterol is an essential component of fungal cell membranes that determines the fluidity, permeability and activity of membrane-associated proteins. Ergosterol biosynthesis is a complex and highly energy-consuming pathway that involves the participation of many enzymes. Deficiencies in sterol biosynthesis cause pleiotropic defects that limit cellular proliferation and adaptation to stress. Thereby, fungal ergosterol levels are tightly controlled by the bioavailability of particular metabolites (e.g., sterols, oxygen and iron) and environmental conditions. The regulation of ergosterol synthesis is achieved by overlapping mechanisms that include transcriptional expression, feedback inhibition of enzymes and changes in their subcellular localization. In the budding yeast , the sterol regulatory element (SRE)-binding proteins Upc2 and Ecm22, the heme-binding protein Hap1 and the repressor factors Rox1 and Mot3 coordinate ergosterol biosynthesis () gene expression. Here, we summarize the sterol biosynthesis, transport and detoxification systems of , as well as its adaptive response to sterol depletion, low oxygen, hyperosmotic stress and iron deficiency. Because of the large number of genes and the crosstalk between different environmental signals and pathways, many aspects of ergosterol regulation are still unknown. The study of sterol metabolism and its regulation is highly relevant due to its wide applications in antifungal treatments, as well as in food and pharmaceutical industries.
Topics: DNA-Binding Proteins; Drug Resistance, Fungal; Ergosterol; Gene Expression Regulation, Fungal; Promoter Regions, Genetic; Repressor Proteins; Saccharomyces cerevisiae; Saccharomyces cerevisiae Proteins; Sterols; Trans-Activators; Transcription Factors
PubMed: 32679672
DOI: 10.3390/genes11070795 -
Nature Nov 2023Decades of previous efforts to develop renal-sparing polyene antifungals were misguided by the classic membrane permeabilization model. Recently, the clinically vital...
Decades of previous efforts to develop renal-sparing polyene antifungals were misguided by the classic membrane permeabilization model. Recently, the clinically vital but also highly renal-toxic small-molecule natural product amphotericin B was instead found to kill fungi primarily by forming extramembraneous sponge-like aggregates that extract ergosterol from lipid bilayers. Here we show that rapid and selective extraction of fungal ergosterol can yield potent and renal-sparing polyene antifungals. Cholesterol extraction was found to drive the toxicity of amphotericin B to human renal cells. Our examination of high-resolution structures of amphotericin B sponges in sterol-free and sterol-bound states guided us to a promising structural derivative that does not bind cholesterol and is thus renal sparing. This derivative was also less potent because it extracts ergosterol more slowly. Selective acceleration of ergosterol extraction with a second structural modification yielded a new polyene, AM-2-19, that is renal sparing in mice and primary human renal cells, potent against hundreds of pathogenic fungal strains, resistance evasive following serial passage in vitro and highly efficacious in animal models of invasive fungal infections. Thus, rational tuning of the dynamics of interactions between small molecules may lead to better treatments for fungal infections that still kill millions of people annually and potentially other resistance-evasive antimicrobials, including those that have recently been shown to operate through supramolecular structures that target specific lipids.
Topics: Animals; Humans; Mice; Amphotericin B; Antifungal Agents; Cells, Cultured; Cholesterol; Drug Resistance, Fungal; Ergosterol; Kidney; Kinetics; Microbial Sensitivity Tests; Mycoses; Polyenes; Serial Passage; Sterols; Time Factors
PubMed: 37938782
DOI: 10.1038/s41586-023-06710-4 -
MBio Aug 2023Ergosterol, the major sterol in fungal membranes, is critical for defining membrane fluidity and regulating cellular processes. Although ergosterol synthesis has been...
Ergosterol, the major sterol in fungal membranes, is critical for defining membrane fluidity and regulating cellular processes. Although ergosterol synthesis has been well defined in model yeast, little is known about sterol organization in the context of fungal pathogenesis. We identified a retrograde sterol transporter, Ysp2, in the opportunistic fungal pathogen . We found that the lack of Ysp2 under host-mimicking conditions leads to abnormal accumulation of ergosterol at the plasma membrane, invagination of the plasma membrane, and malformation of the cell wall, which can be functionally rescued by inhibiting ergosterol synthesis with the antifungal drug fluconazole. We also observed that cells lacking Ysp2 mislocalize the cell surface protein Pma1 and have abnormally thin and permeable capsules. As a result of perturbed ergosterol distribution and its consequences, ∆ cells cannot survive in physiologically relevant environments such as host phagocytes and are dramatically attenuated in virulence. These findings expand our knowledge of cryptococcal biology and underscore the importance of sterol homeostasis in fungal pathogenesis. IMPORTANCE is an opportunistic fungal pathogen that kills over 100,000 people worldwide each year. Only three drugs are available to treat cryptococcosis, and these are variously limited by toxicity, availability, cost, and resistance. Ergosterol is the most abundant sterol in fungi and a key component in modulating membrane behavior. Two of the drugs used for cryptococcal infection, amphotericin B and fluconazole, target this lipid and its synthesis, highlighting its importance as a therapeutic target. We discovered a cryptococcal ergosterol transporter, Ysp2, and demonstrated its key roles in multiple aspects of cryptococcal biology and pathogenesis. These studies demonstrate the role of ergosterol homeostasis in virulence, deepen our understanding of a pathway with proven therapeutic importance, and open a new area of study.
Topics: Humans; Virulence; Ergosterol; Fluconazole; Cryptococcosis; Cryptococcus neoformans; Antifungal Agents; Saccharomyces cerevisiae; Sterols; Membrane Transport Proteins; Fungal Proteins
PubMed: 37409809
DOI: 10.1128/mbio.01353-23 -
The Journal of Steroid Biochemistry and... Oct 2023Lumisterol (L2) is a photoproduct of UVB action on the fungal membrane sterol, ergosterol. Like vitamin D, it is present in edible mushrooms, especially after UV...
Lumisterol (L2) is a photoproduct of UVB action on the fungal membrane sterol, ergosterol. Like vitamin D, it is present in edible mushrooms, especially after UV irradiation. Lumisterol is similarly produced in human skin from 7-dehydrocholesterol by UVB and can be converted to hydroxy-metabolites by CYP27A1 and CYP11A1. These products are biologically active on human cells with actions that include photoprotection and inhibition of proliferation. The aim of this study was to test the ability of CYP11A1 and CYP27A1 to metabolise L2. Purified CYP27A1 was found to efficiently metabolise L2 to three major products and several minor products, whilst CYP11A1 did not act appreciably on L2. The three major products of CYP27A1 action on L2 were identified by mass spectrometry and NMR as 24-hydroxyL2, 27-hydroxyL2 and 28-hydroxyL2. Minor products included two dihydroxy L2 species, one which was identified as 24,27(OH)L2, and another metabolite with one oxo and one hydroxyl group added. A comparison on the kinetics of the metabolism of L2 by CYP27A1 with that of the structurally similar compounds, L3 and ergosterol, was carried out with substrates incorporated into phospholipid vesicles. CYP27A1 displayed a 12-fold lower K with L2 as substrate compared to L3 and a 5-fold lower turnover number (k), resulting in a 2.2 fold higher catalytic efficiency (k/K) for L2 metabolism. L2 was a much better substrate for CYP27A1 than its precursor, ergosterol, with a catalytic efficiency 18-fold higher. The major CYP27A1-derived hydroxy-L2 products, 24-hydroxyL2, 27-hydroxyL2 and 28-hydroxyL2, inhibited the proliferation of melanoma and epidermoid cancer cell lines. In conclusion, this study shows that L2 is not metabolized appreciably by CYP11A1, but it is a good substrate for CYP27A1 which hydroxylates its side chain to produce 3 major products that display anti-proliferative activity on skin-cancer cell lines.
Topics: Humans; Ergosterol; Cholesterol Side-Chain Cleavage Enzyme; Hydroxylation; Mass Spectrometry; Ergocalciferols; Cholestanetriol 26-Monooxygenase
PubMed: 37499840
DOI: 10.1016/j.jsbmb.2023.106370 -
Molecular Plant Pathology Sep 2014Fungal pathogens continue to pose a significant threat to crop production and food supply. The early stages of plant-fungus interactions are mostly mediated by... (Review)
Review
Fungal pathogens continue to pose a significant threat to crop production and food supply. The early stages of plant-fungus interactions are mostly mediated by microbe-associated molecular pattern (MAMP) molecules, perceived by plant pattern recognition receptors (PRRs). Currently, the identified fungal MAMP molecules include chitin, chitosan, β-glucans, elicitins and ergosterol. Although the molecular battles between host plants and infecting fungal phytopathogens have been studied extensively, many aspects still need to be investigated to obtain a holistic understanding of the intrinsic mechanisms, which is paramount in combating fungal plant diseases. Here, an overview is given of the most recent findings concerning an 'orphan' fungal MAMP molecule, ergosterol, and we present what is currently known from a synopsis of different genes, proteins and metabolites found to play key roles in induced immune responses in plant-fungus interactions. Clearly, integrative investigations are still needed to provide a comprehensive systems-based understanding of the dynamics associated with molecular mechanisms in plant-ergosterol interactions and associated host responses.
Topics: Ergosterol; Fungi; Immunity, Innate; Plants; Signal Transduction
PubMed: 24528492
DOI: 10.1111/mpp.12127 -
Molecules (Basel, Switzerland) Oct 2018Metabolomics has become a powerful tool in chemical biology. Profiling the human sterolome has resulted in the discovery of noncanonical sterols, including oxysterols... (Review)
Review
Metabolomics has become a powerful tool in chemical biology. Profiling the human sterolome has resulted in the discovery of noncanonical sterols, including oxysterols and meiosis-activating sterols. They are important to immune responses and development, and have been reviewed extensively. The triterpenoid metabolite fusidic acid has developed clinical relevance, and many steroidal metabolites from microbial sources possess varying bioactivities. Beyond the prospect of pharmacognostical agents, the profiling of minor metabolites can provide insight into an organism's biosynthesis and phylogeny, as well as inform drug discovery about infectious diseases. This review aims to highlight recent discoveries from detailed sterolomic profiling in microorganisms and their phylogenic and pharmacological implications.
Topics: Communicable Diseases; Ergosterol; Humans; Metabolomics; Oxysterols; Phylogeny; Phytosterols; Sterols
PubMed: 30366429
DOI: 10.3390/molecules23112768 -
Microbiology Spectrum Jun 2017The application of environmental DNA techniques and increased genome sequencing of microbial diversity, combined with detailed study of cellular characters, has... (Review)
Review
The application of environmental DNA techniques and increased genome sequencing of microbial diversity, combined with detailed study of cellular characters, has consistently led to the reexamination of our understanding of the tree of life. This has challenged many of the definitions of taxonomic groups, especially higher taxonomic ranks such as eukaryotic kingdoms. The Fungi is an example of a kingdom which, together with the features that define it and the taxa that are grouped within it, has been in a continual state of flux. In this article we aim to summarize multiple lines of data pertinent to understanding the early evolution and definition of the Fungi. These include ongoing cellular and genomic comparisons that, we will argue, have generally undermined all attempts to identify a synapomorphic trait that defines the Fungi. This article will also summarize ongoing work focusing on taxon discovery, combined with phylogenomic analysis, which has identified novel groups that lie proximate/adjacent to the fungal clade-wherever the boundary that defines the Fungi may be. Our hope is that, by summarizing these data in the form of a discussion, we can illustrate the ongoing efforts to understand what drove the evolutionary diversification of fungi.
Topics: Amino Acids; Biodiversity; Biological Evolution; Cell Wall; DNA, Fungal; Ecology; Ergosterol; Eukaryota; Evolution, Molecular; Fungi; Genes, Fungal; Genomics; Microbial Interactions; Phylogeny; Symbiosis
PubMed: 28643626
DOI: 10.1128/microbiolspec.FUNK-0044-2017 -
Virulence Aug 2016Sterols are the basal components of the membranes of the fungal pathogen Candida albicans, and these membranes determine the susceptibility of C. albicans cells to a... (Review)
Review
Sterols are the basal components of the membranes of the fungal pathogen Candida albicans, and these membranes determine the susceptibility of C. albicans cells to a variety of stresses, such as ionic, osmotic and oxidative pressures, and treatment with antifungal drugs. The common antifungal azoles in clinical use are targeted to the biosynthesis of ergosterol. In the past years, the synthesis, storage and metabolism of ergosterol in Saccharomyces cerevisiae has been characterized in some detail; however, these processes has not been as well investigated in the human opportunistic pathogen C. albicans. In this review, we summarize the genes involved in ergosterol synthesis and regulation in C. albicans. As well, genes in S. cerevisiae implicated in ergosterol storage and conversions with other lipids are noted, as these provide us clues and directions for the study of the homologous genes in C. albicans. In this report we have particularly focused on the essential roles of ergosterol in the dynamic process of cell biology and its fundamental status in the biological membrane system that includes lipid rafts, lipid droplets, vacuoles and mitochondria. We believe that a thorough understanding of this classic and essential pathway will give us new ideas about drug resistance and morphological switching in C. albicans.
Topics: Antifungal Agents; Azoles; Candida albicans; Drug Resistance, Fungal; Ergosterol; Gene Expression Regulation, Fungal; Humans; Lipid Droplets; Membrane Microdomains; Microbial Sensitivity Tests; Mitochondria; Saccharomyces cerevisiae; Sterols
PubMed: 27221657
DOI: 10.1080/21505594.2016.1188236 -
Trends in Biochemical Sciences Jun 2019In eukaryotes, organelles and vesicles modulate their contents and identities through highly regulated membrane fusion events. Membrane trafficking and fusion are... (Review)
Review
In eukaryotes, organelles and vesicles modulate their contents and identities through highly regulated membrane fusion events. Membrane trafficking and fusion are carried out through a series of stages that lead to the formation of SNARE complexes between cellular compartment membranes to trigger fusion. Although the protein catalysts of membrane fusion are well characterized, their response to their surrounding microenvironment, provided by the lipid composition of the membrane, remains to be fully understood. Membranes are composed of bulk lipids (e.g., phosphatidylcholine), as well as regulatory lipids that undergo constant modifications by kinases, phosphatases, and lipases. These lipids include phosphoinositides, diacylglycerol, phosphatidic acid, and cholesterol/ergosterol. Here we describe the roles of these lipids throughout the stages of yeast vacuole homotypic fusion.
Topics: Cholesterol; Ergosterol; Glycerides; Humans; Membrane Fusion; Phosphatidic Acids; Phosphatidylinositols; Vacuoles
PubMed: 30587414
DOI: 10.1016/j.tibs.2018.12.003 -
Cell Biochemistry and Biophysics Jun 2020We have previously described new pathways of vitamin D3 activation by CYP11A1 to produce a variety of metabolites including 20(OH)D3 and 20,23(OH)D3. These can be... (Review)
Review
We have previously described new pathways of vitamin D3 activation by CYP11A1 to produce a variety of metabolites including 20(OH)D3 and 20,23(OH)D3. These can be further hydroxylated by CYP27B1 to produce their C1α-hydroxyderivatives. CYP11A1 similarly initiates the metabolism of lumisterol (L3) through sequential hydroxylation of the side chain to produce 20(OH)L3, 22(OH)L3, 20,22(OH)L3 and 24(OH)L3. CYP11A1 also acts on 7-dehydrocholesterol (7DHC) producing 22(OH)7DHC, 20,22(OH)7DHC and 7-dehydropregnenolone (7DHP) which can be converted to the D3 and L3 configurations following exposure to UVB. These CYP11A1-derived compounds are produced in vivo and are biologically active displaying anti-proliferative, anti-inflammatory, anti-cancer and pro-differentiation properties. Since the protective role of the classical form of vitamin D3 (1,25(OH)D3) against UVB-induced damage is recognized, we recently tested whether novel CYP11A1-derived D3- and L3-hydroxyderivatives protect against UVB-induced damage in epidermal human keratinocytes and melanocytes. We found that along with 1,25(OH)D3, CYP11A1-derived D3-hydroxyderivatives and L3 and its hydroxyderivatives exert photoprotective effects. These included induction of intracellular free radical scavenging and attenuation and repair of DNA damage. The protection of human keratinocytes against DNA damage included the activation of the NRF2-regulated antioxidant response, p53-phosphorylation and its translocation to the nucleus, and DNA repair induction. These data indicate that novel derivatives of vitamin D3 and lumisterol are promising photoprotective agents. However, detailed mechanisms of action, and the involvement of specific nuclear receptors, other vitamin D binding proteins or mitochondria, remain to be established.
Topics: 25-Hydroxyvitamin D3 1-alpha-Hydroxylase; Animals; Anti-Inflammatory Agents; Antioxidants; Cell Line; Cell Proliferation; Cholecalciferol; Cholesterol Side-Chain Cleavage Enzyme; DNA Damage; Ergosterol; Humans; Keratinocytes; Melanocytes; Mitochondria; Radiation-Protective Agents; Receptors, Calcitriol; Signal Transduction; Ultraviolet Rays
PubMed: 32441029
DOI: 10.1007/s12013-020-00913-6