Gene expression response to eupolauridine-9591 (E9591) and liriodenine methiodide (LMT) in Saccharomyces cerevisiae
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ABSTRACT: Eupolauridine and liriodenine are plant-derived aporphinoid alkaloids that exhibit potent inhibitory activity against the opportunistic fungal pathogens Candida albicans and Cryptococcus neoformans. However, the molecular mechanism of this antifungal activity is unknown. In this study, we show that eupolauridine 9591 (E9591), a synthetic analog of eupolauridine, and liriodenine methiodide (LMT), a methiodide salt of liriodenine, mediate their antifungal activities by disrupting mitochondrial iron-sulfur (Fe-S) cluster synthesis. Several lines of evidence supported this conclusion. First, both E9591 and LMT elicited a transcriptional response indicative of iron imbalance, causing the induction of genes that are required for iron uptake and for the maintenance of cellular iron homeostasis. Second, a genome-wide fitness profile analysis showed that yeast mutants with deletions in iron homeostasis–related genes were hypersensitive to E9591 and LMT. Third, treatment of wild-type yeast cells with E9591 or LMT generated cellular defects that mimicked deficiencies in mitochondrial Fe-S cluster synthesis, including an increase in mitochondrial iron levels, a decrease in the activities of Fe-S cluster enzymes, a decrease in respiratory function, and an increase in oxidative stress. Collectively, our results demonstrate that E9591 and LMT perturb mitochondrial Fe-S cluster biosynthesis; thus, these two compounds target a cellular pathway that is distinct from the pathways commonly targeted by clinically used antifungal drugs. Therefore, the identification of this pathway as a target for antifungal compounds has potential applications in the development of new antifungal therapies.
Project description:We investigated the transcriptional response of yeast to the loss of a single copy of ARH1; an oxidoreductase of the mitochondrial inner membrane, which is among the few mitochondrial proteins that is essential for viability in yeast, ATM1; the mitochondrial inner membrane ATP-binding cassette (ABC) transporter, and of YFH1; the mitochondrial matrix iron chaperone, which oxidizes and stores iron, and interacts with Isu1p to promote Fe-S cluster assembly.
Project description:The biogenesis of iron-sulfur proteins in eukaryotes is an essential process involving the mitochondrial iron-sulfur cluster (ISC) assembly and export machineries and the cytosolic Fe/S protein assembly (CIA) apparatus. To define the integration of Fe/S protein biogenesis into cellular homeostasis, we compared the global transcriptional responses to defects in the three biogenesis systems in S. cerevisiae using DNA microarrays. Microarray analyses were carried out with regulatable yeast mutants in which representatives of each of the three biosynthetic systems could be depleted. In particular, we used the mutants Gal-YAH1, Gal-ATM1 and Gal-NBP35.
Project description:Expression of the yeast Cth2 protein stimulates degradation of mRNAs encoding proteins with Fe-dependent functions in metabolism, in iron storage and in other cellular processes. We demonstrate that in response to Fe deprivation, the Cth2-homologue, Cth1, stimulates specific degradation of mRNAs involved in mitochondrially localized activities that include respiration and amino acid biosynthesis. Furthermore, yeast cells grown under Fe deprivation accumulate mRNAs encoding proteins that function in glucose metabolism. These studies demonstrate a reprogramming of cellular metabolism during Fe-starvation dependent on the coordinated activities of two mRNA binding proteins. Keywords: Messenger RNAs down regulated by Cth1 and Cth2 proteins in response to Fe-limitation
Project description:Expression of the yeast Cth2 protein stimulates degradation of mRNAs encoding proteins with Fe-dependent functions in metabolism, in iron storage and in other cellular processes. We demonstrate that in response to Fe deprivation, the Cth2-homologue, Cth1, stimulates specific degradation of mRNAs involved in mitochondrially localized activities that include respiration and amino acid biosynthesis. Furthermore, yeast cells grown under Fe deprivation accumulate mRNAs encoding proteins that function in glucose metabolism. These studies demonstrate a reprogramming of cellular metabolism during Fe-starvation dependent on the coordinated activities of two mRNA binding proteins. Experiment Overall Design: cth1cth2 cells independently transformed with pRS416 (V), pRS416-CTH1 (C) or pRS416-CTH2 (T) were grown in triplicate in SC-Ura containing 100 μM BPS until exponential growth phase (approximately 6hrs) at 30 degrees, RNA was extracted using a standard glass beads protocol, labeled and hybridized to Yeast Genome S98 Afffymetrix arrays.
Project description:Disruptions to iron-sulfur (Fe-S) clusters, essential cofactors for a broad range of proteins, cause widespread cellular defects resulting in human disease. An underappreciated source of damage to Fe-S clusters are cuprous (Cu1+) ions. Since histone H3 enzymatically produces Cu1+ to support copper-dependent functions, we asked whether this activity could become detrimental to Fe-S clusters. Here, we report that histone H3-mediated Cu1+ toxicity is a major determinant of cellular Fe-S cluster quotient in the budding yeast. Inadequate Fe-S cluster supply, due to diminished assembly as occurs in Friedreich’s Ataxia, causes substantial growth defects and numerous transcriptional responses. Decreasing Cu1+ abundance, through attenuation of histone cupric reductase activity via the H3H113N mutation, prevented the widespread transcriptional rewiring. Our findings reveal a novel interplay between chromatin and mitochondria in Fe-S cluster homeostasis.
Project description:Friedreich’s ataxia (FA) is the most common monogenic mitochondrial disease. FA is caused by a depletion of the mitochondrial protein frataxin (FXN), an iron-sulfur (Fe-S) cluster biogenesis factor. To better understand the cellular consequences of FA, we performed quantitative proteome profiling of human cells depleted for FXN. Nearly every known Fe-S cluster-containing protein was depleted in the absence of FXN, indicating that as a rule, cluster binding confers stability to Fe-S proteins. Proteomic and genetic interaction mapping identified impaired mitochondrial translation downstream of FXN loss, and specifically highlighted the methyltransferase-like protein METTL17 as a candidate effector. Using comparative sequence analysis, mutagenesis, biochemistry and cryogenic electron microscopy we show that METTL17 binds to the mitoribosomal small subunit during late assembly and harbors a previously unrecognized [Fe4S4]2+ cluster required for its stability on the mitoribosome. Notably, METTL17 overexpression rescued the mitochondrial translation and bioenergetic defects, but not the cellular growth, of FXN depleted cells. Our data suggest that METTL17 serves as an Fe-S cluster checkpoint: promoting the translation and assembly of Fe-S cluster rich OXPHOS proteins only when Fe-S cluster levels are replete.
Project description:Disruption of iron metabolism is closely related to metabolic diseases. Iron deficiency is frequently associated with obesity and hepatic steatosis. However, the effects of iron supplementation on obesity and energy metabolism remain unclear. Here we show that a high-fat diet supplemented with iron reduces body weight gain and hepatic lipid accumulation in mice. Iron supplementation was found to reduce mitochondrial morphological abnormalities and upregulate gene transcription involved in mitochondrial function and beta oxidation in the liver and skeletal muscle. In both these tissues, iron supplementation increased the expression of genes involved in heme or iron–sulfur (Fe–S) cluster synthesis. Heme and Fe–S cluster, which are iron prosthetic groups contained in electron transport chain complex subunits, are essential for mitochondrial respiration. The findings of this study demonstrated that iron regulates mitochondrial signaling pathways—gene transcription of mitochondrial component molecules synthesis and their energy metabolism. Overall, the study elucidates the molecular basis underlying the relationship between iron supplementation and obesity and hepatic steatosis progression, and the role of iron as a signaling molecule.
Project description:Disruption of iron metabolism is closely related to metabolic diseases. Iron deficiency is frequently associated with obesity and hepatic steatosis. However, the effects of iron supplementation on obesity and energy metabolism remain unclear. Here we show that a high-fat diet supplemented with iron reduces body weight gain and hepatic lipid accumulation in mice. Iron supplementation was found to reduce mitochondrial morphological abnormalities and upregulate gene transcription involved in mitochondrial function and beta oxidation in the liver and skeletal muscle. In both these tissues, iron supplementation increased the expression of genes involved in heme or iron–sulfur (Fe–S) cluster synthesis. Heme and Fe–S cluster, which are iron prosthetic groups contained in electron transport chain complex subunits, are essential for mitochondrial respiration. The findings of this study demonstrated that iron regulates mitochondrial signaling pathways—gene transcription of mitochondrial component molecules synthesis and their energy metabolism. Overall, the study elucidates the molecular basis underlying the relationship between iron supplementation and obesity and hepatic steatosis progression, and the role of iron as a signaling molecule.
Project description:Friedreich’s ataxia (FA) is the most common monogenic mitochondrial disease. FA is caused by a depletion of the mitochondrial protein frataxin (FXN), an iron-sulfur (Fe-S) cluster biogenesis factor. To better understand the cellular consequences of FA, we performed genetic interaction mapping in control or FXN edited cells. This screen identified impaired mitochondrial translation downstream of FXN loss, and specifically highlighted the methyltransferase-like protein METTL17 as a candidate effector.
Project description:Disruptions to iron-sulfur (Fe-S) clusters, essential cofactors for a broad range of proteins, cause widespread cellular defects resulting in human disease. An underappreciated source of damage to Fe-S clusters are cuprous (Cu1+) ions. Since histone H3 enzymatically produces Cu1+ to support copper-dependent functions, we asked whether this activity could become detrimental to Fe-S clusters. Here, we report that histone H3-mediated Cu1+ toxicity is a major determinant of cellular functional pool of Fe-S clusters. Inadequate Fe-S cluster supply, either due to diminished assembly as occurs in Friedreich’s Ataxia or defective distribution, causes severe metabolic and growth defects in S. cerevisiae. Decreasing Cu1+ abundance, through attenuation of histone cupric reductase activity or depletion of total cellular copper, restored Fe-S cluster-dependent metabolism and growth. Our findings reveal a novel interplay between chromatin and mitochondria in Fe-S cluster homeostasis, and a potential pathogenic role for histone enzyme activity and Cu1+ in diseases with Fe-S cluster dysfunction.