Acute loss of iron-sulfur clusters results in metabolic reprogramming and generation of lipid droplets in mammalian cells (original) (raw)
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Iron-sulfur cluster biogenesis and human disease
Trends in Genetics, 2008
Iron–sulfur (Fe–S) clusters are essential for numerous biological processes, including mitochondrial respiratory chain activity and various other enzymatic and regulatory functions. Human Fe–S cluster assembly proteins are frequently encoded by single genes, and inherited defects in some of these genes cause disease. Recently, the spectrum of diseases attributable to abnormal Fe–S cluster biogenesis has extended beyond Friedreich ataxia to include a sideroblastic anemia with deficiency of glutaredoxin 5 and a myopathy associated with a deficiency of a Fe–S cluster assembly scaffold protein, ISCU. Mutations within other mammalian Fe–S cluster assembly genes could be causative for human diseases that manifest distinctive combinations of tissue-specific impairments. Thus, defects in the iron–sulfur cluster biogenesis pathway could underlie many human diseases.
Iron–Sulfur Cluster Biogenesis as a Critical Target in Cancer
Antioxidants, 2021
Cancer cells preferentially accumulate iron (Fe) relative to non-malignant cells; however, the underlying rationale remains elusive. Iron–sulfur (Fe–S) clusters are critical cofactors that aid in a wide variety of cellular functions (e.g., DNA metabolism and electron transport). In this article, we theorize that a differential need for Fe–S biogenesis in tumor versus non-malignant cells underlies the Fe-dependent cell growth demand of cancer cells to promote cell division and survival by promoting genomic stability via Fe–S containing DNA metabolic enzymes. In this review, we outline the complex Fe–S biogenesis process and its potential upregulation in cancer. We also discuss three therapeutic strategies to target Fe–S biogenesis: (i) redox manipulation, (ii) Fe chelation, and (iii) Fe mimicry.
Global Identification of Genes Affecting Iron-Sulfur Cluster Biogenesis and Iron Homeostasis
Journal of Bacteriology, 2014
Iron-sulfur (Fe-S) clusters are ubiquitous cofactors that are crucial for many physiological processes in all organisms. In Escherichia coli , assembly of Fe-S clusters depends on the activity of the iron-sulfur cluster (ISC) assembly and sulfur mobilization (SUF) apparatus. However, the underlying molecular mechanisms and the mechanisms that control Fe-S cluster biogenesis and iron homeostasis are still poorly defined. In this study, we performed a global screen to identify the factors affecting Fe-S cluster biogenesis and iron homeostasis using the Keio collection, which is a library of 3,815 single-gene E. coli knockout mutants. The approach was based on radiolabeling of the cells with [2- 14 C]dihydrouracil, which entirely depends on the activity of an Fe-S enzyme, dihydropyrimidine dehydrogenase. We identified 49 genes affecting Fe-S cluster biogenesis and/or iron homeostasis, including 23 genes important only under microaerobic/anaerobic conditions. This study defines key prot...
Human Molecular Genetics, 2009
The LYR family consists of proteins of diverse functions that contain the conserved tripeptide 'LYR' near the N-terminus, and it includes Isd11, which was previously observed to have an important role in iron-sulfur (Fe-S) cluster biogenesis in Saccharomyces cerevisiae. Here, we have cloned and characterized human ISD11 and shown that human ISD11 forms a stable complex in vivo with the human cysteine desulfurase (ISCS), which generates the inorganic sulfur needed for Fe-S protein biogenesis. Similar to ISCS, we have found that ISD11 localizes to the mitochondrial compartment, as expected, but also to the nucleus of mammalian cells. Using RNA-interference techniques, we have shown that suppression of human ISD11 inactivated mitochondrial and cytosolic aconitases. In addition, ISD11 suppression activated iron-responsive element-binding activity of iron regulatory protein 1, increased protein levels of iron regulatory protein 2, and resulted in abnormal punctate ferric iron accumulations in cells. These results indicate that ISD11 is important in the biogenesis of Fe-S clusters in mammalian cells, and its loss disrupts normal mitochondrial and cytosolic iron homeostasis.
Accounts of Chemical Research, 2004
Iron-sulfur clusters are among the most complex metal-containing prosthetic centers in biology. Most if not all of the proteins involved in the biosynthesis of "simple" Fe-S clusters have been identified. The structural and functional chemistry of these proteins has been the subject of intense research efforts, and many of the key details are now understood in structural and mechanistic detail. The fact that Fe-S cluster-binding proteins can be reconstituted in vitro with no accessory proteins provides an important indicator of the intracellular roles for many proteins on the Fe-S cluster assembly pathway. Indeed, such proteins are more correctly viewed as carrier proteins, rather than as catalysts for the reaction, that both avoid the toxicity associated with free iron and sulfide and allow delivery at lower intracellular concentrations of these species. The IscU (or ISU) family of proteins serves a key role as scaffolding proteins on which [2Fe-2S] building blocks are assembled prior to transfer to final apo target proteins. IscU in particular exhibits highly unusual conformational flexibility that appears critical to its function. † Our research on Fe-S
Journal of Biological Chemistry, 2006
Iron-sulfur clusters are prosthetic groups composed of sulfur and iron that are found in respiratory chain complexes and numerous enzymes. Iron-sulfur clusters are synthesized in a multistep process that utilizes cysteine desulfurases, scaffold proteins, chaperones, and iron donors. Assembly of iron-sulfur clusters occurs in the mitochondrial matrix of mammalian cells, but cytosolic isoforms of three major mammalian iron-sulfur cluster (ISC) assembly components have been found, raising the possibility that de novo ironsulfur cluster biogenesis also occurs in cytosol. The human cysteine desulfurase, ISCS, has two isoforms, one of which targets to the mitochondria, whereas the other less abundant form is cytosolic and nuclear. The open-reading frame of cytosolic mammalian ISCS begins at the second AUG of the transcript and lacks mitochondrial targeting information. Yeast complementation experiments have suggested that the human cytosolic ISCS isoform (c-ISCS) cannot be functional. To evaluate function of c-ISCS, we overexpressed the human cytosolic ISCS in yeast Pichia pastoris and showed that the cytosolic form of ISCS is an active cysteine desulfurase that covalently binds 35 S acquired from desulfuration of radiolabeled cysteine. Human cytosolic ISCS dimerized as efficiently as bacterial ISCS and formed a complex in vitro with overexpressed cytosolic human ISCU. When incubated with iron regulatory protein 1, cysteine, and iron, the cytosolic forms of ISCS and ISCU facilitated efficient formation of a [4Fe-4S] cluster on IRP1. Thus, the cytosolic form of ISCS is a functional cysteine desulfurase that can collaborate with cytosolic ISCU to promote de novo iron-sulfur cluster formation.
Cellular responses to high iron: the critical role of iron--sulfur clusters
Iron is a key element required by all eukaryotes. It is utilized by cells in many fundamental biological processes, but it could also damage cells via Fenton chemistry. Therefore cellular iron must be tightly regulated. Cells have developed sophisticated strategies to cope with various iron availabilities. Cellular responses to low iron have been extensively studied and reviewed. The scope of this review is to summarize the current understanding of the cellular responses to high iron. In yeast Saccharomyces cerevisiae high iron induces the expression of CCC1, which encodes the main vacuolar iron transporter, thereby promoting the storage of iron into vacuoles for detoxification. The expression of CCC1 is regulated by the transcription factor Yap5p. Recently published results indicate that Yap5--dependent gene induction depends on the mitochondrial iron--sulfur (Fe--S) cluster synthesis and lacks direct correlation with cytosolic iron level. In mammalian cells high--iron responses involve the transcription factor IRP1. High iron converts IRP1 into aconitase, an iron--sulfur cluster containing protein that lacks mRNA binding ability. This decreases iron acquisition and increases iron storage protein ferritin. Iron sulfur clusters seem to play a revolutionarily conserved role in high iron sensing and responses in cells.
Iron-sulfur clusters in mitochondrial metabolism: Multifaceted roles of a simple cofactor
Biokhimiya, 2016
Iron-sulfur metabolism is essential for cellular function and is a key process in mitochondria. In this review, we focus on the structure and assembly of mitochondrial iron-sulfur clusters and their roles in various metabolic processes that occur in mitochondria. Iron-sulfur clusters are crucial in mitochondrial respiration, in which they are required for the assembly, stability, and function of respiratory complexes I, II, and III. They also serve important functions in the citric acid cycle, DNA metabolism, and apoptosis. Whereas the identification of iron-sulfur containing proteins and their roles in numerous aspects of cellular function has been a long-standing research area, that in mitochondria is comparatively recent, and it is likely that their roles within mitochondria have been only partially revealed. We review the status of the field and provide examples of other cellular iron-sulfur proteins to highlight their multifarious roles.
Metabolic regulation of citrate and iron by aconitases: role of iron–sulfur cluster biogenesis
BioMetals, 2007
Iron and citrate are essential for the metabolism of most organisms, and regulation of iron and citrate biology at both the cellular and systemic levels is critical for normal physiology and survival. Mitochondrial and cytosolic aconitases catalyze the interconversion of citrate and isocitrate, and aconitase activities are affected by iron levels, oxidative stress and by the status of the Fe-S cluster biogenesis apparatus. Assembly and disassembly of Fe-S clusters is a key process not only in regulating the enzymatic activity of mitochondrial aconitase in the citric acid cycle, but also in controlling the iron sensing and RNA binding activities of cytosolic aconitase (also known as iron regulatory protein IRP1). This review discusses the central role of aconitases in intermediary metabolism and explores how iron homeostasis and Fe-S cluster biogenesis regulate the Fe-S cluster switch and modulate intracellular citrate flux.