51
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Saneto RP. Mitochondrial diseases: expanding the diagnosis in the era of genetic testing. JOURNAL OF TRANSLATIONAL GENETICS AND GENOMICS 2020; 4:384-428. [PMID: 33426505 PMCID: PMC7791531 DOI: 10.20517/jtgg.2020.40] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Mitochondrial diseases are clinically and genetically heterogeneous. These diseases were initially described a little over three decades ago. Limited diagnostic tools created disease descriptions based on clinical, biochemical analytes, neuroimaging, and muscle biopsy findings. This diagnostic mechanism continued to evolve detection of inherited oxidative phosphorylation disorders and expanded discovery of mitochondrial physiology over the next two decades. Limited genetic testing hampered the definitive diagnostic identification and breadth of diseases. Over the last decade, the development and incorporation of massive parallel sequencing has identified approximately 300 genes involved in mitochondrial disease. Gene testing has enlarged our understanding of how genetic defects lead to cellular dysfunction and disease. These findings have expanded the understanding of how mechanisms of mitochondrial physiology can induce dysfunction and disease, but the complete collection of disease-causing gene variants remains incomplete. This article reviews the developments in disease gene discovery and the incorporation of gene findings with mitochondrial physiology. This understanding is critical to the development of targeted therapies.
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Affiliation(s)
- Russell P. Saneto
- Center for Integrative Brain Research, Neuroscience Institute, Seattle, WA 98101, USA
- Department of Neurology/Division of Pediatric Neurology, Seattle Children’s Hospital/University of Washington, Seattle, WA 98105, USA
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52
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Systemic Delivery of AAV-Fdxr Mitigates the Phenotypes of Mitochondrial Disorders in Fdxr Mutant Mice. Mol Ther Methods Clin Dev 2020; 18:84-97. [PMID: 32995353 PMCID: PMC7488755 DOI: 10.1016/j.omtm.2020.05.021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Accepted: 05/19/2020] [Indexed: 11/23/2022]
Abstract
Gene therapy now provides a novel approach for treating inherited monogenetic disorders, including nuclear gene mutations associated with mitochondrial diseases. In this study, we have utilized a mouse model carrying a p.Arg389Gln mutation of the mitochondrial Ferredoxin Reductase gene (Fdxr) and treated them with neurotropic AAV-PHP.B vector loaded with the mouse Fdxr cDNA sequence. We then used immunofluorescence staining and western blot to test the transduction efficiency of this vector. Toluidine blue staining and electronic microscopy were also utilized to assess the morphology of optic and sciatic nerves, and the mitochondrial respiratory chain activity was determined as well. The AAV vector effectively transduced in the central nervous system and peripheral organs, and AAV-Fdxr treatment reversed almost all the symptoms of the mutants (FdxrR389Q/R389Q). This therapy also improved the electronic conductivity of the sciatic nerves, prevented optic atrophy, improved mobility, and restored mitochondrial complex function. Most notably, the sensory neuropathy, neurodegeneration, and chronic neuroinflammation in the brain were alleviated. Overall, we present the first demonstration of a potential definitive treatment that significantly improves optic and sciatic nerve atrophy, sensory neuropathy, and mitochondrial dysfunction in FDXR-related mitochondriopathy. Our study provides substantial support for the translation of AAV-based Fdxr gene therapy into clinical applications.
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53
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Li Y, Lou W, Grevel A, Böttinger L, Liang Z, Ji J, Patil VA, Liu J, Ye C, Hüttemann M, Becker T, Greenberg ML. Cardiolipin-deficient cells have decreased levels of the iron-sulfur biogenesis protein frataxin. J Biol Chem 2020; 295:11928-11937. [PMID: 32636300 PMCID: PMC7450130 DOI: 10.1074/jbc.ra120.013960] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2020] [Revised: 07/02/2020] [Indexed: 12/12/2022] Open
Abstract
Cardiolipin (CL) is the signature phospholipid of mitochondrial membranes, where it is synthesized locally and plays an important role in mitochondrial bioenergetics. Previous studies in the yeast model have indicated that CL is required for optimal iron homeostasis, which is disrupted by a mechanism not yet determined in the yeast CL mutant, crd1Δ. This finding has implications for the severe genetic disorder, Barth syndrome (BTHS), in which CL metabolism is perturbed because of mutations in the CL-remodeling enzyme, tafazzin. Here, we investigate the effects of tafazzin deficiency on iron homeostasis in the mouse myoblast model of BTHS tafazzin knockout (TAZ-KO) cells. Similarly to CL-deficient yeast cells, TAZ-KO cells exhibited elevated sensitivity to iron, as well as to H2O2, which was alleviated by the iron chelator deferoxamine. TAZ-KO cells exhibited increased expression of the iron exporter ferroportin and decreased expression of the iron importer transferrin receptor, likely reflecting a regulatory response to elevated mitochondrial iron. Reduced activities of mitochondrial iron-sulfur cluster enzymes suggested that the mechanism underlying perturbation of iron homeostasis was defective iron-sulfur biogenesis. We observed decreased levels of Yfh1/frataxin, an essential component of the iron-sulfur biogenesis machinery, in mitochondria from TAZ-KO mouse cells and in CL-deleted yeast crd1Δ cells, indicating that the role of CL in iron-sulfur biogenesis is highly conserved. Yeast crd1Δ cells exhibited decreased processing of the Yfh1 precursor upon import, which likely contributes to the iron homeostasis defects. Implications for understanding the pathogenesis of BTHS are discussed.
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Affiliation(s)
- Yiran Li
- Department of Biological Sciences, Wayne State University, Detroit, Michigan, USA
| | - Wenjia Lou
- Department of Biological Sciences, Wayne State University, Detroit, Michigan, USA
| | - Alexander Grevel
- Institute for Biochemistry and Molecular Biology, Faculty of Medicine, University of Freiburg, Freiburg, Germany
- Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Lena Böttinger
- Institute for Biochemistry and Molecular Biology, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Zhuqing Liang
- Department of Biological Sciences, Wayne State University, Detroit, Michigan, USA
| | - Jiajia Ji
- Department of Biological Sciences, Wayne State University, Detroit, Michigan, USA
| | - Vinay A Patil
- Department of Biological Sciences, Wayne State University, Detroit, Michigan, USA
| | - Jenney Liu
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, Michigan, USA
| | - Cunqi Ye
- Department of Biological Sciences, Wayne State University, Detroit, Michigan, USA
| | - Maik Hüttemann
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, Michigan, USA
| | - Thomas Becker
- Institute for Biochemistry and Molecular Biology, Faculty of Medicine, University of Freiburg, Freiburg, Germany
- CIBSS Centre for Integrative Biological Signaling Studies, University of Freiburg, Freiburg, Germany
- Institute of Biochemistry and Molecular Biology, Faculty of Medicine, University of Bonn, Bonn, Germany
| | - Miriam L Greenberg
- Department of Biological Sciences, Wayne State University, Detroit, Michigan, USA
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Mitochondrial [4Fe-4S] protein assembly involves reductive [2Fe-2S] cluster fusion on ISCA1-ISCA2 by electron flow from ferredoxin FDX2. Proc Natl Acad Sci U S A 2020; 117:20555-20565. [PMID: 32817474 DOI: 10.1073/pnas.2003982117] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The essential process of iron-sulfur (Fe/S) cluster assembly (ISC) in mitochondria occurs in three major phases. First, [2Fe-2S] clusters are synthesized on the scaffold protein ISCU2; second, these clusters are transferred to the monothiol glutaredoxin GLRX5 by an Hsp70 system followed by insertion into [2Fe-2S] apoproteins; third, [4Fe-4S] clusters are formed involving the ISC proteins ISCA1-ISCA2-IBA57 followed by target-specific apoprotein insertion. The third phase is poorly characterized biochemically, because previous in vitro assembly reactions involved artificial reductants and lacked at least one of the in vivo-identified ISC components. Here, we reconstituted the maturation of mitochondrial [4Fe-4S] aconitase without artificial reductants and verified the [2Fe-2S]-containing GLRX5 as cluster donor. The process required all components known from in vivo studies (i.e., ISCA1-ISCA2-IBA57), yet surprisingly also depended on mitochondrial ferredoxin FDX2 and its NADPH-coupled reductase FDXR. Electrons from FDX2 catalyze the reductive [2Fe-2S] cluster fusion on ISCA1-ISCA2 in an IBA57-dependent fashion. This previously unidentified electron transfer was occluded during previous in vivo studies due to the earlier FDX2 requirement for [2Fe-2S] cluster synthesis on ISCU2. The FDX2 function is specific, because neither FDX1, a mitochondrial ferredoxin involved in steroid production, nor other cellular reducing systems, supported maturation. In contrast to ISC factor-assisted [4Fe-4S] protein assembly, [2Fe-2S] cluster transfer from GLRX5 to [2Fe-2S] apoproteins occurred spontaneously within seconds, clearly distinguishing the mechanisms of [2Fe-2S] and [4Fe-4S] protein maturation. Our study defines the physiologically relevant mechanistic action of late-acting ISC factors in mitochondrial [4Fe-4S] cluster synthesis, trafficking, and apoprotein insertion.
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55
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Eriksson SE, Ceder S, Bykov VJN, Wiman KG. p53 as a hub in cellular redox regulation and therapeutic target in cancer. J Mol Cell Biol 2020; 11:330-341. [PMID: 30892598 PMCID: PMC6734141 DOI: 10.1093/jmcb/mjz005] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Revised: 12/21/2018] [Accepted: 02/11/2019] [Indexed: 12/25/2022] Open
Abstract
The TP53 tumor suppressor gene encodes a DNA-binding transcription factor that regulates multiple cellular processes including cell growth and cell death. The ability of p53 to bind to DNA and activate transcription is tightly regulated by post-translational modifications and is dependent on a reducing cellular environment. Some p53 transcriptional target genes are involved in regulation of the cellular redox homeostasis, e.g. TIGAR and GLS2. A large fraction of human tumors carry TP53 mutations, most commonly missense mutations that lead to single amino acid substitutions in the core domain. Mutant p53 proteins can acquire so called gain-of-function activities and influence the cellular redox balance in various ways, for instance by binding of the Nrf2 transcription factor, a major regulator of cellular redox state. The DNA-binding core domain of p53 has 10 cysteine residues, three of which participate in holding a zinc atom that is critical for p53 structure and function. Several novel compounds that refold and reactivate missense mutant p53 bind to specific p53 cysteine residues. These compounds can also react with other thiols and target components of the cellular redox system, such as glutathione. Dual targeting of mutant p53 and redox homeostasis may allow more efficient treatment of cancer.
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Affiliation(s)
- Sofi E Eriksson
- Karolinska Institutet, Department of Oncology-Pathology, BioClinicum, Stockholm, Sweden
| | - Sophia Ceder
- Karolinska Institutet, Department of Oncology-Pathology, BioClinicum, Stockholm, Sweden
| | - Vladimir J N Bykov
- Karolinska Institutet, Department of Oncology-Pathology, BioClinicum, Stockholm, Sweden
| | - Klas G Wiman
- Karolinska Institutet, Department of Oncology-Pathology, BioClinicum, Stockholm, Sweden
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56
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Abstract
Mitochondria are essential in most eukaryotes and are involved in numerous biological functions including ATP production, cofactor biosyntheses, apoptosis, lipid synthesis, and steroid metabolism. Work over the past two decades has uncovered the biogenesis of cellular iron-sulfur (Fe/S) proteins as the essential and minimal function of mitochondria. This process is catalyzed by the bacteria-derived iron-sulfur cluster assembly (ISC) machinery and has been dissected into three major steps: de novo synthesis of a [2Fe-2S] cluster on a scaffold protein; Hsp70 chaperone-mediated trafficking of the cluster and insertion into [2Fe-2S] target apoproteins; and catalytic conversion of the [2Fe-2S] into a [4Fe-4S] cluster and subsequent insertion into recipient apoproteins. ISC components of the first two steps are also required for biogenesis of numerous essential cytosolic and nuclear Fe/S proteins, explaining the essentiality of mitochondria. This review summarizes the molecular mechanisms underlying the ISC protein-mediated maturation of mitochondrial Fe/S proteins and the importance for human disease.
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Affiliation(s)
- Roland Lill
- Institut für Zytobiologie, Philipps-Universität Marburg, 35032 Marburg, Germany;
- SYNMIKRO Zentrum für synthetische Mikrobiologie, Philipps-Universität Marburg, 35043 Marburg, Germany
| | - Sven-A Freibert
- Institut für Zytobiologie, Philipps-Universität Marburg, 35032 Marburg, Germany;
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57
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Integrated analysis of the molecular pathogenesis of FDXR-associated disease. Cell Death Dis 2020; 11:423. [PMID: 32499495 PMCID: PMC7272433 DOI: 10.1038/s41419-020-2637-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2019] [Revised: 05/05/2020] [Accepted: 05/06/2020] [Indexed: 12/18/2022]
Abstract
The mitochondrial flavoprotein ferredoxin reductase (FDXR) is required for biogenesis of iron-sulfur clusters and for steroidogenesis. Iron-sulfur (Fe-S) clusters are ubiquitous cofactors essential to various cellular processes, and an increasing number of disorders are associated with disruptions in the synthesis of Fe-S clusters. Our previous studies have demonstrated that hypomorphic mutations in FDXR cause a novel mitochondriopathy and optic atrophy in humans and mice, attributed in part to reduced function of the electron transport chain (ETC) as well as elevated production of reactive oxygen species (ROS). Inflammation and peripheral neuropathy are also hallmarks of this disease. In this paper, we demonstrate that FDXR mutation leads to significant optic transport defects that are likely to underlie optic atrophy, a major clinical presentation in FDXR patients, as well as a neurodegenerative loss of cells in the central nervous system (CNS). Molecular analysis indicates that FDXR mutation also leads to mitochondrial iron overload and an associated depolarization of the mitochondrial membrane, further supporting the hypothesis that FDXR mutations cause neurodegeneration by affecting FDXR's critical role in iron homeostasis.
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58
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Zhang J, Kong X, Zhang Y, Sun W, Wang J, Chen M, Chen X. FDXR regulates TP73 tumor suppressor via IRP2 to modulate aging and tumor suppression. J Pathol 2020; 251:284-296. [PMID: 32304229 DOI: 10.1002/path.5451] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Revised: 02/27/2020] [Accepted: 04/03/2020] [Indexed: 11/10/2022]
Abstract
Ferredoxin reductase (FDXR) is a mitochondrial flavoprotein that initiates electron transport from NADPH to several cytochromes P450 via two electron carriers, ferredoxin 1 (FDX1) and FDX2. FDXR is the sole ferredoxin reductase in humans and plays a critical role in steroidogenesis and biosynthesis of heme and iron-sulfur clusters. However, much less is known about the role of FDXR in cancer. Here, we show that FDXR plays a role in tumorigenesis by modulating expression of the tumor suppressor p73. By using genetically modified mouse models, we recently showed that mice deficient in either Fdxr or Trp73 had a shorter lifespan and were prone to spontaneous tumors as compared with wild-type (WT) mice. Interestingly, compound Trp73 +/- ;Fdxr +/- mice lived longer and developed fewer tumors when compared with Fdxr +/- or Trp73 +/- mice. Moreover, we found that cellular senescence was increased in Trp73 +/- and Fdxr +/- mouse embryonic fibroblasts (MEFs), which was further increased in Trp73 +/- ;Fdxr +/- MEFs, as compared with that in WT MEFs. As FDXR is regulated by p73, we examined whether there was a feedback regulation between p73 and FDXR. Indeed, we found that Trp73 expression was decreased by loss of Fdxr in MEFs and that FDXR is required for p73 expression in multiple human cancer cell lines independent of p53. Mechanistically, we found that loss of FDXR, via FDX2, increased expression of iron-binding protein 2 (IRP2), which subsequently repressed TP73 mRNA stability. We also showed that TP73 transcript contained an iron response element in its 3'UTR, which was required for IRP2 to destabilize TP73 mRNA. Together, these data reveal a novel regulation of p73 by FDXR via IRP2 and that the FDXR-p73 axis plays a critical role in aging and tumor suppression. © 2020 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
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Affiliation(s)
- Jin Zhang
- Comparative Oncology Laboratory, Schools of Veterinary Medicine and Medicine, University of California at Davis, Davis, CA, USA
| | - Xiangmudong Kong
- Comparative Oncology Laboratory, Schools of Veterinary Medicine and Medicine, University of California at Davis, Davis, CA, USA
| | - Yanhong Zhang
- Comparative Oncology Laboratory, Schools of Veterinary Medicine and Medicine, University of California at Davis, Davis, CA, USA
| | - Wenqiang Sun
- Comparative Oncology Laboratory, Schools of Veterinary Medicine and Medicine, University of California at Davis, Davis, CA, USA
| | - Jian Wang
- School of Medicine, Wayne State University, Detroit, MI, USA
| | - Mingyi Chen
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Xinbin Chen
- Comparative Oncology Laboratory, Schools of Veterinary Medicine and Medicine, University of California at Davis, Davis, CA, USA
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59
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Baussier C, Fakroun S, Aubert C, Dubrac S, Mandin P, Py B, Barras F. Making iron-sulfur cluster: structure, regulation and evolution of the bacterial ISC system. Adv Microb Physiol 2020; 76:1-39. [PMID: 32408945 DOI: 10.1016/bs.ampbs.2020.01.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Iron sulfur (Fe-S) clusters rank among the most ancient and conserved prosthetic groups. Fe-S clusters containing proteins are present in most, if not all, organisms. Fe-S clusters containing proteins are involved in a wide range of cellular processes, from gene regulation to central metabolism, via gene expression, RNA modification or bioenergetics. Fe-S clusters are built by biogenesis machineries conserved throughout both prokaryotes and eukaryotes. We focus mostly on bacterial ISC machinery, but not exclusively, as we refer to eukaryotic ISC system when it brings significant complementary information. Besides covering the structural and regulatory aspects of Fe-S biogenesis, this review aims to highlight Fe-S biogenesis facets remaining matters of discussion, such as the role of frataxin, or the link between fatty acid metabolism and Fe-S homeostasis. Last, we discuss recent advances on strategies used by different species to make and use Fe-S clusters in changing redox environmental conditions.
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Affiliation(s)
- Corentin Baussier
- Laboratoire de Chimie Bactérienne, CNRS-Aix Marseille Université, UMR 7283, Institut de Microbiologie de la Méditerranée, Institut de Microbiologie, Bioénergies et Biotechnologies, Marseille, France
| | - Soufyan Fakroun
- Stress Adaptation and Metabolism Unit, Department of Microbiology, Institut Pasteur, Paris, France; ERL CNRS 6002, CNRS, Paris, France; Université Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - Corinne Aubert
- Laboratoire de Chimie Bactérienne, CNRS-Aix Marseille Université, UMR 7283, Institut de Microbiologie de la Méditerranée, Institut de Microbiologie, Bioénergies et Biotechnologies, Marseille, France
| | - Sarah Dubrac
- Stress Adaptation and Metabolism Unit, Department of Microbiology, Institut Pasteur, Paris, France; ERL CNRS 6002, CNRS, Paris, France
| | - Pierre Mandin
- Laboratoire de Chimie Bactérienne, CNRS-Aix Marseille Université, UMR 7283, Institut de Microbiologie de la Méditerranée, Institut de Microbiologie, Bioénergies et Biotechnologies, Marseille, France
| | - Béatrice Py
- Laboratoire de Chimie Bactérienne, CNRS-Aix Marseille Université, UMR 7283, Institut de Microbiologie de la Méditerranée, Institut de Microbiologie, Bioénergies et Biotechnologies, Marseille, France
| | - Frédéric Barras
- Stress Adaptation and Metabolism Unit, Department of Microbiology, Institut Pasteur, Paris, France; ERL CNRS 6002, CNRS, Paris, France
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60
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Outlining the Complex Pathway of Mammalian Fe-S Cluster Biogenesis. Trends Biochem Sci 2020; 45:411-426. [PMID: 32311335 DOI: 10.1016/j.tibs.2020.02.001] [Citation(s) in RCA: 79] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Revised: 01/27/2020] [Accepted: 02/04/2020] [Indexed: 12/14/2022]
Abstract
Iron-sulfur (Fe-S) clusters (ISCs) are ubiquitous cofactors essential to numerous fundamental cellular processes. Assembly of ISCs and their insertion into apoproteins involves the function of complex cellular machineries that operate in parallel in the mitochondrial and cytosolic/nuclear compartments of mammalian cells. The spectrum of diseases caused by inherited defects in genes that encode the Fe-S assembly proteins has recently expanded to include multiple rare human diseases, which manifest distinctive combinations and severities of global and tissue-specific impairments. In this review, we provide an overview of our understanding of ISC biogenesis in mammalian cells, discuss recent work that has shed light on the molecular interactions that govern ISC assembly, and focus on human diseases caused by failures of the biogenesis pathway.
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61
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Gao F. Iron-Sulfur Cluster Biogenesis and Iron Homeostasis in Cyanobacteria. Front Microbiol 2020; 11:165. [PMID: 32184761 PMCID: PMC7058544 DOI: 10.3389/fmicb.2020.00165] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2019] [Accepted: 01/23/2020] [Indexed: 01/23/2023] Open
Abstract
Iron–sulfur (Fe–S) clusters are ancient and ubiquitous cofactors and are involved in many important biological processes. Unlike the non-photosynthetic bacteria, cyanobacteria have developed the sulfur utilization factor (SUF) mechanism as their main assembly pathway for Fe–S clusters, supplemented by the iron–sulfur cluster and nitrogen-fixing mechanisms. The SUF system consists of cysteine desulfurase SufS, SufE that can enhance SufS activity, SufBC2D scaffold complex, carrier protein SufA, and regulatory repressor SufR. The S source for the Fe–S cluster assembly mainly originates from L-cysteine, but the Fe donor remains elusive. This minireview mainly focuses on the biogenesis pathway of the Fe–S clusters in cyanobacteria and its relationship with iron homeostasis. Future challenges of studying Fe–S clusters in cyanobacteria are also discussed.
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Affiliation(s)
- Fudan Gao
- College of Life Sciences, Shanghai Normal University, Shanghai, China
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62
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Nasta V, Suraci D, Gourdoupis S, Ciofi-Baffoni S, Banci L. A pathway for assembling [4Fe-4S] 2+ clusters in mitochondrial iron-sulfur protein biogenesis. FEBS J 2019; 287:2312-2327. [PMID: 31724821 DOI: 10.1111/febs.15140] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Revised: 10/08/2019] [Accepted: 11/13/2019] [Indexed: 12/16/2022]
Abstract
During its late steps, the mitochondrial iron-sulfur cluster (ISC) assembly machinery leads to the formation of [4Fe-4S] clusters. In vivo studies revealed that several proteins are implicated in the biosynthesis and trafficking of [4Fe-4S] clusters in mitochondria. However, they do not provide a clear picture into how these proteins cooperate. Here, we showed that three late-acting components of the mitochondrial ISC assembly machinery (GLRX5, BOLA3, and NFU1) are part of a ISC assembly pathway leading to the synthesis of a [4Fe-4S]2+ cluster on NFU1. We showed that the [2Fe-2S]2+ GLRX5-BOLA3 complex transfers its cluster to monomeric apo NFU1 to form, in the presence of a reductant, a [4Fe-4S]2+ cluster bound to dimeric NFU1. The cluster formation on NFU1 does not occur with [2Fe-2S]2+ GLRX5, and thus, the [4Fe-4S] cluster assembly pathway is activated only in the presence of BOLA3. These results define NFU1 as an 'assembler' of [4Fe-4S] clusters, that is, a protein able of converting two [2Fe-2S]2+ clusters into a [4Fe-4S]2+ cluster. Finally, we found that the [4Fe-4S]2+ cluster bound to NFU1 has a coordination site which is easily accessible to sulfur-containing ligands, as is typically observed in metallochaperones. This finding supports a role for NFU1 in promoting rapid and controlled cluster-exchange reaction.
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Affiliation(s)
- Veronica Nasta
- Magnetic Resonance Center CERM, University of Florence, Italy.,Department of Chemistry, University of Florence, Italy
| | - Dafne Suraci
- Magnetic Resonance Center CERM, University of Florence, Italy
| | | | - Simone Ciofi-Baffoni
- Magnetic Resonance Center CERM, University of Florence, Italy.,Department of Chemistry, University of Florence, Italy
| | - Lucia Banci
- Magnetic Resonance Center CERM, University of Florence, Italy.,Department of Chemistry, University of Florence, Italy
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63
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Clarke SL, Thompson LR, Dandekar E, Srinivasan A, Montgomery MR. Distinct TP53 Mutation Subtypes Differentially Influence Cellular Iron Metabolism. Nutrients 2019; 11:nu11092144. [PMID: 31500291 PMCID: PMC6769808 DOI: 10.3390/nu11092144] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Revised: 09/02/2019] [Accepted: 09/05/2019] [Indexed: 01/31/2023] Open
Abstract
The most commonly mutated gene in all human cancers is the tumor suppressor gene TP53; however, in addition to the loss of tumor suppressor functions, mutations in TP53 can also promote cancer progression by altering cellular iron acquisition and metabolism. The primary objective of this work was to determine how TP53 mutation status influences the molecular control of iron homeostasis. The effect of TP53 mutation type on cellular iron homeostasis was examined using cell lines with inducible versions of either wild-type TP53 or a representative mutated TP53 gene from exemplary "hotspot" mutations in the DNA binding domain (R248, R273, and R175) as well as H193Y. The introduction of distinct TP53 mutation types alone was sufficient to disrupt cellular iron metabolism. These effects were mediated, at least in part, due to differences in the responsiveness of iron regulatory proteins (IRPs) to cellular iron availability. IRPs are considered the master regulators of intracellular iron homeostasis because they coordinate the expression of iron storage (ferritin) and iron uptake (transferrin receptor) genes. In response to changes in iron availability, cells harboring either a wild-type TP53 or R273H TP53 mutation displayed canonical IRP-mediated responses, but neither IRP1 RNA binding activity nor IRP2 protein levels were affected by changes in iron status in cells harboring the R175H mutation type. However, all mutation types exhibited robust changes in ferritin and transferrin receptor protein expression in response to iron loading and iron chelation, respectively. These findings suggest a novel, IRP-independent mode of iron regulation in cells expressing distinct TP53 mutations. As TP53 is mutated in nearly half of all human cancers, and iron is necessary for cancer cell growth and proliferation, the studies have implications for a wide range of clinically important cancers.
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Affiliation(s)
- Stephen L Clarke
- Department of Nutritional Sciences, Oklahoma State University, Stillwater, OK 74074, USA.
| | - Laurie R Thompson
- Department of Nutritional Sciences, Oklahoma State University, Stillwater, OK 74074, USA.
| | - Eshan Dandekar
- Department of Nutritional Sciences, Oklahoma State University, Stillwater, OK 74074, USA.
| | - Aishwarya Srinivasan
- Department of Nutritional Sciences, Oklahoma State University, Stillwater, OK 74074, USA.
| | - McKale R Montgomery
- Department of Nutritional Sciences, Oklahoma State University, Stillwater, OK 74074, USA.
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64
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Zhang Y, Feng X, Zhang J, Chen M, Huang E, Chen X. Iron regulatory protein 2 is a suppressor of mutant p53 in tumorigenesis. Oncogene 2019; 38:6256-6269. [PMID: 31332290 DOI: 10.1038/s41388-019-0876-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2019] [Revised: 06/12/2019] [Accepted: 06/25/2019] [Indexed: 01/20/2023]
Abstract
p53 is known to play a role in iron homeostasis and is required for FDXR-mediated iron metabolism via iron regulatory protein 2 (IRP2). Interestingly, p53 is frequently mutated in tumors wherein iron is often accumulated, suggesting that mutant p53 may exert its gain of function by altering iron metabolism. In this study, we found that FDXR deficiency decreased mutant p53 expression along with altered iron metabolism in p53R270H/- MEFs and cancer cells carrying mutant p53. Consistently, we found that decreased expression of mutant p53 by FDXR deficiency inhibited mutant p53-R270H to induce carcinoma and high grade pleomorphic sarcoma in FDXR+/-; p53R270H/- mice as compared with p53R270H/- mice. Moreover, we found that like its effect on wild-type p53, loss of IRP2 increased mutant p53 expression. However, unlike its effect to suppress cell growth in cells carrying wild-type p53, loss of IRP2 promoted cell growth in cancer cells expressing mutant p53. Finally, we found that ectopic expression of IRP2 suppressed cell growth in a mutant p53-dependent manner. Together, our data indicate that mutant p53 gain-of-function can be suppressed by IRP2 and FDXR deficiency, both of which may be explored to target tumors carrying mutant p53.
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Affiliation(s)
- Yanhong Zhang
- Comparative Oncology Laboratory, Schools of Medicine and Veterinary Medicine, University of California at Davis, Davis, CA, 95616, USA
| | - Xiuli Feng
- Comparative Oncology Laboratory, Schools of Medicine and Veterinary Medicine, University of California at Davis, Davis, CA, 95616, USA.,College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China
| | - Jin Zhang
- Comparative Oncology Laboratory, Schools of Medicine and Veterinary Medicine, University of California at Davis, Davis, CA, 95616, USA
| | - Minyi Chen
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Eric Huang
- Department of Pathology, University of Washington, Seattle, WA, 98104, USA
| | - Xinbin Chen
- Comparative Oncology Laboratory, Schools of Medicine and Veterinary Medicine, University of California at Davis, Davis, CA, 95616, USA.
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65
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Alfadhel M, Nashabat M, Abu Ali Q, Hundallah K. Mitochondrial iron-sulfur cluster biogenesis from molecular understanding to clinical disease. ACTA ACUST UNITED AC 2019; 22:4-13. [PMID: 28064324 PMCID: PMC5726836 DOI: 10.17712/nsj.2017.1.20160542] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
Iron–sulfur clusters (ISCs) are known to play a major role in various protein functions. Located in the mitochondria, cytosol, endoplasmic reticulum and nucleus, they contribute to various core cellular functions. Until recently, only a few human diseases related to mitochondrial ISC biogenesis defects have been described. Such diseases include Friedreich ataxia, combined oxidative phosphorylation deficiency 19, infantile complex II/III deficiency defect, hereditary myopathy with lactic acidosis and mitochondrial muscle myopathy, lipoic acid biosynthesis defects, multiple mitochondrial dysfunctions syndromes and non ketotic hyperglycinemia due to glutaredoxin 5 gene defect. Disorders of mitochondrial import, export and translation, including sideroblastic anemia with ataxia, EVEN-PLUS syndrome and mitochondrial complex I deficiency due to nucleotide-binding protein-like protein gene defect, have also been implicated in ISC biogenesis defects. With advances in next generation sequencing technologies, more disorders related to ISC biogenesis defects are expected to be elucidated. In this article, we aim to shed the light on mitochondrial ISC biogenesis, related proteins and their function, pathophysiology, clinical phenotypes of related disorders, diagnostic approach, and future implications.
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Affiliation(s)
- Majid Alfadhel
- Division of Genetics, Department of Pediatrics, King Saud bin Abdulaziz University for Health Sciences, King Abdulaziz Medical City, Riyadh, Kingdom of Saudi Arabia
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66
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Tsvetkov P, Detappe A, Cai K, Keys HR, Brune Z, Ying W, Thiru P, Reidy M, Kugener G, Rossen J, Kocak M, Kory N, Tsherniak A, Santagata S, Whitesell L, Ghobrial IM, Markley JL, Lindquist S, Golub TR. Mitochondrial metabolism promotes adaptation to proteotoxic stress. Nat Chem Biol 2019; 15:681-689. [PMID: 31133756 PMCID: PMC8183600 DOI: 10.1038/s41589-019-0291-9] [Citation(s) in RCA: 272] [Impact Index Per Article: 54.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Accepted: 04/16/2019] [Indexed: 12/17/2022]
Abstract
The mechanisms by which cells adapt to proteotoxic stress are largely unknown, but key to understanding how tumor cells, particularly in vivo, are largely resistant to proteasome inhibitors. Analysis of cancer cell lines, mouse xenografts and patient-derived tumor samples all showed an association between mitochondrial metabolism and proteasome inhibitor sensitivity. When cells were forced to use oxidative phosphorylation rather than glycolysis, they became proteasome inhibitor-resistant. This mitochondrial state, however, creates a unique vulnerability: sensitivity to the small-molecule compound elesclomol. Genome-wide CRISPR/Cas9 screening showed that a single gene, encoding the mitochondrial reductase FDX1, could rescue elesclomol-induced cell death. Enzymatic function and NMR-based analyses further showed that FDX1 is the direct target of elesclomol, which promotes a unique form of copper-dependent cell death. These studies elucidate a fundamental mechanism by which cells adapt to proteotoxic stress and suggests strategies to mitigate proteasome inhibitor-resistance.
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Affiliation(s)
| | - Alexandre Detappe
- Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA, USA
| | - Kai Cai
- Biochemistry Department, University of Wisconsin-Madison, Madison, WI, USA
| | - Heather R Keys
- Whitehead Institute for Biomedical Research, Cambridge, MA, USA
| | - Zarina Brune
- Whitehead Institute for Biomedical Research, Cambridge, MA, USA
| | - Weiwen Ying
- OnTarget Pharmaceutical Consulting LLC, Lexington, MA, USA
| | - Prathapan Thiru
- Whitehead Institute for Biomedical Research, Cambridge, MA, USA
| | - Mairead Reidy
- Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA, USA
| | | | - Jordan Rossen
- Broad Institute of Harvard and MIT, Cambridge, MA, USA
| | - Mustafa Kocak
- Broad Institute of Harvard and MIT, Cambridge, MA, USA
| | - Nora Kory
- Whitehead Institute for Biomedical Research, Cambridge, MA, USA
| | | | - Sandro Santagata
- Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA.,Ludwig Center at Harvard, Harvard Medical School, Boston, MA, USA
| | - Luke Whitesell
- Whitehead Institute for Biomedical Research, Cambridge, MA, USA.,Molecular Genetics Department, University of Toronto, Toronto, ON, Canada
| | - Irene M Ghobrial
- Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA, USA
| | - John L Markley
- Biochemistry Department, University of Wisconsin-Madison, Madison, WI, USA
| | - Susan Lindquist
- Whitehead Institute for Biomedical Research, Cambridge, MA, USA.,Howard Hughes Medical Institute, Chevy Chase, MD, USA
| | - Todd R Golub
- Broad Institute of Harvard and MIT, Cambridge, MA, USA. .,Howard Hughes Medical Institute, Chevy Chase, MD, USA. .,Harvard Medical School, Boston, MA, USA. .,Department of Pediatric Oncology, Dana-Farber Cancer Institute, Boston, MA, USA.
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67
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Ciofi-Baffoni S, Nasta V, Banci L. Protein networks in the maturation of human iron-sulfur proteins. Metallomics 2019; 10:49-72. [PMID: 29219157 DOI: 10.1039/c7mt00269f] [Citation(s) in RCA: 67] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The biogenesis of iron-sulfur (Fe-S) proteins in humans is a multistage process occurring in different cellular compartments. The mitochondrial iron-sulfur cluster (ISC) assembly machinery composed of at least 17 proteins assembles mitochondrial Fe-S proteins. A cytosolic iron-sulfur assembly (CIA) machinery composed of at least 13 proteins has been more recently identified and shown to be responsible for the Fe-S cluster incorporation into cytosolic and nuclear Fe-S proteins. Cytosolic and nuclear Fe-S protein maturation requires not only the CIA machinery, but also the components of the mitochondrial ISC assembly machinery. An ISC export machinery, composed of a protein transporter located in the mitochondrial inner membrane, has been proposed to act in mediating the export process of a still unknown component that is required for the CIA machinery. Several functional and molecular aspects of the protein networks operative in the three machineries are still largely obscure. This Review focuses on the Fe-S protein maturation processes in humans with the specific aim of providing a molecular picture of the currently known protein-protein interaction networks. The human ISC and CIA machineries are presented, and the ISC export machinery is discussed with respect to possible molecules being the substrates of the mitochondrial protein transporter.
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Affiliation(s)
- Simone Ciofi-Baffoni
- Magnetic Resonance Center-CERM, University of Florence, Via Luigi Sacconi 6, 50019, Sesto Fiorentino, Florence, Italy.
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68
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Slone J, Peng Y, Chamberlin A, Harris B, Kaylor J, McDonald MT, Lemmon M, El-Dairi MA, Tchapyjnikov D, Gonzalez-Krellwitz LA, Sellars EA, McConkie-Rosell A, Reinholdt LG, Huang T. Biallelic mutations in FDXR cause neurodegeneration associated with inflammation. J Hum Genet 2018; 63:1211-1222. [PMID: 30250212 DOI: 10.1038/s10038-018-0515-y] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Revised: 08/24/2018] [Accepted: 08/26/2018] [Indexed: 01/09/2023]
Abstract
Mitochondrial dysfunction lies behind many neurodegenerative disorders, owing largely to the intense energy requirements of most neurons. Such mitochondrial dysfunction may work through a variety of mechanisms, from direct disruption of the electron transport chain to abnormal mitochondrial biogenesis. Recently, we have identified biallelic mutations in the mitochondrial flavoprotein "ferredoxin reductase" (FDXR) gene as a novel cause of mitochondriopathy, peripheral neuropathy, and optic atrophy. In this report, we expand upon those results by describing two new cases of disease-causing FDXR variants in patients with variable severity of phenotypes, including evidence of an inflammatory response in brain autopsy. To investigate the underlying pathogenesis, we examined neurodegeneration in a mouse model. We found that Fdxr mutant mouse brain tissues share pathological changes similar to those seen in patient autopsy material, including increased astrocytes. Furthermore, we show that these abnormalities are associated with increased levels of markers for both neurodegeneration and gliosis, with the latter implying inflammation as a major factor in the pathology of Fdxr mutations. These data provide further insight into the pathogenic mechanism of FDXR-mediated central neuropathy, and suggest an avenue for mechanistic studies that will ultimately inform treatment.
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Affiliation(s)
- Jesse Slone
- Division of Human Genetics, Children's Hospital Medical Center, Cincinnati, OH, USA, 45229
| | - Yanyan Peng
- Division of Human Genetics, Children's Hospital Medical Center, Cincinnati, OH, USA, 45229
| | | | | | - Julie Kaylor
- University of Arkansas for Medical Sciences, Section of Genetics and Metabolism, 1 Children's Way, Little Rock, AR, USA, 72202
| | - Marie T McDonald
- Department of Pediatrics, Duke University School of Medicine, Durham, NC, USA, 27710
| | - Monica Lemmon
- Department of Pediatrics, Duke University School of Medicine, Durham, NC, USA, 27710
| | | | - Dmitry Tchapyjnikov
- Department of Pediatrics, Duke University School of Medicine, Durham, NC, USA, 27710
| | | | - Elizabeth A Sellars
- University of Arkansas for Medical Sciences, Section of Genetics and Metabolism, 1 Children's Way, Little Rock, AR, USA, 72202
| | - Allyn McConkie-Rosell
- Department of Pediatrics, Duke University School of Medicine, Durham, NC, USA, 27710
| | | | - Taosheng Huang
- Division of Human Genetics, Children's Hospital Medical Center, Cincinnati, OH, USA, 45229. .,Human Aging Research Institute, Nanchang University, Nanchang, China.
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69
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Zhang J, Chen X. p53 tumor suppressor and iron homeostasis. FEBS J 2018; 286:620-629. [PMID: 30133149 DOI: 10.1111/febs.14638] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Revised: 07/16/2018] [Accepted: 08/20/2018] [Indexed: 12/20/2022]
Abstract
Iron is an essential nutrient for all living organisms and plays a vital role in many fundamental biochemical processes, such as oxygen transport, energy metabolism, and DNA synthesis. Due to its capability to produce free radicals, iron has deleterious effects and thus, its level needs to be tightly controlled in the body. Deregulation of iron metabolism is known to cause diseases, including anemia by iron deficiency and hereditary hemochromatosis by iron overload. Interestingly, dysregulated iron metabolism occurs frequently in tumor cells and contributes to tumorigenesis. In this review, we will discuss the role of p53 tumor suppressor in iron homeostasis.
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Affiliation(s)
- Jin Zhang
- Comparative Oncology Laboratory, School of Veterinary Medicine and Medicine, University of California at Davis, CA, USA
| | - Xinbin Chen
- Comparative Oncology Laboratory, School of Veterinary Medicine and Medicine, University of California at Davis, CA, USA
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70
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Miller WL. MECHANISMS IN ENDOCRINOLOGY: Rare defects in adrenal steroidogenesis. Eur J Endocrinol 2018; 179:R125-R141. [PMID: 29880708 DOI: 10.1530/eje-18-0279] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Accepted: 06/06/2018] [Indexed: 12/12/2022]
Abstract
Congenital adrenal hyperplasia (CAH) is a group of genetic disorders of adrenal steroidogenesis that impair cortisol synthesis, with compensatory increases in ACTH leading to hyperplastic adrenals. The term 'CAH' is generally used to mean 'steroid 21-hydroxylase deficiency' (21OHD) as 21OHD accounts for about 95% of CAH in most populations; the incidences of the rare forms of CAH vary with ethnicity and geography. These forms of CAH are easily understood on the basis of the biochemistry of steroidogenesis. Defects in the steroidogenic acute regulatory protein, StAR, disrupt all steroidogenesis and are the second-most common form of CAH in Japan and Korea; very rare defects in the cholesterol side-chain cleavage enzyme, P450scc, are clinically indistinguishable from StAR defects. Defects in 3β-hydroxysteroid dehydrogenase, which also causes disordered sexual development, were once thought to be fairly common, but genetic analyses show that steroid measurements are generally unreliable for this disorder. Defects in 17-hydroxylase/17,20-lyase ablate synthesis of sex steroids and also cause mineralocorticoid hypertension; these are common in Brazil and in China. Isolated 17,20-lyase deficiency can be caused by rare mutations in at least three different proteins. P450 oxidoreductase (POR) is a co-factor used by 21-hydroxylase, 17-hydroxylase/17,20-lyase and aromatase; various POR defects, found in different populations, affect these enzymes differently. 11-Hydroxylase deficiency is the second-most common form of CAH in European populations but the retention of aldosterone synthesis distinguishes it from 21OHD. Aldosterone synthase deficiency is a rare salt-losing disorder. Mild, 'non-classic' defects in all of these factors have been described. Both the severe and non-classic disorders can be treated if recognized.
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Affiliation(s)
- Walter L Miller
- Department of Pediatrics, Center for Reproductive Sciences, and Institute of Human Genetics, University of California, San Francisco, California, USA
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71
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NMR as a Tool to Investigate the Processes of Mitochondrial and Cytosolic Iron-Sulfur Cluster Biosynthesis. Molecules 2018; 23:molecules23092213. [PMID: 30200358 PMCID: PMC6205161 DOI: 10.3390/molecules23092213] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Revised: 08/03/2018] [Accepted: 08/20/2018] [Indexed: 12/15/2022] Open
Abstract
Iron-sulfur (Fe-S) clusters, the ubiquitous protein cofactors found in all kingdoms of life, perform a myriad of functions including nitrogen fixation, ribosome assembly, DNA repair, mitochondrial respiration, and metabolite catabolism. The biogenesis of Fe-S clusters is a multi-step process that involves the participation of many protein partners. Recent biophysical studies, involving X-ray crystallography, nuclear magnetic resonance (NMR) spectroscopy, mass spectrometry (MS), and small angle X-ray scattering (SAXS), have greatly improved our understanding of these steps. In this review, after describing the biological importance of iron sulfur proteins, we focus on the contributions of NMR spectroscopy has made to our understanding of the structures, dynamics, and interactions of proteins involved in the biosynthesis of Fe-S cluster proteins.
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72
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Peng Y, Shinde DN, Valencia CA, Mo JS, Rosenfeld J, Truitt Cho M, Chamberlin A, Li Z, Liu J, Gui B, Brockhage R, Basinger A, Alvarez-Leon B, Heydemann P, Magoulas PL, Lewis AM, Scaglia F, Gril S, Chong SC, Bower M, Monaghan KG, Willaert R, Plona MR, Dineen R, Milan F, Hoganson G, Powis Z, Helbig KL, Keller-Ramey J, Harris B, Anderson LC, Green T, Sukoff Rizzo SJ, Kaylor J, Chen J, Guan MX, Sellars E, Sparagana SP, Gibson JB, Reinholdt LG, Tang S, Huang T. Biallelic mutations in the ferredoxin reductase gene cause novel mitochondriopathy with optic atrophy. Hum Mol Genet 2018; 26:4937-4950. [PMID: 29040572 PMCID: PMC5886230 DOI: 10.1093/hmg/ddx377] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2017] [Accepted: 10/02/2017] [Indexed: 11/13/2022] Open
Abstract
Iron-sulfur (Fe-S) clusters are ubiquitous cofactors essential to various cellular processes, including mitochondrial respiration, DNA repair, and iron homeostasis. A steadily increasing number of disorders are being associated with disrupted biogenesis of Fe-S clusters. Here, we conducted whole-exome sequencing of patients with optic atrophy and other neurological signs of mitochondriopathy and identified 17 individuals from 13 unrelated families with recessive mutations in FDXR, encoding the mitochondrial membrane-associated flavoprotein ferrodoxin reductase required for electron transport from NADPH to cytochrome P450. In vitro enzymatic assays in patient fibroblast cells showed deficient ferredoxin NADP reductase activity and mitochondrial dysfunction evidenced by low oxygen consumption rates (OCRs), complex activities, ATP production and increased reactive oxygen species (ROS). Such defects were rescued by overexpression of wild-type FDXR. Moreover, we found that mice carrying a spontaneous mutation allelic to the most common mutation found in patients displayed progressive gait abnormalities and vision loss, in addition to biochemical defects consistent with the major clinical features of the disease. Taken together, these data provide the first demonstration that germline, hypomorphic mutations in FDXR cause a novel mitochondriopathy and optic atrophy in humans.
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Affiliation(s)
- Yanyan Peng
- Division of Human Genetics, Cincinnati Children's Hospital, Cincinnati, OH 45229, USA
| | | | - C Alexander Valencia
- Division of Human Genetics, Cincinnati Children's Hospital, Cincinnati, OH 45229, USA
| | - Jun-Song Mo
- Division of Human Genetics, Cincinnati Children's Hospital, Cincinnati, OH 45229, USA
| | - Jill Rosenfeld
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | | | - Adam Chamberlin
- Clinical Genomics, Ambry Genetics, Aliso Viejo, CA 92656, USA
| | - Zhuo Li
- Division of Human Genetics, Cincinnati Children's Hospital, Cincinnati, OH 45229, USA
| | - Jie Liu
- Division of Human Genetics, Cincinnati Children's Hospital, Cincinnati, OH 45229, USA
| | - Baoheng Gui
- Division of Human Genetics, Cincinnati Children's Hospital, Cincinnati, OH 45229, USA
| | - Rachel Brockhage
- Division of Human Genetics, Cincinnati Children's Hospital, Cincinnati, OH 45229, USA
| | - Alice Basinger
- Department of Metabolic Genetics, Cook Children's Physician Network, Fort Worth, TX 76104, USA
| | - Brenda Alvarez-Leon
- Department of Metabolic Genetics, Cook Children's Physician Network, Fort Worth, TX 76104, USA
| | - Peter Heydemann
- Section of Pediatric Neurology, Rush University Medical Center, Chicago, IL 60612, USA
| | - Pilar L Magoulas
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Andrea M Lewis
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Fernando Scaglia
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Solange Gril
- Neuropediatric Department, Raul Carrea Institute for Neurological Research -FLENI, Montañeses 2325 (C1428AQK), Argentina
| | - Shuk Ching Chong
- Center of Inborn Errors of Metabolism, Department of Paediatrics, The Chinese University of Hong Kong, Hong Kong, China
| | - Matthew Bower
- Fairview Molecular Diagnostics Laboratory Neurology Clinic, University of Minnesota Medical Center, Minneapolis, MN 55454, USA
| | | | | | - Maria-Renee Plona
- Pediatric Genetics, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Rich Dineen
- Pediatric Genetics, University of Illinois at Chicago, Chicago, IL 60607, USA
| | | | - George Hoganson
- Pediatric Genetics, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Zoe Powis
- Clinical Genomics, Ambry Genetics, Aliso Viejo, CA 92656, USA
| | | | | | | | | | | | | | - Julie Kaylor
- Arkansas Children's Hospital, Little Rock, AR 72202, USA
| | - Jiani Chen
- University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Min-Xin Guan
- Institute of Genetics, Zhejiang University, Hangzhou, China
| | | | - Steven P Sparagana
- Pediatric Neurology, Texas Scottish Rite Hospital for Children, Dallas, TX 75219, USA
| | | | | | - Sha Tang
- Clinical Genomics, Ambry Genetics, Aliso Viejo, CA 92656, USA
| | - Taosheng Huang
- Division of Human Genetics, Cincinnati Children's Hospital, Cincinnati, OH 45229, USA
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73
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Cai K, Frederick RO, Tonelli M, Markley JL. Interactions of iron-bound frataxin with ISCU and ferredoxin on the cysteine desulfurase complex leading to Fe-S cluster assembly. J Inorg Biochem 2018; 183:107-116. [PMID: 29576242 PMCID: PMC5951399 DOI: 10.1016/j.jinorgbio.2018.03.007] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2017] [Revised: 03/08/2018] [Accepted: 03/12/2018] [Indexed: 12/15/2022]
Abstract
Frataxin (FXN) is involved in mitochondrial iron‑sulfur (Fe-S) cluster biogenesis and serves to accelerate Fe-S cluster formation. FXN deficiency is associated with Friedreich ataxia, a neurodegenerative disease. We have used a combination of isothermal titration calorimetry and multinuclear NMR spectroscopy to investigate interactions among the components of the biological machine that carries out the assembly of iron‑sulfur clusters in human mitochondria. Our results show that FXN tightly binds a single Fe2+ but not Fe3+. While FXN (with or without bound Fe2+) does not bind the scaffold protein ISCU directly, the two proteins interact mutually when each is bound to the cysteine desulfurase complex ([NFS1]2:[ISD11]2:[Acp]2), abbreviated as (NIA)2, where "N" represents the cysteine desulfurase (NFS1), "I" represents the accessory protein (ISD11), and "A" represents acyl carrier protein (Acp). FXN binds (NIA)2 weakly in the absence of ISCU but more strongly in its presence. Fe2+-FXN binds to the (NIA)2-ISCU2 complex without release of iron. However, upon the addition of both l-cysteine and a reductant (either reduced FDX2 or DTT), Fe2+ is released from FXN as consistent with Fe2+-FXN being the proximal source of iron for Fe-S cluster assembly.
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Affiliation(s)
- Kai Cai
- National Magnetic Resonance Facility at Madison and Biochemistry Department, University of Wisconsin-Madison, 433 Babcock Drive, Madison, WI 53706, United States
| | - Ronnie O Frederick
- National Magnetic Resonance Facility at Madison and Biochemistry Department, University of Wisconsin-Madison, 433 Babcock Drive, Madison, WI 53706, United States
| | - Marco Tonelli
- National Magnetic Resonance Facility at Madison and Biochemistry Department, University of Wisconsin-Madison, 433 Babcock Drive, Madison, WI 53706, United States
| | - John L Markley
- National Magnetic Resonance Facility at Madison and Biochemistry Department, University of Wisconsin-Madison, 433 Babcock Drive, Madison, WI 53706, United States.
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74
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Banci L, Camponeschi F, Ciofi-Baffoni S, Piccioli M. The NMR contribution to protein-protein networking in Fe-S protein maturation. J Biol Inorg Chem 2018; 23:665-685. [PMID: 29569085 PMCID: PMC6006191 DOI: 10.1007/s00775-018-1552-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Accepted: 03/12/2018] [Indexed: 12/12/2022]
Abstract
Iron–sulfur proteins were among the first class of metalloproteins that were actively studied using NMR spectroscopy tailored to paramagnetic systems. The hyperfine shifts, their temperature dependencies and the relaxation rates of nuclei of cluster-bound residues are an efficient fingerprint of the nature and the oxidation state of the Fe–S cluster. NMR significantly contributed to the analysis of the magnetic coupling patterns and to the understanding of the electronic structure occurring in [2Fe–2S], [3Fe–4S] and [4Fe–4S] clusters bound to proteins. After the first NMR structure of a paramagnetic protein was obtained for the reduced E. halophila HiPIP I, many NMR structures were determined for several Fe–S proteins in different oxidation states. It was found that differences in chemical shifts, in patterns of unobserved residues, in internal mobility and in thermodynamic stability are suitable data to map subtle changes between the two different oxidation states of the protein. Recently, the interaction networks responsible for maturing human mitochondrial and cytosolic Fe–S proteins have been largely characterized by combining solution NMR standard experiments with those tailored to paramagnetic systems. We show here the contribution of solution NMR in providing a detailed molecular view of “Fe–S interactomics”. This contribution was particularly effective when protein–protein interactions are weak and transient, and thus difficult to be characterized at high resolution with other methodologies.
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Affiliation(s)
- Lucia Banci
- Magnetic Resonance Center CERM, University of Florence, Via Luigi Sacconi 6, Sesto Fiorentino, 50019, Florence, Italy. .,Department of Chemistry, University of Florence, Via della Lastruccia 3, Sesto Fiorentino, 50019, Florence, Italy.
| | - Francesca Camponeschi
- Magnetic Resonance Center CERM, University of Florence, Via Luigi Sacconi 6, Sesto Fiorentino, 50019, Florence, Italy.,Department of Chemistry, University of Florence, Via della Lastruccia 3, Sesto Fiorentino, 50019, Florence, Italy
| | - Simone Ciofi-Baffoni
- Magnetic Resonance Center CERM, University of Florence, Via Luigi Sacconi 6, Sesto Fiorentino, 50019, Florence, Italy.,Department of Chemistry, University of Florence, Via della Lastruccia 3, Sesto Fiorentino, 50019, Florence, Italy
| | - Mario Piccioli
- Magnetic Resonance Center CERM, University of Florence, Via Luigi Sacconi 6, Sesto Fiorentino, 50019, Florence, Italy. .,Department of Chemistry, University of Florence, Via della Lastruccia 3, Sesto Fiorentino, 50019, Florence, Italy.
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75
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Cardenas-Rodriguez M, Chatzi A, Tokatlidis K. Iron-sulfur clusters: from metals through mitochondria biogenesis to disease. J Biol Inorg Chem 2018; 23:509-520. [PMID: 29511832 PMCID: PMC6006200 DOI: 10.1007/s00775-018-1548-6] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2017] [Accepted: 02/22/2018] [Indexed: 01/12/2023]
Abstract
Iron–sulfur clusters are ubiquitous inorganic co-factors that contribute to a wide range of cell pathways including the maintenance of DNA integrity, regulation of gene expression and protein translation, energy production, and antiviral response. Specifically, the iron–sulfur cluster biogenesis pathways include several proteins dedicated to the maturation of apoproteins in different cell compartments. Given the complexity of the biogenesis process itself, the iron–sulfur research area constitutes a very challenging and interesting field with still many unaddressed questions. Mutations or malfunctions affecting the iron–sulfur biogenesis machinery have been linked with an increasing amount of disorders such as Friedreich’s ataxia and various cardiomyopathies. This review aims to recap the recent discoveries both in the yeast and human iron–sulfur cluster arena, covering recent discoveries from chemistry to disease.
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Affiliation(s)
- Mauricio Cardenas-Rodriguez
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Afroditi Chatzi
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Kostas Tokatlidis
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 8QQ, UK.
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76
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Cai K, Frederick RO, Tonelli M, Markley JL. ISCU(M108I) and ISCU(D39V) Differ from Wild-Type ISCU in Their Failure To Form Cysteine Desulfurase Complexes Containing Both Frataxin and Ferredoxin. Biochemistry 2018; 57:1491-1500. [PMID: 29406711 PMCID: PMC5842376 DOI: 10.1021/acs.biochem.7b01234] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Revised: 02/06/2018] [Indexed: 01/09/2023]
Abstract
Whereas iron-sulfur (Fe-S) cluster assembly on the wild-type scaffold protein ISCU, as catalyzed by the human cysteine desulfurase complex (NIA)2, exhibits a requirement for frataxin (FXN), in yeast, ISCU variant M108I has been shown to bypass the FXN requirement. Wild-type ISCU populates two interconverting conformational states: one structured and one dynamically disordered. We show here that variants ISCU(M108I) and ISCU(D39V) of human ISCU populate only the structured state. We have compared the properties of ISCU, ISCU(M108I), and ISCU(D39V), with and without FXN, in both the cysteine desulfurase step of Fe-S cluster assembly and the overall Fe-S cluster assembly reaction catalyzed by (NIA)2. In the cysteine desulfurase step with dithiothreitol (DTT) as the reductant, FXN was found to stimulate cysteine desulfurase activity with both the wild-type and structured variants, although the effect was less prominent with ISCU(D39V) than with the wild-type or ISCU(M108I). In overall Fe-S cluster assembly, frataxin was found to stimulate cluster assembly with both the wild-type and structured variants when the reductant was DTT; however, with the physiological reductant, reduced ferredoxin 2 (rdFDX2), FXN stimulated the reaction with wild-type ISCU but not with either ISCU(M108I) or ISCU(D39V). Nuclear magnetic resonance titration experiments revealed that wild-type ISCU, FXN, and rdFDX2 all bind to (NIA)2. However, when ISCU was replaced by the fully structured variant ISCU(M108I), the addition of rdFDX2 to the [NIA-ISCU(M108I)-FXN]2 complex led to the release of FXN. Thus, the displacement of FXN by rdFDX2 explains the failure of FXN to stimulate Fe-S cluster assembly on ISCU(M108I).
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Affiliation(s)
- Kai Cai
- National Magnetic Resonance
Facility at Madison and Department of Biochemistry, University of Wisconsin—Madison, 433 Babcock Drive, Madison, Wisconsin 53706, United States
| | - Ronnie O. Frederick
- National Magnetic Resonance
Facility at Madison and Department of Biochemistry, University of Wisconsin—Madison, 433 Babcock Drive, Madison, Wisconsin 53706, United States
| | - Marco Tonelli
- National Magnetic Resonance
Facility at Madison and Department of Biochemistry, University of Wisconsin—Madison, 433 Babcock Drive, Madison, Wisconsin 53706, United States
| | - John L. Markley
- National Magnetic Resonance
Facility at Madison and Department of Biochemistry, University of Wisconsin—Madison, 433 Babcock Drive, Madison, Wisconsin 53706, United States
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77
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Wachnowsky C, Fidai I, Cowan JA. Iron-sulfur cluster biosynthesis and trafficking - impact on human disease conditions. Metallomics 2018; 10:9-29. [PMID: 29019354 PMCID: PMC5783746 DOI: 10.1039/c7mt00180k] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Iron-sulfur clusters (Fe-S) are one of the most ancient, ubiquitous and versatile classes of metal cofactors found in nature. Proteins that contain Fe-S clusters constitute one of the largest families of proteins, with varied functions that include electron transport, regulation of gene expression, substrate binding and activation, radical generation, and, more recently discovered, DNA repair. Research during the past two decades has shown that mitochondria are central to the biogenesis of Fe-S clusters in eukaryotic cells via a conserved cluster assembly machinery (ISC assembly machinery) that also controls the synthesis of Fe-S clusters of cytosolic and nuclear proteins. Several key steps for synthesis and trafficking have been determined for mitochondrial Fe-S clusters, as well as the cytosol (CIA - cytosolic iron-sulfur protein assembly), but detailed mechanisms of cluster biosynthesis, transport, and exchange are not well established. Genetic mutations and the instability of certain steps in the biosynthesis and maturation of mitochondrial, cytosolic and nuclear Fe-S cluster proteins affects overall cellular iron homeostasis and can lead to severe metabolic, systemic, neurological and hematological diseases, often resulting in fatality. In this review we briefly summarize the current molecular understanding of both mitochondrial ISC and CIA assembly machineries, and present a comprehensive overview of various associated inborn human disease states.
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Affiliation(s)
- C Wachnowsky
- Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, USA.
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78
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Freibert SA, Weiler BD, Bill E, Pierik AJ, Mühlenhoff U, Lill R. Biochemical Reconstitution and Spectroscopic Analysis of Iron-Sulfur Proteins. Methods Enzymol 2018; 599:197-226. [PMID: 29746240 DOI: 10.1016/bs.mie.2017.11.034] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
Iron-sulfur (Fe/S) proteins are involved in numerous key biological functions such as respiration, metabolic processes, protein translation, DNA synthesis, and DNA repair. The simplest types of Fe/S clusters include [2Fe-2S], [3Fe-4S], and [4Fe-4S] forms that sometimes are present in multiple copies. De novo assembly of Fe/S cofactors and their insertion into apoproteins in living cells requires complex proteinaceous machineries that are frequently highly conserved. In eukaryotes such as yeast and mammals, the mitochondrial iron-sulfur cluster assembly machinery and the cytosolic iron-sulfur protein assembly system consist of more than 30 components that cooperate in the generation of some 50 cellular Fe/S proteins. Both the mechanistic dissection of the intracellular Fe/S protein assembly pathways and the identification and characterization of Fe/S proteins rely on tool boxes of in vitro and in vivo methods. These cell biological, biochemical, and biophysical techniques help to determine the extent, stability, and type of bound Fe/S cluster. They also serve to distinguish bona fide Fe/S proteins from other metal-binding proteins containing similar cofactor coordination motifs. Here, we present a collection of in vitro methods that have proven useful for basic biochemical and biophysical characterization of Fe/S proteins. First, we describe the chemical assembly of [2Fe-2S] or [4Fe-4S] clusters on purified apoproteins. Then, we summarize a reconstitution system reproducing the de novo synthesis of a [2Fe-2S] cluster in mitochondria. Finally, we explain the use of UV-vis, CD, electron paramagnetic resonance, and Mössbauer spectroscopy for the routine characterization of Fe/S proteins.
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Affiliation(s)
| | | | - Eckhard Bill
- Max-Planck-Institut für Chemische Energiekonversion, Mülheim an der Ruhr, Germany
| | - Antonio J Pierik
- Chemistry and Biochemistry, Technical University of Kaiserlautern, Kaiserlautern, Germany
| | | | - Roland Lill
- Institut für Zytobiologie, Philipps-Universität, Marburg, Germany; LOEWE Zentrum für Synthetische Mikrobiologie SynMikro, Marburg, Germany.
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79
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Stehling O, Paul VD, Bergmann J, Basu S, Lill R. Biochemical Analyses of Human Iron–Sulfur Protein Biogenesis and of Related Diseases. Methods Enzymol 2018; 599:227-263. [DOI: 10.1016/bs.mie.2017.11.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
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80
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Structure of the human monomeric NEET protein MiNT and its role in regulating iron and reactive oxygen species in cancer cells. Proc Natl Acad Sci U S A 2017; 115:272-277. [PMID: 29259115 DOI: 10.1073/pnas.1715842115] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The NEET family is a relatively new class of three related [2Fe-2S] proteins (CISD1-3), important in human health and disease. While there has been growing interest in the homodimeric gene products of CISD1 (mitoNEET) and CISD2 (NAF-1), the importance of the inner mitochondrial CISD3 protein has only recently been recognized in cancer. The CISD3 gene encodes for a monomeric protein that contains two [2Fe-2S] CDGSH motifs, which we term mitochondrial inner NEET protein (MiNT). It folds with a pseudosymmetrical fold that provides a hydrophobic motif on one side and a relatively hydrophilic surface on the diametrically opposed surface. Interestingly, as shown by molecular dynamics simulation, the protein displays distinct asymmetrical backbone motions, unlike its homodimeric counterparts that face the cytosolic side of the outer mitochondrial membrane/endoplasmic reticulum (ER). However, like its counterparts, our biological studies indicate that knockdown of MiNT leads to increased accumulation of mitochondrial labile iron, as well as increased mitochondrial reactive oxygen production. Taken together, our study suggests that the MiNT protein functions in the same pathway as its homodimeric counterparts (mitoNEET and NAF-1), and could be a key player in this pathway within the mitochondria. As such, it represents a target for anticancer or antidiabetic drug development.
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81
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Legati A, Reyes A, Ceccatelli Berti C, Stehling O, Marchet S, Lamperti C, Ferrari A, Robinson AJ, Mühlenhoff U, Lill R, Zeviani M, Goffrini P, Ghezzi D. A novel de novo dominant mutation in ISCU associated with mitochondrial myopathy. J Med Genet 2017; 54:815-824. [PMID: 29079705 PMCID: PMC5740555 DOI: 10.1136/jmedgenet-2017-104822] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Revised: 08/16/2017] [Accepted: 08/22/2017] [Indexed: 02/02/2023]
Abstract
BACKGROUND Hereditary myopathy with lactic acidosis and myopathy with deficiency of succinate dehydrogenase and aconitase are variants of a recessive disorder characterised by childhood-onset early fatigue, dyspnoea and palpitations on trivial exercise. The disease is non-progressive, but life-threatening episodes of widespread weakness, metabolic acidosis and rhabdomyolysis may occur. So far, this disease has been molecularly defined only in Swedish patients, all homozygous for a deep intronic splicing affecting mutation in ISCU encoding a scaffold protein for the assembly of iron-sulfur (Fe-S) clusters. A single Scandinavian family was identified with a different mutation, a missense change in compound heterozygosity with the common intronic mutation. The aim of the study was to identify the genetic defect in our proband. METHODS A next-generation sequencing (NGS) approach was carried out on an Italian male who presented in childhood with ptosis, severe muscle weakness and exercise intolerance. His disease was slowly progressive, with partial recovery between episodes. Patient's specimens and yeast models were investigated. RESULTS Histochemical and biochemical analyses on muscle biopsy showed multiple defects affecting mitochondrial respiratory chain complexes. We identified a single heterozygous mutation p.Gly96Val in ISCU, which was absent in DNA from his parents indicating a possible de novo dominant effect in the patient. Patient fibroblasts showed normal levels of ISCU protein and a few variably affected Fe-S cluster-dependent enzymes. Yeast studies confirmed both pathogenicity and dominance of the identified missense mutation. CONCLUSION We describe the first heterozygous dominant mutation in ISCU which results in a phenotype reminiscent of the recessive disease previously reported.
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Affiliation(s)
- Andrea Legati
- Molecular Neurogenetics Unit, Foundation IRCCS Neurological Institute Besta, Milan, Italy
| | - Aurelio Reyes
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge, UK
| | - Camilla Ceccatelli Berti
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, Parma, Italy
| | - Oliver Stehling
- Department of Medicine, Institut für Zytobiologie und Zytopathologie, Philipps-Universität, Marburg, Germany
| | - Silvia Marchet
- Molecular Neurogenetics Unit, Foundation IRCCS Neurological Institute Besta, Milan, Italy
| | - Costanza Lamperti
- Molecular Neurogenetics Unit, Foundation IRCCS Neurological Institute Besta, Milan, Italy
| | - Alberto Ferrari
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, Parma, Italy
| | - Alan J Robinson
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge, UK
| | - Ulrich Mühlenhoff
- Department of Medicine, Institut für Zytobiologie und Zytopathologie, Philipps-Universität, Marburg, Germany
| | - Roland Lill
- Department of Medicine, Institut für Zytobiologie und Zytopathologie, Philipps-Universität, Marburg, Germany,Unit of Metabolism, LOEWE Zentrum für Synthetische Mikrobiologie SynMikro, Marburg, Germany
| | - Massimo Zeviani
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge, UK
| | - Paola Goffrini
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, Parma, Italy
| | - Daniele Ghezzi
- Molecular Neurogenetics Unit, Foundation IRCCS Neurological Institute Besta, Milan, Italy
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82
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Dutkiewicz R, Nowak M. Molecular chaperones involved in mitochondrial iron-sulfur protein biogenesis. J Biol Inorg Chem 2017; 23:569-579. [PMID: 29124426 PMCID: PMC6006194 DOI: 10.1007/s00775-017-1504-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Accepted: 10/28/2017] [Indexed: 12/16/2022]
Abstract
Iron-sulfur (FeS) clusters are prosthetic groups critical for the function of many proteins in all domains of life. FeS proteins function in processes ranging from oxidative phosphorylation and cofactor biosyntheses to DNA/RNA metabolism and regulation of gene expression. In eukaryotic cells, mitochondria play a central role in the process of FeS biogenesis and support maturation of FeS proteins localized within mitochondria and in other cellular compartments. In humans, defects in mitochondrial FeS cluster biogenesis lead to numerous pathologies, which are often fatal. The generation of FeS clusters in mitochondria is a complex process. The [2Fe-2S] cluster is first assembled on a dedicated scaffold protein (Isu1) by the action of protein factors that interact with Isu1 to form the "assembly complex". Next, the FeS cluster is transferred onto a recipient apo-protein. Genetic and biochemical evidence implicates participation of a specialized J-protein co-chaperone Jac1 and its mitochondrial (mt)Hsp70 chaperone partner, and the glutaredoxin Grx5 in the FeS cluster transfer process. Finally, various specialized ISC components assist in the generation of [4Fe-4S] clusters and cluster insertion into specific target apoproteins. Although a framework of protein components that are involved in the mitochondrial FeS cluster biogenesis has been established based on genetic and biochemical studies, detailed molecular mechanisms involved in this important and medically relevant process are not well understood. This review summarizes our molecular knowledge on chaperone proteins' functions during the FeS protein biogenesis.
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Affiliation(s)
- Rafal Dutkiewicz
- Intercollegiate Faculty of Biotechnology, University of Gdansk and Medical University of Gdansk, Abrahama 58, 80-307, Gdańsk, Poland.
| | - Malgorzata Nowak
- Intercollegiate Faculty of Biotechnology, University of Gdansk and Medical University of Gdansk, Abrahama 58, 80-307, Gdańsk, Poland
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83
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Maio N, Rouault TA. Mammalian Fe-S proteins: definition of a consensus motif recognized by the co-chaperone HSC20. Metallomics 2017; 8:1032-1046. [PMID: 27714045 DOI: 10.1039/c6mt00167j] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Iron-sulfur (Fe-S) clusters are inorganic cofactors that are fundamental to several biological processes in all three kingdoms of life. In most organisms, Fe-S clusters are initially assembled on a scaffold protein, ISCU, and subsequently transferred to target proteins or to intermediate carriers by a dedicated chaperone/co-chaperone system. The delivery of assembled Fe-S clusters to recipient proteins is a crucial step in the biogenesis of Fe-S proteins, and, in mammals, it relies on the activity of a multiprotein transfer complex that contains the chaperone HSPA9, the co-chaperone HSC20 and the scaffold ISCU. How the transfer complex efficiently engages recipient Fe-S target proteins involves specific protein interactions that are not fully understood. This mini review focuses on recent insights into the molecular mechanism of amino acid motif recognition and discrimination by the co-chaperone HSC20, which guides Fe-S cluster delivery.
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Affiliation(s)
- N Maio
- Molecular Medicine Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, 9000 Rockville Pike, 20892 Bethesda, MD, USA.
| | - T A Rouault
- Molecular Medicine Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, 9000 Rockville Pike, 20892 Bethesda, MD, USA.
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84
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Fidai I, Wachnowsky C, Cowan JA. Mapping cellular Fe-S cluster uptake and exchange reactions - divergent pathways for iron-sulfur cluster delivery to human ferredoxins. Metallomics 2017; 8:1283-1293. [PMID: 27878189 DOI: 10.1039/c6mt00193a] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Ferredoxins are protein mediators of biological electron-transfer reactions and typically contain either [2Fe-2S] or [4Fe-4S] clusters. Two ferredoxin homologues have been identified in the human genome, Fdx1 and Fdx2, that share 43% identity and 69% similarity in protein sequence and both bind [2Fe-2S] clusters. Despite the high similarity, the two ferredoxins play very specific roles in distinct physiological pathways and cannot replace each other in function. Both eukaryotic and prokaryotic ferredoxins and homologues have been reported to receive their Fe-S cluster from scaffold/delivery proteins such as IscU, Isa, glutaredoxins, and Nfu. However, the preferred and physiologically relevant pathway for receiving the [2Fe-2S] cluster by ferredoxins is subject to speculation and is not clearly identified. In this work, we report on in vitro UV-visible (UV-vis) circular dichroism studies of [2Fe-2S] cluster transfer to the ferredoxins from a variety of partners. The results reveal rapid and quantitative transfer to both ferredoxins from several donor proteins (IscU, Isa1, Grx2, and Grx3). Transfer from Isa1 to Fdx2 was also observed to be faster than that of IscU to Fdx2, suggesting that Fdx2 could receive its cluster from Isa1 instead of IscU. Several other transfer combinations were also investigated and the results suggest a complex, but kinetically detailed map for cellular cluster trafficking. This is the first step toward building a network map for all of the possible iron-sulfur cluster transfer pathways in the mitochondria and cytosol, providing insights on the most likely cellular pathways and possible redundancies in these pathways.
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Affiliation(s)
- Insiya Fidai
- Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, USA. and The Biophysics Graduate Program, The Ohio State University, USA
| | - Christine Wachnowsky
- Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, USA. and The Ohio State Biochemistry Program, The Ohio State University, USA
| | - J A Cowan
- Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, USA. and The Biophysics Graduate Program, The Ohio State University, USA and The Ohio State Biochemistry Program, The Ohio State University, USA
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85
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FDXR Mutations Cause Sensorial Neuropathies and Expand the Spectrum of Mitochondrial Fe-S-Synthesis Diseases. Am J Hum Genet 2017; 101:630-637. [PMID: 28965846 DOI: 10.1016/j.ajhg.2017.09.007] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Accepted: 09/11/2017] [Indexed: 11/21/2022] Open
Abstract
Hearing loss and visual impairment in childhood have mostly genetic origins, some of them being related to sensorial neuronal defects. Here, we report on eight subjects from four independent families affected by auditory neuropathy and optic atrophy. Whole-exome sequencing revealed biallelic mutations in FDXR in affected subjects of each family. FDXR encodes the mitochondrial ferredoxin reductase, the sole human ferredoxin reductase implicated in the biosynthesis of iron-sulfur clusters (ISCs) and in heme formation. ISC proteins are involved in enzymatic catalysis, gene expression, and DNA replication and repair. We observed deregulated iron homeostasis in FDXR mutant fibroblasts and indirect evidence of mitochondrial iron overload. Functional complementation in a yeast strain in which ARH1, the human FDXR ortholog, was deleted established the pathogenicity of these mutations. These data highlight the wide clinical heterogeneity of mitochondrial disorders related to ISC synthesis.
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86
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Vallières C, Holland SL, Avery SV. Mitochondrial Ferredoxin Determines Vulnerability of Cells to Copper Excess. Cell Chem Biol 2017; 24:1228-1237.e3. [PMID: 28867595 PMCID: PMC5654725 DOI: 10.1016/j.chembiol.2017.08.005] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Revised: 03/02/2017] [Accepted: 08/01/2017] [Indexed: 01/17/2023]
Abstract
The essential micronutrient copper is tightly regulated in organisms, as environmental exposure or homeostasis defects can cause toxicity and neurodegenerative disease. The principal target(s) of copper toxicity have not been pinpointed, but one key effect is impaired supply of iron-sulfur (FeS) clusters to the essential protein Rli1 (ABCE1). Here, to find upstream FeS biosynthesis/delivery protein(s) responsible for this, we compared copper sensitivity of yeast-overexpressing candidate targets. Overexpression of the mitochondrial ferredoxin Yah1 produced copper hyper-resistance. 55Fe turnover assays revealed that FeS integrity of Yah1 was particularly vulnerable to copper among the test proteins. Furthermore, destabilization of the FeS domain of Yah1 produced copper hypersensitivity, and YAH1 overexpression rescued Rli1 dysfunction. This copper-resistance function was conserved in the human ferredoxin, Fdx2. The data indicate that the essential mitochondrial ferredoxin is an important copper target, determining a tipping point where plentiful copper supply becomes excessive. This knowledge could help in tackling copper-related diseases.
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Affiliation(s)
- Cindy Vallières
- School of Life Sciences, University of Nottingham, University Park, Nottingham NG7 2RD, UK
| | - Sara L Holland
- School of Life Sciences, University of Nottingham, University Park, Nottingham NG7 2RD, UK
| | - Simon V Avery
- School of Life Sciences, University of Nottingham, University Park, Nottingham NG7 2RD, UK.
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87
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88
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Rouault TA, Maio N. Biogenesis and functions of mammalian iron-sulfur proteins in the regulation of iron homeostasis and pivotal metabolic pathways. J Biol Chem 2017; 292:12744-12753. [PMID: 28615439 PMCID: PMC5546015 DOI: 10.1074/jbc.r117.789537] [Citation(s) in RCA: 114] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Fe-S cofactors are composed of iron and inorganic sulfur in various stoichiometries. A complex assembly pathway conducts their initial synthesis and subsequent binding to recipient proteins. In this minireview, we discuss how discovery of the role of the mammalian cytosolic aconitase, known as iron regulatory protein 1 (IRP1), led to the characterization of the function of its Fe-S cluster in sensing and regulating cellular iron homeostasis. Moreover, we present an overview of recent studies that have provided insights into the mechanism of Fe-S cluster transfer to recipient Fe-S proteins.
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Affiliation(s)
- Tracey A Rouault
- Molecular Medicine Branch, Eunice Kennedy Shriver NICHD, National Institutes of Health, Bethesda, Maryland 20892.
| | - Nunziata Maio
- Molecular Medicine Branch, Eunice Kennedy Shriver NICHD, National Institutes of Health, Bethesda, Maryland 20892
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89
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Abstract
The biogenesis of iron-sulfur (Fe/S) proteins in eukaryotes is a multistage, multicompartment process that is essential for a broad range of cellular functions, including genome maintenance, protein translation, energy conversion, and the antiviral response. Genetic and cell biological studies over almost 2 decades have revealed some 30 proteins involved in the synthesis of cellular [2Fe-2S] and [4Fe-4S] clusters and their incorporation into numerous apoproteins. Mechanistic aspects of Fe/S protein biogenesis continue to be elucidated by biochemical and ultrastructural investigations. Here, we review recent developments in the pursuit of constructing a comprehensive model of Fe/S protein assembly in the mitochondrion.
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Affiliation(s)
- Joseph J Braymer
- Institut für Zytobiologie und Zytopathologie, Philipps-Universität Marburg, Robert-Koch-Strasse 6, 35032 Marburg
| | - Roland Lill
- Institut für Zytobiologie und Zytopathologie, Philipps-Universität Marburg, Robert-Koch-Strasse 6, 35032 Marburg; LOEWE Zentrum für Synthetische Mikrobiologie SynMikro, Hans-Meerwein-Strasse, 35043 Marburg, Germany.
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90
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Zhang Y, Qian Y, Zhang J, Yan W, Jung YS, Chen M, Huang E, Lloyd K, Duan Y, Wang J, Liu G, Chen X. Ferredoxin reductase is critical for p53-dependent tumor suppression via iron regulatory protein 2. Genes Dev 2017; 31:1243-1256. [PMID: 28747430 PMCID: PMC5558926 DOI: 10.1101/gad.299388.117] [Citation(s) in RCA: 89] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Accepted: 06/26/2017] [Indexed: 01/20/2023]
Abstract
In this study, Chen and colleagues investigated the biological function of ferredoxin reductase (FDXR), a target of p53. They generated a Fdxr-deficient mouse model and found that the signal from FDXR to iron homeostasis and the p53 pathway was transduced by ferredoxin 2, a substrate of FDXR, and that p53 played a role in iron homeostasis and was required for FDXR-mediated iron metabolism, suggesting that the FDXR–p53 loop is critical for tumor suppression via iron homeostasis. Ferredoxin reductase (FDXR), a target of p53, modulates p53-dependent apoptosis and is necessary for steroidogenesis and biogenesis of iron–sulfur clusters. To determine the biological function of FDXR, we generated a Fdxr-deficient mouse model and found that loss of Fdxr led to embryonic lethality potentially due to iron overload in developing embryos. Interestingly, mice heterozygous in Fdxr had a short life span and were prone to spontaneous tumors and liver abnormalities, including steatosis, hepatitis, and hepatocellular carcinoma. We also found that FDXR was necessary for mitochondrial iron homeostasis and proper expression of several master regulators of iron metabolism, including iron regulatory protein 2 (IRP2). Surprisingly, we found that p53 mRNA translation was suppressed by FDXR deficiency via IRP2. Moreover, we found that the signal from FDXR to iron homeostasis and the p53 pathway was transduced by ferredoxin 2, a substrate of FDXR. Finally, we found that p53 played a role in iron homeostasis and was required for FDXR-mediated iron metabolism. Together, we conclude that FDXR and p53 are mutually regulated and that the FDXR–p53 loop is critical for tumor suppression via iron homeostasis.
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Affiliation(s)
- Yanhong Zhang
- Comparative Oncology Laboratory, Schools of Veterinary Medicine and Medicine, University of California at Davis, Davis, California 95616, USA
| | - Yingjuan Qian
- Comparative Oncology Laboratory, Schools of Veterinary Medicine and Medicine, University of California at Davis, Davis, California 95616, USA.,College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210014, China
| | - Jin Zhang
- Comparative Oncology Laboratory, Schools of Veterinary Medicine and Medicine, University of California at Davis, Davis, California 95616, USA
| | - Wensheng Yan
- Comparative Oncology Laboratory, Schools of Veterinary Medicine and Medicine, University of California at Davis, Davis, California 95616, USA
| | - Yong-Sam Jung
- Comparative Oncology Laboratory, Schools of Veterinary Medicine and Medicine, University of California at Davis, Davis, California 95616, USA.,College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210014, China
| | - Mingyi Chen
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
| | - Eric Huang
- Department of Pathology, School of Medicine, University of California at Davis Health, Sacramento, California 95817, USA
| | - Kent Lloyd
- Department of Surgery, School of Medicine, University of California at Davis Health, Sacramento, California 95817, USA
| | - Yuyou Duan
- Department of Dermatology and Internal Medicine, University of California at Davis Health, Sacramento, California 95616, USA
| | - Jian Wang
- Department of Pathology, School of Medicine, Wayne State University, Detroit, Michigan 48201 USA
| | - Gang Liu
- Department of Medicine, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA
| | - Xinbin Chen
- Comparative Oncology Laboratory, Schools of Veterinary Medicine and Medicine, University of California at Davis, Davis, California 95616, USA
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91
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Cory SA, Van Vranken JG, Brignole EJ, Patra S, Winge DR, Drennan CL, Rutter J, Barondeau DP. Structure of human Fe-S assembly subcomplex reveals unexpected cysteine desulfurase architecture and acyl-ACP-ISD11 interactions. Proc Natl Acad Sci U S A 2017; 114:E5325-E5334. [PMID: 28634302 PMCID: PMC5502623 DOI: 10.1073/pnas.1702849114] [Citation(s) in RCA: 108] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
In eukaryotes, sulfur is mobilized for incorporation into multiple biosynthetic pathways by a cysteine desulfurase complex that consists of a catalytic subunit (NFS1), LYR protein (ISD11), and acyl carrier protein (ACP). This NFS1-ISD11-ACP (SDA) complex forms the core of the iron-sulfur (Fe-S) assembly complex and associates with assembly proteins ISCU2, frataxin (FXN), and ferredoxin to synthesize Fe-S clusters. Here we present crystallographic and electron microscopic structures of the SDA complex coupled to enzyme kinetic and cell-based studies to provide structure-function properties of a mitochondrial cysteine desulfurase. Unlike prokaryotic cysteine desulfurases, the SDA structure adopts an unexpected architecture in which a pair of ISD11 subunits form the dimeric core of the SDA complex, which clarifies the critical role of ISD11 in eukaryotic assemblies. The different quaternary structure results in an incompletely formed substrate channel and solvent-exposed pyridoxal 5'-phosphate cofactor and provides a rationale for the allosteric activator function of FXN in eukaryotic systems. The structure also reveals the 4'-phosphopantetheine-conjugated acyl-group of ACP occupies the hydrophobic core of ISD11, explaining the basis of ACP stabilization. The unexpected architecture for the SDA complex provides a framework for understanding interactions with acceptor proteins for sulfur-containing biosynthetic pathways, elucidating mechanistic details of eukaryotic Fe-S cluster biosynthesis, and clarifying how defects in Fe-S cluster assembly lead to diseases such as Friedreich's ataxia. Moreover, our results support a lock-and-key model in which LYR proteins associate with acyl-ACP as a mechanism for fatty acid biosynthesis to coordinate the expression, Fe-S cofactor maturation, and activity of the respiratory complexes.
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Affiliation(s)
- Seth A Cory
- Department of Chemistry, Texas A&M University, College Station, TX 77842
| | - Jonathan G Van Vranken
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT 84112
| | - Edward J Brignole
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139
- Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Shachin Patra
- Department of Chemistry, Texas A&M University, College Station, TX 77842
| | - Dennis R Winge
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT 84112
- Department of Medicine, University of Utah School of Medicine, Salt Lake City, UT 84132
| | - Catherine L Drennan
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139
- Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA 02139
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Jared Rutter
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT 84112
- Howard Hughes Medical Institute, University of Utah School of Medicine, Salt Lake City, UT 84132
| | - David P Barondeau
- Department of Chemistry, Texas A&M University, College Station, TX 77842;
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92
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Cai K, Tonelli M, Frederick RO, Markley JL. Human Mitochondrial Ferredoxin 1 (FDX1) and Ferredoxin 2 (FDX2) Both Bind Cysteine Desulfurase and Donate Electrons for Iron-Sulfur Cluster Biosynthesis. Biochemistry 2017; 56:487-499. [PMID: 28001042 PMCID: PMC5267338 DOI: 10.1021/acs.biochem.6b00447] [Citation(s) in RCA: 83] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Revised: 12/20/2016] [Indexed: 02/02/2023]
Abstract
Ferredoxins play an important role as an electron donor in iron-sulfur (Fe-S) cluster biosynthesis. Two ferredoxins, human mitochondrial ferredoxin 1 (FDX1) and human mitochondrial ferredoxin 2 (FDX2), are present in the matrix of human mitochondria. Conflicting results have been reported regarding their respective function in mitochondrial iron-sulfur cluster biogenesis. We report here biophysical studies of the interaction of these two ferredoxins with other proteins involved in mitochondrial iron-sulfur cluster assembly. Results from nuclear magnetic resonance spectroscopy show that both FDX1 and FDX2 (in both their reduced and oxidized states) interact with the protein complex responsible for cluster assembly, which contains cysteine desulfurase (NFS1), ISD11 (also known as LYRM4), and acyl carrier protein (Acp). In all cases, ferredoxin residues close to the Fe-S cluster are involved in the interaction with this complex. Isothermal titration calorimetry results showed that FDX2 binds more tightly to the cysteine desulfurase complex than FDX1 does. The reduced form of each ferredoxin became oxidized in the presence of the cysteine desulfurase complex when l-cysteine was added, leading to its conversion to l-alanine and the generation of sulfide. In an in vitro reaction, the reduced form of each ferredoxin was found to support Fe-S cluster assembly on ISCU; the rate of cluster assembly was faster with FDX2 than with FDX1. Taken together, these results show that both FDX1 and FDX2 can function in Fe-S cluster assembly in vitro.
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Affiliation(s)
- Kai Cai
- Mitochondrial
Protein Partnership, Center for Eukaryotic
Structural Genomics, and National Magnetic Resonance Facility at Madison,
Biochemistry
Department, University of Wisconsin—Madison, Madison, Wisconsin 53706, United States
| | - Marco Tonelli
- Mitochondrial
Protein Partnership, Center for Eukaryotic
Structural Genomics, and National Magnetic Resonance Facility at Madison,
Biochemistry
Department, University of Wisconsin—Madison, Madison, Wisconsin 53706, United States
| | - Ronnie O. Frederick
- Mitochondrial
Protein Partnership, Center for Eukaryotic
Structural Genomics, and National Magnetic Resonance Facility at Madison,
Biochemistry
Department, University of Wisconsin—Madison, Madison, Wisconsin 53706, United States
| | - John L. Markley
- Mitochondrial
Protein Partnership, Center for Eukaryotic
Structural Genomics, and National Magnetic Resonance Facility at Madison,
Biochemistry
Department, University of Wisconsin—Madison, Madison, Wisconsin 53706, United States
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93
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Stiban J, So M, Kaguni LS. Iron-Sulfur Clusters in Mitochondrial Metabolism: Multifaceted Roles of a Simple Cofactor. BIOCHEMISTRY (MOSCOW) 2017; 81:1066-1080. [PMID: 27908232 DOI: 10.1134/s0006297916100059] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
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.
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Affiliation(s)
- Johnny Stiban
- Birzeit University, Department of Biology and Biochemistry, West Bank Birzeit, 627, Palestine.
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94
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Miller WL. Disorders in the initial steps of steroid hormone synthesis. J Steroid Biochem Mol Biol 2017; 165:18-37. [PMID: 26960203 DOI: 10.1016/j.jsbmb.2016.03.009] [Citation(s) in RCA: 120] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Revised: 03/01/2016] [Accepted: 03/03/2016] [Indexed: 12/29/2022]
Abstract
Steroidogenesis begins with cellular internalization of low-density lipoprotein particles and subsequent intracellular processing of cholesterol. Disorders in these steps include Adrenoleukodystrophy, Wolman Disease and its milder variant Cholesterol Ester Storage Disease, and Niemann-Pick Type C Disease, all of which may present with adrenal insufficiency. The means by which cholesterol is directed to steroidogenic mitochondria remains incompletely understood. Once cholesterol reaches the outer mitochondrial membrane, its delivery to the inner mitochondrial membrane is regulated by the steroidogenic acute regulatory protein (StAR). Severe StAR mutations cause classic congenital lipoid adrenal hyperplasia, characterized by lipid accumulation in the adrenal, adrenal insufficiency, and disordered sexual development in 46,XY individuals. The lipoid CAH phenotype, including spontaneous puberty in 46,XX females, is explained by a two-hit model. StAR mutations that retain partial function cause a milder, non-classic disease characterized by glucocorticoid deficiency, with lesser disorders of mineralocorticoid and sex steroid synthesis. Once inside the mitochondria, cholesterol is converted to pregnenolone by the cholesterol side-chain cleavage enzyme, P450scc, encoded by the CYP11A1 gene. Rare patients with mutations of P450scc are clinically and hormonally indistinguishable from those with lipoid CAH, and may also present as milder non-classic disease. Patients with P450scc defects do not have the massive adrenal hyperplasia that characterizes lipoid CAH, but adrenal imaging may occasionally fail to distinguish these, necessitating DNA sequencing.
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Affiliation(s)
- Walter L Miller
- Center for Reproductive Sciences, University of California, San Francisco, CA 94143-0556, United States.
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95
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Chiang S, Kovacevic Z, Sahni S, Lane DJR, Merlot AM, Kalinowski DS, Huang MLH, Richardson DR. Frataxin and the molecular mechanism of mitochondrial iron-loading in Friedreich's ataxia. Clin Sci (Lond) 2016; 130:853-70. [PMID: 27129098 DOI: 10.1042/cs20160072] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Accepted: 02/16/2016] [Indexed: 12/19/2022]
Abstract
The mitochondrion is a major site for the metabolism of the transition metal, iron, which is necessary for metabolic processes critical for cell vitality. The enigmatic mitochondrial protein, frataxin, is known to play a significant role in both cellular and mitochondrial iron metabolism due to its iron-binding properties and its involvement in iron-sulfur cluster (ISC) and heme synthesis. The inherited neuro- and cardio-degenerative disease, Friedreich's ataxia (FA), is caused by the deficient expression of frataxin that leads to deleterious alterations in iron metabolism. These changes lead to the accumulation of inorganic iron aggregates in the mitochondrial matrix that are presumed to play a key role in the oxidative damage and subsequent degenerative features of this disease. Furthermore, the concurrent dys-regulation of cellular antioxidant defense, which coincides with frataxin deficiency, exacerbates oxidative stress. Hence, the pathogenesis of FA underscores the importance of the integrated homeostasis of cellular iron metabolism and the cytoplasmic and mitochondrial redox environments. This review focuses on describing the pathogenesis of the disease, the molecular mechanisms involved in mitochondrial iron-loading and the dys-regulation of cellular antioxidant defense due to frataxin deficiency. In turn, current and emerging therapeutic strategies are also discussed.
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Affiliation(s)
- Shannon Chiang
- Molecular Pharmacology and Pathology Program, Department of Pathology, University of Sydney, Sydney, New South Wales 2006, Australia
| | - Zaklina Kovacevic
- Molecular Pharmacology and Pathology Program, Department of Pathology, University of Sydney, Sydney, New South Wales 2006, Australia
| | - Sumit Sahni
- Molecular Pharmacology and Pathology Program, Department of Pathology, University of Sydney, Sydney, New South Wales 2006, Australia
| | - Darius J R Lane
- Molecular Pharmacology and Pathology Program, Department of Pathology, University of Sydney, Sydney, New South Wales 2006, Australia
| | - Angelica M Merlot
- Molecular Pharmacology and Pathology Program, Department of Pathology, University of Sydney, Sydney, New South Wales 2006, Australia
| | - Danuta S Kalinowski
- Molecular Pharmacology and Pathology Program, Department of Pathology, University of Sydney, Sydney, New South Wales 2006, Australia
| | - Michael L-H Huang
- Molecular Pharmacology and Pathology Program, Department of Pathology, University of Sydney, Sydney, New South Wales 2006, Australia )
| | - Des R Richardson
- Molecular Pharmacology and Pathology Program, Department of Pathology, University of Sydney, Sydney, New South Wales 2006, Australia )
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96
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Rouault TA. Mitochondrial iron overload: causes and consequences. Curr Opin Genet Dev 2016; 38:31-37. [PMID: 27026139 DOI: 10.1016/j.gde.2016.02.004] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Revised: 02/08/2016] [Accepted: 02/21/2016] [Indexed: 02/07/2023]
Abstract
Pathological overload of iron in the mitochondrial matrix has been observed in numerous diseases, including sideroblastic anemias, which have many causes, and in genetic diseases that affect iron-sulfur cluster biogenesis, heme synthesis, and mitochondrial protein translation and its products. Although high expression of the mitochondrial iron importer, mitoferrin, appears to be an underlying common feature, it is unclear what drives high mitoferrin expression and what other proteins are involved in trapping excess toxic iron in the mitochondrial matrix. Numerous examples of human diseases and model systems suggest that mitochondrial iron homeostasis is coordinated through transcriptional remodeling. A cytosolic/nuclear molecule may affect a transcriptional factor to coordinate the events that lead to iron accumulation, but no candidates for this role have yet been identified.
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Affiliation(s)
- Tracey A Rouault
- Eunice Kennedy Shriver, National Institute of Child Health and Human Development, Bethesda, MD 20892, United States.
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97
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Affiliation(s)
- Walter L Miller
- Center for Reproductive Sciences (W.L.M.), University of California, San Francisco, California 94143-0556; and Institute of Molecular Biology Academia Sinica (B.-c.C.), Taipei, 115 Taiwan
| | - Bon-Chu Chung
- Center for Reproductive Sciences (W.L.M.), University of California, San Francisco, California 94143-0556; and Institute of Molecular Biology Academia Sinica (B.-c.C.), Taipei, 115 Taiwan
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98
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Lill R, Srinivasan V, Mühlenhoff U. The role of mitochondria in cytosolic-nuclear iron–sulfur protein biogenesis and in cellular iron regulation. Curr Opin Microbiol 2015; 22:111-9. [PMID: 25460804 DOI: 10.1016/j.mib.2014.09.015] [Citation(s) in RCA: 99] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2014] [Revised: 09/20/2014] [Accepted: 09/24/2014] [Indexed: 12/16/2022]
Abstract
Mitochondria are indispensable in eukaryotes because of their function in the maturation of cytosolic and nuclear iron–sulfur proteins that are essential for DNA synthesis and repair, tRNA modification, and protein translation. The mitochondrial Fe/S cluster assembly machinery not only generates the organelle's iron–sulfur proteins, but also extra-mitochondrial ones. Biogenesis of the latter proteins requires the mitochondrial ABC transporter Atm1 that exports a sulfur-containing compound in a glutathione-dependent fashion. The process is further assisted by the cytosolic iron–sulfur protein assembly machinery. Here, we discuss the knowns and unknowns of the mitochondrial export process that is also crucial for signaling the cellular iron status to the regulatory systems involved in the maintenance of cellular iron homeostasis.
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Affiliation(s)
- Roland Lill
- Institut für Zytobiologie, Philipps-Universität Marburg, Robert-Koch-Str. 6, 35032 Marburg, Germany.
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99
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Peters DG, Connor JR, Meadowcroft MD. The relationship between iron dyshomeostasis and amyloidogenesis in Alzheimer's disease: Two sides of the same coin. Neurobiol Dis 2015; 81:49-65. [PMID: 26303889 DOI: 10.1016/j.nbd.2015.08.007] [Citation(s) in RCA: 105] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Revised: 08/04/2015] [Accepted: 08/12/2015] [Indexed: 12/21/2022] Open
Abstract
The dysregulation of iron metabolism in Alzheimer's disease is not accounted for in the current framework of the amyloid cascade hypothesis. Accumulating evidence suggests that impaired iron homeostasis is an early event in Alzheimer's disease progression. Iron dyshomeostasis leads to a loss of function in several enzymes requiring iron as a cofactor, the formation of toxic oxidative species, and the elevated production of beta-amyloid proteins. Several common genetic polymorphisms that cause increased iron levels and dyshomeostasis have been associated with Alzheimer's disease but the pathoetiology is not well understood. A full picture is necessary to explain how heterogeneous circumstances lead to iron loading and amyloid deposition. There is evidence to support a causative interplay between the concerted loss of iron homeostasis and amyloid plaque formation. We hypothesize that iron misregulation and beta-amyloid plaque pathology are synergistic in the process of neurodegeneration and ultimately cause a downward cascade of events that spiral into the manifestation of Alzheimer's disease. In this review, we amalgamate recent findings of brain iron metabolism in healthy versus Alzheimer's disease brains and consider unique mechanisms of iron transport in different brain cells as well as how disturbances in iron regulation lead to disease etiology and propagate Alzheimer's pathology.
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Affiliation(s)
- Douglas G Peters
- Department of Neurosurgery, The Pennsylvania State University, College of Medicine, Milton S. Hershey Medical Center, Hershey, PA, USA; Department of Neural and Behavioral Sciences, The Pennsylvania State University, College of Medicine, Milton S. Hershey Medical Center, Hershey, PA, USA
| | - James R Connor
- Department of Neurosurgery, The Pennsylvania State University, College of Medicine, Milton S. Hershey Medical Center, Hershey, PA, USA
| | - Mark D Meadowcroft
- Department of Neurosurgery, The Pennsylvania State University, College of Medicine, Milton S. Hershey Medical Center, Hershey, PA, USA; Department of Radiology, The Center for NMR Research, The Pennsylvania State University, College of Medicine, Milton S. Hershey Medical Center, Hershey, PA, USA.
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100
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Liddell JR. Targeting mitochondrial metal dyshomeostasis for the treatment of neurodegeneration. Neurodegener Dis Manag 2015; 5:345-64. [DOI: 10.2217/nmt.15.19] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Mitochondrial impairment and metal dyshomeostasis are suggested to be associated with many neurodegenerative disorders including Alzheimer's disease, Parkinson's disease, Huntington's disease, amyotrophic lateral sclerosis and Friedreich's ataxia. Treatments aimed at restoring metal homeostasis are highly effective in models of these diseases, and clinical trials hold promise. However, in general, the effect of these treatments on mitochondrial metal homeostasis is unclear, and the contribution of mitochondrial metal dyshomeostasis to disease pathogenesis requires further investigation. This review describes the role of metals in mitochondria in health, how mitochondrial metals are disrupted in neurodegenerative diseases, and potential therapeutics aimed at restoring mitochondrial metal homeostasis and function.
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Affiliation(s)
- Jeffrey R Liddell
- Department of Pathology, University of Melbourne, Victoria 3010, Australia
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