51
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Silva RMB, Grodick MA, Barton JK. UvrC Coordinates an O 2-Sensitive [4Fe4S] Cofactor. J Am Chem Soc 2020; 142:10964-10977. [PMID: 32470300 DOI: 10.1021/jacs.0c01671] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Recent advances have led to numerous landmark discoveries of [4Fe4S] clusters coordinated by essential enzymes in repair, replication, and transcription across all domains of life. The cofactor has notably been challenging to observe for many nucleic acid processing enzymes due to several factors, including a weak bioinformatic signature of the coordinating cysteines and lability of the metal cofactor. To overcome these challenges, we have used sequence alignments, an anaerobic purification method, iron quantification, and UV-visible and electron paramagnetic resonance spectroscopies to investigate UvrC, the dual-incision endonuclease in the bacterial nucleotide excision repair (NER) pathway. The characteristics of UvrC are consistent with [4Fe4S] coordination with 60-70% cofactor incorporation, and additionally, we show that, bound to UvrC, the [4Fe4S] cofactor is susceptible to oxidative degradation with aggregation of apo species. Importantly, in its holo form with the cofactor bound, UvrC forms high affinity complexes with duplexed DNA substrates; the apparent dissociation constants to well-matched and damaged duplex substrates are 100 ± 20 nM and 80 ± 30 nM, respectively. This high affinity DNA binding contrasts reports made for isolated protein lacking the cofactor. Moreover, using DNA electrochemistry, we find that the cluster coordinated by UvrC is redox-active and participates in DNA-mediated charge transport chemistry with a DNA-bound midpoint potential of 90 mV vs NHE. This work highlights that the [4Fe4S] center is critical to UvrC.
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Affiliation(s)
- Rebekah M B Silva
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Michael A Grodick
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Jacqueline K Barton
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
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52
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Abstract
Iron deficiency or overload poses an increasingly complex issue in cardiovascular disease, especially heart failure. The potential benefits and side effects of iron supplementation are still a matter of concern, even though current guidelines suggest therapeutic management of iron deficiency. In this review, we sought to examine the iron metabolism and to identify the rationale behind iron supplementation and iron chelation. Cardiovascular disease is increasingly linked with iron dysmetabolism, with an increased proportion of heart failure patients being affected by decreased plasma iron levels and in turn, by the decreased quality of life. Multiple studies have concluded on a benefit of iron administration, even if just for symptomatic relief. However, new studies field evidence for negative effects of dysregulated non-bound iron and its reactive oxygen species production, with concern to heart diseases. The molecular targets of iron usage, such as the mitochondria, are prone to deleterious effects of the polyvalent metal, added by the scarcely described processes of iron elimination. Iron supplementation and iron chelation show promise of therapeutic benefit in heart failure, with the extent and mechanisms of both prospects not being entirely understood. It may be that a state of decreased systemic and increased mitochondrial iron levels proves to be a useful frame for future advancements in understanding the interconnection of heart failure and iron metabolism.
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53
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Cai K, Frederick RO, Markley JL. ISCU interacts with NFU1, and ISCU[4Fe-4S] transfers its Fe-S cluster to NFU1 leading to the production of holo-NFU1. J Struct Biol 2020; 210:107491. [PMID: 32151725 PMCID: PMC7261492 DOI: 10.1016/j.jsb.2020.107491] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2019] [Revised: 02/17/2020] [Accepted: 03/04/2020] [Indexed: 01/30/2023]
Abstract
NFU1 is a late-acting factor in the biogenesis of human mitochondrial iron-sulfur proteins. Mutations in NFU1 are associated with genetic diseases such as multiple mitochondrial dysfunctions syndrome 1 (MMDS1) that involve defects in mitochondrial [4Fe-4S] proteins. We present results from NMR spectroscopy, small angle X-ray scattering, size exclusion chromatography, and isothermal titration calorimetry showing that the structured conformer of human ISCU binds human NFU1. The dissociation constant determined by ITC is Kd = 1.1 ± 0.2 μM. NMR and SAXS studies led to a structural model for the complex in which the cluster binding region of ISCU interacts with two α-helices in the C-terminal domain of NFU1. In vitro experiments demonstrate that ISCU[4Fe-4S] transfers its Fe-S cluster to apo-NFU1, in the absence of a chaperone, leading to the assembly of holo-NFU1. By contrast, the cluster of ISCU[2Fe-2S] remains bound to ISCU in the presence of apo-NFU1.
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Affiliation(s)
- Kai Cai
- Biochemistry Department, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Ronnie O Frederick
- Biochemistry Department, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - John L Markley
- Biochemistry Department, University of Wisconsin-Madison, Madison, WI 53706, USA
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54
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La P, Oved JH, Ghiaccio V, Rivella S. Mitochondria Biogenesis Modulates Iron-Sulfur Cluster Synthesis to Increase Cellular Iron Uptake. DNA Cell Biol 2020; 39:756-765. [PMID: 32282232 DOI: 10.1089/dna.2019.5123] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Iron-sulfur (Fe-S) clusters are required for mitochondrial function. Fe-S cluster synthesis occurs in the mitochondria and iron uptake is required for mitochondrial biogenesis. However, Fe-S clusters inhibit the expression of the iron importer transferrin receptor 1 (TfR1), whereas lack of the Fe-S cluster stimulates TfR1 expression. Yet, it is unclear whether Fe-S cluster synthesis increases with mitochondria biogenesis and, in turn, whether this negatively modulates TfR1 expression. We manipulated peroxisome proliferator-activated receptor-gamma coactivator-1α expression to control mitochondrial biogenesis in a variety of cell types, including erythroid cells. We demonstrated that Fe-S cluster synthesis increases with mitochondria biogenesis but does not interfere with increasing TfR1 expression. In fact, TfR1 expression is stimulated through alternative means to meet iron requirement for mitochondria biogenesis. Furthermore, under enhanced mitochondria biogenesis, increased Fe-S cluster synthesis inhibits the function of iron-regulating protein (IRP)1 and hence stimulates the expression of 5'-aminolevulinate synthase 2 (ALAS2), a target of IRP1 and rate-limiting enzyme in erythroid heme biogenesis. Increased ALAS2 expression leads to enhanced heme production, hemoglobinization, and erythropoiesis. Therefore, our study also provides a mechanism to link mitochondrial biogenesis with erythropoiesis and has a potential therapeutic value in the treatment of blood disorders.
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Affiliation(s)
- Ping La
- Division of Hematology, Department of Pediatrics, Children's Hospital of Philadelphia, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Joseph H Oved
- Division of Hematology, Department of Pediatrics, Children's Hospital of Philadelphia, University of Pennsylvania, Philadelphia, Pennsylvania, USA.,Cell Therapy and Transplant Section, Division of Oncology, Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - Valentina Ghiaccio
- Division of Hematology, Department of Pediatrics, Children's Hospital of Philadelphia, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Stefano Rivella
- Division of Hematology, Department of Pediatrics, Children's Hospital of Philadelphia, University of Pennsylvania, Philadelphia, Pennsylvania, USA.,Cell and Molecular Biology Affinity Group (CAMB)-Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA.,Penn Center for Musculoskeletal Disorders, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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55
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Wang H, Shi H, Rajan M, Canarie ER, Hong S, Simoneschi D, Pagano M, Bush MF, Stoll S, Leibold EA, Zheng N. FBXL5 Regulates IRP2 Stability in Iron Homeostasis via an Oxygen-Responsive [2Fe2S] Cluster. Mol Cell 2020; 78:31-41.e5. [PMID: 32126207 DOI: 10.1016/j.molcel.2020.02.011] [Citation(s) in RCA: 82] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Revised: 12/30/2019] [Accepted: 02/11/2020] [Indexed: 12/21/2022]
Abstract
Cellular iron homeostasis is dominated by FBXL5-mediated degradation of iron regulatory protein 2 (IRP2), which is dependent on both iron and oxygen. However, how the physical interaction between FBXL5 and IRP2 is regulated remains elusive. Here, we show that the C-terminal substrate-binding domain of FBXL5 harbors a [2Fe2S] cluster in the oxidized state. A cryoelectron microscopy (cryo-EM) structure of the IRP2-FBXL5-SKP1 complex reveals that the cluster organizes the FBXL5 C-terminal loop responsible for recruiting IRP2. Interestingly, IRP2 binding to FBXL5 hinges on the oxidized state of the [2Fe2S] cluster maintained by ambient oxygen, which could explain hypoxia-induced IRP2 stabilization. Steric incompatibility also allows FBXL5 to physically dislodge IRP2 from iron-responsive element RNA to facilitate its turnover. Taken together, our studies have identified an iron-sulfur cluster within FBXL5, which promotes IRP2 polyubiquitination and degradation in response to both iron and oxygen concentrations.
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Affiliation(s)
- Hui Wang
- Department of Pharmacology, University of Washington, Seattle, WA 98195, USA; Howard Hughes Medical Institute, University of Washington, Seattle, WA 98195, USA
| | - Hui Shi
- Department of Pharmacology, University of Washington, Seattle, WA 98195, USA; Howard Hughes Medical Institute, University of Washington, Seattle, WA 98195, USA
| | - Malini Rajan
- Division of Hematology and Hematologic Malignancies and Molecular Medicine Program, University of Utah, Salt Lake City, UT 84112, USA
| | | | - Seoyeon Hong
- Department of Chemistry, University of Washington, Seattle, WA 98195, USA
| | - Daniele Simoneschi
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY 10016, USA; NYU Perlmutter Cancer Center, New York University School of Medicine, New York, NY 10016, USA
| | - Michele Pagano
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY 10016, USA; NYU Perlmutter Cancer Center, New York University School of Medicine, New York, NY 10016, USA; Howard Hughes Medical Institute, New York University School of Medicine, New York, NY 10016, USA
| | - Matthew F Bush
- Department of Chemistry, University of Washington, Seattle, WA 98195, USA
| | - Stefan Stoll
- Department of Chemistry, University of Washington, Seattle, WA 98195, USA
| | - Elizabeth A Leibold
- Division of Hematology and Hematologic Malignancies and Molecular Medicine Program, University of Utah, Salt Lake City, UT 84112, USA
| | - Ning Zheng
- Department of Pharmacology, University of Washington, Seattle, WA 98195, USA; Howard Hughes Medical Institute, University of Washington, Seattle, WA 98195, USA.
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56
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Wang Y, Singh R, Tong E, Tang M, Zheng L, Fang H, Li R, Guo L, Song J, Srinivasan R, Sharma A, Lin L, Trujillo JA, Manshardt R, Chen LY, Ming R, Yu Q. Positional cloning and characterization of the papaya diminutive mutant reveal a truncating mutation in the CpMMS19 gene. THE NEW PHYTOLOGIST 2020; 225:2006-2021. [PMID: 31733154 DOI: 10.1111/nph.16325] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2018] [Accepted: 10/19/2019] [Indexed: 06/10/2023]
Abstract
The papaya diminutive mutant exhibits miniature stature, retarded growth and reduced fertility. This undesirable mutation appeared in the variety 'Sunset', the progenitor of the transgenic line 'SunUp', and was accidentally carried forward into breeding populations. The diminutive mutation was mapped to chromosome 2 and fine mapped to scaffold 25. Sequencing of a bacterial artificial chromosome in the fine mapped region led to the identification of the target gene responsible for the diminutive mutant, a gene orthologous to MMS19 with a 36.8 kb deletion co-segregating with the diminutive mutant. The genomic sequence of CpMMS19 is 62 kb, consisting of 20 exons and 19 introns. It encodes a protein of 1143 amino acids while the diminutive allele encodes a truncated protein of 287 amino acids. Expression of the full-length CpMMS19 was able to complement the thermosensitive growth of the yeast mms19 deletion mutant while expression of the diminutive allele resulted in increased thermosensitivity. Over-expression of the diminutive allele in Arabidopsis met18 mutant results in a high frequency of seed abortion. The papaya diminutive phenotype is caused by an alteration in gene function rather than a loss-of-function mutation. SCAR (sequence characterized amplified region) markers were developed for rapid detection of the diminutive allele in breeding populations.
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Affiliation(s)
- Ying Wang
- College of Crop Science, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
- FAFU and UIUC-SIB Joint Center for Genomics and Biotechnology, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Ratnesh Singh
- Texas A&M AgriLife Research Center at Dallas, Texas A&M University System, Dallas, TX, 75252, USA
| | - Eric Tong
- Hawaii Agriculture Research Center, Kunia, HI, 96759, USA
| | - Min Tang
- FAFU and UIUC-SIB Joint Center for Genomics and Biotechnology, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
- College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Liwei Zheng
- Texas A&M AgriLife Research Center at Dallas, Texas A&M University System, Dallas, TX, 75252, USA
| | - Hongkun Fang
- FAFU and UIUC-SIB Joint Center for Genomics and Biotechnology, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
- College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Ruoyu Li
- College of Crop Science, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
- FAFU and UIUC-SIB Joint Center for Genomics and Biotechnology, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Lin Guo
- FAFU and UIUC-SIB Joint Center for Genomics and Biotechnology, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
- College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Jinjin Song
- FAFU and UIUC-SIB Joint Center for Genomics and Biotechnology, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
- College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Rajeswari Srinivasan
- Department of Tropical Plant & Soil Sciences, University of Hawaii, Honolulu, HI, 96822, USA
| | - Anupma Sharma
- Texas A&M AgriLife Research Center at Dallas, Texas A&M University System, Dallas, TX, 75252, USA
| | - Lianyu Lin
- Texas A&M AgriLife Research Center at Dallas, Texas A&M University System, Dallas, TX, 75252, USA
- College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Jorge A Trujillo
- Department of Biology, University of Texas Rio Grande Valley, Edinburg, TX, 78539, USA
| | - Richard Manshardt
- Department of Tropical Plant & Soil Sciences, University of Hawaii, Honolulu, HI, 96822, USA
| | - Li-Yu Chen
- FAFU and UIUC-SIB Joint Center for Genomics and Biotechnology, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Ray Ming
- Department of Plant Biology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Qingyi Yu
- Texas A&M AgriLife Research Center at Dallas, Texas A&M University System, Dallas, TX, 75252, USA
- Hawaii Agriculture Research Center, Kunia, HI, 96759, USA
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57
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Teo RD, Migliore A, Beratan DN. Mutation effects on charge transport through the p58c iron-sulfur protein. Chem Sci 2020; 11:7076-7085. [PMID: 33250976 PMCID: PMC7690218 DOI: 10.1039/d0sc02245d] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Accepted: 06/16/2020] [Indexed: 12/25/2022] Open
Abstract
Growing experimental evidence indicates that iron–sulfur proteins play key roles in DNA repair and replication. In particular, charge transport between [Fe4S4] clusters, mediated by proteins and DNA, may convey signals to coordinate enzyme action. Human primase is a well studied [Fe4S4] protein, and its p58c domain (which contains an [Fe4S4] cluster) plays a role in the initiation of DNA replication. The Y345C mutation in p58c is linked to gastric tumors and may influence the protein-mediated charge transport. The complexity of protein–DNA systems, and the intricate electronic structure of [Fe4S4] clusters, have impeded progress into understanding functional charge transport in these systems. In this study, we built force fields to describe the high potential [Fe4S4] cluster in both oxidation states. The parameterization is compatible with AMBER force fields and enabled well-balanced molecular dynamics simulations of the p58c–RNA/DNA complex relevant to the initiation of DNA replication. Using the molecular mechanics Poisson–Boltzmann and surface area solvation method on the molecular dynamics trajectories, we find that the p58c mutation induces a modest change in the p58c–duplex binding free energy in agreement with recent experiments. Through kinetic modeling and analysis, we identify key features of the main charge transport pathways in p58c. In particular, we find that the Y345C mutation partially changes the composition and frequency of the most efficient (and potentially relevant to the biological function) charge transport pathways between the [Fe4S4] cluster and the duplex. Moreover, our approach sets the stage for a deeper understanding of functional charge transfer in [Fe4S4] protein–DNA complexes. Functional electron transfer between the [Fe4S4] cluster and the nucleic acid is impacted by a Y345C mutation in the p58c subunit of human primase.![]()
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Affiliation(s)
- Ruijie D Teo
- Department of Chemistry , Duke University , Durham , North Carolina 27708 , USA . ;
| | - Agostino Migliore
- Department of Chemistry , Duke University , Durham , North Carolina 27708 , USA . ;
| | - David N Beratan
- Department of Chemistry , Duke University , Durham , North Carolina 27708 , USA . ; .,Department of Physics , Duke University , Durham , North Carolina 27708 , USA.,Department of Biochemistry , Duke University , Durham , North Carolina 27710 , USA
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58
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Culley MK, Perk D, Chan SY. NFU1, Iron-Sulfur Biogenesis, and Pulmonary Arterial Hypertension: A (Metabolic) Shift in Our Thinking. Am J Respir Cell Mol Biol 2020; 62:136-138. [PMID: 31526282 PMCID: PMC6993537 DOI: 10.1165/rcmb.2019-0309ed] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Affiliation(s)
- Miranda K Culley
- Department of MedicineUniversity of Pittsburgh School of MedicinePittsburgh, Pennsylvaniaand
- University of Pittsburgh Medical CenterPittsburgh, Pennsylvania
| | - Dror Perk
- Department of MedicineUniversity of Pittsburgh School of MedicinePittsburgh, Pennsylvaniaand
- University of Pittsburgh Medical CenterPittsburgh, Pennsylvania
| | - Stephen Y Chan
- Department of MedicineUniversity of Pittsburgh School of MedicinePittsburgh, Pennsylvaniaand
- University of Pittsburgh Medical CenterPittsburgh, Pennsylvania
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59
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Bogenhagen DF, Haley JD. Pulse-chase SILAC-based analyses reveal selective oversynthesis and rapid turnover of mitochondrial protein components of respiratory complexes. J Biol Chem 2020; 295:2544-2554. [PMID: 31974161 DOI: 10.1074/jbc.ra119.011791] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2019] [Revised: 01/17/2020] [Indexed: 12/20/2022] Open
Abstract
Mammalian mitochondria assemble four complexes of the respiratory chain (RCI, RCIII, RCIV, and RCV) by combining 13 polypeptides synthesized within mitochondria on mitochondrial ribosomes (mitoribosomes) with over 70 polypeptides encoded in nuclear DNA, translated on cytoplasmic ribosomes, and imported into mitochondria. We have previously observed that mitoribosome assembly is inefficient because some mitoribosomal proteins are produced in excess, but whether this is the case for other mitochondrial assemblies such as the RCs is unclear. We report here that pulse-chase stable isotope labeling with amino acids in cell culture (SILAC) is a valuable technique to study RC assembly because it can reveal considerable differences in the assembly rates and efficiencies of the different complexes. The SILAC analyses of HeLa cells indicated that assembly of RCV, comprising F1/Fo-ATPase, is rapid with little excess subunit synthesis, but that assembly of RCI (i.e. NADH dehydrogenase) is far less efficient, with dramatic oversynthesis of numerous proteins, particularly in the matrix-exposed N and Q domains. Unassembled subunits were generally degraded within 3 h. We also observed differential assembly kinetics for individual complexes that were immunoprecipitated with complex-specific antibodies. Immunoprecipitation with an antibody that recognizes the ND1 subunit of RCI co-precipitated a number of proteins implicated in FeS cluster assembly and newly synthesized ubiquinol-cytochrome c reductase Rieske iron-sulfur polypeptide 1 (UQCRFS1), the Rieske FeS protein in RCIII, reflecting some coordination between RCI and RCIII assemblies. We propose that pulse-chase SILAC labeling is a useful tool for studying rates of protein complex assembly and degradation.
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Affiliation(s)
- Daniel F Bogenhagen
- Department of Pharmacological Sciences, Stony Brook University, Stony Brook, New York 11794-8651.
| | - John D Haley
- Department of Pathology, Stony Brook University, Stony Brook, New York 11794-8691; Proteomics Center, Stony Brook University, Stony Brook, New York 11794-8691
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60
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Santos MCFD, Anderson CP, Neschen S, Zumbrennen-Bullough KB, Romney SJ, Kahle-Stephan M, Rathkolb B, Gailus-Durner V, Fuchs H, Wolf E, Rozman J, de Angelis MH, Cai WM, Rajan M, Hu J, Dedon PC, Leibold EA. Irp2 regulates insulin production through iron-mediated Cdkal1-catalyzed tRNA modification. Nat Commun 2020; 11:296. [PMID: 31941883 PMCID: PMC6962211 DOI: 10.1038/s41467-019-14004-5] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Accepted: 12/06/2019] [Indexed: 12/12/2022] Open
Abstract
Regulation of cellular iron homeostasis is crucial as both iron excess and deficiency cause hematological and neurodegenerative diseases. Here we show that mice lacking iron-regulatory protein 2 (Irp2), a regulator of cellular iron homeostasis, develop diabetes. Irp2 post-transcriptionally regulates the iron-uptake protein transferrin receptor 1 (TfR1) and the iron-storage protein ferritin, and dysregulation of these proteins due to Irp2 loss causes functional iron deficiency in β cells. This impairs Fe-S cluster biosynthesis, reducing the function of Cdkal1, an Fe-S cluster enzyme that catalyzes methylthiolation of t6A37 in tRNALysUUU to ms2t6A37. As a consequence, lysine codons in proinsulin are misread and proinsulin processing is impaired, reducing insulin content and secretion. Iron normalizes ms2t6A37 and proinsulin lysine incorporation, restoring insulin content and secretion in Irp2-/- β cells. These studies reveal a previously unidentified link between insulin processing and cellular iron deficiency that may have relevance to type 2 diabetes in humans.
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Affiliation(s)
- Maria C Ferreira Dos Santos
- Department of Medicine, Division of Hematology, University of Utah, Salt Lake City, UT, 84112, USA.,Molecular Medicine Program, University of Utah, Salt Lake City, UT, 84112, USA
| | - Cole P Anderson
- Molecular Medicine Program, University of Utah, Salt Lake City, UT, 84112, USA.,Department of Oncological Sciences, University of Utah, Salt Lake City, UT, 84112, USA.,Landstuhl Regional Medical Center, 66849, Landstuhl, Germany
| | - Susanne Neschen
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Zentrum München, Ingolstädter Landstraße 1, 85764, Neuherberg, Germany.,German Center for Diabetes Research (DZD), Ingolstädter Landstraße 1, 85764, Neuherberg, Germany
| | - Kimberly B Zumbrennen-Bullough
- Molecular Medicine Program, University of Utah, Salt Lake City, UT, 84112, USA.,Department of Oncological Sciences, University of Utah, Salt Lake City, UT, 84112, USA
| | - Steven J Romney
- Department of Medicine, Division of Hematology, University of Utah, Salt Lake City, UT, 84112, USA.,Molecular Medicine Program, University of Utah, Salt Lake City, UT, 84112, USA.,Thermo Fisher Scientific, Waltham, MA, 02451, USA
| | - Melanie Kahle-Stephan
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Zentrum München, Ingolstädter Landstraße 1, 85764, Neuherberg, Germany.,Medizinische Hochschule Brandenburg Theodor Fontane Institut für Sozialmedizin und Epidemiologie, 14770, Brandenburg an der Havel, Germany
| | - Birgit Rathkolb
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Zentrum München, Ingolstädter Landstraße 1, 85764, Neuherberg, Germany.,German Center for Diabetes Research (DZD), Ingolstädter Landstraße 1, 85764, Neuherberg, Germany.,Institute of Molecular Animal Breeding and Biotechnology, Gene Center, Ludwig-Maximilians-Universität München, Feodor-Lynen Strasse 25, 81377, Munich, Germany
| | - Valerie Gailus-Durner
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Zentrum München, Ingolstädter Landstraße 1, 85764, Neuherberg, Germany
| | - Helmut Fuchs
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Zentrum München, Ingolstädter Landstraße 1, 85764, Neuherberg, Germany
| | - Eckhard Wolf
- Institute of Molecular Animal Breeding and Biotechnology, Gene Center, Ludwig-Maximilians-Universität München, Feodor-Lynen Strasse 25, 81377, Munich, Germany
| | - Jan Rozman
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Zentrum München, Ingolstädter Landstraße 1, 85764, Neuherberg, Germany.,German Center for Diabetes Research (DZD), Ingolstädter Landstraße 1, 85764, Neuherberg, Germany.,Czech Centre for Phenogenomics, Institute of Molecular Genetics of the Czech Academy of Sciences, Prumyslova, 595, 252 50 Vestec, Czech Republic
| | - Martin Hrabe de Angelis
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Zentrum München, Ingolstädter Landstraße 1, 85764, Neuherberg, Germany.,German Center for Diabetes Research (DZD), Ingolstädter Landstraße 1, 85764, Neuherberg, Germany.,Chair of Experimental Genetics, School of Life Science Weihenstephan, Technische Universität München, Alte Akademie 8, 85354, Freising, Germany
| | - Weiling Maggie Cai
- Department of Microbiology, National University of Singapore, Singapore, Singapore, 119077.,Antimicrobial Resistance Interdisciplinary Research Group (IRG), Singapore-MIT Alliance for Research and Technology, 1 CREATE Way, Singapore, Singapore, 138602.,Agilent Technologies, 1 Yishun Ave 7, Singapore, Singapore, 768923
| | - Malini Rajan
- Department of Medicine, Division of Hematology, University of Utah, Salt Lake City, UT, 84112, USA.,Molecular Medicine Program, University of Utah, Salt Lake City, UT, 84112, USA
| | - Jennifer Hu
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.,Celgene Corporation, 1616 Eastlake Ave East, Seattle, WA, 98102, USA
| | - Peter C Dedon
- Antimicrobial Resistance Interdisciplinary Research Group (IRG), Singapore-MIT Alliance for Research and Technology, 1 CREATE Way, Singapore, Singapore, 138602.,Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Elizabeth A Leibold
- Department of Medicine, Division of Hematology, University of Utah, Salt Lake City, UT, 84112, USA. .,Molecular Medicine Program, University of Utah, Salt Lake City, UT, 84112, USA. .,Department of Oncological Sciences, University of Utah, Salt Lake City, UT, 84112, USA.
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61
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Yambire KF, Rostosky C, Watanabe T, Pacheu-Grau D, Torres-Odio S, Sanchez-Guerrero A, Senderovich O, Meyron-Holtz EG, Milosevic I, Frahm J, West AP, Raimundo N. Impaired lysosomal acidification triggers iron deficiency and inflammation in vivo. eLife 2019; 8:51031. [PMID: 31793879 PMCID: PMC6917501 DOI: 10.7554/elife.51031] [Citation(s) in RCA: 120] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Accepted: 12/02/2019] [Indexed: 12/21/2022] Open
Abstract
Lysosomal acidification is a key feature of healthy cells. Inability to maintain lysosomal acidic pH is associated with aging and neurodegenerative diseases. However, the mechanisms elicited by impaired lysosomal acidification remain poorly understood. We show here that inhibition of lysosomal acidification triggers cellular iron deficiency, which results in impaired mitochondrial function and non-apoptotic cell death. These effects are recovered by supplying iron via a lysosome-independent pathway. Notably, iron deficiency is sufficient to trigger inflammatory signaling in cultured primary neurons. Using a mouse model of impaired lysosomal acidification, we observed a robust iron deficiency response in the brain, verified by in vivo magnetic resonance imaging. Furthermore, the brains of these mice present a pervasive inflammatory signature associated with instability of mitochondrial DNA (mtDNA), both corrected by supplementation of the mice diet with iron. Our results highlight a novel mechanism linking impaired lysosomal acidification, mitochondrial malfunction and inflammation in vivo.
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Affiliation(s)
- King Faisal Yambire
- Institute of Cellular Biochemistry, University Medical Center Goettingen, Goettingen, Germany
| | - Christine Rostosky
- European Neuroscience Institute, a Joint Initiative of the Max-Planck Institute and of the University Medical Center Goettingen, Goettingen, Germany
| | - Takashi Watanabe
- Biomedizinische NMR, Max-Planck Institute for Biophysical Chemistry, Goettingen, Germany
| | - David Pacheu-Grau
- Institute of Cellular Biochemistry, University Medical Center Goettingen, Goettingen, Germany
| | - Sylvia Torres-Odio
- Department of Microbial Pathogenesis and Immunology, Texas A&M University Health Science Center, Austin, United States
| | - Angela Sanchez-Guerrero
- Institute of Cellular Biochemistry, University Medical Center Goettingen, Goettingen, Germany.,European Neuroscience Institute, a Joint Initiative of the Max-Planck Institute and of the University Medical Center Goettingen, Goettingen, Germany
| | - Ola Senderovich
- Faculty of Biotechnology and Food Engineering, Technion Israel Institute of Technology, Haifa, Israel
| | - Esther G Meyron-Holtz
- Faculty of Biotechnology and Food Engineering, Technion Israel Institute of Technology, Haifa, Israel
| | - Ira Milosevic
- European Neuroscience Institute, a Joint Initiative of the Max-Planck Institute and of the University Medical Center Goettingen, Goettingen, Germany
| | - Jens Frahm
- Biomedizinische NMR, Max-Planck Institute for Biophysical Chemistry, Goettingen, Germany
| | - A Phillip West
- Department of Microbial Pathogenesis and Immunology, Texas A&M University Health Science Center, Austin, United States
| | - Nuno Raimundo
- Institute of Cellular Biochemistry, University Medical Center Goettingen, Goettingen, Germany
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62
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Patra S, Barondeau DP. Mechanism of activation of the human cysteine desulfurase complex by frataxin. Proc Natl Acad Sci U S A 2019; 116:19421-19430. [PMID: 31511419 PMCID: PMC6765240 DOI: 10.1073/pnas.1909535116] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The function of frataxin (FXN) has garnered great scientific interest since its depletion was linked to the incurable neurodegenerative disease Friedreich's ataxia (FRDA). FXN has been shown to be necessary for iron-sulfur (Fe-S) cluster biosynthesis and proper mitochondrial function. The structural and functional core of the Fe-S cluster assembly complex is a low-activity pyridoxal 5'-phosphate (PLP)-dependent cysteine desulfurase enzyme that consists of catalytic (NFS1), LYRM protein (ISD11), and acyl carrier protein (ACP) subunits. Although previous studies show that FXN stimulates the activity of this assembly complex, the mechanism of FXN activation is poorly understood. Here, we develop a radiolabeling assay and use stopped-flow kinetics to establish that FXN is functionally linked to the mobile S-transfer loop cysteine of NFS1. Our results support key roles for this essential cysteine residue in substrate binding, as a general acid to advance the Cys-quinonoid PLP intermediate, as a nucleophile to form an NFS1 persulfide, and as a sulfur delivery agent to generate a persulfide species on the Fe-S scaffold protein ISCU2. FXN specifically accelerates each of these individual steps in the mechanism. Our resulting architectural switch model explains why the human Fe-S assembly system has low inherent activity and requires activation, the connection between the functional mobile S-transfer loop cysteine and FXN binding, and why the prokaryotic system does not require a similar FXN-based activation. Together, these results provide mechanistic insights into the allosteric-activator role of FXN and suggest new strategies to replace FXN function in the treatment of FRDA.
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Affiliation(s)
- Shachin Patra
- Department of Chemistry, Texas A&M University, College Station, TX 77842
| | - David P Barondeau
- Department of Chemistry, Texas A&M University, College Station, TX 77842
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63
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Wachnowsky C, Hendricks AL, Wesley NA, Ferguson C, Fidai I, Cowan JA. Understanding the Mechanism of [4Fe-4S] Cluster Assembly on Eukaryotic Mitochondrial and Cytosolic Aconitase. Inorg Chem 2019; 58:13686-13695. [PMID: 31436962 DOI: 10.1021/acs.inorgchem.9b01278] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Iron-sulfur (Fe-S) clusters are common prosthetic groups that are found within a variety of proteins responsible for functions that include electron transfer, regulation of gene expression, and substrate binding and activation. Acquisition of a [4Fe-4S] cluster is essential for the functionality of many such roles, and dysfunctions in Fe-S cluster synthesis and trafficking often result in human disease, such as multiple mitochondrial dysfunctions syndrome. While the topic of [2Fe-2S] cluster biosynthesis and trafficking has been relatively well studied, the understanding of such processes involving [4Fe-4S] centers is less developed. Herein, we focus on the mechanism of the assembly of [4Fe-4S] clusters on two members of the aconitase family, differing also in organelle placement (mitochondrion and cytosol) and biochemical function. Two mechanistic models are evaluated by a combination of kinetic and spectroscopic models, namely, a consecutive model (I), in which two [2Fe-2S] clusters are sequentially delivered to the target, and a prereaction equilibrium model (II), in which a [4Fe-4S] cluster transiently forms on a donor protein before transfer to the target. The paper also addresses the issue of cluster nuclearity for functionally active forms of ISCU, NFU, and ISCA trafficking proteins, each of which has been postulated to exist in both [2Fe-2S] and [4Fe-4S] bound states. By the application of kinetic assays and electron paramagnetic resonance spectroscopy to examine delivery pathways from a variety of potential [2Fe-2S] donor proteins to eukaryotic forms of both aconitase and iron regulatory protein, we conclude that a consecutive model following the delivery of [2Fe-2S] clusters from NFU1 is the most likely mechanism for these target proteins.
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Affiliation(s)
- Christine Wachnowsky
- Department of Chemistry and Biochemistry , The Ohio State University , 100 West 18th Avenue , Columbus , Ohio 43210 , United States.,The Ohio State Biochemistry Program , The Ohio State University , 484 West 12th Avenue , Columbus , Ohio 43210 , United States
| | - Amber L Hendricks
- Department of Chemistry and Biochemistry , The Ohio State University , 100 West 18th Avenue , Columbus , Ohio 43210 , United States
| | - Nathaniel A Wesley
- Department of Chemistry and Biochemistry , The Ohio State University , 100 West 18th Avenue , Columbus , Ohio 43210 , United States
| | - Connor Ferguson
- Department of Chemistry and Biochemistry , The Ohio State University , 100 West 18th Avenue , Columbus , Ohio 43210 , United States
| | - Insiya Fidai
- Department of Chemistry and Biochemistry , The Ohio State University , 100 West 18th Avenue , Columbus , Ohio 43210 , United States.,The Biophysics Graduate Program , The Ohio State University , 484 West 12th Avenue , Columbus , Ohio 43210 , United States
| | - J A Cowan
- Department of Chemistry and Biochemistry , The Ohio State University , 100 West 18th Avenue , Columbus , Ohio 43210 , United States.,The Ohio State Biochemistry Program , The Ohio State University , 484 West 12th Avenue , Columbus , Ohio 43210 , United States.,The Biophysics Graduate Program , The Ohio State University , 484 West 12th Avenue , Columbus , Ohio 43210 , United States
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64
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Abstract
Organisms from all kingdoms of life use iron-proteins in a multitude of functional processes. We applied a bioinformatics approach to investigate the human portfolio of iron-proteins. We separated iron-proteins based on the chemical nature of their metal-containing cofactors: individual iron ions, heme cofactors and iron-sulfur clusters. We found that about 2% of human genes encode an iron-protein. Of these, 35% are proteins binding individual iron ions, 48% are heme-binding proteins and 17% are iron-sulfur proteins. More than half of the human iron-proteins have a catalytic function. Indeed, we predict that 6.5% of all human enzymes are iron-dependent. This percentage is quite different for the various enzyme classes. Human oxidoreductases feature the largest fraction of iron-dependent family members (about 37%). The distribution of iron proteins in the various cellular compartments is uneven. In particular, the mitochondrion and the endoplasmic reticulum are enriched in iron-proteins with respect to the average content of the cell. Finally, we observed that genes encoding iron-proteins are more frequently associated to pathologies than the all other human genes on average. The present research provides an extensive overview of iron usage by the human proteome, and highlights several specific features of the physiological role of iron ions in human cells.
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Affiliation(s)
- Claudia Andreini
- Magnetic Resonance Center, University of Florence, Via Luigi Sacconi 6, Sesto Fiorentino 50019, Italy.
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65
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Ubiquinone Biosynthesis over the Entire O 2 Range: Characterization of a Conserved O 2-Independent Pathway. mBio 2019; 10:mBio.01319-19. [PMID: 31289180 PMCID: PMC6747719 DOI: 10.1128/mbio.01319-19] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
In order to colonize environments with large O2 gradients or fluctuating O2 levels, bacteria have developed metabolic responses that remain incompletely understood. Such adaptations have been recently linked to antibiotic resistance, virulence, and the capacity to develop in complex ecosystems like the microbiota. Here, we identify a novel pathway for the biosynthesis of ubiquinone, a molecule with a key role in cellular bioenergetics. We link three uncharacterized genes of Escherichia coli to this pathway and show that the pathway functions independently from O2. In contrast, the long-described pathway for ubiquinone biosynthesis requires O2 as a substrate. In fact, we find that many proteobacteria are equipped with the O2-dependent and O2-independent pathways, supporting that they are able to synthesize ubiquinone over the entire O2 range. Overall, we propose that the novel O2-independent pathway is part of the metabolic plasticity developed by proteobacteria to face various environmental O2 levels. Most bacteria can generate ATP by respiratory metabolism, in which electrons are shuttled from reduced substrates to terminal electron acceptors, via quinone molecules like ubiquinone. Dioxygen (O2) is the terminal electron acceptor of aerobic respiration and serves as a co-substrate in the biosynthesis of ubiquinone. Here, we characterize a novel, O2-independent pathway for the biosynthesis of ubiquinone. This pathway relies on three proteins, UbiT (YhbT), UbiU (YhbU), and UbiV (YhbV). UbiT contains an SCP2 lipid-binding domain and is likely an accessory factor of the biosynthetic pathway, while UbiU and UbiV (UbiU-UbiV) are involved in hydroxylation reactions and represent a novel class of O2-independent hydroxylases. We demonstrate that UbiU-UbiV form a heterodimer, wherein each protein binds a 4Fe-4S cluster via conserved cysteines that are essential for activity. The UbiT, -U, and -V proteins are found in alpha-, beta-, and gammaproteobacterial clades, including several human pathogens, supporting the widespread distribution of a previously unrecognized capacity to synthesize ubiquinone in the absence of O2. Together, the O2-dependent and O2-independent ubiquinone biosynthesis pathways contribute to optimizing bacterial metabolism over the entire O2 range.
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66
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Barton JK, Silva RMB, O'Brien E. Redox Chemistry in the Genome: Emergence of the [4Fe4S] Cofactor in Repair and Replication. Annu Rev Biochem 2019; 88:163-190. [PMID: 31220976 PMCID: PMC6590699 DOI: 10.1146/annurev-biochem-013118-110644] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Many DNA-processing enzymes have been shown to contain a [4Fe4S] cluster, a common redox cofactor in biology. Using DNA electrochemistry, we find that binding of the DNA polyanion promotes a negative shift in [4Fe4S] cluster potential, which corresponds thermodynamically to a ∼500-fold increase in DNA-binding affinity for the oxidized [4Fe4S]3+ cluster versus the reduced [4Fe4S]2+ cluster. This redox switch can be activated from a distance using DNA charge transport (DNA CT) chemistry. DNA-processing proteins containing the [4Fe4S] cluster are enumerated, with possible roles for the redox switch highlighted. A model is described where repair proteins may signal one another using DNA-mediated charge transport as a first step in their search for lesions. The redox switch in eukaryotic DNA primases appears to regulate polymerase handoff, and in DNA polymerase δ, the redox switch provides a means to modulate replication in response to oxidative stress. We thus describe redox signaling interactions of DNA-processing [4Fe4S] enzymes, as well as the most interesting potential players to consider in delineating new DNA-mediated redox signaling networks.
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Affiliation(s)
- Jacqueline K Barton
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, USA;
| | - Rebekah M B Silva
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, USA;
| | - Elizabeth O'Brien
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, USA;
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67
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Das D, Patra S, Bridwell-Rabb J, Barondeau DP. Mechanism of frataxin "bypass" in human iron-sulfur cluster biosynthesis with implications for Friedreich's ataxia. J Biol Chem 2019; 294:9276-9284. [PMID: 30975898 PMCID: PMC6556584 DOI: 10.1074/jbc.ra119.007716] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Revised: 04/10/2019] [Indexed: 11/06/2022] Open
Abstract
In humans, mitochondrial iron-sulfur cluster biosynthesis is an essential biochemical process mediated by the assembly complex consisting of cysteine desulfurase (NFS1), LYR protein (ISD11), acyl-carrier protein (ACP), and the iron-sulfur cluster assembly scaffold protein (ISCU2). The protein frataxin (FXN) is an allosteric activator that binds the assembly complex and stimulates the cysteine desulfurase and iron-sulfur cluster assembly activities. FXN depletion causes loss of activity of iron-sulfur-dependent enzymes and the development of the neurodegenerative disease Friedreich's ataxia. Recently, a mutation that suppressed the loss of the FXN homolog in Saccharomyces cerevisiae was identified that encodes an amino acid substitution equivalent to the human variant ISCU2 M140I. Here, we developed iron-sulfur cluster synthesis and transfer functional assays and determined that the human ISCU2 M140I variant can substitute for FXN in accelerating the rate of iron-sulfur cluster formation on the monothiol glutaredoxin (GRX5) acceptor protein. Incorporation of both FXN and the M140I substitution had an additive effect, suggesting an acceleration of distinct steps in iron-sulfur cluster biogenesis. In contrast to the canonical role of FXN in stimulating the formation of [2Fe-2S]-ISCU2 intermediates, we found here that the M140I substitution in ISCU2 promotes the transfer of iron-sulfur clusters to GRX5. Together, these results reveal an unexpected mechanism that replaces FXN-based stimulation of the iron-sulfur cluster biosynthetic pathway and suggest new strategies to overcome the loss of cellular FXN that may be relevant to the development of therapeutics for Friedreich's ataxia.
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Affiliation(s)
- Deepika Das
- From the Department of Chemistry, Texas A & M University, College Station, Texas 77842
| | - Shachin Patra
- From the Department of Chemistry, Texas A & M University, College Station, Texas 77842
| | | | - David P Barondeau
- From the Department of Chemistry, Texas A & M University, College Station, Texas 77842
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68
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Pandey AK, Pain J, Dancis A, Pain D. Mitochondria export iron-sulfur and sulfur intermediates to the cytoplasm for iron-sulfur cluster assembly and tRNA thiolation in yeast. J Biol Chem 2019; 294:9489-9502. [PMID: 31040179 DOI: 10.1074/jbc.ra119.008600] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2019] [Revised: 04/26/2019] [Indexed: 12/28/2022] Open
Abstract
Iron-sulfur clusters are essential cofactors of proteins. In eukaryotes, iron-sulfur cluster biogenesis requires a mitochondrial iron-sulfur cluster machinery (ISC) and a cytoplasmic iron-sulfur protein assembly machinery (CIA). Here we used mitochondria and cytoplasm isolated from yeast cells, and [35S]cysteine to detect cytoplasmic Fe-35S cluster assembly on a purified apoprotein substrate. We showed that mitochondria generate an intermediate, called (Fe-S)int, needed for cytoplasmic iron-sulfur cluster assembly. The mitochondrial biosynthesis of (Fe-S)int required ISC components such as Nfs1 cysteine desulfurase, Isu1/2 scaffold, and Ssq1 chaperone. Mitochondria then exported (Fe-S)int via the Atm1 transporter in the inner membrane, and we detected (Fe-S)int in active form. When (Fe-S)int was added to cytoplasm, CIA utilized it for iron-sulfur cluster assembly without any further help from the mitochondria. We found that both iron and sulfur for cytoplasmic iron-sulfur cluster assembly originate from the mitochondria, revealing a surprising and novel mitochondrial role. Mitochondrial (Fe-S)int export was most efficient in the presence of cytoplasm containing an apoprotein substrate, suggesting that mitochondria respond to the cytoplasmic demand for iron-sulfur cluster synthesis. Of note, the (Fe-S)int is distinct from the sulfur intermediate called Sint, which is also made and exported by mitochondria but is instead used for cytoplasmic tRNA thiolation. In summary, our findings establish a direct and vital role of mitochondria in cytoplasmic iron-sulfur cluster assembly in yeast cells.
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Affiliation(s)
- Ashutosh K Pandey
- From the Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School, Rutgers University, Newark, New Jersey 07103 and
| | - Jayashree Pain
- From the Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School, Rutgers University, Newark, New Jersey 07103 and
| | - Andrew Dancis
- the Department of Medicine, Division of Hematology-Oncology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Debkumar Pain
- From the Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School, Rutgers University, Newark, New Jersey 07103 and
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69
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TLR-activated repression of Fe-S cluster biogenesis drives a metabolic shift and alters histone and tubulin acetylation. Blood Adv 2019; 2:1146-1156. [PMID: 29784770 DOI: 10.1182/bloodadvances.2018015669] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2018] [Accepted: 04/21/2018] [Indexed: 12/16/2022] Open
Abstract
Given the essential roles of iron-sulfur (Fe-S) cofactors in mediating electron transfer in the mitochondrial respiratory chain and supporting heme biosynthesis, mitochondrial dysfunction is a common feature in a growing list of human Fe-S cluster biogenesis disorders, including Friedreich ataxia and GLRX5-related sideroblastic anemia. Here, our studies showed that restriction of Fe-S cluster biogenesis not only compromised mitochondrial oxidative metabolism but also resulted in decreased overall histone acetylation and increased H3K9me3 levels in the nucleus and increased acetylation of α-tubulin in the cytosol by decreasing the lipoylation of the pyruvate dehydrogenase complex, decreasing levels of succinate dehydrogenase and the histone acetyltransferase ELP3, and increasing levels of the tubulin acetyltransferase MEC17. Previous studies have shown that the metabolic shift in Toll-like receptor (TLR)-activated myeloid cells involves rapid activation of glycolysis and subsequent mitochondrial respiratory failure due to nitric oxide (NO)-mediated damage to Fe-S proteins. Our studies indicated that TLR activation also actively suppresses many components of the Fe-S cluster biogenesis machinery, which exacerbates NO-mediated damage to Fe-S proteins by interfering with cluster recovery. These results reveal new regulatory pathways and novel roles of the Fe-S cluster biogenesis machinery in modifying the epigenome and acetylome and provide new insights into the etiology of Fe-S cluster biogenesis disorders.
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70
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Rouault TA. The indispensable role of mammalian iron sulfur proteins in function and regulation of multiple diverse metabolic pathways. Biometals 2019; 32:343-353. [PMID: 30923992 PMCID: PMC6584224 DOI: 10.1007/s10534-019-00191-7] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Accepted: 03/18/2019] [Indexed: 02/07/2023]
Abstract
In recent years, iron sulfur (Fe–S) proteins have been identified as key players in mammalian metabolism, ranging from long-known roles in the respiratory complexes and the citric acid cycle, to more recently recognized roles in RNA and DNA metabolism. Fe–S cofactors have often been missed because of their intrinsic lability and oxygen sensitivity. More Fe–S proteins have now been identified owing to detection of their direct interactions with components of the Fe–S biogenesis machinery, and through use of informatics to detect a motif that binds the co-chaperone responsible for transferring nascent Fe–S clusters to domains of recipient proteins. Dissection of the molecular steps involved in Fe–S transfer to Fe–S proteins has revealed that direct and shielded transfer occurs through highly conserved pathways that operate in parallel in the mitochondrial matrix and in the cytosolic/nuclear compartments of eukaryotic cells. Because Fe–S clusters have the unusual ability to accept or donate single electrons in chemical reactions, their presence renders complex chemical reactions possible. In addition, Fe–S clusters may function as sensors that interconnect activity of metabolic pathways with cellular redox status. Presence in pathways that control growth and division may enable cells to regulate their growth according to sufficiency of energy stores represented by redox capacity, and oxidation of such proteins could diminish anabolic activities to give cells an opportunity to restore energy supplies. This review will discuss mechanisms of Fe–S biogenesis and delivery, and methods that will likely reveal important roles of Fe–S proteins in proteins not yet recognized as Fe–S proteins.
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71
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Kato T, Kumazaki K, Wada M, Taniguchi R, Nakane T, Yamashita K, Hirata K, Ishitani R, Ito K, Nishizawa T, Nureki O. Crystal structure of plant vacuolar iron transporter VIT1. NATURE PLANTS 2019; 5:308-315. [PMID: 30742036 DOI: 10.1038/s41477-019-0367-2] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2018] [Accepted: 01/11/2019] [Indexed: 06/09/2023]
Abstract
The iron ion is an essential cofactor in several vital enzymatic reactions, such as DNA replication, oxygen transport, and respiratory and photosynthetic electron transfer chains, but its excess accumulation induces oxidative stress in cells. Vacuolar iron transporter 1 (VIT1) is important for iron homeostasis in plants, by transporting cytoplasmic ferrous ions into vacuoles. Modification of the VIT1 gene leads to increased iron content in crops, which could be used for the treatment of human iron deficiency diseases. Furthermore, a VIT1 from the malaria-causing parasite Plasmodium is considered as a potential drug target for malaria. Here we report the crystal structure of VIT1 from rose gum Eucalyptus grandis, which probably functions as a H+-dependent antiporter for Fe2+ and other transition metal ions. VIT1 adopts a novel protein fold forming a dimer of five membrane-spanning domains, with an ion-translocating pathway constituted by the conserved methionine and carboxylate residues at the dimer interface. The second transmembrane helix protrudes from the lipid membrane by about 40 Å and connects to a three-helical bundle, triangular cytoplasmic domain, which binds to the substrate metal ions and stabilizes their soluble form, thus playing an essential role in their transport. These mechanistic insights will provide useful information for the further design of genetically modified crops and the development of anti-malaria drugs.
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Affiliation(s)
- Takafumi Kato
- Department of Biological Science, Graduate School of Science, The University of Tokyo, Tokyo, Japan
| | - Kaoru Kumazaki
- Department of Biological Science, Graduate School of Science, The University of Tokyo, Tokyo, Japan
| | - Miki Wada
- Department of computational biology and medical sciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, Japan
| | - Reiya Taniguchi
- Department of Biological Science, Graduate School of Science, The University of Tokyo, Tokyo, Japan
| | - Takanori Nakane
- Department of Biological Science, Graduate School of Science, The University of Tokyo, Tokyo, Japan
- Structural Studies Division, MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, UK
| | | | - Kunio Hirata
- RIKEN SPring-8 Center, Sayo, Japan
- Precursory Research for Embryonic Science and Technology , Japan Science and Technology Agency, Kawaguchi, Japan
| | - Ryuichiro Ishitani
- Department of Biological Science, Graduate School of Science, The University of Tokyo, Tokyo, Japan
| | - Koichi Ito
- Department of computational biology and medical sciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, Japan
| | - Tomohiro Nishizawa
- Department of Biological Science, Graduate School of Science, The University of Tokyo, Tokyo, Japan.
- Precursory Research for Embryonic Science and Technology , Japan Science and Technology Agency, Kawaguchi, Japan.
| | - Osamu Nureki
- Department of Biological Science, Graduate School of Science, The University of Tokyo, Tokyo, Japan.
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72
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Gourdoupis S, Nasta V, Ciofi-Baffoni S, Banci L, Calderone V. In-house high-energy-remote SAD phasing using the magic triangle: how to tackle the P1 low symmetry using multiple orientations of the same crystal of human IBA57 to increase the multiplicity. ACTA CRYSTALLOGRAPHICA SECTION D-STRUCTURAL BIOLOGY 2019; 75:317-324. [DOI: 10.1107/s2059798319000214] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Accepted: 01/04/2019] [Indexed: 11/10/2022]
Abstract
This article describes the approach used to solve the structure of human IBA57 in-house by 5-amino-2,4,6-triiodoisophthalic acid (I3C) high-energy-remote single-wavelength anomalous dispersion (SAD) phasing. Multiple orientations of the same triclinic crystal were exploited to acquire sufficient real data multiplicity for phasing. How the collection of an in-house native data set and its joint use with the I3C derivative through a SIRAS approach decreases the data multiplicity needed by almost 50% is described. Furthermore, it is illustrated that there is a clear data-multiplicity threshold value for success and failure in phasing, and how adding further data does not significantly affect substructure solution and model building. To our knowledge, this is the only structure present in the PDB that has been solved in-house by remote SAD phasing in space group P1 using only one crystal. All of the raw data used, derived from the different orientations, have been uploaded to Zenodo in order to enable software developers to improve methods for data processing and structure solution, and for educational purposes.
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73
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Schatton D, Rugarli EI. A concert of RNA-binding proteins coordinates mitochondrial function. Crit Rev Biochem Mol Biol 2019; 53:652-666. [DOI: 10.1080/10409238.2018.1553927] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Désirée Schatton
- Institute for Genetics and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
| | - Elena I. Rugarli
- Institute for Genetics and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
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74
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Depletion of thiol reducing capacity impairs cytosolic but not mitochondrial iron-sulfur protein assembly machineries. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2019; 1866:240-251. [DOI: 10.1016/j.bbamcr.2018.11.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2018] [Revised: 11/01/2018] [Accepted: 11/06/2018] [Indexed: 02/07/2023]
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75
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Tse EM, Zwang TJ, Bedoya S, Barton JK. Effective Distance for DNA-Mediated Charge Transport between Repair Proteins. ACS CENTRAL SCIENCE 2019; 5:65-72. [PMID: 30693326 PMCID: PMC6346725 DOI: 10.1021/acscentsci.8b00566] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Indexed: 05/23/2023]
Abstract
The stacked aromatic base pairs within the DNA double helix facilitate charge transport down its length in the absence of lesions, mismatches, and other stacking perturbations. DNA repair proteins containing [4Fe4S] clusters can take advantage of DNA charge transport (CT) chemistry to scan the genome for mistakes more efficiently. Here we examine the effective length over which charge can be transported along DNA between these repair proteins. We define the effective CT distance as the length of DNA within which two proteins are able to influence their ensemble affinity to the DNA duplex via CT. Endonuclease III, a DNA repair glycosylase containing a [4Fe4S] cluster, was incubated with DNA duplexes of different lengths (1.5-9 kb), and atomic force microscopy was used to quantify the binding of proteins to these duplexes to determine how the relative protein affinity changes with increasing DNA length. A sharp change in binding slope is observed at 3509 base pairs, or about 1.2 μm, that supports the existence of two regimes for protein binding, one within the range for DNA CT, one outside of the range for CT; DNA CT between the redox proteins bound to DNA effectively decreases the ensemble binding affinity of oxidized and reduced proteins to DNA. Utilizing an Endonuclease III mutant Y82A, which is defective in carrying out DNA CT, shows only one regime for protein binding. Decreasing the temperature to 4 °C or including metallointercalators on the duplex, both of which should enhance base stacking and decrease DNA floppiness, leads to extending the effective length for DNA charge transport to ∼5300 bp or 1.8 μm. These results thus support DNA charge transport between repair proteins over kilobase distances. The results furthermore highlight the ability of DNA repair proteins to search the genome quickly and efficiently using DNA charge transport chemistry.
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76
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Abstract
The general framework of pathways by which iron-sulfur (Fe-S) clusters are assembled in cells is well-known, but the cellular consequences of disruptions to that framework are not fully understood. Crooks et al. report a novel cellular system that creates an acute Fe-S cluster deficiency, using mutants of ISCU, the main scaffold protein for Fe-S cluster assembly. Surprisingly, the resultant metabolic reprogramming leads to the accumulation of lipid droplets, a situation encountered in many poorly understood pathological conditions, highlighting unanticipated links between Fe-S assembly machinery and human disease.
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Affiliation(s)
- Olivier Berteau
- Micalis Institute, ChemSyBio, INRA, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France.
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77
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Strangers in strange lands: mitochondrial proteins found at extra-mitochondrial locations. Biochem J 2019; 476:25-37. [DOI: 10.1042/bcj20180473] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Revised: 11/23/2018] [Accepted: 11/27/2018] [Indexed: 12/18/2022]
Abstract
Abstract
The mitochondrial proteome is estimated to contain ∼1100 proteins, the vast majority of which are nuclear-encoded, with only 13 proteins encoded by the mitochondrial genome. The import of these nuclear-encoded proteins into mitochondria was widely believed to be unidirectional, but recent discoveries have revealed that many these ‘mitochondrial’ proteins are exported, and have extra-mitochondrial activities divergent from their mitochondrial function. Surprisingly, three of the exported proteins discovered thus far are mitochondrially encoded and have significantly different extra-mitochondrial roles than those performed within the mitochondrion. In this review, we will detail the wide variety of proteins once thought to only reside within mitochondria, but now known to ‘emigrate’ from mitochondria in order to attain ‘dual citizenship’, present both within mitochondria and elsewhere.
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78
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Jain A, Dashner ZS, Connolly EL. Mitochondrial Iron Transporters (MIT1 and MIT2) Are Essential for Iron Homeostasis and Embryogenesis in Arabidopsis thaliana. FRONTIERS IN PLANT SCIENCE 2019; 10:1449. [PMID: 31850005 PMCID: PMC6889801 DOI: 10.3389/fpls.2019.01449] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2019] [Accepted: 10/17/2019] [Indexed: 05/08/2023]
Abstract
Iron (Fe) is an essential nutrient for virtually all organisms, where it functions in critical electron transfer processes, like those involved in respiration. Photosynthetic organisms have special requirements for Fe due to its importance in photosynthesis. While the importance of Fe for mitochondria- and chloroplast-localized processes is clear, our understanding of the molecular mechanisms that underlie the trafficking of Fe to these compartments is not complete. Here, we describe the Arabidopsis mitochondrial iron transporters, MIT1 and MIT2, that belong to the mitochondrial carrier family (MCF) of transport proteins. MIT1 and MIT2 display considerable homology with known mitochondrial Fe transporters of other organisms. Expression of MIT1 or MIT2 rescues the phenotype of the yeast mrs3mrs4 mutant, which is defective in mitochondrial iron transport. Although the Arabidopsis mit1 and mit2 single mutants do not show any significant visible phenotypes, the double mutant mit1mit2 displays embryo lethality. Analysis of a mit1 -- /mit2 + - line revealed that MIT1 and MIT2 are essential for iron acquisition by mitochondria and proper mitochondrial function. In addition, loss of MIT function results in mislocalization of Fe, which in turn causes upregulation of the root high affinity Fe uptake pathway. Thus, MIT1 and MIT2 are required for the maintenance of both mitochondrial and whole plant Fe homeostasis, which, in turn, is important for the proper growth and development of the plant.
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Affiliation(s)
- Anshika Jain
- Department of Biological Sciences, University of South Carolina, Columbia, SC, United States
| | - Zachary S. Dashner
- Department of Plant Science, The Pennsylvania State University, University Park, PA, United States
| | - Erin L. Connolly
- Department of Biological Sciences, University of South Carolina, Columbia, SC, United States
- Department of Plant Science, The Pennsylvania State University, University Park, PA, United States
- *Correspondence: Erin L. Connolly,
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79
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Castro IH, Pignataro MF, Sewell KE, Espeche LD, Herrera MG, Noguera ME, Dain L, Nadra AD, Aran M, Smal C, Gallo M, Santos J. Frataxin Structure and Function. Subcell Biochem 2019; 93:393-438. [PMID: 31939159 DOI: 10.1007/978-3-030-28151-9_13] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Mammalian frataxin is a small mitochondrial protein involved in iron sulfur cluster assembly. Frataxin deficiency causes the neurodegenerative disease Friedreich's Ataxia. Valuable knowledge has been gained on the structural dynamics of frataxin, metal-ion-protein interactions, as well as on the effect of mutations on protein conformation, stability and internal motions. Additionally, laborious studies concerning the enzymatic reactions involved have allowed for understanding the capability of frataxin to modulate Fe-S cluster assembly function. Remarkably, frataxin biological function depends on its interaction with some proteins to form a supercomplex, among them NFS1 desulfurase and ISCU, the scaffolding protein. By combining multiple experimental tools including high resolution techniques like NMR and X-ray, but also SAXS, crosslinking and mass-spectrometry, it was possible to build a reliable model of the structure of the desulfurase supercomplex NFS1/ACP-ISD11/ISCU/frataxin. In this chapter, we explore these issues showing how the scientific view concerning frataxin structure-function relationships has evolved over the last years.
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Affiliation(s)
- Ignacio Hugo Castro
- Departamento de Fisiología y Biología Molecular y Celular, Facultad de Ciencia Exactas y Naturales, Instituto de Biociencias, Biotecnología y Biomedicina (iB3), Universidad de Buenos Aires, Intendente Güiraldes 2160-Ciudad Universitaria, 1428EGA, C.A.B.A, Argentina
- Intituto de Química y Fisicoquímica Biológicas, Dr. Alejandro Paladini Universidad de Buenos Aires, CONICET, Junín 956, 1113AAD, C.A.B.A, Argentina
| | - María Florencia Pignataro
- Departamento de Fisiología y Biología Molecular y Celular, Facultad de Ciencia Exactas y Naturales, Instituto de Biociencias, Biotecnología y Biomedicina (iB3), Universidad de Buenos Aires, Intendente Güiraldes 2160-Ciudad Universitaria, 1428EGA, C.A.B.A, Argentina
- Intituto de Química y Fisicoquímica Biológicas, Dr. Alejandro Paladini Universidad de Buenos Aires, CONICET, Junín 956, 1113AAD, C.A.B.A, Argentina
| | - Karl Ellioth Sewell
- Departamento de Fisiología y Biología Molecular y Celular, Facultad de Ciencia Exactas y Naturales, Instituto de Biociencias, Biotecnología y Biomedicina (iB3), Universidad de Buenos Aires, Intendente Güiraldes 2160-Ciudad Universitaria, 1428EGA, C.A.B.A, Argentina
- Intituto de Química y Fisicoquímica Biológicas, Dr. Alejandro Paladini Universidad de Buenos Aires, CONICET, Junín 956, 1113AAD, C.A.B.A, Argentina
| | - Lucía Daniela Espeche
- Departamento de Diagnóstico Genético, Centro Nacional de Genética Médica "Dr. Eduardo E. Castilla"-A.N.L.I.S, Av. Las Heras 2670, C1425ASQ, C.A.B.A, Argentina
| | - María Georgina Herrera
- Departamento de Fisiología y Biología Molecular y Celular, Facultad de Ciencia Exactas y Naturales, Instituto de Biociencias, Biotecnología y Biomedicina (iB3), Universidad de Buenos Aires, Intendente Güiraldes 2160-Ciudad Universitaria, 1428EGA, C.A.B.A, Argentina
| | - Martín Ezequiel Noguera
- Departamento de Fisiología y Biología Molecular y Celular, Facultad de Ciencia Exactas y Naturales, Instituto de Biociencias, Biotecnología y Biomedicina (iB3), Universidad de Buenos Aires, Intendente Güiraldes 2160-Ciudad Universitaria, 1428EGA, C.A.B.A, Argentina
- Intituto de Química y Fisicoquímica Biológicas, Dr. Alejandro Paladini Universidad de Buenos Aires, CONICET, Junín 956, 1113AAD, C.A.B.A, Argentina
- Departamento de Ciencia y Tecnología, Universidad Nacional de Quilmes, Roque Sáenz Peña 352, B1876BXD, Bernal, Provincia de Buenos Aires, Argentina
| | - Liliana Dain
- Departamento de Fisiología y Biología Molecular y Celular, Facultad de Ciencia Exactas y Naturales, Instituto de Biociencias, Biotecnología y Biomedicina (iB3), Universidad de Buenos Aires, Intendente Güiraldes 2160-Ciudad Universitaria, 1428EGA, C.A.B.A, Argentina
- Departamento de Diagnóstico Genético, Centro Nacional de Genética Médica "Dr. Eduardo E. Castilla"-A.N.L.I.S, Av. Las Heras 2670, C1425ASQ, C.A.B.A, Argentina
| | - Alejandro Daniel Nadra
- Departamento de Fisiología y Biología Molecular y Celular, Facultad de Ciencia Exactas y Naturales, Instituto de Biociencias, Biotecnología y Biomedicina (iB3), Universidad de Buenos Aires, Intendente Güiraldes 2160-Ciudad Universitaria, 1428EGA, C.A.B.A, Argentina
- Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales (IQUIBICEN), Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina
| | - Martín Aran
- Fundación Instituto Leloir E IIBBA-CONICET, Av. Patricias Argentinas 435, C1405BWE, Buenos Aires, Argentina
| | - Clara Smal
- Fundación Instituto Leloir E IIBBA-CONICET, Av. Patricias Argentinas 435, C1405BWE, Buenos Aires, Argentina
| | - Mariana Gallo
- IRBM Science Park S.p.A, Via Pontina km 30,600, 00071, Pomezia, RM, Italy
| | - Javier Santos
- Departamento de Fisiología y Biología Molecular y Celular, Facultad de Ciencia Exactas y Naturales, Instituto de Biociencias, Biotecnología y Biomedicina (iB3), Universidad de Buenos Aires, Intendente Güiraldes 2160-Ciudad Universitaria, 1428EGA, C.A.B.A, Argentina.
- Intituto de Química y Fisicoquímica Biológicas, Dr. Alejandro Paladini Universidad de Buenos Aires, CONICET, Junín 956, 1113AAD, C.A.B.A, Argentina.
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80
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Abstract
Eukaryotic DNA primases contain a [4Fe4S] cluster in the C-terminal domain of the p58 subunit (p58C) that affects substrate affinity but is not required for catalysis. We show that, in yeast primase, the cluster serves as a DNA-mediated redox switch governing DNA binding, just as in human primase. Despite a different structural arrangement of tyrosines to facilitate electron transfer between the DNA substrate and [4Fe4S] cluster, in yeast, mutation of tyrosines Y395 and Y397 alters the same electron transfer chemistry and redox switch. Mutation of conserved tyrosine 395 diminishes the extent of p58C participation in normal redox-switching reactions, whereas mutation of conserved tyrosine 397 causes oxidative cluster degradation to the [3Fe4S]+ species during p58C redox signaling. Switching between oxidized and reduced states in the presence of the Y397 mutations thus puts primase [4Fe4S] cluster integrity and function at risk. Consistent with these observations, we find that yeast tolerate mutations to Y395 in p58C, but the single-residue mutation Y397L in p58C is lethal. Our data thus show that a constellation of tyrosines for protein-DNA electron transfer mediates the redox switch in eukaryotic primases and is required for primase function in vivo.
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81
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O'Brien E, Holt ME, Salay LE, Chazin WJ, Barton JK. Substrate Binding Regulates Redox Signaling in Human DNA Primase. J Am Chem Soc 2018; 140:17153-17162. [PMID: 30433774 DOI: 10.1021/jacs.8b09914] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Generation of daughter strands during DNA replication requires the action of DNA primase to synthesize an initial short RNA primer on the single-stranded DNA template. Primase is a heterodimeric enzyme containing two domains whose activity must be coordinated during primer synthesis: an RNA polymerase domain in the small subunit (p48) and a [4Fe4S] cluster-containing C-terminal domain of the large subunit (p58C). Here we examine the redox switching properties of the [4Fe4S] cluster in the full p48/p58 heterodimer using DNA electrochemistry. Unlike with isolated p58C, robust redox signaling in the primase heterodimer requires binding of both DNA and NTPs; NTP binding shifts the p48/p58 cluster redox potential into the physiological range, generating a signal near 160 mV vs NHE. Preloading of primase with NTPs enhances catalytic activity on primed DNA, suggesting that primase configurations promoting activity are more highly populated in the NTP-bound protein. We propose that p48/p58 binding of anionic DNA and NTPs affects the redox properties of the [4Fe4S] cluster; this electrostatic change is likely influenced by the alignment of primase subunits during activity because the configuration affects the [4Fe4S] cluster environment and coupling to DNA bases for redox signaling. Thus, both binding of polyanionic substrates and configurational dynamics appear to influence [4Fe4S] redox signaling properties. These results suggest that these factors should be considered generally in characterizing signaling networks of large, multisubunit DNA-processing [4Fe4S] enzymes.
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Affiliation(s)
- Elizabeth O'Brien
- Division of Chemistry and Chemical Engineering , California Institute of Technology , Pasadena , California 91125 , United States
| | - Marilyn E Holt
- Departments of Biochemistry and Chemistry, Center for Structural Biology , Vanderbilt University , Nashville , Tennessee 37240 , United States
| | - Lauren E Salay
- Departments of Biochemistry and Chemistry, Center for Structural Biology , Vanderbilt University , Nashville , Tennessee 37240 , United States
| | - Walter J Chazin
- Departments of Biochemistry and Chemistry, Center for Structural Biology , Vanderbilt University , Nashville , Tennessee 37240 , United States
| | - Jacqueline K Barton
- Division of Chemistry and Chemical Engineering , California Institute of Technology , Pasadena , California 91125 , United States
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82
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Charge Transfer between [4Fe4S] Proteins and DNA Is Unidirectional: Implications for Biomolecular Signaling. Chem 2018; 5:122-137. [PMID: 30714018 DOI: 10.1016/j.chempr.2018.09.026] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Recent experiments suggest that DNA-mediated charge transport might enable signaling between the [4Fe4S] clusters in the C-terminal domains of human DNA primase and polymerase α, as well as the signaling between other replication and repair high-potential [4Fe4S] proteins. Our theoretical study demonstrates that the redox signaling cannot be accomplished exclusively by DNA-mediated charge transport because part of the charge transfer chain has an unfavorable free energy profile. We show that hole or excess electron transfer between a [4Fe4S] cluster and a nucleic acid duplex through a protein medium can occur within microseconds in one direction, while it is kinetically hindered in the opposite direction. We present a set of signaling mechanisms that may occur with the assistance of oxidants or reductants, using the allowed charge transfer processes. These mechanisms would enable the coordinated action of [4Fe4S] proteins on DNA, engaging the [4Fe4S] oxidation state dependence of the protein-DNA binding affinity.
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83
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Links Between Iron and Lipids: Implications in Some Major Human Diseases. Pharmaceuticals (Basel) 2018; 11:ph11040113. [PMID: 30360386 PMCID: PMC6315991 DOI: 10.3390/ph11040113] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Revised: 10/18/2018] [Accepted: 10/19/2018] [Indexed: 12/30/2022] Open
Abstract
Maintenance of iron homeostasis is critical to cellular health as both its excess and insufficiency are detrimental. Likewise, lipids, which are essential components of cellular membranes and signaling mediators, must also be tightly regulated to hinder disease progression. Recent research, using a myriad of model organisms, as well as data from clinical studies, has revealed links between these two metabolic pathways, but the mechanisms behind these interactions and the role these have in the progression of human diseases remains unclear. In this review, we summarize literature describing cross-talk between iron and lipid pathways, including alterations in cholesterol, sphingolipid, and lipid droplet metabolism in response to changes in iron levels. We discuss human diseases correlating with both iron and lipid alterations, including neurodegenerative disorders, and the available evidence regarding the potential mechanisms underlying how iron may promote disease pathogenesis. Finally, we review research regarding iron reduction techniques and their therapeutic potential in treating patients with these debilitating conditions. We propose that iron-mediated alterations in lipid metabolic pathways are involved in the progression of these diseases, but further research is direly needed to elucidate the mechanisms involved.
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84
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Gourdoupis S, Nasta V, Calderone V, Ciofi-Baffoni S, Banci L. IBA57 Recruits ISCA2 to Form a [2Fe-2S] Cluster-Mediated Complex. J Am Chem Soc 2018; 140:14401-14412. [DOI: 10.1021/jacs.8b09061] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Spyridon Gourdoupis
- Magnetic Resonance Center CERM, University of Florence, Via Luigi Sacconi 6, 50019 Sesto Fiorentino, Florence, Italy
| | - Veronica Nasta
- Magnetic Resonance Center CERM, University of Florence, Via Luigi Sacconi 6, 50019 Sesto Fiorentino, Florence, Italy
- Department of Chemistry, University of Florence, Via della Lastruccia 3, 50019 Sesto Fiorentino, Florence, Italy
| | - Vito Calderone
- Magnetic Resonance Center CERM, University of Florence, Via Luigi Sacconi 6, 50019 Sesto Fiorentino, Florence, Italy
- Department of Chemistry, University of Florence, Via della Lastruccia 3, 50019 Sesto Fiorentino, Florence, Italy
| | - Simone Ciofi-Baffoni
- Magnetic Resonance Center CERM, University of Florence, Via Luigi Sacconi 6, 50019 Sesto Fiorentino, Florence, Italy
- Department of Chemistry, University of Florence, Via della Lastruccia 3, 50019 Sesto Fiorentino, Florence, Italy
| | - Lucia Banci
- Magnetic Resonance Center CERM, University of Florence, Via Luigi Sacconi 6, 50019 Sesto Fiorentino, Florence, Italy
- Department of Chemistry, University of Florence, Via della Lastruccia 3, 50019 Sesto Fiorentino, Florence, Italy
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85
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Fox NG, Martelli A, Nabhan JF, Janz J, Borkowska O, Bulawa C, Yue WW. Zinc(II) binding on human wild-type ISCU and Met140 variants modulates NFS1 desulfurase activity. Biochimie 2018; 152:211-218. [PMID: 30031876 PMCID: PMC6098246 DOI: 10.1016/j.biochi.2018.07.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Accepted: 07/18/2018] [Indexed: 12/01/2022]
Abstract
Human de novo iron-sulfur (Fe-S) assembly complex consists of cysteine desulfurase NFS1, accessory protein ISD11, acyl carrier protein ACP, scaffold protein ISCU, and allosteric activator frataxin (FXN). FXN binds the NFS1-ISD11-ACP-ISCU complex (SDAU), to activate the desulfurase activity and Fe-S cluster biosynthesis. In the absence of FXN, the NFS1-ISD11-ACP (SDA) complex was reportedly inhibited by binding of recombinant ISCU. Recent studies also reported a substitution at position Met141 on the yeast ISCU orthologue Isu, to Ile, Leu, Val, or Cys, could bypass the requirement of FXN for Fe-S cluster biosynthesis and cell viability. Here, we show that recombinant human ISCU binds zinc(II) ion, as previously demonstrated with the E. coli orthologue IscU. Surprisingly, the relative proportion between zinc-bound and zinc-depleted forms varies among purification batches. Importantly the presence of zinc in ISCU impacts SDAU desulfurase activity. Indeed, removal of zinc(II) ion from ISCU causes a moderate but significant increase in activity compared to SDA alone, and FXN can activate both zinc-depleted and zinc-bound forms of ISCU complexed to SDA. Taking into consideration the inhibition of desulfurase activity by zinc-bound ISCU, we characterized wild type ISCU and the M140I, M140L, and M140V variants under both zinc-bound and zinc-depleted conditions, and did not observe significant differences in the biochemical and biophysical properties between wild-type and variants. Importantly, in the absence of FXN, ISCU variants behaved like wild-type and did not stimulate the desulfurase activity of the SDA complex. This study therefore identifies an important regulatory role for zinc-bound ISCU in modulation of the human Fe-S assembly system in vitro and reports no 'FXN bypass' effect on mutations at position Met140 in human ISCU. Furthermore, this study also calls for caution in interpreting studies involving recombinant ISCU by taking into consideration the influence of the bound zinc(II) ion on SDAU complex activity.
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Affiliation(s)
- Nicholas G Fox
- Structural Genomics Consortium, Nuffield Department of Clinical Medicine, University of Oxford, OX3 7DQ, UK
| | - Alain Martelli
- Pfizer Rare Disease Research Unit, Worldwide Research and Development, Pfizer Inc., 610 Main Street, Cambridge, MA, 02139, United States
| | - Joseph F Nabhan
- Pfizer Rare Disease Research Unit, Worldwide Research and Development, Pfizer Inc., 610 Main Street, Cambridge, MA, 02139, United States
| | - Jay Janz
- Pfizer Rare Disease Research Unit, Worldwide Research and Development, Pfizer Inc., 610 Main Street, Cambridge, MA, 02139, United States
| | - Oktawia Borkowska
- Structural Genomics Consortium, Nuffield Department of Clinical Medicine, University of Oxford, OX3 7DQ, UK
| | - Christine Bulawa
- Pfizer Rare Disease Research Unit, Worldwide Research and Development, Pfizer Inc., 610 Main Street, Cambridge, MA, 02139, United States.
| | - Wyatt W Yue
- Structural Genomics Consortium, Nuffield Department of Clinical Medicine, University of Oxford, OX3 7DQ, UK.
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86
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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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87
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Cai K, Frederick RO, Dashti H, Markley JL. Architectural Features of Human Mitochondrial Cysteine Desulfurase Complexes from Crosslinking Mass Spectrometry and Small-Angle X-Ray Scattering. Structure 2018; 26:1127-1136.e4. [PMID: 29983374 PMCID: PMC6082693 DOI: 10.1016/j.str.2018.05.017] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Revised: 04/16/2018] [Accepted: 05/24/2018] [Indexed: 11/19/2022]
Abstract
Cysteine desulfurase plays a central role in mitochondrial iron-sulfur cluster biogenesis by generating sulfur through the conversion of L-cysteine to L-alanine and by serving as the platform for assembling other components of the biosynthetic machinery, including ISCU, frataxin, and ferredoxin. The human mitochondrial cysteine desulfurase complex consists of two copies each of NFS1, ISD11, and acyl carrier protein. We describe results from chemical crosslinking coupled with tandem mass spectrometry and small-angle X-ray scattering studies that are consistent with a closed NFS1 dimer rather than an open one for both the cysteine desulfurase-ISCU and cysteine desulfurase-ISCU-frataxin complexes. We present a structural model for the cysteine desulfurase-ISCU-frataxin complex derived from chemical crosslinking restraints in conjunction with the recent crystal structure of the cysteine desulfurase-ISCU-zinc complex and distance constraints from nuclear magnetic resonance.
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Affiliation(s)
- Kai Cai
- Biochemistry Department, University of Wisconsin-Madison, 433 Babcock Drive, Madison, WI 53706, USA
| | - Ronnie O Frederick
- Biochemistry Department, University of Wisconsin-Madison, 433 Babcock Drive, Madison, WI 53706, USA
| | - Hesam Dashti
- Biochemistry Department, University of Wisconsin-Madison, 433 Babcock Drive, Madison, WI 53706, USA
| | - John L Markley
- Biochemistry Department, University of Wisconsin-Madison, 433 Babcock Drive, Madison, WI 53706, USA.
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88
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Pala ZR, Saxena V, Saggu GS, Garg S. Recent Advances in the [Fe-S] Cluster Biogenesis (SUF) Pathway Functional in the Apicoplast of Plasmodium. Trends Parasitol 2018; 34:800-809. [PMID: 30064903 DOI: 10.1016/j.pt.2018.05.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2018] [Revised: 05/26/2018] [Accepted: 05/31/2018] [Indexed: 10/28/2022]
Abstract
Iron-sulfur [Fe-S] clusters are one of the most ancient, ubiquitous, structurally and functionally versatile natural biosynthetic prosthetic groups required by various proteins involved in important metabolic processes. Genome mining and localization studies in Plasmodium have shown two evolutionarily distinct biogenesis pathways: the ISC pathway in mitochondria and the SUF pathway in the apicoplast. In recent years, the myriad efforts made to elucidate the SUF pathway have deciphered the role of various proteins involved in the pathway and their importance for the parasite life cycle in both asexual and sexual stages. This review aims to discuss recent research in the apicoplast [Fe-S] biogenesis pathway from Plasmodium to enhance our current understanding of parasite biology with an overall aim to identify gaps to strengthen our fight against malaria.
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Affiliation(s)
- Zarna Rajeshkumar Pala
- Department of Biological Sciences, Birla Institute of Technology and Science, Pilani, Pilani Campus, Rajasthan, India
| | - Vishal Saxena
- Department of Biological Sciences, Birla Institute of Technology and Science, Pilani, Pilani Campus, Rajasthan, India
| | - Gagandeep Singh Saggu
- Laboratory of Malaria and Vector Research, National Institute of Allergic and Infectious Diseases, National Institute of Health, Rockville, MD, USA
| | - Shilpi Garg
- Department of Biological Sciences, Birla Institute of Technology and Science, Pilani, Pilani Campus, Rajasthan, India.
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89
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Garza-Lombó C, Posadas Y, Quintanar L, Gonsebatt ME, Franco R. Neurotoxicity Linked to Dysfunctional Metal Ion Homeostasis and Xenobiotic Metal Exposure: Redox Signaling and Oxidative Stress. Antioxid Redox Signal 2018; 28:1669-1703. [PMID: 29402131 PMCID: PMC5962337 DOI: 10.1089/ars.2017.7272] [Citation(s) in RCA: 129] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
SIGNIFICANCE Essential metals such as copper, iron, manganese, and zinc play a role as cofactors in the activity of a wide range of processes involved in cellular homeostasis and survival, as well as during organ and tissue development. Throughout our life span, humans are also exposed to xenobiotic metals from natural and anthropogenic sources, including aluminum, arsenic, cadmium, lead, and mercury. It is well recognized that alterations in the homeostasis of essential metals and an increased environmental/occupational exposure to xenobiotic metals are linked to several neurological disorders, including neurodegeneration and neurodevelopmental alterations. Recent Advances: The redox activity of essential metals is key for neuronal homeostasis and brain function. Alterations in redox homeostasis and signaling are central to the pathological consequences of dysfunctional metal ion homeostasis and increased exposure to xenobiotic metals. Both redox-active and redox-inactive metals trigger oxidative stress and damage in the central nervous system, and the exact mechanisms involved are starting to become delineated. CRITICAL ISSUES In this review, we aim to appraise the role of essential metals in determining the redox balance in the brain and the mechanisms by which alterations in the homeostasis of essential metals and exposure to xenobiotic metals disturb the cellular redox balance and signaling. We focus on recent literature regarding their transport, metabolism, and mechanisms of toxicity in neural systems. FUTURE DIRECTIONS Delineating the specific mechanisms by which metals alter redox homeostasis is key to understand the pathological processes that convey chronic neuronal dysfunction in neurodegenerative and neurodevelopmental disorders. Antioxid. Redox Signal. 28, 1669-1703.
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Affiliation(s)
- Carla Garza-Lombó
- 1 Redox Biology Center and School of Veterinary Medicine and Biomedical Sciences, University of Nebraska-Lincoln , Lincoln, Nebraska.,2 Departamento de Medicina Genómica y Toxicología Ambiental, Instituto de Investigaciones Biomédicas , Universidad Nacional Autónoma de México, Mexico City, México
| | - Yanahi Posadas
- 3 Departamentos de Farmacología y de, Centro de Investigación y de Estudios Avanzados (CINVESTAV) , Mexico City, México .,4 Departamentos de Química, Centro de Investigación y de Estudios Avanzados (CINVESTAV) , Mexico City, México
| | - Liliana Quintanar
- 4 Departamentos de Química, Centro de Investigación y de Estudios Avanzados (CINVESTAV) , Mexico City, México
| | - María E Gonsebatt
- 2 Departamento de Medicina Genómica y Toxicología Ambiental, Instituto de Investigaciones Biomédicas , Universidad Nacional Autónoma de México, Mexico City, México
| | - Rodrigo Franco
- 1 Redox Biology Center and School of Veterinary Medicine and Biomedical Sciences, University of Nebraska-Lincoln , Lincoln, Nebraska
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90
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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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91
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Alsina D, Ros J, Tamarit J. Nitric oxide prevents Aft1 activation and metabolic remodeling in frataxin-deficient yeast. Redox Biol 2018; 14:131-141. [PMID: 28918000 PMCID: PMC5602528 DOI: 10.1016/j.redox.2017.09.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Revised: 08/25/2017] [Accepted: 09/02/2017] [Indexed: 11/30/2022] Open
Abstract
Yeast frataxin homolog (Yfh1) is the orthologue of human frataxin, a mitochondrial protein whose deficiency causes Friedreich Ataxia. Yfh1 deficiency activates Aft1, a transcription factor governing iron homeostasis in yeast cells. Although the mechanisms causing this activation are not completely understood, it is assumed that it may be caused by iron-sulfur deficiency. However, several evidences indicate that activation of Aft1 occurs in the absence of iron-sulfur deficiency. Besides, Yfh1 deficiency also leads to metabolic remodeling (mainly consisting in a shift from respiratory to fermentative metabolism) and to induction of Yhb1, a nitric oxide (NO) detoxifying enzyme. In this work, we have used conditional Yfh1 mutant yeast strains to investigate the relationship between NO, Aft1 activation and metabolic remodeling. We have observed that NO prevents Aft1 activation caused by Yfh1 deficiency. This phenomenon is not observed when Aft1 is activated by iron scarcity or impaired iron-sulfur biogenesis. In addition, analyzing key metabolic proteins by a targeted proteomics approach, we have observed that NO prevents the metabolic remodeling caused by Yfh1 deficiency. We conclude that Aft1 activation in Yfh1-deficient yeasts is not caused by iron-sulfur deficiency or iron scarcity. Our hypothesis is that Yfh1 deficiency leads to the presence of anomalous iron species that can compromise iron bioavailability and activate a signaling cascade that results in Aft1 activation and metabolic remodeling.
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Affiliation(s)
- David Alsina
- Departament de Ciències Mèdiques Bàsiques, IRBLleida, Universitat de Lleida, Lleida, Spain
| | - Joaquim Ros
- Departament de Ciències Mèdiques Bàsiques, IRBLleida, Universitat de Lleida, Lleida, Spain
| | - Jordi Tamarit
- Departament de Ciències Mèdiques Bàsiques, IRBLleida, Universitat de Lleida, Lleida, Spain.
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92
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Crooks DR, Maio N, Lane AN, Jarnik M, Higashi RM, Haller RG, Yang Y, Fan TWM, Linehan WM, Rouault TA. Acute loss of iron-sulfur clusters results in metabolic reprogramming and generation of lipid droplets in mammalian cells. J Biol Chem 2018. [PMID: 29523684 DOI: 10.1074/jbc.ra118.001885] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Iron-sulfur (Fe-S) clusters are ancient cofactors in cells and participate in diverse biochemical functions, including electron transfer and enzymatic catalysis. Although cell lines derived from individuals carrying mutations in the Fe-S cluster biogenesis pathway or siRNA-mediated knockdown of the Fe-S assembly components provide excellent models for investigating Fe-S cluster formation in mammalian cells, these experimental strategies focus on the consequences of prolonged impairment of Fe-S assembly. Here, we constructed and expressed dominant-negative variants of the primary Fe-S biogenesis scaffold protein iron-sulfur cluster assembly enzyme 2 (ISCU2) in human HEK293 cells. This approach enabled us to study the early metabolic reprogramming associated with loss of Fe-S-containing proteins in several major cellular compartments. Using multiple metabolomics platforms, we observed a ∼12-fold increase in intracellular citrate content in Fe-S-deficient cells, a surge that was due to loss of aconitase activity. The excess citrate was generated from glucose-derived acetyl-CoA, and global analysis of cellular lipids revealed that fatty acid biosynthesis increased markedly relative to cellular proliferation rates in Fe-S-deficient cells. We also observed intracellular lipid droplet accumulation in both acutely Fe-S-deficient cells and iron-starved cells. We conclude that deficient Fe-S biogenesis and acute iron deficiency rapidly increase cellular citrate concentrations, leading to fatty acid synthesis and cytosolic lipid droplet formation. Our findings uncover a potential cause of cellular steatosis in nonadipose tissues.
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Affiliation(s)
- Daniel R Crooks
- Urologic Oncology Branch, Center for Cancer Research, NCI, National Institutes of Health, Bethesda, Maryland 20892
| | - Nunziata Maio
- Section on Human Iron Metabolism, National Institutes of Health, Bethesda, Maryland 20892
| | - Andrew N Lane
- Center for Environmental and Systems Biochemistry, Department of Toxicology and Cancer Biology, and Markey Cancer Center, University of Kentucky, Lexington, Kentucky 40536
| | - Michal Jarnik
- Section on Cell Biology and Metabolism, Eunice Kennedy Shriver NICHD, National Institutes of Health, Bethesda, Maryland 20892
| | - Richard M Higashi
- Center for Environmental and Systems Biochemistry, Department of Toxicology and Cancer Biology, and Markey Cancer Center, University of Kentucky, Lexington, Kentucky 40536
| | - Ronald G Haller
- Department of Neurology, University of Texas Southwestern Medical Center, Dallas, Texas 75390; Veterans Affairs North Texas Medical Center, Dallas, Texas 75216; Neuromuscular Center, Institute for Exercise and Environmental Medicine, Dallas, Texas 75231
| | - Ye Yang
- Urologic Oncology Branch, Center for Cancer Research, NCI, National Institutes of Health, Bethesda, Maryland 20892
| | - Teresa W-M Fan
- Center for Environmental and Systems Biochemistry, Department of Toxicology and Cancer Biology, and Markey Cancer Center, University of Kentucky, Lexington, Kentucky 40536
| | - W Marston Linehan
- Urologic Oncology Branch, Center for Cancer Research, NCI, National Institutes of Health, Bethesda, Maryland 20892
| | - Tracey A Rouault
- Section on Human Iron Metabolism, National Institutes of Health, Bethesda, Maryland 20892.
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93
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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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94
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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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95
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Haskamp V, Karrie S, Mingers T, Barthels S, Alberge F, Magalon A, Müller K, Bill E, Lubitz W, Kleeberg K, Schweyen P, Bröring M, Jahn M, Jahn D. The radical SAM protein HemW is a heme chaperone. J Biol Chem 2018; 293:2558-2572. [PMID: 29282292 PMCID: PMC5818191 DOI: 10.1074/jbc.ra117.000229] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Revised: 12/14/2017] [Indexed: 11/06/2022] Open
Abstract
Radical S-adenosylmethionine (SAM) enzymes exist in organisms from all kingdoms of life, and all of these proteins generate an adenosyl radical via the homolytic cleavage of the S-C(5') bond of SAM. Of particular interest are radical SAM enzymes, such as heme chaperones, that insert heme into respiratory enzymes. For example, heme chaperones insert heme into target proteins but have been studied only for the formation of cytochrome c-type hemoproteins. Here, we report that a radical SAM protein, the heme chaperone HemW from bacteria, is required for the insertion of heme b into respiratory chain enzymes. As other radical SAM proteins, HemW contains three cysteines and one SAM coordinating an [4Fe-4S] cluster, and we observed one heme per subunit of HemW. We found that an intact iron-sulfur cluster was required for HemW dimerization and HemW-catalyzed heme transfer but not for stable heme binding. A bacterial two-hybrid system screen identified bacterioferritins and the heme-containing subunit NarI of the respiratory nitrate reductase NarGHI as proteins that interact with HemW. We also noted that the bacterioferritins potentially serve as heme donors for HemW. Of note, heme that was covalently bound to HemW was actively transferred to a heme-depleted, catalytically inactive nitrate reductase, restoring its nitrate-reducing enzyme activity. Finally, the human HemW orthologue radical SAM domain-containing 1 (RSAD1) stably bound heme. In conclusion, our findings indicate that the radical SAM protein family HemW/RSAD1 is a heme chaperone catalyzing the insertion of heme into hemoproteins.
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Affiliation(s)
| | | | | | | | - François Alberge
- Laboratoire de Chimie Bactérienne UMR7283, CNRS, Aix-Marseille Université, 13009 Marseille, France, and
| | - Axel Magalon
- Laboratoire de Chimie Bactérienne UMR7283, CNRS, Aix-Marseille Université, 13009 Marseille, France, and
| | | | - Eckhard Bill
- Max Planck Institute for Chemical Energy Conversion, D-45470 Mülheim an der Ruhr, Germany
| | - Wolfgang Lubitz
- Max Planck Institute for Chemical Energy Conversion, D-45470 Mülheim an der Ruhr, Germany
| | | | | | | | | | - Dieter Jahn
- Braunschweig Centre of Integrated Systems Biology (BRICS), University Braunschweig, D-38106 Braunschweig, Germany,
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96
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The unique fold and lability of the [2Fe-2S] clusters of NEET proteins mediate their key functions in health and disease. J Biol Inorg Chem 2018; 23:599-612. [PMID: 29435647 PMCID: PMC6006223 DOI: 10.1007/s00775-018-1538-8] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Accepted: 01/26/2018] [Indexed: 02/08/2023]
Abstract
NEET proteins comprise a new class of [2Fe-2S] cluster proteins. In human, three genes encode for NEET proteins: cisd1 encodes mitoNEET (mNT), cisd2 encodes the Nutrient-deprivation autophagy factor-1 (NAF-1) and cisd3 encodes MiNT (Miner2). These recently discovered proteins play key roles in many processes related to normal metabolism and disease. Indeed, NEET proteins are involved in iron, Fe-S, and reactive oxygen homeostasis in cells and play an important role in regulating apoptosis and autophagy. mNT and NAF-1 are homodimeric and reside on the outer mitochondrial membrane. NAF-1 also resides in the membranes of the ER associated mitochondrial membranes (MAM) and the ER. MiNT is a monomer with distinct asymmetry in the molecular surfaces surrounding the clusters. Unlike its paralogs mNT and NAF-1, it resides within the mitochondria. NAF-1 and mNT share similar backbone folds to the plant homodimeric NEET protein (At-NEET), while MiNT's backbone fold resembles a bacterial MiNT protein. Despite the variation of amino acid composition among these proteins, all NEET proteins retained their unique CDGSH domain harboring their unique 3Cys:1His [2Fe-2S] cluster coordination through evolution. The coordinating exposed His was shown to convey the lability to the NEET proteins' [2Fe-2S] clusters. In this minireview, we discuss the NEET fold and its structural elements. Special attention is given to the unique lability of the NEETs' [2Fe-2S] cluster and the implication of the latter to the NEET proteins' cellular and systemic function in health and disease.
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97
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Alaimo JT, Besse A, Alston CL, Pang K, Appadurai V, Samanta M, Smpokou P, McFarland R, Taylor RW, Bonnen PE. Loss-of-function mutations in ISCA2 disrupt 4Fe-4S cluster machinery and cause a fatal leukodystrophy with hyperglycinemia and mtDNA depletion. Hum Mutat 2018; 39:537-549. [PMID: 29297947 PMCID: PMC5839994 DOI: 10.1002/humu.23396] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2016] [Revised: 12/09/2017] [Accepted: 12/27/2017] [Indexed: 12/26/2022]
Abstract
Iron–sulfur (Fe–S) clusters are essential cofactors for proteins that participate in fundamental cellular processes including metabolism, DNA replication and repair, transcriptional regulation, and the mitochondrial electron transport chain (ETC). ISCA2 plays a role in the biogenesis of Fe–S clusters and a recent report described subjects displaying infantile‐onset leukodystrophy due to bi‐allelic mutation of ISCA2. We present two additional unrelated cases, and provide a more complete clinical description that includes hyperglycinemia, leukodystrophy of the brainstem with longitudinally extensive spinal cord involvement, and mtDNA deficiency. Additionally, we characterize the role of ISCA2 in mitochondrial bioenergetics and Fe–S cluster assembly using subject cells and ISCA2 cellular knockdown models. Loss of ISCA2 diminished mitochondrial membrane potential, the mitochondrial network, basal and maximal respiration, ATP production, and activity of ETC complexes II and IV. We specifically tested the impact of loss of ISCA2 on 2Fe–2S proteins versus 4Fe–4S proteins and observed deficits in the functioning of 4Fe–4S but not 2Fe–2S proteins. Together these data indicate loss of ISCA2 impaired function of 4Fe–4S proteins resulting in a fatal encephalopathy accompanied by a relatively unusual combination of features including mtDNA depletion alongside complex II deficiency and hyperglycinemia that may facilitate diagnosis of ISCA2 deficiency patients.
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Affiliation(s)
- Joseph T Alaimo
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas
| | - Arnaud Besse
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas
| | - Charlotte L Alston
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Newcastle upon Tyne, Tyne and Wear, UK
| | - Ki Pang
- Royal Victoria Infirmary, Great North Children's Hospital, Newcastle upon Tyne, Newcastle Upon Tyne, UK
| | - Vivek Appadurai
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas
| | - Monisha Samanta
- Division of Genetics & Metabolism, Children's National Health System, Washington, District of Columbia
| | - Patroula Smpokou
- Division of Genetics & Metabolism, Children's National Health System, Washington, District of Columbia.,Department of Pediatrics, The George Washington University School of Medicine and Health Sciences, Washington, District of Columbia
| | - Robert McFarland
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Newcastle upon Tyne, Tyne and Wear, UK
| | - Robert W Taylor
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Newcastle upon Tyne, Tyne and Wear, UK
| | - Penelope E Bonnen
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas
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98
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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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99
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Cytosolic Iron-Sulfur Assembly Is Evolutionarily Tuned by a Cancer-Amplified Ubiquitin Ligase. Mol Cell 2018; 69:113-125.e6. [DOI: 10.1016/j.molcel.2017.11.010] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Revised: 10/04/2017] [Accepted: 11/08/2017] [Indexed: 01/04/2023]
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100
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Tsai CL, Tainer JA. Robust Production, Crystallization, Structure Determination, and Analysis of [Fe-S] Proteins: Uncovering Control of Electron Shuttling and Gating in the Respiratory Metabolism of Molybdopterin Guanine Dinucleotide Enzymes. Methods Enzymol 2017; 599:157-196. [PMID: 29746239 DOI: 10.1016/bs.mie.2017.11.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
[Fe-S] clusters are essential cofactors in all domains of life. They play many biological roles due to their unique abilities for electron transfer and conformational control. Yet, producing and analyzing Fe-S proteins can be difficult and even misleading if not done anaerobically. Due to unique redox properties of [Fe-S] clusters and their oxygen sensitivity, they pose multiple challenges and can lose enzymatic activity or cause their component proteins to be structurally disordered due to [Fe-S] cluster oxidation and loss in air. Here we highlight tested protocols and strategies enabling efficient and stable [Fe-S] protein production, purification, crystallization, X-ray diffraction data collection, and structure determination. From multiple high-resolution anaerobic crystal structures, we furthermore analyze exemplary data defining [Fe-S] clusters, substrate entry, and product exit for the functional oxidation states of type II molybdo-bis(molybdopterin guanine dinucleotide) (Mo-bisMGD) enzymes. Notably, these enzymes perform electron shuttling between quinone pools and specific substrates to catalyze respiratory metabolism. The identified structure-activity relationships for this enzyme class have broad implications germane to perchlorate environments on Earth and Mars extending to an alternative mechanism underlying metabolic origins for the evolution of the oxygen atmosphere. Integrated structural analyses of type II Mo-bisMGD enzymes unveil novel distinctive shared molecular mechanisms for dynamic control of substrate entry and product release gated by hydrophobic residues. Collective findings support a prototypic model for type II Mo-bisMGD enzymes including insights for a fundamental molecular mechanistic understanding of selectivity and regulation by a conformationally gated channel with general implications for [Fe-S] cluster respiratory enzymes.
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Affiliation(s)
- Chi-Lin Tsai
- The University of Texas M. D. Anderson Cancer Center, Houston, TX, United States
| | - John A Tainer
- The University of Texas M. D. Anderson Cancer Center, Houston, TX, United States; Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA, United States.
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