1
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Flatt S, Busiello DM, Zamuner S, De Los Rios P. ABC transporters are billion-year-old Maxwell Demons. COMMUNICATIONS PHYSICS 2023; 6:205. [PMID: 38665399 PMCID: PMC11041718 DOI: 10.1038/s42005-023-01320-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Accepted: 07/26/2023] [Indexed: 04/28/2024]
Abstract
ATP-Binding Cassette (ABC) transporters are a broad family of biological machines, found in most prokaryotic and eukaryotic cells, performing the crucial import or export of substrates through both plasma and organellar membranes, and maintaining a steady concentration gradient driven by ATP hydrolysis. Building upon the present biophysical and biochemical characterization of ABC transporters, we propose here a model whose solution reveals that these machines are an exact molecular realization of the autonomous Maxwell Demon, a century-old abstract device that uses an energy source to drive systems away from thermodynamic equilibrium. In particular, the Maxwell Demon does not perform any direct mechanical work on the system, but simply selects which spontaneous processes to allow and which ones to forbid based on information that it collects and processes. In its autonomous version, the measurement device is embedded in the system itself. In the molecular model introduced here, the different operations that characterize Maxwell Demons (measurement, feedback, resetting) are features that emerge from the biochemical and structural properties of ABC transporters, revealing the crucial role of allostery to process information. Our framework allows us to develop an explicit bridge between the molecular-level description and the higher-level language of information theory for ABC transporters.
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Affiliation(s)
- Solange Flatt
- Institute of Physics, School of Basic Sciences, École Polytechnique Fédérale de Lausanne—EPFL, Lausanne, 1015 Switzerland
| | - Daniel Maria Busiello
- Institute of Physics, School of Basic Sciences, École Polytechnique Fédérale de Lausanne—EPFL, Lausanne, 1015 Switzerland
- Max Planck Institute for the Physics of Complex Systems, Dresden, 01187 Germany
| | - Stefano Zamuner
- Institute of Physics, School of Basic Sciences, École Polytechnique Fédérale de Lausanne—EPFL, Lausanne, 1015 Switzerland
| | - Paolo De Los Rios
- Institute of Physics, School of Basic Sciences, École Polytechnique Fédérale de Lausanne—EPFL, Lausanne, 1015 Switzerland
- Institute of Bioengineering, School of Life Sciences, École Polytechnique Fédérale de Lausanne—EPFL, Lausanne, 1015 Switzerland
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2
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Rottet S, Iqbal S, Xifaras R, Singer MT, Scott C, Deplazes E, Callaghan R. Biochemical interactions between the Atm1-like transporter from Novosphingobium aromaticivorans and heavy metals. Arch Biochem Biophys 2023:109696. [PMID: 37481198 DOI: 10.1016/j.abb.2023.109696] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 06/23/2023] [Accepted: 07/19/2023] [Indexed: 07/24/2023]
Abstract
Novosphingobium aromaticivorans has the ability to survive in harsh environments by virtue of its suite of iron-containing oxygenases that biodegrade an astonishing array of aromatic compounds. It is also resistant to heavy metals through Atm1, an ATP-binding cassette protein that mediates active efflux of heavy metals conjugated to glutathione. However, Atm1 orthologues in higher organisms have been implicated in the intracellular transport of organic iron complexes. Our hypothesis suggests that the ability of Atm1 to remove heavy metals is related to the need for regulated iron handling in N. aromaticivorans to support high oxygenase activity. Here we provide the first data demonstrating a direct interaction between an iron-porphyrin compound (hemin) and NaAtm1. Hemin displayed considerably higher binding affinity and lower EC50 to stimulate ATP hydrolysis by Atm1 than Ag-GSH, GSSG or GSH, established substrates of the transporter. Co-incubation of NaAtm1, hemin with Ag-GSH in ATPase assays revealed a non-competitive interaction, indicating distinct binding sites on NaAtm1 and this property was reinforced using molecular docking analysis. Our data suggests that NaAtm1 has considerable versatility in transporting organic conjugates of metals and that this versatility enables it to play roles in detoxification processes for toxic metals and in homeostasis of iron. The ability to play these distinct roles is enabled by the plasticity of the substrate binding site within the central cavity of NaAtm1.
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Affiliation(s)
- Sarah Rottet
- CSIRO Synthetic Biology Future Science Platform, GPO Box 1700, Acton, Canberra, ACT, 2601, Australia
| | - Shagufta Iqbal
- Research School of Biology, Australian National University, Canberra, ACT, 2601, Australia
| | - Rachel Xifaras
- Research School of Biology, Australian National University, Canberra, ACT, 2601, Australia
| | - Michael T Singer
- CSIRO Synthetic Biology Future Science Platform, GPO Box 1700, Acton, Canberra, ACT, 2601, Australia
| | - Colin Scott
- CSIRO Synthetic Biology Future Science Platform, GPO Box 1700, Acton, Canberra, ACT, 2601, Australia
| | - Evelyne Deplazes
- School of Chemistry and Molecular Biosciences, University of Queensland, St Lucia, Australia
| | - Richard Callaghan
- Research School of Biology, Australian National University, Canberra, ACT, 2601, Australia; School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, United Kingdom.
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3
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Feng H, Meng P, Zhang S, Chen W, Wang H, Wang C. Insights from comparative transcriptome analysis in the responses of Pb-tolerant fungi Curvularia tsudae to Pb stress. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2023; 249:114476. [PMID: 38321691 DOI: 10.1016/j.ecoenv.2022.114476] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2022] [Revised: 12/06/2022] [Accepted: 12/23/2022] [Indexed: 02/08/2024]
Abstract
The fungus Curvularia tsudae can survive in environments that are extremely contaminated by heavy metals; however, the underlying molecular mechanisms of heavy metal tolerance are not clear. In this study, we determined the effects of lead (Pb) stress on the growth of C. tsudae and used RNA-Seq to identify significant genes and biological processes involved. The present study showed that C. tsudae had an outstanding resistant capacity to Pb stress and could survive at a concentration of 1600 mg L-1 Pb. Although an obvious inhibition on the growth was observed, the fungus exhibited tolerance as it continued to grow at a Pb concentration of 1600 mg L-1 for seven days. A total of 9997 (9020 up and 977 down) differentially expressed genes (DEGs) were detected in the mycelium of C. tsudae at Pb free (0 mg L-1) and Pb stressed samples. Pathway enrichment analysis identified several biological processes for managing Pb stress. Genes involved in carbohydrate metabolism tended to be modulated in response to Pb stress, while amino acids and the lipid metabolism would also be induced by Pb stress, and up-regulated genes involved in antioxidant substances and ABC transporters may be committed to high Pb tolerance. Our study contributes to the current literature on C. tsudae response to Pb stress and provides a useful reference for fungi as bioremediators in heavy metal-contaminated environments.
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Affiliation(s)
- Huan Feng
- College of Forestry, Northwest A&F University, Yangling 712100, Shaanxi, China
| | - Panpan Meng
- College of Forestry, Northwest A&F University, Yangling 712100, Shaanxi, China
| | - Shouxia Zhang
- College of Forestry, Northwest A&F University, Yangling 712100, Shaanxi, China
| | - Wei Chen
- College of Forestry, Northwest A&F University, Yangling 712100, Shaanxi, China
| | - Haihua Wang
- North Florida Research and Education Center, University of Florida, 155 Research Road, Quincy, FL 32351, USA
| | - Chunyan Wang
- College of Forestry, Northwest A&F University, Yangling 712100, Shaanxi, China.
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4
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Li P, Hendricks AL, Wang Y, Villones RLE, Lindkvist-Petersson K, Meloni G, Cowan JA, Wang K, Gourdon P. Structures of Atm1 provide insight into [2Fe-2S] cluster export from mitochondria. Nat Commun 2022; 13:4339. [PMID: 35896548 PMCID: PMC9329353 DOI: 10.1038/s41467-022-32006-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Accepted: 07/11/2022] [Indexed: 01/22/2023] Open
Abstract
In eukaryotes, iron-sulfur clusters are essential cofactors for numerous physiological processes, but these clusters are primarily biosynthesized in mitochondria. Previous studies suggest mitochondrial ABCB7-type exporters are involved in maturation of cytosolic iron-sulfur proteins. However, the molecular mechanism for how the ABCB7-type exporters participate in this process remains elusive. Here, we report a series of cryo-electron microscopy structures of a eukaryotic homolog of human ABCB7, CtAtm1, determined at average resolutions ranging from 2.8 to 3.2 Å, complemented by functional characterization and molecular docking in silico. We propose that CtAtm1 accepts delivery from glutathione-complexed iron-sulfur clusters. A partially occluded state links cargo-binding to residues at the mitochondrial matrix interface that line a positively charged cavity, while the binding region becomes internalized and is partially divided in an early occluded state. Collectively, our findings substantially increase the understanding of the transport mechanism of eukaryotic ABCB7-type proteins.
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Affiliation(s)
- Ping Li
- Department of Experimental Medical Science, Lund University, Sölvegatan 19, SE-221 84, Lund, Sweden
| | - Amber L Hendricks
- Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, OH, 43210, USA
| | - Yong Wang
- Institute of Quantitative Biology, College of Life Sciences, Zhejiang University, Hangzhou, 310027, China
- The Provincial International Science and Technology Cooperation Base on Engineering Biology, International Campus of Zhejiang University, Haining, 314400, China
| | - Rhiza Lyne E Villones
- Department of Chemistry and Biochemistry, The University of Texas at Dallas, 800 W Campbell Rd., Richardson, TX, 75080, USA
| | | | - Gabriele Meloni
- Department of Chemistry and Biochemistry, The University of Texas at Dallas, 800 W Campbell Rd., Richardson, TX, 75080, USA
| | - J A Cowan
- Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, OH, 43210, USA
| | - Kaituo Wang
- Department of Biomedical Sciences, Copenhagen University, Maersk Tower 7-9, Nørre Allé 14, DK-2200, Copenhagen N, Denmark.
| | - Pontus Gourdon
- Department of Experimental Medical Science, Lund University, Sölvegatan 19, SE-221 84, Lund, Sweden.
- Department of Biomedical Sciences, Copenhagen University, Maersk Tower 7-9, Nørre Allé 14, DK-2200, Copenhagen N, Denmark.
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5
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Fan C, Rees DC. Glutathione binding to the plant AtAtm3 transporter and implications for the conformational coupling of ABC transporters. eLife 2022; 11:76140. [PMID: 35333177 PMCID: PMC9000953 DOI: 10.7554/elife.76140] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Accepted: 03/23/2022] [Indexed: 11/13/2022] Open
Abstract
The ATP Binding Cassette (ABC) transporter of mitochondria (Atm) from Arabidopsis thaliana (AtAtm3) has been implicated in the maturation of cytosolic iron-sulfur proteins and heavy metal detoxification, plausibly by exporting glutathione derivatives. Using single-particle cryo-electron microscopy, we have determined four structures of AtAtm3 in three different conformational states: two inward-facing conformations (with and without bound oxidized glutathione (GSSG)), together with closed and outward-facing states stabilized by MgADP-VO4. These structures not only provide a structural framework for defining the alternating access transport cycle, but also reveal the paucity of cysteine residues in the glutathione binding site that could potentially form inhibitory mixed disulfides with GSSG. Despite extensive efforts, we were unable to prepare the ternary complex of AtAtm3 containing both GSSG and MgATP. A survey of structurally characterized type IV ABC transporters that includes AtAtm3 establishes that while nucleotides are found associated with all conformational states, they are effectively required to stabilize occluded, closed, and outward-facing conformations. In contrast, transport substrates have only been observed associated with inward-facing conformations. The absence of structures with dimerized nucleotide binding domains containing both nucleotide and transport substrate suggests that this form of the ternary complex exists only transiently during the transport cycle.
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Affiliation(s)
- Chengcheng Fan
- Division of Chemistry and Chemical Engineering, Howard Hughes Medical Institute, California Institute of Technology, Pasadena, United States
| | - Douglas C Rees
- Division of Chemistry and Chemical Engineering, Howard Hughes Medical Institute, California Institute of Technology, Pasadena, United States
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6
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Ellinghaus TL, Marcellino T, Srinivasan V, Lill R, Kühlbrandt W. Conformational changes in the yeast mitochondrial ABC transporter Atm1 during the transport cycle. SCIENCE ADVANCES 2021; 7:eabk2392. [PMID: 34936443 PMCID: PMC8694623 DOI: 10.1126/sciadv.abk2392] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
The mitochondrial inner membrane ABC transporter Atm1 exports an unknown substrate to the cytosol for iron-sulfur protein biogenesis, cellular iron regulation, and tRNA thio-modification. Mutations in the human relative ABCB7 cause the iron storage disease XLSA/A. We determined 3D structures of two complementary states of Atm1 in lipid nanodiscs by electron cryo-microscopy at 2.9- to 3.4-Å resolution. The inward-open structure resembled the known crystal structure of nucleotide-free apo-Atm1 closely. The occluded conformation with bound AMP-PNP-Mg2+ showed a tight association of the two nucleotide-binding domains, a rearrangement of the C-terminal helices, and closure of the putative substrate-binding cavity in the homodimeric transporter. We identified a hydrophobic patch on the C-terminal helices of yeast Atm1, which is unique among type IV ABC transporters of known structure. Truncation mutants of yeast Atm1 suggest that the C-terminal helices stabilize the dimer, yet are not necessary for closure of the nucleotide-binding domains.
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Affiliation(s)
- Thomas L. Ellinghaus
- Max-Planck Institute of Biophysics, Max-von-Laue-Str. 3, 60438 Frankfurt, Germany
| | - Thomas Marcellino
- Institut für Zytobiologie, Philipps-Universität Marburg, Karl-von-Frisch-Str. 14, 35032 Marburg, Germany
- SYNMIKRO Center for Synthetic Microbiology, Philipps-Universität Marburg, Karl-von-Frisch-Str. 14, 35032 Marburg, Germany
| | - Vasundara Srinivasan
- SYNMIKRO Center for Synthetic Microbiology, Philipps-Universität Marburg, Karl-von-Frisch-Str. 14, 35032 Marburg, Germany
- Universität Hamburg, Department of Chemistry, Institute of Biochemistry and Molecular Biology, Laboratory for Structural Biology of Infection and Inflammation, Build. 22a, c/o DESY, Notkestr. 85, 22607 Hamburg, Germany
| | - Roland Lill
- Institut für Zytobiologie, Philipps-Universität Marburg, Karl-von-Frisch-Str. 14, 35032 Marburg, Germany
- SYNMIKRO Center for Synthetic Microbiology, Philipps-Universität Marburg, Karl-von-Frisch-Str. 14, 35032 Marburg, Germany
- Corresponding author. (W.K.); (R.L.)
| | - Werner Kühlbrandt
- Max-Planck Institute of Biophysics, Max-von-Laue-Str. 3, 60438 Frankfurt, Germany
- Corresponding author. (W.K.); (R.L.)
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7
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Fan C, Rees DC. Modeling the stimulation by glutathione of the steady state kinetics of an adenosine triphosphate binding cassette transporter. Protein Sci 2021; 31:752-757. [PMID: 34878193 PMCID: PMC8862428 DOI: 10.1002/pro.4250] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Revised: 12/03/2021] [Accepted: 12/03/2021] [Indexed: 11/14/2022]
Abstract
We report the steady state ATPase activities of the ATP Binding Cassette (ABC) exporter NaAtm1 in the absence and presence of a transported substrate, oxidized glutathione (GSSG), in detergent, nanodiscs, and proteoliposomes. The steady state kinetic data were fit to the “nonessential activator model” where the basal ATPase rate of the transporter is stimulated by GSSG. The detailed kinetic parameters varied between the different reconstitution conditions, highlighting the importance of the lipid environment for NaAtm1 function. The increased ATPase rates in the presence of GSSG more than compensate for the modest negative cooperativity observed between MgATP and GSSG in lipid environments. These studies highlight the central role of the elusive ternary complex in accelerating the ATPase rate that is at the heart of coupling mechanism between substrate transport and ATP hydrolysis.
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Affiliation(s)
- Chengcheng Fan
- Division of Chemistry and Chemical Engineering, Howard Hughes Medical Institute, MC 114-96, California Institute of Technology, Pasadena, California, USA
| | - Douglas C Rees
- Division of Chemistry and Chemical Engineering, Howard Hughes Medical Institute, MC 114-96, California Institute of Technology, Pasadena, California, USA
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8
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Pearson SA, Wachnowsky C, Cowan JA. Defining the mechanism of the mitochondrial Atm1p [2Fe-2S] cluster exporter. Metallomics 2021; 12:902-915. [PMID: 32337520 DOI: 10.1039/c9mt00286c] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Iron-sulfur cluster proteins play key roles in a multitude of physiological processes; including gene expression, nitrogen and oxygen sensing, electron transfer, and DNA repair. Biosynthesis of iron-sulfur clusters occurs in mitochondria on iron-sulfur cluster scaffold proteins in the form of [2Fe-2S] cores that are then transferred to apo targets within metabolic or respiratory pathways. The mechanism by which cytosolic Fe-S cluster proteins mature to their holo forms remains controversial. The mitochondrial inner membrane protein Atm1p can transport glutathione-coordinated iron-sulfur clusters, which may connect the mitochondrial and cytosolic iron-sulfur cluster assembly systems. Herein we describe experiments on the yeast Atm1p/ABCB7 exporter that provide additional support for a glutathione-complexed cluster as the natural physiological substrate and a reflection of the endosymbiotic model of mitochondrial evolution. These studies provide insight on the mechanism of cluster transport and the molecular basis of human disease conditions related to ABCB7. Recruitment of MgATP following cluster binding promotes a structural transition from closed to open conformations that is mediated by coupling helices, with MgATP hydrolysis facilitating the return to the closed state.
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Affiliation(s)
- Stephen A Pearson
- The Ohio State University Biophysics Program, The Ohio State University, 484 West 12th Avenue, Columbus, Ohio, USA43210.
| | - Christine Wachnowsky
- The Ohio State University Biochemistry Program, The Ohio State University, 484 West 12th Avenue, Columbus, Ohio, USA43210
| | - J A Cowan
- The Ohio State University Biophysics Program, The Ohio State University, 484 West 12th Avenue, Columbus, Ohio, USA43210. and The Ohio State University Biochemistry Program, The Ohio State University, 484 West 12th Avenue, Columbus, Ohio, USA43210 and Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio, USA43210
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9
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Abstract
ABCB6 plays a crucial role in energy-dependent porphyrin transport, drug resistance, toxic metal resistance, porphyrin biosynthesis, protection against stress, and encoding a blood group system Langereis antigen. However, the mechanism underlying porphyrin transport is still unclear. Here, we determined the cryo-electron microscopy (cryo-EM) structures of nanodisc-reconstituted human ABCB6 trapped in an apo-state and an ATP-bound state at resolutions of 3.6 and 3.5 Å, respectively. Our structures reveal a unique loop in the transmembrane domain (TMD) of ABCB6, which divides the TMD into two cavities. It restrains the access of substrates in the inward-facing state and is removed by ATP-driven conformational change. No ligand cavities were observed in the nucleotide-bound state, indicating a state following substrate release but prior to ATP hydrolysis. Structural analyses and functional characterizations suggest an "ATP-switch" model and further reveal the conformational changes of the substrate-binding pockets triggered by the ATP-driven regulation.
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10
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Luo ZW, Ahn JH, Chae TU, Choi SY, Park SY, Choi Y, Kim J, Prabowo CPS, Lee JA, Yang D, Han T, Xu H, Lee SY. Metabolic Engineering of
Escherichia
coli. Metab Eng 2021. [DOI: 10.1002/9783527823468.ch11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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11
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A structural framework for unidirectional transport by a bacterial ABC exporter. Proc Natl Acad Sci U S A 2020; 117:19228-19236. [PMID: 32703810 PMCID: PMC7430982 DOI: 10.1073/pnas.2006526117] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
A specific ATP-binding cassette (ABC) transporter is generally viewed to function as either an exporter or an importer, but in principle ABC transporters can transport substrates in both directions across the membrane. Structural studies of the prokaryotic ABC exporter NaAtm1 demonstrate that progression through the transport cycle is accompanied by changes in transmembrane helix 6 (TM6) that modulate the binding cavity for transported substrate. Significantly, kinking of TM6 in a post-ATP hydrolysis state stabilized by MgADPVO4 eliminates the substrate-binding cavity. The presence of this cavity during the transition from the inward-facing to outward-facing conformational states, and its absence in the reverse direction, thereby provide an elegant and conceptually simple mechanism for enforcing the export directionality of transport. The ATP-binding cassette (ABC) transporter of mitochondria (Atm1) mediates iron homeostasis in eukaryotes, while the prokaryotic homolog from Novosphingobium aromaticivorans (NaAtm1) can export glutathione derivatives and confer protection against heavy-metal toxicity. To establish the structural framework underlying the NaAtm1 transport mechanism, we determined eight structures by X-ray crystallography and single-particle cryo-electron microscopy in distinct conformational states, stabilized by individual disulfide crosslinks and nucleotides. As NaAtm1 progresses through the transport cycle, conformational changes in transmembrane helix 6 (TM6) alter the glutathione-binding site and the associated substrate-binding cavity. Significantly, kinking of TM6 in the post-ATP hydrolysis state stabilized by MgADPVO4 eliminates this cavity, precluding uptake of glutathione derivatives. The presence of this cavity during the transition from the inward-facing to outward-facing conformational states, and its absence in the reverse direction, thereby provide an elegant and conceptually simple mechanism for enforcing the export directionality of transport by NaAtm1. One of the disulfide crosslinked NaAtm1 variants characterized in this work retains significant glutathione transport activity, suggesting that ATP hydrolysis and substrate transport by Atm1 may involve a limited set of conformational states with minimal separation of the nucleotide-binding domains in the inward-facing conformation.
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12
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Rottet S, Iqbal S, Beales PA, Lin A, Lee J, Rug M, Scott C, Callaghan R. Characterisation of Hybrid Polymersome Vesicles Containing the Efflux Pumps NaAtm1 or P-Glycoprotein. Polymers (Basel) 2020; 12:E1049. [PMID: 32375237 PMCID: PMC7284524 DOI: 10.3390/polym12051049] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Revised: 04/24/2020] [Accepted: 04/25/2020] [Indexed: 11/18/2022] Open
Abstract
Investigative systems for purified membrane transporters are almost exclusively reliant on the use of phospholipid vesicles or liposomes. Liposomes provide an environment to support protein function; however, they also have numerous drawbacks and should not be considered as a "one-size fits all" system. The use of artificial vesicles comprising block co-polymers (polymersomes) offers considerable advantages in terms of structural stability; provision of sufficient lateral pressure; and low passive permeability, which is a particular issue for transport assays using hydrophobic compounds. The present investigation demonstrates strategies to reconstitute ATP binding cassette (ABC) transporters into hybrid vesicles combining phospholipids and the block co-polymer poly (butadiene)-poly (ethylene oxide). Two efflux pumps were chosen; namely the Novosphingobium aromaticivorans Atm1 protein and human P-glycoprotein (Pgp). Polymersomes were generated with one of two lipid partners, either purified palmitoyl-oleoyl-phosphatidylcholine, or a mixture of crude E. coli lipid extract and cholesterol. Hybrid polymersomes were characterised for size, structural homogeneity, stability to detergents, and permeability. Two transporters, NaAtm1 and P-gp, were successfully reconstituted into pre-formed and surfactant-destabilised hybrid polymersomes using a detergent adsorption strategy. Reconstitution of both proteins was confirmed by density gradient centrifugation and the hybrid polymersomes supported substrate dependent ATPase activity of both transporters. The hybrid polymersomes also displayed low passive permeability to a fluorescent probe (calcein acetomethoxyl-ester (C-AM)) and offer the potential for quantitative measurements of transport activity for hydrophobic compounds.
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Affiliation(s)
- Sarah Rottet
- CSIRO Synthetic Biology Future Science Platform, GPO Box 1700, Acton, Canberra 2601, Australia; (S.R.); (C.S.)
| | - Shagufta Iqbal
- Research School of Biology, and the Medical School, Australian National University, Canberra 2601, Australia; (S.I.); (A.L.)
| | - Paul A. Beales
- School of Chemistry Bragg Centre for Materials Research and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK;
| | - Anran Lin
- Research School of Biology, and the Medical School, Australian National University, Canberra 2601, Australia; (S.I.); (A.L.)
| | - Jiwon Lee
- Centre for Advanced Microscopy, Australian National University, Canberra 2601, Australia; (J.L.); (M.R.)
| | - Melanie Rug
- Centre for Advanced Microscopy, Australian National University, Canberra 2601, Australia; (J.L.); (M.R.)
| | - Colin Scott
- CSIRO Synthetic Biology Future Science Platform, GPO Box 1700, Acton, Canberra 2601, Australia; (S.R.); (C.S.)
| | - Richard Callaghan
- Research School of Biology, and the Medical School, Australian National University, Canberra 2601, Australia; (S.I.); (A.L.)
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13
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Sabrialabed S, Yang JG, Yariv E, Ben-Tal N, Lewinson O. Substrate recognition and ATPase activity of the E. coli cysteine/cystine ABC transporter YecSC-FliY. J Biol Chem 2020; 295:5245-5256. [PMID: 32144203 PMCID: PMC7170509 DOI: 10.1074/jbc.ra119.012063] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Revised: 03/03/2020] [Indexed: 12/20/2022] Open
Abstract
Sulfur is essential for biological processes such as amino acid biogenesis, iron-sulfur cluster formation, and redox homeostasis. To acquire sulfur-containing compounds from the environment, bacteria have evolved high-affinity uptake systems, predominant among which is the ABC transporter family. Theses membrane-embedded enzymes use the energy of ATP hydrolysis for transmembrane transport of a wide range of biomolecules against concentration gradients. Three distinct bacterial ABC import systems of sulfur-containing compounds have been identified, but the molecular details of their transport mechanism remain poorly characterized. Here we provide results from a biochemical analysis of the purified Escherichia coli YecSC-FliY cysteine/cystine import system. We found that the substrate-binding protein FliY binds l-cystine, l-cysteine, and d-cysteine with micromolar affinities. However, binding of the l- and d-enantiomers induced different conformational changes of FliY, where the l- enantiomer-substrate-binding protein complex interacted more efficiently with the YecSC transporter. YecSC had low basal ATPase activity that was moderately stimulated by apo FliY, more strongly by d-cysteine-bound FliY, and maximally by l-cysteine- or l-cystine-bound FliY. However, at high FliY concentrations, YecSC reached maximal ATPase rates independent of the presence or nature of the substrate. These results suggest that FliY exists in a conformational equilibrium between an open, unliganded form that does not bind to the YecSC transporter and closed, unliganded and closed, liganded forms that bind this transporter with variable affinities but equally stimulate its ATPase activity. These findings differ from previous observations for similar ABC transporters, highlighting the extent of mechanistic diversity in this large protein family.
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Affiliation(s)
- Siwar Sabrialabed
- Department of Biochemistry and the Rappaport Institute for Medical Sciences, Faculty of Medicine, Technion-Israel Institute of Technology, Haifa 31096, Israel
| | - Janet G Yang
- Department of Chemistry, University of San Francisco, San Francisco, California 94117
| | - Elon Yariv
- Department of Biochemistry and Molecular Biology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 6139001, Israel
| | - Nir Ben-Tal
- Department of Biochemistry and Molecular Biology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 6139001, Israel
| | - Oded Lewinson
- Department of Biochemistry and the Rappaport Institute for Medical Sciences, Faculty of Medicine, Technion-Israel Institute of Technology, Haifa 31096, Israel.
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14
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Riedel S, Siemiatkowska B, Watanabe M, Müller CS, Schünemann V, Hoefgen R, Leimkühler S. The ABCB7-Like Transporter PexA in Rhodobacter capsulatus Is Involved in the Translocation of Reactive Sulfur Species. Front Microbiol 2019; 10:406. [PMID: 30918498 PMCID: PMC6424863 DOI: 10.3389/fmicb.2019.00406] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Accepted: 02/15/2019] [Indexed: 12/23/2022] Open
Abstract
The mitochondrial ATP-binding cassette (ABC) transporters ABCB7 in humans, Atm1 in yeast and ATM3 in plants, are highly conserved in their overall architecture and particularly in their glutathione binding pocket located within the transmembrane spanning domains. These transporters have attracted interest in the last two decades based on their proposed role in connecting the mitochondrial iron-sulfur (Fe-S) cluster assembly with its cytosolic Fe-S cluster assembly (CIA) counterpart. So far, the specific compound that is transported across the membrane remains unknown. In this report we characterized the ABCB7-like transporter Rcc02305 in Rhodobacter capsulatus, which shares 47% amino acid sequence identity with its mitochondrial counterpart. The constructed interposon mutant strain in R. capsulatus displayed increased levels of intracellular reactive oxygen species without a simultaneous accumulation of the cellular iron levels. The inhibition of endogenous glutathione biosynthesis resulted in an increase of total glutathione levels in the mutant strain. Bioinformatic analysis of the amino acid sequence motifs revealed a potential aminotransferase class-V pyridoxal-5'-phosphate (PLP) binding site that overlaps with the Walker A motif within the nucleotide binding domains of the transporter. PLP is a well characterized cofactor of L-cysteine desulfurases like IscS and NFS1 which has a role in the formation of a protein-bound persulfide group within these proteins. We therefore suggest renaming the ABCB7-like transporter Rcc02305 in R. capsulatus to PexA for PLP binding exporter. We further suggest that this ABC-transporter in R. capsulatus is involved in the formation and export of polysulfide species to the periplasm.
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Affiliation(s)
- Simona Riedel
- Institute of Biochemistry and Biology, Department of Molecular Enzymology, University of Potsdam, Potsdam, Germany
| | - Beata Siemiatkowska
- Department of Organelle Biology, Biotechnology and Molecular Ecophysiology, Max Planck Institute of Molecular Plant Physiology, Potsdam, Germany
| | - Mutsumi Watanabe
- Department of Molecular Physiology, Max Planck Institute of Molecular Plant Physiology, Potsdam, Germany
| | - Christina S Müller
- Biophysics and Medical Physics Group, Department of Physics, Technische Universität Kaiserslautern, Kaiserslautern, Germany
| | - Volker Schünemann
- Biophysics and Medical Physics Group, Department of Physics, Technische Universität Kaiserslautern, Kaiserslautern, Germany
| | - Rainer Hoefgen
- Department of Molecular Physiology, Max Planck Institute of Molecular Plant Physiology, Potsdam, Germany
| | - Silke Leimkühler
- Institute of Biochemistry and Biology, Department of Molecular Enzymology, University of Potsdam, Potsdam, Germany
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15
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Ciofi-Baffoni S, Nasta V, Banci L. Protein networks in the maturation of human iron-sulfur proteins. Metallomics 2019; 10:49-72. [PMID: 29219157 DOI: 10.1039/c7mt00269f] [Citation(s) in RCA: 67] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The biogenesis of iron-sulfur (Fe-S) proteins in humans is a multistage process occurring in different cellular compartments. The mitochondrial iron-sulfur cluster (ISC) assembly machinery composed of at least 17 proteins assembles mitochondrial Fe-S proteins. A cytosolic iron-sulfur assembly (CIA) machinery composed of at least 13 proteins has been more recently identified and shown to be responsible for the Fe-S cluster incorporation into cytosolic and nuclear Fe-S proteins. Cytosolic and nuclear Fe-S protein maturation requires not only the CIA machinery, but also the components of the mitochondrial ISC assembly machinery. An ISC export machinery, composed of a protein transporter located in the mitochondrial inner membrane, has been proposed to act in mediating the export process of a still unknown component that is required for the CIA machinery. Several functional and molecular aspects of the protein networks operative in the three machineries are still largely obscure. This Review focuses on the Fe-S protein maturation processes in humans with the specific aim of providing a molecular picture of the currently known protein-protein interaction networks. The human ISC and CIA machineries are presented, and the ISC export machinery is discussed with respect to possible molecules being the substrates of the mitochondrial protein transporter.
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Affiliation(s)
- Simone Ciofi-Baffoni
- Magnetic Resonance Center-CERM, University of Florence, Via Luigi Sacconi 6, 50019, Sesto Fiorentino, Florence, Italy.
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16
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Pandey A, Pain J, Dziuba N, Pandey AK, Dancis A, Lindahl PA, Pain D. Mitochondria Export Sulfur Species Required for Cytosolic tRNA Thiolation. Cell Chem Biol 2018; 25:738-748.e3. [PMID: 29706592 PMCID: PMC6014917 DOI: 10.1016/j.chembiol.2018.04.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Revised: 03/09/2018] [Accepted: 04/03/2018] [Indexed: 12/15/2022]
Abstract
In eukaryotes, mitochondria have been hypothesized to generate sulfur species required for tRNA thiolation in the cytosol, although no direct evidence thus far exists. Here we have detected these sulfur species, making use of our observation that isolated yeast cytosol alone is unable to thiolate tRNAs but can do so upon addition of mitochondria. Mitochondria were found to utilize the cysteine desulfurase Nfs1 to produce sulfur-containing species with masses ranging from 700 to 1,100 Da. Mitochondria exported these species via the Atm1 transporter in the inner membrane. Once exported to the cytosol, these sulfur species promoted cytosolic tRNA thiolation with no further requirement of mitochondria. Furthermore, we found that the Isu1/2 scaffolds but not the Ssq1 chaperone of the mitochondrial iron-sulfur cluster machinery were required for cytosolic tRNA thiolation, and thus the sulfur utilization pathway bifurcates at the Isu1/2 site for intra-organellar use in mitochondria or export to the cytosol.
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Affiliation(s)
- Alok Pandey
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School, Rutgers University, Newark, NJ 07103, USA
| | - Jayashree Pain
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School, Rutgers University, Newark, NJ 07103, USA
| | - Nathaniel Dziuba
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, USA
| | - Ashutosh K Pandey
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School, Rutgers University, Newark, NJ 07103, USA
| | - Andrew Dancis
- Department of Medicine, Division of Hematology-Oncology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Paul A Lindahl
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, USA; Department of Chemistry, Texas A&M University, College Station, TX 77843, USA
| | - Debkumar Pain
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School, Rutgers University, Newark, NJ 07103, USA.
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17
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Abstract
SIGNIFICANCE Glutathione (GSH) is the most abundant cellular low-molecular-weight thiol in the majority of organisms in all kingdoms of life. Therefore, functions of GSH and disturbed regulation of its concentration are associated with numerous physiological and pathological situations. Recent Advances: The function of GSH as redox buffer or antioxidant is increasingly being questioned. New functions, especially functions connected to the cellular iron homeostasis, were elucidated. Via the formation of iron complexes, GSH is an important player in all aspects of iron metabolism: sensing and regulation of iron levels, iron trafficking, and biosynthesis of iron cofactors. The variety of GSH coordinated iron complexes and their functions with a special focus on FeS-glutaredoxins are summarized in this review. Interestingly, GSH analogues that function as major low-molecular-weight thiols in organisms lacking GSH resemble the functions in iron homeostasis. CRITICAL ISSUES Since these iron-related functions are most likely also connected to thiol redox chemistry, it is difficult to distinguish between mechanisms related to either redox or iron metabolisms. FUTURE DIRECTIONS The ability of GSH to coordinate iron in different complexes with or without proteins needs further investigation. The discovery of new Fe-GSH complexes and their physiological functions will significantly advance our understanding of cellular iron homeostasis. Antioxid. Redox Signal. 27, 1235-1251.
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Affiliation(s)
- Carsten Berndt
- 1 Department of Neurology, Medical Faculty, Life Science Center , Heinrich-Heine-Universität, Düsseldorf, Germany
| | - Christopher Horst Lillig
- 2 Institute for Medical Biochemistry and Molecular Biology, University Medicine Greifswald , Greifswald, Germany
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18
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Neumann J, Rose-Sperling D, Hellmich UA. Diverse relations between ABC transporters and lipids: An overview. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1859:605-618. [PMID: 27693344 DOI: 10.1016/j.bbamem.2016.09.023] [Citation(s) in RCA: 103] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Revised: 09/24/2016] [Accepted: 09/26/2016] [Indexed: 12/19/2022]
Abstract
It was first discovered in 1992 that P-glycoprotein (Pgp, ABCB1), an ATP binding cassette (ABC) transporter, can transport phospholipids such as phosphatidylcholine, -ethanolamine and -serine as well as glucosylceramide and glycosphingolipids. Subsequently, many other ABC transporters were identified to act as lipid transporters. For substrate transport by ABC transporters, typically a classic, alternating access model with an ATP-dependent conformational switch between a high and a low affinity substrate binding site is evoked. Transport of small hydrophilic substrates can easily be imagined this way, as the molecule can in principle enter and exit the transporter in the same orientation. Lipids on the other hand need to undergo a 180° degree turn as they translocate from one membrane leaflet to the other. Lipids and lipidated molecules are highly diverse, so there may be various ways how to achieve their flipping and flopping. Nonetheless, an increase in biophysical, biochemical and structural data is beginning to shed some light on specific aspects of lipid transport by ABC transporters. In addition, there is now abundant evidence that lipids affect ABC transporter conformation, dynamics as well as transport and ATPase activity in general. In this review, we will discuss different ways in which lipids and ABC transporters interact and how lipid translocation may be achieved with a focus on the techniques used to investigate these processes. This article is part of a Special Issue entitled: Lipid order/lipid defects and lipid-control of protein activity edited by Dirk Schneider.
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Affiliation(s)
- Jennifer Neumann
- Institute of Pharmacy and Biochemistry, Johannes Gutenberg University Mainz, Johann-Joachim-Becher-Weg 30, 55128 Mainz, Germany
| | - Dania Rose-Sperling
- Institute of Pharmacy and Biochemistry, Johannes Gutenberg University Mainz, Johann-Joachim-Becher-Weg 30, 55128 Mainz, Germany
| | - Ute A Hellmich
- Institute of Pharmacy and Biochemistry, Johannes Gutenberg University Mainz, Johann-Joachim-Becher-Weg 30, 55128 Mainz, Germany.
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19
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Pyrih J, Pyrihová E, Kolísko M, Stojanovová D, Basu S, Harant K, Haindrich AC, Doležal P, Lukeš J, Roger A, Tachezy J. Minimal cytosolic iron-sulfur cluster assembly machinery of Giardia intestinalis is partially associated with mitosomes. Mol Microbiol 2016; 102:701-714. [PMID: 27582265 DOI: 10.1111/mmi.13487] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/21/2016] [Indexed: 01/10/2023]
Abstract
Iron-sulfur (Fe-S) clusters are essential cofactors that enable proteins to transport electrons, sense signals, or catalyze chemical reactions. The maturation of dozens of Fe-S proteins in various compartments of every eukaryotic cell is driven by several assembly pathways. The ubiquitous cytosolic Fe-S cluster assembly (CIA) pathway, typically composed of eight highly conserved proteins, depends on mitochondrial Fe-S cluster assembly (ISC) machinery. Giardia intestinalis contains one of the smallest eukaryotic genomes and the mitosome, an extremely reduced mitochondrion. Because the only pathway known to be retained within this organelle is the synthesis of Fe-S clusters mediated by ISC machinery, a likely function of the mitosome is to cooperate with the CIA pathway. We investigated the cellular localization of CIA components in G. intestinalis and the origin and distribution of CIA-related components and Tah18-like proteins in other Metamonada. We show that orthologs of Tah18 and Dre2 are missing in these eukaryotes. In Giardia, all CIA components are exclusively cytosolic, with the important exception of Cia2 and two Nbp35 paralogs, which are present in the mitosomes. We propose that the dual localization of Cia2 and Nbp35 proteins in Giardia might represent a novel connection between the ISC and the CIA pathways.
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Affiliation(s)
- Jan Pyrih
- Department of Parasitology, Charles University in Prague, Vestec, 252 42, Czech Republic
| | - Eva Pyrihová
- Department of Parasitology, Charles University in Prague, Vestec, 252 42, Czech Republic
| | - Martin Kolísko
- Centre for Comparative Genomics and Evolutionary Bioinformatics, Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS, B3H 4R2, Canada
| | - Darja Stojanovová
- Department of Parasitology, Charles University in Prague, Vestec, 252 42, Czech Republic
| | - Somsuvro Basu
- Institute of Parasitology, Biology Centre, České Budějovice, Budweis, 37005, Czech Republic
| | - Karel Harant
- Department of Parasitology, Charles University in Prague, Vestec, 252 42, Czech Republic
| | - Alexander C Haindrich
- Institute of Parasitology, Biology Centre, České Budějovice, Budweis, 37005, Czech Republic.,Faculty of Sciences, University of South Bohemia, České Budějovice, Budweis, 37005, Czech Republic
| | - Pavel Doležal
- Department of Parasitology, Charles University in Prague, Vestec, 252 42, Czech Republic
| | - Julius Lukeš
- Institute of Parasitology, Biology Centre, České Budějovice, Budweis, 37005, Czech Republic.,Faculty of Sciences, University of South Bohemia, České Budějovice, Budweis, 37005, Czech Republic.,Canadian Institute for Advanced Research, Toronto, ON, M5G 1Z8, Canada
| | - Andrew Roger
- Centre for Comparative Genomics and Evolutionary Bioinformatics, Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS, B3H 4R2, Canada.,Canadian Institute for Advanced Research, Toronto, ON, M5G 1Z8, Canada
| | - Jan Tachezy
- Department of Parasitology, Charles University in Prague, Vestec, 252 42, Czech Republic
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20
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Abstract
A small number of physiologically important ATP-binding cassette (ABC) transporters are found in mitochondria. Most are half transporters of the B group forming homodimers and their topology suggests they function as exporters. The results of mutant studies point towards involvement in iron cofactor biosynthesis. In particular, ABC subfamily B member 7 (ABCB7) and its homologues in yeast and plants are required for iron-sulfur (Fe-S) cluster biosynthesis outside of the mitochondria, whereas ABCB10 is involved in haem biosynthesis. They also play a role in preventing oxidative stress. Mutations in ABCB6 and ABCB7 have been linked to human disease. Recent crystal structures of yeast Atm1 and human ABCB10 have been key to identifying substrate-binding sites and transport mechanisms. Combined with in vitro and in vivo studies, progress is being made to find the physiological substrates of the different mitochondrial ABC transporters.
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21
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Li J, Pearson SA, Fenk KD, Cowan JA. Glutathione-coordinated [2Fe-2S] cluster is stabilized by intramolecular salt bridges. J Biol Inorg Chem 2015; 20:1221-7. [PMID: 26468125 DOI: 10.1007/s00775-015-1301-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Accepted: 09/22/2015] [Indexed: 02/06/2023]
Abstract
Halide salts of alkali and alkaline earth metals were used to probe the contributions of intramolecular salt bridge formation on the stability of glutathione-coordinated [2Fe-2S] cluster toward hydrolysis. The effect of ionic strength on cluster stability was quantitatively investigated by application of Debye-Hückel theory to the rates of hydrolysis. Results from this study demonstrate that ionic strength influences the stability of the cluster, with the rate of cluster degradation depending on the charge density, hydrated ionic radius, and hydration energy. The identity of the salt ions was also observed to be correlated with the binding affinity toward the cluster. Based on the modified Debye-Hückel equation and counterion screening effect, these results suggest that interactions between glutathione molecules in the [2Fe-2S](GS)4 cluster is via salt bridges, in agreement with our previous results where modifications of glutathione carboxylates and amines prevented solution aggregation and cluster formation. These results not only provide a rationale for the stability of such clusters under physiological conditions, but also suggest that the formation of glutathione-complexed [2Fe-2S] cluster from a glutathione tetramer may be facilitated by salt bridge interactions between glutathione molecules prior to cluster assembly, in a manner consistent with Nature's equivalent of dynamic combinatorial chemistry.
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Affiliation(s)
- Jingwei Li
- Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, OH, 43210, USA
| | - Stephen A Pearson
- The Ohio State University Biophysics Program, The Ohio State University, 484 West 12th Avenue, Columbus, OH, 43210, USA
| | - Kevin D Fenk
- Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, OH, 43210, USA
| | - J A Cowan
- Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, OH, 43210, USA. .,The Ohio State University Biophysics Program, The Ohio State University, 484 West 12th Avenue, Columbus, OH, 43210, USA.
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22
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Lill R, Srinivasan V, Mühlenhoff U. The role of mitochondria in cytosolic-nuclear iron–sulfur protein biogenesis and in cellular iron regulation. Curr Opin Microbiol 2015; 22:111-9. [PMID: 25460804 DOI: 10.1016/j.mib.2014.09.015] [Citation(s) in RCA: 99] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2014] [Revised: 09/20/2014] [Accepted: 09/24/2014] [Indexed: 12/16/2022]
Abstract
Mitochondria are indispensable in eukaryotes because of their function in the maturation of cytosolic and nuclear iron–sulfur proteins that are essential for DNA synthesis and repair, tRNA modification, and protein translation. The mitochondrial Fe/S cluster assembly machinery not only generates the organelle's iron–sulfur proteins, but also extra-mitochondrial ones. Biogenesis of the latter proteins requires the mitochondrial ABC transporter Atm1 that exports a sulfur-containing compound in a glutathione-dependent fashion. The process is further assisted by the cytosolic iron–sulfur protein assembly machinery. Here, we discuss the knowns and unknowns of the mitochondrial export process that is also crucial for signaling the cellular iron status to the regulatory systems involved in the maintenance of cellular iron homeostasis.
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Affiliation(s)
- Roland Lill
- Institut für Zytobiologie, Philipps-Universität Marburg, Robert-Koch-Str. 6, 35032 Marburg, Germany.
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23
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Lill R, Dutkiewicz R, Freibert SA, Heidenreich T, Mascarenhas J, Netz DJ, Paul VD, Pierik AJ, Richter N, Stümpfig M, Srinivasan V, Stehling O, Mühlenhoff U. The role of mitochondria and the CIA machinery in the maturation of cytosolic and nuclear iron–sulfur proteins. Eur J Cell Biol 2015; 94:280-91. [DOI: 10.1016/j.ejcb.2015.05.002] [Citation(s) in RCA: 138] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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24
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Li J, Cowan JA. Glutathione-coordinated [2Fe-2S] cluster: a viable physiological substrate for mitochondrial ABCB7 transport. Chem Commun (Camb) 2015; 51:2253-5. [PMID: 25556595 PMCID: PMC4522903 DOI: 10.1039/c4cc09175b] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The glutathione-coordinated [2Fe-2S] cluster is demonstrated to be a viable and likely substrate for physiological iron-sulfur cluster transport by Atm1p, a mitochondrial ABC export protein. Flow cytometry and colorimetric assays demonstrate a quantitative methodology for study of metal translocation proteins and their proteoliposome products.
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Affiliation(s)
- Jingwei Li
- Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Ave, Columbus, OH 43210, USA.
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25
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Qi W, Li J, Cowan JA. A structural model for glutathione-complexed iron-sulfur cluster as a substrate for ABCB7-type transporters. Chem Commun (Camb) 2014; 50:3795-8. [PMID: 24584132 DOI: 10.1039/c3cc48239a] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Glutathione-complexed [2Fe-2S] cluster is shown to significantly stimulate the ATPase activity of an ABCB7-type transporter in both solution and proteoliposome-bound forms (KD ∼ 68 μM). The cluster is a likely natural substrate for this transporter, which has been implicated in cytosolic Fe-S cluster protein maturation. A possible substrate-binding site is identified on a new structural model for the active transporter.
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Affiliation(s)
- Wenbin Qi
- Ohio State Biochemistry Program, The Ohio State University, USA.
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26
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Maio N, Rouault TA. Iron-sulfur cluster biogenesis in mammalian cells: New insights into the molecular mechanisms of cluster delivery. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1853:1493-512. [PMID: 25245479 DOI: 10.1016/j.bbamcr.2014.09.009] [Citation(s) in RCA: 155] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Accepted: 09/07/2014] [Indexed: 01/19/2023]
Abstract
Iron-sulfur (Fe-S) clusters are ancient, ubiquitous cofactors composed of iron and inorganic sulfur. The combination of the chemical reactivity of iron and sulfur, together with many variations of cluster composition, oxidation states and protein environments, enables Fe-S clusters to participate in numerous biological processes. Fe-S clusters are essential to redox catalysis in nitrogen fixation, mitochondrial respiration and photosynthesis, to regulatory sensing in key metabolic pathways (i.e. cellular iron homeostasis and oxidative stress response), and to the replication and maintenance of the nuclear genome. Fe-S cluster biogenesis is a multistep process that involves a complex sequence of catalyzed protein-protein interactions and coupled conformational changes between the components of several dedicated multimeric complexes. Intensive studies of the assembly process have clarified key points in the biogenesis of Fe-S proteins. However several critical questions still remain, such as: what is the role of frataxin? Why do some defects of Fe-S cluster biogenesis cause mitochondrial iron overload? How are specific Fe-S recipient proteins recognized in the process of Fe-S transfer? This review focuses on the basic steps of Fe-S cluster biogenesis, drawing attention to recent advances achieved on the identification of molecular features that guide selection of specific subsets of nascent Fe-S recipients by the cochaperone HSC20. Additionally, it outlines the distinctive phenotypes of human diseases due to mutations in the components of the basic pathway. This article is part of a Special Issue entitled: Fe/S proteins: Analysis, structure, function, biogenesis and diseases.
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Affiliation(s)
- Nunziata Maio
- Molecular Medicine Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, 9000 Rockville Pike, 20892 Bethesda, MD, USA
| | - Tracey A Rouault
- Molecular Medicine Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, 9000 Rockville Pike, 20892 Bethesda, MD, USA.
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27
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Schaedler TA, Thornton JD, Kruse I, Schwarzländer M, Meyer AJ, van Veen HW, Balk J. A conserved mitochondrial ATP-binding cassette transporter exports glutathione polysulfide for cytosolic metal cofactor assembly. J Biol Chem 2014; 289:23264-74. [PMID: 25006243 PMCID: PMC4156053 DOI: 10.1074/jbc.m114.553438] [Citation(s) in RCA: 116] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
An ATP-binding cassette transporter located in the inner mitochondrial membrane is involved in iron-sulfur cluster and molybdenum cofactor assembly in the cytosol, but the transported substrate is unknown. ATM3 (ABCB25) from Arabidopsis thaliana and its functional orthologue Atm1 from Saccharomyces cerevisiae were expressed in Lactococcus lactis and studied in inside-out membrane vesicles and in purified form. Both proteins selectively transported glutathione disulfide (GSSG) but not reduced glutathione in agreement with a 3-fold stimulation of ATPase activity by GSSG. By contrast, Fe2+ alone or in combination with glutathione did not stimulate ATPase activity. Arabidopsis atm3 mutants were hypersensitive to an inhibitor of glutathione biosynthesis and accumulated GSSG in the mitochondria. The growth phenotype of atm3-1 was strongly enhanced by depletion of the mitochondrion-localized, GSH-dependent persulfide oxygenase ETHE1, suggesting that the physiological substrate of ATM3 contains persulfide in addition to glutathione. Consistent with this idea, a transportomics approach using mass spectrometry showed that glutathione trisulfide (GS-S-SG) was transported by Atm1. We propose that mitochondria export glutathione polysulfide, containing glutathione and persulfide, for iron-sulfur cluster assembly in the cytosol.
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Affiliation(s)
- Theresia A Schaedler
- From the John Innes Centre, Norwich Research Park, Norwich NR4 7UH, United Kingdom, the Department of Plant Sciences, University of Cambridge, Cambridge CB2 3EA, United Kingdom
| | - Jeremy D Thornton
- From the John Innes Centre, Norwich Research Park, Norwich NR4 7UH, United Kingdom
| | - Inga Kruse
- From the John Innes Centre, Norwich Research Park, Norwich NR4 7UH, United Kingdom, the School of Biological Sciences, University of East Anglia, Norwich NR4 7TJ, United Kingdom
| | - Markus Schwarzländer
- the Institute of Crop Science and Resource Conservation, University of Bonn, 53113 Bonn, Germany
| | - Andreas J Meyer
- the Institute of Crop Science and Resource Conservation, University of Bonn, 53113 Bonn, Germany
| | - Hendrik W van Veen
- the Department of Pharmacology, University of Cambridge, Cambridge CB2 1PD, United Kingdom, and
| | - Janneke Balk
- From the John Innes Centre, Norwich Research Park, Norwich NR4 7UH, United Kingdom, the School of Biological Sciences, University of East Anglia, Norwich NR4 7TJ, United Kingdom
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28
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Yamashita M, Shepherd M, Booth WI, Xie H, Postis V, Nyathi Y, Tzokov SB, Poole RK, Baldwin SA, Bullough PA. Structure and function of the bacterial heterodimeric ABC transporter CydDC: stimulation of ATPase activity by thiol and heme compounds. J Biol Chem 2014; 289:23177-23188. [PMID: 24958725 PMCID: PMC4132815 DOI: 10.1074/jbc.m114.590414] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
In Escherichia coli, the biogenesis of both cytochrome bd-type quinol oxidases and periplasmic cytochromes requires the ATP-binding cassette-type cysteine/GSH transporter, CydDC. Recombinant CydDC was purified as a heterodimer and found to be an active ATPase both in soluble form with detergent and when reconstituted into a lipid environment. Two-dimensional crystals of CydDC were analyzed by electron cryomicroscopy, and the protein was shown to be made up of two non-identical domains corresponding to the putative CydD and CydC subunits, with dimensions characteristic of other ATP-binding cassette transporters. CydDC binds heme b. Detergent-solubilized CydDC appears to adopt at least two structural states, each associated with a characteristic level of bound heme. The purified protein in detergent showed a weak basal ATPase activity (approximately 100 nmol Pi/min/mg) that was stimulated ∼3-fold by various thiol compounds, suggesting that CydDC could act as a thiol transporter. The presence of heme (either intrinsic or added in the form of hemin) led to a further enhancement of thiol-stimulated ATPase activity, although a large excess of heme inhibited activity. Similar responses of the ATPase activity were observed with CydDC reconstituted into E. coli lipids. These results suggest that heme may have a regulatory role in CydDC-mediated transmembrane thiol transport.
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Affiliation(s)
- Masao Yamashita
- Krebs Institute for Biomolecular Research, Department of Molecular Biology and Biotechnology, The University of Sheffield, Sheffield S10 2TN, United Kingdom and
| | - Mark Shepherd
- Krebs Institute for Biomolecular Research, Department of Molecular Biology and Biotechnology, The University of Sheffield, Sheffield S10 2TN, United Kingdom and
| | - Wesley I Booth
- Krebs Institute for Biomolecular Research, Department of Molecular Biology and Biotechnology, The University of Sheffield, Sheffield S10 2TN, United Kingdom and
| | - Hao Xie
- School of Biomedical Sciences, The Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Vincent Postis
- School of Biomedical Sciences, The Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Yvonne Nyathi
- School of Biomedical Sciences, The Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Svetomir B Tzokov
- Krebs Institute for Biomolecular Research, Department of Molecular Biology and Biotechnology, The University of Sheffield, Sheffield S10 2TN, United Kingdom and
| | - Robert K Poole
- Krebs Institute for Biomolecular Research, Department of Molecular Biology and Biotechnology, The University of Sheffield, Sheffield S10 2TN, United Kingdom and
| | - Stephen A Baldwin
- School of Biomedical Sciences, The Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Per A Bullough
- Krebs Institute for Biomolecular Research, Department of Molecular Biology and Biotechnology, The University of Sheffield, Sheffield S10 2TN, United Kingdom and.
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29
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Srinivasan V, Pierik AJ, Lill R. Crystal structures of nucleotide-free and glutathione-bound mitochondrial ABC transporter Atm1. Science 2014; 343:1137-40. [PMID: 24604199 DOI: 10.1126/science.1246729] [Citation(s) in RCA: 168] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The yeast mitochondrial ABC transporter Atm1, in concert with glutathione, functions in the export of a substrate required for cytosolic-nuclear iron-sulfur protein biogenesis and cellular iron regulation. Defects in the human ortholog ABCB7 cause the sideroblastic anemia XLSA/A. Here, we report the crystal structures of free and glutathione-bound Atm1 in inward-facing, open conformations at 3.06- and 3.38-angstrom resolution, respectively. The glutathione binding site includes a residue mutated in XLSA/A and is located close to the inner membrane surface in a large cavity. The two nucleotide-free adenosine 5'-triphosphate binding domains do not interact yet are kept in close vicinity through tight interaction of the two C-terminal α-helices of the Atm1 dimer. The resulting protein stabilization may be a common structural feature of all ABC exporters.
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Affiliation(s)
- Vasundara Srinivasan
- Institut für Zytobiologie, Philipps-Universität Marburg, Robert-Koch-Strasse 6, 35032 Marburg, Germany
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30
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Lee JY, Yang JG, Zhitnitsky D, Lewinson O, Rees DC. Structural basis for heavy metal detoxification by an Atm1-type ABC exporter. Science 2014; 343:1133-6. [PMID: 24604198 PMCID: PMC4151877 DOI: 10.1126/science.1246489] [Citation(s) in RCA: 129] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Although substantial progress has been achieved in the structural analysis of exporters from the superfamily of adenosine triphosphate (ATP)-binding cassette (ABC) transporters, much less is known about how they selectively recognize substrates and how substrate binding is coupled to ATP hydrolysis. We have addressed these questions through crystallographic analysis of the Atm1/ABCB7/HMT1/ABCB6 ortholog from Novosphingobium aromaticivorans DSM 12444, NaAtm1, at 2.4 angstrom resolution. Consistent with a physiological role in cellular detoxification processes, functional studies showed that glutathione derivatives can serve as substrates for NaAtm1 and that its overexpression in Escherichia coli confers protection against silver and mercury toxicity. The glutathione binding site highlights the articulated design of ABC exporters, with ligands and nucleotides spanning structurally conserved elements to create adaptable interfaces accommodating conformational rearrangements during the transport cycle.
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Affiliation(s)
- Jonas Y. Lee
- Howard Hughes Medical Institute and Division of Chemistry and Chemical Engineering, Mail Code 114-96, California Institute of Technology, Pasadena, CA 91125, USA
| | - Janet G. Yang
- Howard Hughes Medical Institute and Division of Chemistry and Chemical Engineering, Mail Code 114-96, California Institute of Technology, Pasadena, CA 91125, USA
| | - Daniel Zhitnitsky
- Department of Microbiology, The Rappaport Family Institute for Research, Faculty of Medicine, The Technion-Israel Institute of Technology, Haifa, Israel
| | - Oded Lewinson
- Department of Microbiology, The Rappaport Family Institute for Research, Faculty of Medicine, The Technion-Israel Institute of Technology, Haifa, Israel
| | - Douglas C. Rees
- Howard Hughes Medical Institute and Division of Chemistry and Chemical Engineering, Mail Code 114-96, California Institute of Technology, Pasadena, CA 91125, USA
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31
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Liang X, Qin L, Liu P, Wang M, Ye H. Genes for iron-sulphur cluster assembly are targets of abiotic stress in rice, Oryza sativa. PLANT, CELL & ENVIRONMENT 2014; 37:780-94. [PMID: 24028141 DOI: 10.1111/pce.12198] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Revised: 08/27/2013] [Accepted: 09/01/2013] [Indexed: 05/14/2023]
Abstract
Iron-sulphur (Fe-S) cluster assembly occurs in chloroplasts, mitochondria and cytosol, involving dozens of genes in higher plants. In this study, we have identified 41 putative Fe-S cluster assembly genes in rice (Oryza sativa) genome, and the expression of all genes was verified. To investigate the role of Fe-S cluster assembly as a metabolic pathway, we applied abiotic stresses to rice seedlings and analysed Fe-S cluster assembly gene expression by qRT-PCR. Our data showed that genes for Fe-S cluster assembly in chloroplasts of leaves are particularly sensitive to heavy metal treatments, and that Fe-S cluster assembly genes in roots were up-regulated in response to iron toxicity, oxidative stress and some heavy metal assault. The effect of each stress treatment on the Fe-S cluster assembly machinery demonstrated an unexpected tissue or organelle specificity, suggesting that the physiological relevance of the Fe-S cluster assembly is more complex than thought. Furthermore, our results may reveal potential candidate genes for molecular breeding of rice.
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Affiliation(s)
- Xuejiao Liang
- Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China
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32
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Qi W, Li J, Chain CY, Pasquevich G, Pasquevich AF, Cowan JA. Glutathione-complexed iron-sulfur clusters. Reaction intermediates and evidence for a template effect promoting assembly and stability. Chem Commun (Camb) 2013; 49:6313-5. [PMID: 23739324 PMCID: PMC3738052 DOI: 10.1039/c3cc43620a] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Assembly and stabilization of a glutathione-complexed [2Fe-2S] cluster is promoted by aggregation of glutathione. The cluster core selects the tetramer species from a collection of equilibrating solution aggregate species, and in turn the core is stabilized toward hydrolytic degradation. Studies of glutathione derivatives, in combination with mass spectrometric and Mössbauer investigations provide insight on reaction intermediates during formation of [2Fe-2S](GS)4(2-).
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Affiliation(s)
- Wenbin Qi
- Ohio State Biochemistry Program, The Ohio State University, 100 West 18th Ave, Columbus, OH 43210
| | - Jingwei Li
- Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Ave, Columbus, OH 43210
| | - C. Y Chain
- Departamento de Física, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Argentina
| | - G.A. Pasquevich
- Departamento de Física, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Argentina
| | - A. F. Pasquevich
- Departamento de Física, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Argentina
| | - J. A. Cowan
- Ohio State Biochemistry Program, The Ohio State University, 100 West 18th Ave, Columbus, OH 43210
- Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Ave, Columbus, OH 43210
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33
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Chavan H, Khan MMT, Tegos G, Krishnamurthy P. Efficient purification and reconstitution of ATP binding cassette transporter B6 (ABCB6) for functional and structural studies. J Biol Chem 2013; 288:22658-69. [PMID: 23792964 DOI: 10.1074/jbc.m113.485284] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The mitochondrial ATP binding cassette transporter ABCB6 has been associated with a broad range of physiological functions, including growth and development, therapy-related drug resistance, and the new blood group system Langereis. ABCB6 has been proposed to regulate heme synthesis by shuttling coproporphyrinogen III from the cytoplasm into the mitochondria. However, direct functional information of the transport complex is not known. To understand the role of ABCB6 in mitochondrial transport, we developed an in vitro system with pure and active protein. ABCB6 overexpressed in HEK293 cells was solubilized from mitochondrial membranes and purified to homogeneity. Purified ABCB6 showed a high binding affinity for MgATP (Kd = 0.18 μM) and an ATPase activity with a Km of 0.99 mM. Reconstitution of ABCB6 into liposomes allowed biochemical characterization of the ATPase including (i) substrate-stimulated ATPase activity, (ii) transport kinetics of its proposed endogenous substrate coproporphyrinogen III, and (iii) transport kinetics of substrates identified using a high throughput screening assay. Mutagenesis of the conserved lysine to alanine (K629A) in the Walker A motif abolished ATP hydrolysis and substrate transport. These results suggest a direct interaction between mitochondrial ABCB6 and its transport substrates that is critical for the activity of the transporter. Furthermore, the simple immunoaffinity purification of ABCB6 to near homogeneity and efficient reconstitution of ABCB6 into liposomes might provide the basis for future studies on the structure/function of ABCB6.
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Affiliation(s)
- Hemantkumar Chavan
- Department of Pharmacology, Toxicology and Therapeutics, University of Kansas Medical Center, Kansas City, Kansas 66160, USA
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Bernard DG, Netz DJA, Lagny TJ, Pierik AJ, Balk J. Requirements of the cytosolic iron-sulfur cluster assembly pathway in Arabidopsis. Philos Trans R Soc Lond B Biol Sci 2013; 368:20120259. [PMID: 23754812 DOI: 10.1098/rstb.2012.0259] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The assembly of iron-sulfur (Fe-S) clusters requires dedicated protein factors inside the living cell. Striking similarities between prokaryotic and eukaryotic assembly proteins suggest that plant cells inherited two different pathways through endosymbiosis: the ISC pathway in mitochondria and the SUF pathway in plastids. Fe-S proteins are also found in the cytosol and nucleus, but little is known about how they are assembled in plant cells. Here, we show that neither plastid assembly proteins nor the cytosolic cysteine desulfurase ABA3 are required for the activity of cytosolic aconitase, which depends on a [4Fe-4S] cluster. In contrast, cytosolic aconitase activity depended on the mitochondrial cysteine desulfurase NFS1 and the mitochondrial transporter ATM3. In addition, we were able to complement a yeast mutant in the cytosolic Fe-S cluster assembly pathway, dre2, with the Arabidopsis homologue AtDRE2, but only when expressed together with the diflavin reductase AtTAH18. Spectroscopic characterization showed that purified AtDRE2 could bind up to two Fe-S clusters. Purified AtTAH18 bound one flavin per molecule and was able to accept electrons from NAD(P)H. These results suggest that the proteins involved in cytosolic Fe-S cluster assembly are highly conserved, and that dependence on the mitochondria arose before the second endosymbiosis event leading to plastids.
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Affiliation(s)
- Delphine G Bernard
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, UK
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35
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Structures of ABCB10, a human ATP-binding cassette transporter in apo- and nucleotide-bound states. Proc Natl Acad Sci U S A 2013; 110:9710-5. [PMID: 23716676 DOI: 10.1073/pnas.1217042110] [Citation(s) in RCA: 183] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
ABCB10 is one of the three ATP-binding cassette (ABC) transporters found in the inner membrane of mitochondria. In mammals ABCB10 is essential for erythropoiesis, and for protection of mitochondria against oxidative stress. ABCB10 is therefore a potential therapeutic target for diseases in which increased mitochondrial reactive oxygen species production and oxidative stress play a major role. The crystal structure of apo-ABCB10 shows a classic exporter fold ABC transporter structure, in an open-inwards conformation, ready to bind the substrate or nucleotide from the inner mitochondrial matrix or membrane. Unexpectedly, however, ABCB10 adopts an open-inwards conformation when complexed with nonhydrolysable ATP analogs, in contrast to other transporter structures which adopt an open-outwards conformation in complex with ATP. The three complexes of ABCB10/ATP analogs reported here showed varying degrees of opening of the transport substrate binding site, indicating that in this conformation there is some flexibility between the two halves of the protein. These structures suggest that the observed plasticity, together with a portal between two helices in the transmembrane region of ABCB10, assist transport substrate entry into the substrate binding cavity. These structures indicate that ABC transporters may exist in an open-inwards conformation when nucleotide is bound. We discuss ways in which this observation can be aligned with the current views on mechanisms of ABC transporters.
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36
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Patil VA, Fox JL, Gohil VM, Winge DR, Greenberg ML. Loss of cardiolipin leads to perturbation of mitochondrial and cellular iron homeostasis. J Biol Chem 2012. [PMID: 23192348 DOI: 10.1074/jbc.m112.428938] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Cardiolipin (CL) is the signature phospholipid of mitochondrial membranes, where it is synthesized locally and plays a critical role in mitochondrial bioenergetic functions. The importance of CL in human health is underscored by the observation that perturbation of CL biosynthesis causes the severe genetic disorder Barth syndrome. To fully understand the cellular response to the loss of CL, we carried out genome-wide expression profiling of the yeast CL mutant crd1Δ. Our results show that the loss of CL in this mutant leads to increased expression of iron uptake genes accompanied by elevated levels of mitochondrial iron and increased sensitivity to iron and hydrogen peroxide. Previous studies have shown that increased mitochondrial iron levels result from perturbations in iron-sulfur (Fe-S) cluster biogenesis. Consistent with an Fe-S defect, deletion of ISU1, one of two ISU genes that encode the mitochondrial Fe-S scaffolding protein essential for the synthesis of Fe-S clusters, led to synthetic growth defects with the crd1Δ mutant. We further show that crd1Δ cells have reduced activities of mitochondrial Fe-S enzymes (aconitase, succinate dehydrogenase, and ubiquinol-cytochrome c oxidoreductase), as well as cytosolic Fe-S enzymes (sulfite reductase and isopropylmalate isomerase). Increased expression of ATM1 or YAP1 did not rescue the Fe-S defects in crd1Δ. These findings show for the first time that CL is required for Fe-S biogenesis to maintain mitochondrial and cellular iron homeostasis.
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Affiliation(s)
- Vinay A Patil
- Department of Biological Sciences, Wayne State University, Detroit, Michigan 48202, USA
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37
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Rouault TA. Biogenesis of iron-sulfur clusters in mammalian cells: new insights and relevance to human disease. Dis Model Mech 2012; 5:155-64. [PMID: 22382365 PMCID: PMC3291637 DOI: 10.1242/dmm.009019] [Citation(s) in RCA: 247] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Iron-sulfur (Fe-S) clusters are ubiquitous cofactors composed of iron and inorganic sulfur. They are required for the function of proteins involved in a wide range of activities, including electron transport in respiratory chain complexes, regulatory sensing, photosynthesis and DNA repair. The proteins involved in the biogenesis of Fe-S clusters are evolutionarily conserved from bacteria to humans, and many insights into the process of Fe-S cluster biogenesis have come from studies of model organisms, including bacteria, fungi and plants. It is now clear that several rare and seemingly dissimilar human diseases are attributable to defects in the basic process of Fe-S cluster biogenesis. Although these diseases –which include Friedreich’s ataxia (FRDA), ISCU myopathy, a rare form of sideroblastic anemia, an encephalomyopathy caused by dysfunction of respiratory chain complex I and multiple mitochondrial dysfunctions syndrome – affect different tissues, a feature common to many of them is that mitochondrial iron overload develops as a secondary consequence of a defect in Fe-S cluster biogenesis. This Commentary outlines the basic steps of Fe-S cluster biogenesis as they have been defined in model organisms. In addition, it draws attention to refinements of the process that might be specific to the subcellular compartmentalization of Fe-S cluster biogenesis proteins in some eukaryotes, including mammals. Finally, it outlines several important unresolved questions in the field that, once addressed, should offer important clues into how mitochondrial iron homeostasis is regulated, and how dysfunction in Fe-S cluster biogenesis can contribute to disease.
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Affiliation(s)
- Tracey A Rouault
- National Institute of Child Health and Human Development, Bethesda, MD 20892, USA.
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Abstract
Glutathione (γ-glutamyl-cysteinyl-glycine, GSH) is a major thiol-containing peptide with cellular levels of up to 10 mM. (1) Several recent reports have demonstrated glutaredoxins (Grx) to form [Fe(2)S(2)] cluster-bridged dimers, where glutathione provides two exogenous thiol ligands, and have implicated such species in cellular iron sulfur cluster biosynthesis. We report the finding that glutathione alone can coordinate and stabilize an [Fe(2)S(2)] cluster under physiological conditions, with optical, redox, Mössbauer, and NMR characteristics that are consistent with a [Fe(2)S(2)](GS)(4) composition. The Fe-S assembly protein ISU catalyzes formation of [Fe(2)S(2)](GS)(4) from iron and sulfide ions in the presence of glutathione, and the [Fe(2)S(2)] core undergoes reversible exchange between apo ISU and free glutathione.
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Affiliation(s)
- Wenbin Qi
- Ohio State Biochemistry Program, The Ohio State University, 100 West 18th Ave, Columbus, OH 43210
| | - Jingwei Li
- Department of Chemistry, The Ohio State University, 100 West 18th Ave, Columbus, OH 43210
| | - C. Y Chain
- Departamento de Física, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Argentina
| | - G.A. Pasquevich
- Departamento de Física, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Argentina
| | - A. F. Pasquevich
- Departamento de Física, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Argentina
| | - J. A. Cowan
- Ohio State Biochemistry Program, The Ohio State University, 100 West 18th Ave, Columbus, OH 43210
- Department of Chemistry, The Ohio State University, 100 West 18th Ave, Columbus, OH 43210
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Kiss K, Brozik A, Kucsma N, Toth A, Gera M, Berry L, Vallentin A, Vial H, Vidal M, Szakacs G. Shifting the paradigm: the putative mitochondrial protein ABCB6 resides in the lysosomes of cells and in the plasma membrane of erythrocytes. PLoS One 2012; 7:e37378. [PMID: 22655043 PMCID: PMC3360040 DOI: 10.1371/journal.pone.0037378] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2012] [Accepted: 04/18/2012] [Indexed: 11/19/2022] Open
Abstract
ABCB6, a member of the adenosine triphosphate–binding cassette (ABC) transporter family, has been proposed to be responsible for the mitochondrial uptake of porphyrins. Here we show that ABCB6 is a glycoprotein present in the membrane of mature erythrocytes and in exosomes released from reticulocytes during the final steps of erythroid maturation. Consistent with its presence in exosomes, endogenous ABCB6 is localized to the endo/lysosomal compartment, and is absent from the mitochondria of cells. Knock-down studies demonstrate that ABCB6 function is not required for de novo heme biosynthesis in differentiating K562 cells, excluding this ABC transporter as a key regulator of porphyrin synthesis. We confirm the mitochondrial localization of ABCB7, ABCB8 and ABCB10, suggesting that only three ABC transporters should be classified as mitochondrial proteins. Taken together, our results challenge the current paradigm linking the expression and function of ABCB6 to mitochondria.
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Affiliation(s)
- Katalin Kiss
- Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary
| | - Anna Brozik
- Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary
| | - Nora Kucsma
- Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary
| | - Alexandra Toth
- Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary
| | - Melinda Gera
- Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary
| | - Laurence Berry
- Unité Mixte de Recherche 5235 (Dynamique des Interactions Membranaires Normales et Pathologiques), Centre National de la Recherche Scientifique, Université Montpellier II, Montpellier, France
| | - Alice Vallentin
- Unité Mixte de Recherche 5235 (Dynamique des Interactions Membranaires Normales et Pathologiques), Centre National de la Recherche Scientifique, Université Montpellier II, Montpellier, France
| | - Henri Vial
- Unité Mixte de Recherche 5235 (Dynamique des Interactions Membranaires Normales et Pathologiques), Centre National de la Recherche Scientifique, Université Montpellier II, Montpellier, France
| | - Michel Vidal
- Unité Mixte de Recherche 5235 (Dynamique des Interactions Membranaires Normales et Pathologiques), Centre National de la Recherche Scientifique, Université Montpellier II, Montpellier, France
| | - Gergely Szakacs
- Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary
- * E-mail:
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Netz DJA, Pierik AJ, Stümpfig M, Bill E, Sharma AK, Pallesen LJ, Walden WE, Lill R. A bridging [4Fe-4S] cluster and nucleotide binding are essential for function of the Cfd1-Nbp35 complex as a scaffold in iron-sulfur protein maturation. J Biol Chem 2012; 287:12365-78. [PMID: 22362766 DOI: 10.1074/jbc.m111.328914] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The essential P-loop NTPases Cfd1 and Nbp35 of the cytosolic iron-sulfur (Fe-S) protein assembly machinery perform a scaffold function for Fe-S cluster synthesis. Both proteins contain a nucleotide binding motif of unknown function and a C-terminal motif with four conserved cysteine residues. The latter motif defines the Mrp/Nbp35 subclass of P-loop NTPases and is suspected to be involved in transient Fe-S cluster binding. To elucidate the function of these two motifs, we first created cysteine mutant proteins of Cfd1 and Nbp35 and investigated the consequences of these mutations by genetic, cell biological, biochemical, and spectroscopic approaches. The two central cysteine residues (CPXC) of the C-terminal motif were found to be crucial for cell viability, protein function, coordination of a labile [4Fe-4S] cluster, and Cfd1-Nbp35 hetero-tetramer formation. Surprisingly, the two proximal cysteine residues were dispensable for all these functions, despite their strict evolutionary conservation. Several lines of evidence suggest that the C-terminal CPXC motifs of Cfd1-Nbp35 coordinate a bridging [4Fe-4S] cluster. Upon mutation of the nucleotide binding motifs Fe-S clusters could no longer be assembled on these proteins unless wild-type copies of Cfd1 and Nbp35 were present in trans. This result indicated that Fe-S cluster loading on these scaffold proteins is a nucleotide-dependent step. We propose that the bridging coordination of the C-terminal Fe-S cluster may be ideal for its facile assembly, labile binding, and efficient transfer to target Fe-S apoproteins, a step facilitated by the cytosolic iron-sulfur (Fe-S) protein assembly proteins Nar1 and Cia1 in vivo.
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Affiliation(s)
- Daili J A Netz
- Institut für Zytobiologie und Zytopathologie, Philipps-Universität Marburg, Robert-Koch Strasse 6, 35032 Marburg, Germany
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Bedekovics T, Li H, Gajdos GB, Isaya G. Leucine biosynthesis regulates cytoplasmic iron-sulfur enzyme biogenesis in an Atm1p-independent manner. J Biol Chem 2011; 286:40878-88. [PMID: 21926174 DOI: 10.1074/jbc.m111.270082] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Fe-S clusters (ISCs) are versatile cofactors utilized by many mitochondrial, cytoplasmic, and nuclear enzymes. Whereas mitochondria can independently initiate and complete ISC synthesis, other cellular compartments are believed to assemble ISCs from putative precursors exported from the mitochondria via an ATP binding cassette (ABC) transporter conserved from yeast (Atm1p) to humans (ABCB7). However, the regulatory interactions between mitochondrial and extramitochondrial ISC synthesis are largely unknown. In yeast, we found that mitochondrial ISC synthesis is regulated by the leucine biosynthetic pathway, which among other proteins involves an abundant cytoplasmic [4Fe-4S] enzyme, Leu1p. Enzymatic blocks in the pathway (i.e. leu1Δ or leu2Δ gene deletion mutations) induced post-transcriptional up-regulation of core components of mitochondrial ISC biosynthesis (i.e. the sulfur donor Nfs1p, the iron donor Yfh1p, and the ISC scaffold Isu1p). In leu2Δ cells, transcriptional mechanisms also led to dramatic up-regulation of Leu1p with concomitant down-regulation of mitochondrial aconitase (Aco1p), a [4Fe-4S] enzyme in the tricarboxylic acid cycle. Accordingly, the leu2Δ deletion mutation exacerbated Aco1p inactivation in cells with mutations in Yfh1p. These data indicate that defects in leucine biosynthesis promote the biogenesis of enzymatically active Leu1p at the expense of Aco1p activity. Surprisingly, this effect is independent of Atm1p; previous reports linking the loss of Leu1p activity to Atm1p depletion were confounded by the fact that LEU2 was used as a selectable marker to create Atm1p-depleted cells, whereas a leu2Δ allele was present in Atm1p-repleted controls. Thus, still largely unknown transcriptional and post-transcriptional mechanisms control ISC distribution between mitochondria and other cellular compartments.
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Affiliation(s)
- Tibor Bedekovics
- Department of Pediatric and Adolescent Medicine, Mayo Clinic, Rochester, Minnesota 55905, USA
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Xu XM, Møller SG. Iron-sulfur clusters: biogenesis, molecular mechanisms, and their functional significance. Antioxid Redox Signal 2011; 15:271-307. [PMID: 20812788 DOI: 10.1089/ars.2010.3259] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Iron-sulfur clusters [Fe-S] are small, ubiquitous inorganic cofactors representing one of the earliest catalysts during biomolecule evolution and are involved in fundamental biological reactions, including regulation of enzyme activity, mitochondrial respiration, ribosome biogenesis, cofactor biogenesis, gene expression regulation, and nucleotide metabolism. Although simple in structure, [Fe-S] biogenesis requires complex protein machineries and pathways for assembly. [Fe-S] are assembled from cysteine-derived sulfur and iron onto scaffold proteins followed by transfer to recipient apoproteins. Several predominant iron-sulfur biogenesis systems have been identified, including nitrogen fixation (NIF), sulfur utilization factor (SUF), iron-sulfur cluster (ISC), and cytosolic iron-sulfur protein assembly (CIA), and many protein components have been identified and characterized. In eukaryotes ISC is mainly localized to mitochondria, cytosolic iron-sulfur protein assembly to the cytosol, whereas plant sulfur utilization factor is localized mainly to plastids. Because of this spatial separation, evidence suggests cross-talk mediated by organelle export machineries and dual targeting mechanisms. Although research efforts in understanding iron-sulfur biogenesis has been centered on bacteria, yeast, and plants, recent efforts have implicated inappropriate [Fe-S] biogenesis to underlie many human diseases. In this review we detail our current understanding of [Fe-S] biogenesis across species boundaries highlighting evolutionary conservation and divergence and assembling our knowledge into a cellular context.
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Affiliation(s)
- Xiang Ming Xu
- Centre for Organelle Research CORE, University of Stavanger, Norway
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43
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Anamorsin Is a [2Fe-2S] Cluster-Containing Substrate of the Mia40-Dependent Mitochondrial Protein Trapping Machinery. ACTA ACUST UNITED AC 2011; 18:794-804. [DOI: 10.1016/j.chembiol.2011.03.015] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2010] [Revised: 02/24/2011] [Accepted: 03/08/2011] [Indexed: 11/24/2022]
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Qi W, Cowan JA. Structural, Mechanistic and Coordination Chemistry of Relevance to the Biosynthesis of Iron-Sulfur and Related Iron Cofactors. Coord Chem Rev 2011; 255:688-699. [PMID: 21499539 DOI: 10.1016/j.ccr.2010.10.016] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Iron-sulfur clusters are an important class of protein-bound prosthetic center that find wide utility in nature. Roles include electron transfer, enzyme catalysis, protein structure stabilization, and regulation of gene expression as transcriptional and translational sensors. In eukaryotes their biosynthesis requires a complex molecular machinery that is located within the mitochondrion, while bacteria exhibit up to three independent cluster assembly pathways. All of these paths share common themes. This review summarizes some key structural and functional properties of three central proteins dedicated to the Fe-S cluster assembly process: namely, the sulfide donor (cysteine desulfurase); iron donor (frataxin), and the iron-sulfur cluster scaffold protein (IscU/ISU).
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Affiliation(s)
- Wenbin Qi
- Ohio State Biochemistry Program, The Ohio State University
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Erythropoiesis and iron sulfur cluster biogenesis. Adv Hematol 2010; 2010. [PMID: 20862391 PMCID: PMC2939393 DOI: 10.1155/2010/329394] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2010] [Revised: 06/04/2010] [Accepted: 08/02/2010] [Indexed: 11/22/2022] Open
Abstract
Erythropoiesis in animals is a synchronized process of erythroid cell differentiation that depends on successful acquisition of iron. Heme synthesis depends on iron through its dependence on iron sulfur (Fe-S) cluster biogenesis. Here, we review the relationship between Fe-S biogenesis and heme synthesis in erythropoiesis, with emphasis on the proteins, GLRX5, ABCB7, ISCA, and C1orf69. These Fe-S biosynthesis proteins are highly expressed in erythroid tissues, and deficiency of each of these proteins has been shown to cause anemia in zebrafish model. GLRX5 is involved in the production and ABCB7 in the export of an unknown factor that may function as a gauge of mitochondrial iron status, which may indirectly modulate activity of iron regulatory proteins (IRPs). ALAS2, the enzyme catalyzing the first step in heme synthesis, is translationally controlled by IRPs. GLRX5 may also provide Fe-S cofactor for ferrochelatase, the last enzyme in heme synthesis. ISCA and C1orf69 are thought to assemble Fe-S clusters for mitochondrial aconitase and for lipoate synthase, the enzyme producing lipoate for pyruvate dehydrogenase complex (PDC). PDC and aconitase are involved in the production of succinyl-CoA, a substrate for heme biosynthesis. Thus, many steps of heme synthesis depend on Fe-S cluster assembly.
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Sharma AK, Pallesen LJ, Spang RJ, Walden WE. Cytosolic iron-sulfur cluster assembly (CIA) system: factors, mechanism, and relevance to cellular iron regulation. J Biol Chem 2010; 285:26745-26751. [PMID: 20522543 DOI: 10.1074/jbc.r110.122218] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
FeS cluster biogenesis is an essential process in virtually all forms of life. Complex protein machineries that are conserved from bacteria through higher eukaryotes facilitate assembly of the FeS cofactor in proteins. In the last several years, significant strides have been made in our understanding of FeS cluster assembly and the functional overlap of this process with cellular iron homeostasis. This minireview summarizes the present understanding of the cytosolic iron-sulfur cluster assembly (CIA) system in eukaryotes, with a focus on information gained from studies in budding yeast and mammalian systems.
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Affiliation(s)
- Anil K Sharma
- Department of Microbiology and Immunology, University of Illinois at Chicago, Chicago, Illinois 60612
| | - Leif J Pallesen
- Department of Microbiology and Immunology, University of Illinois at Chicago, Chicago, Illinois 60612
| | - Robert J Spang
- Department of Microbiology and Immunology, University of Illinois at Chicago, Chicago, Illinois 60612
| | - William E Walden
- Department of Microbiology and Immunology, University of Illinois at Chicago, Chicago, Illinois 60612.
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Miao R, Kim H, Koppolu UMK, Ellis EA, Scott RA, Lindahl PA. Biophysical characterization of the iron in mitochondria from Atm1p-depleted Saccharomyces cerevisiae. Biochemistry 2009; 48:9556-68. [PMID: 19761223 DOI: 10.1021/bi901110n] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Atm1p is an ABC transporter localized in the mitochondrial inner membrane; it functions to export an unknown species into the cytosol and is involved in cellular iron metabolism. Depletion or deletion of Atm1p causes Fe accumulation in mitochondria and a defect in cytosolic Fe/S cluster assembly but reportedly not a defect in mitochondrial Fe/S cluster assembly. In this study the nature of the accumulated Fe was examined using Mossbauer spectroscopy, EPR, electronic absorption spectroscopy, X-ray absorption spectroscopy, and electron microscopy. The Fe that accumulated in aerobically grown cells was in the form of iron(III) phosphate nanoparticles similar to that which accumulates in yeast frataxin Yfh1p-deleted or yeast ferredoxin Yah1p-depleted cells. Relative to WT mitochondria, Fe/S cluster and heme levels in Atm1p-depleted mitochondria from aerobic cells were significantly diminished. Atm1p depletion also caused a buildup of nonheme Fe(II) ions in the mitochondria and an increase in oxidative damage. Atm1p-depleted mitochondria isolated from anaerobically grown cells exhibited WT levels of Fe/S clusters and hemes, and they did not hyperaccumulate Fe. Atm1p-depleted cells lacked Leu1p activity, regardless of whether they were grown aerobically or anaerobically. These results indicate that Atm1p does not participate in mitochondrial Fe/S cluster assembly and that the species exported by Atm1p is required for cytosolic Fe/S cluster assembly. The Fe/S cluster defect and the Fe-accumulation phenotype, resulting from the depletion of Atm1p in aerobic cells (but not in anaerobic cells), may be secondary effects that are observed only when cells are exposed to oxygen during growth. Reactive oxygen species generated under these conditions might degrade iron-sulfur clusters and lower heme levels in the organelle.
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Affiliation(s)
- Ren Miao
- Department of Chemistry, Texas A&M University, College Station, Texas 77843-3255, USA
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Bernard DG, Cheng Y, Zhao Y, Balk J. An allelic mutant series of ATM3 reveals its key role in the biogenesis of cytosolic iron-sulfur proteins in Arabidopsis. PLANT PHYSIOLOGY 2009; 151:590-602. [PMID: 19710232 PMCID: PMC2754654 DOI: 10.1104/pp.109.143651] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
The ATP-binding cassette transporters of mitochondria (ATMs) are highly conserved proteins, but their function in plants is poorly defined. Arabidopsis (Arabidopsis thaliana) has three ATM genes, namely ATM1, ATM2, and ATM3. Using a collection of insertional mutants, we show that only ATM3 has an important function for plant growth. Additional atm3 alleles were identified among sirtinol-resistant lines, correlating with decreased activities of aldehyde oxidases, cytosolic enzymes that convert sirtinol into an auxin analog, and depend on iron-sulfur (Fe-S) and molybdenum cofactor (Moco) as prosthetic groups. In the sirtinol-resistant atm3-3 allele, the highly conserved arginine-612 is replaced by a lysine residue, the negative effect of which could be mimicked in the yeast Atm1p ortholog. Arabidopsis atm3 mutants displayed defects in root growth, chlorophyll content, and seedling establishment. Analyses of selected metal enzymes showed that the activity of cytosolic aconitase (Fe-S) was strongly decreased across the range of atm3 alleles, whereas mitochondrial and plastid Fe-S enzymes were unaffected. Nitrate reductase activity (Moco, heme) was decreased by 50% in the strong atm3 alleles, but catalase activity (heme) was similar to that of the wild type. Strikingly, in contrast to mutants in the yeast and mammalian orthologs, Arabidopsis atm3 mutants did not display a dramatic iron homeostasis defect and did not accumulate iron in mitochondria. Our data suggest that Arabidopsis ATM3 may transport (1) at least two distinct compounds or (2) a single compound required for both Fe-S and Moco assembly machineries in the cytosol, but not iron.
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Affiliation(s)
- Delphine G Bernard
- Department of Plant Sciences, University of Cambridge, Cambridge CB2 3EA, United Kingdom
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Evaluation of Fe(III) reduction by mitochondria induced with a respiratory substrate NADH or succinate, using a Fe(II)-specific chelator bathophenanthroline disulfonate in Saccharomyces cerevisiae. Biologia (Bratisl) 2009. [DOI: 10.2478/s11756-009-0150-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Zutz A, Gompf S, Schägger H, Tampé R. Mitochondrial ABC proteins in health and disease. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2009; 1787:681-90. [PMID: 19248758 DOI: 10.1016/j.bbabio.2009.02.009] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2008] [Revised: 02/12/2009] [Accepted: 02/13/2009] [Indexed: 12/14/2022]
Abstract
ABC transporters represent one of the largest families of membrane proteins that are found in all three phyla of life. Mitochondria comprise up to four ABC systems, ABCB7/ATM1, ABCB10/MDL1, ABCB8 and ABCB6. These half-transporters, which assemble into homodimeric complexes, are involved in a number of key cellular processes, e.g. biogenesis of cytosolic iron-sulfur clusters, heme biosynthesis, iron homeostasis, multidrug resistance, and protection against oxidative stress. Here, we summarize recent advances and emerging themes in our understanding of how these ABC systems in the inner and outer mitochondrial membrane fulfill their functions in important (patho) physiological processes, including neurodegenerative and hematological disorders.
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Affiliation(s)
- Ariane Zutz
- Institute of Biochemistry, Biocenter, Goethe-University, Max-von-Laue-Str. 9, D-60348 Frankfurt a.M., Germany
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