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de Ridder I, Kerkhofs M, Lemos FO, Loncke J, Bultynck G, Parys JB. The ER-mitochondria interface, where Ca 2+ and cell death meet. Cell Calcium 2023; 112:102743. [PMID: 37126911 DOI: 10.1016/j.ceca.2023.102743] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2023] [Revised: 04/20/2023] [Accepted: 04/24/2023] [Indexed: 05/03/2023]
Abstract
Endoplasmic reticulum (ER)-mitochondria contact sites are crucial to allow Ca2+ flux between them and a plethora of proteins participate in tethering both organelles together. Inositol 1,4,5-trisphosphate receptors (IP3Rs) play a pivotal role at such contact sites, participating in both ER-mitochondria tethering and as Ca2+-transport system that delivers Ca2+ from the ER towards mitochondria. At the ER-mitochondria contact sites, the IP3Rs function as a multi-protein complex linked to the voltage-dependent anion channel 1 (VDAC1) in the outer mitochondrial membrane, via the chaperone glucose-regulated protein 75 (GRP75). This IP3R-GRP75-VDAC1 complex supports the efficient transfer of Ca2+ from the ER into the mitochondrial intermembrane space, from which the Ca2+ ions can reach the mitochondrial matrix through the mitochondrial calcium uniporter. Under physiological conditions, basal Ca2+ oscillations deliver Ca2+ to the mitochondrial matrix, thereby stimulating mitochondrial oxidative metabolism. However, when mitochondrial Ca2+ overload occurs, the increase in [Ca2+] will induce the opening of the mitochondrial permeability transition pore, thereby provoking cell death. The IP3R-GRP75-VDAC1 complex forms a hub for several other proteins that stabilize the complex and/or regulate the complex's ability to channel Ca2+ into the mitochondria. These proteins and their mechanisms of action are discussed in the present review with special attention for their role in pathological conditions and potential implication for therapeutic strategies.
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Affiliation(s)
- Ian de Ridder
- KU Leuven, Laboratory for Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine & Leuven Kanker Instituut, Campus Gasthuisberg O/N-1 B-802, Herestraat 49, Leuven BE-3000, Belgium
| | - Martijn Kerkhofs
- KU Leuven, Laboratory for Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine & Leuven Kanker Instituut, Campus Gasthuisberg O/N-1 B-802, Herestraat 49, Leuven BE-3000, Belgium
| | - Fernanda O Lemos
- KU Leuven, Laboratory for Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine & Leuven Kanker Instituut, Campus Gasthuisberg O/N-1 B-802, Herestraat 49, Leuven BE-3000, Belgium
| | - Jens Loncke
- KU Leuven, Laboratory for Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine & Leuven Kanker Instituut, Campus Gasthuisberg O/N-1 B-802, Herestraat 49, Leuven BE-3000, Belgium
| | - Geert Bultynck
- KU Leuven, Laboratory for Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine & Leuven Kanker Instituut, Campus Gasthuisberg O/N-1 B-802, Herestraat 49, Leuven BE-3000, Belgium.
| | - Jan B Parys
- KU Leuven, Laboratory for Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine & Leuven Kanker Instituut, Campus Gasthuisberg O/N-1 B-802, Herestraat 49, Leuven BE-3000, Belgium.
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2
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Studying Peptide-Metal Ion Complex Structures by Solution-State NMR. Int J Mol Sci 2022; 23:ijms232415957. [PMID: 36555599 PMCID: PMC9782655 DOI: 10.3390/ijms232415957] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Revised: 12/06/2022] [Accepted: 12/13/2022] [Indexed: 12/23/2022] Open
Abstract
Metal chelation can provide structural stability and form reactive centers in metalloproteins. Approximately one third of known protein structures are metalloproteins, and metal binding, or the lack thereof, is often implicated in disease, making it necessary to be able to study these systems in detail. Peptide-metal complexes are both present in nature and can provide a means to focus on the binding region of a protein and control experimental variables to a high degree. Structural studies of peptide complexes with metal ions by nuclear magnetic resonance (NMR) were surveyed for all the essential metal complexes and many non-essential metal complexes. The various methods used to study each metal ion are presented together with examples of recent research. Many of these metal systems have been individually reviewed and this current overview of NMR studies of metallopeptide complexes aims to provide a basis for inspiration from structural studies and methodology applied in the field.
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3
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A pair of transporters controls mitochondrial Zn 2+ levels to maintain mitochondrial homeostasis. Protein Cell 2021; 13:180-202. [PMID: 34687432 PMCID: PMC8901913 DOI: 10.1007/s13238-021-00881-4] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Accepted: 09/02/2021] [Indexed: 12/15/2022] Open
Abstract
Zn2+ is required for the activity of many mitochondrial proteins, which regulate mitochondrial dynamics, apoptosis and mitophagy. However, it is not understood how the proper mitochondrial Zn2+ level is achieved to maintain mitochondrial homeostasis. Using Caenorhabditis elegans, we reveal here that a pair of mitochondrion-localized transporters controls the mitochondrial level of Zn2+. We demonstrate that SLC-30A9/ZnT9 is a mitochondrial Zn2+ exporter. Loss of SLC-30A9 leads to mitochondrial Zn2+ accumulation, which damages mitochondria, impairs animal development and shortens the life span. We further identify SLC-25A25/SCaMC-2 as an important regulator of mitochondrial Zn2+ import. Loss of SLC-25A25 suppresses the abnormal mitochondrial Zn2+ accumulation and defective mitochondrial structure and functions caused by loss of SLC-30A9. Moreover, we reveal that the endoplasmic reticulum contains the Zn2+ pool from which mitochondrial Zn2+ is imported. These findings establish the molecular basis for controlling the correct mitochondrial Zn2+ levels for normal mitochondrial structure and functions.
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Kunji ERS, King MS, Ruprecht JJ, Thangaratnarajah C. The SLC25 Carrier Family: Important Transport Proteins in Mitochondrial Physiology and Pathology. Physiology (Bethesda) 2021; 35:302-327. [PMID: 32783608 PMCID: PMC7611780 DOI: 10.1152/physiol.00009.2020] [Citation(s) in RCA: 98] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Members of the mitochondrial carrier family (SLC25) transport a variety of compounds across the inner membrane of mitochondria. These transport steps provide building blocks for the cell and link the pathways of the mitochondrial matrix and cytosol. An increasing number of diseases and pathologies has been associated with their dysfunction. In this review, the molecular basis of these diseases is explained based on our current understanding of their transport mechanism.
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Affiliation(s)
- Edmund R S Kunji
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge, United Kingdom
| | - Martin S King
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge, United Kingdom
| | - Jonathan J Ruprecht
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge, United Kingdom
| | - Chancievan Thangaratnarajah
- Groningen Biomolecular Sciences and Biotechnology Institute, Membrane Enzymology, University of Groningen, Groningen, The Netherlands
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5
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Abstract
Members of the mitochondrial carrier family [solute carrier family 25 (SLC25)] transport nucleotides, amino acids, carboxylic acids, fatty acids, inorganic ions, and vitamins across the mitochondrial inner membrane. They are important for many cellular processes, such as oxidative phosphorylation of lipids and sugars, amino acid metabolism, macromolecular synthesis, ion homeostasis, cellular regulation, and differentiation. Here, we describe the functional elements of the transport mechanism of mitochondrial carriers, consisting of one central substrate-binding site and two gates with salt-bridge networks on either side of the carrier. Binding of the substrate during import causes three gate elements to rotate inward, forming the cytoplasmic network and closing access to the substrate-binding site from the intermembrane space. Simultaneously, three core elements rock outward, disrupting the matrix network and opening the substrate-binding site to the matrix side of the membrane. During export, substrate binding triggers conformational changes involving the same elements but operating in reverse.
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Affiliation(s)
- J J Ruprecht
- Medical Research Council Mitochondrial Biology Unit, Keith Peters Building, University of Cambridge, Cambridge CB2 0XY, United Kingdom; ,
| | - E R S Kunji
- Medical Research Council Mitochondrial Biology Unit, Keith Peters Building, University of Cambridge, Cambridge CB2 0XY, United Kingdom; ,
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6
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Garg A, Pal D. Inferring metal binding sites in flexible regions of proteins. Proteins 2021; 89:1125-1133. [PMID: 33864411 DOI: 10.1002/prot.26085] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Revised: 03/15/2021] [Accepted: 04/12/2021] [Indexed: 12/20/2022]
Abstract
Metal ions are central to the molecular function of many proteins. Thus their knowledge in experimentally determined structure is important; however, such structures often lose bound metal ions during sample preparation. Identification of these metal-binding site(s) becomes difficult when the receptor is novel and/or their conformations differ in the bound/unbound states. Locating such sites in theoretical models also poses a challenge due to the uncertainties with side-chain modeling. We address the problem by employing the Geometric Hashing algorithm to create a template library of functionally important binding sites and match query structures with the available templates. The matching is done on the structure ensemble obtained from coarse-grained molecular dynamics simulation, where metal-specific amino acids are screened to infer the true site. Test on 1347 non-redundant monomer protein structures show that Ca2+ , Zn2+ , Mg2+ , Cu2+ , and Fe3+ binding site residues can be classified at 0.92, 0.95, 0.80, 0.90, and 0.92 aggregate performance (out of 1) across all possible thresholds. The performance for Ca2+ and Zn2+ is notably superior in comparison to state-of-the-art methods like IonCom and MIB. Specific case studies show that additionally predicted metal-binding site residues in proteins have features necessary for ion binding. These include new sites not predicted by other methods. The use of coarse-grained dynamics thus provides a generalized approach to improve metal-binding site prediction. The work is expected to contribute to improving our ability to correctly predict protein molecular function where knowledge of metal binding is a key requirement.
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Affiliation(s)
- Aditi Garg
- Department of Computational and Data Sciences, Indian Institute of Science, Bengaluru, India
| | - Debnath Pal
- Department of Computational and Data Sciences, Indian Institute of Science, Bengaluru, India
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Ca 2+-regulated mitochondrial carriers of ATP-Mg 2+/Pi: Evolutionary insights in protozoans. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2021; 1868:119038. [PMID: 33839167 DOI: 10.1016/j.bbamcr.2021.119038] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Revised: 03/30/2021] [Accepted: 03/31/2021] [Indexed: 11/23/2022]
Abstract
In addition to its uptake across the Ca2+ uniporter, intracellular calcium signals can stimulate mitochondrial metabolism activating metabolite exchangers of the inner mitochondrial membrane belonging to the mitochondrial carrier family (SLC25). One of these Ca2+-regulated mitochondrial carriers (CaMCs) are the reversible ATP-Mg2+/Pi transporters, or SCaMCs, required for maintaining optimal adenine nucleotide (AdN) levels in the mitochondrial matrix representing an alternative transporter to the ADP/ATP translocases (AAC). This CaMC has a distinctive Calmodulin-like (CaM-like) domain fused to the carrier domain that makes its transport activity strictly dependent on cytosolic Ca2+ signals. Here we investigate about its origin analysing its distribution and features in unicellular eukaryotes. Unexpectedly, we find two types of ATP-Mg2+/Pi carriers, the canonical ones and shortened variants lacking the CaM-like domain. Phylogenetic analysis shows that both SCaMC variants have a common origin, unrelated to AACs, suggesting in turn that recurrent losses of the regulatory module have occurred in the different phyla. They are excluding variants that show a more limited distribution and less conservation than AACs. Interestingly, these truncated variants of SCaMC are found almost exclusively in parasitic protists, such as apicomplexans, kinetoplastides or animal-patogenic oomycetes, and in green algae, suggesting that its lost could be related to certain life-styles. In addition, we find an intricate structural diversity in these variants that may be associated with their pathogenicity. The consequences on SCaMC functions of these new SCaMC-b variants are discussed.
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Ruprecht JJ, Kunji ERS. The SLC25 Mitochondrial Carrier Family: Structure and Mechanism. Trends Biochem Sci 2020; 45:244-258. [PMID: 31787485 PMCID: PMC7611774 DOI: 10.1016/j.tibs.2019.11.001] [Citation(s) in RCA: 232] [Impact Index Per Article: 46.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Revised: 10/30/2019] [Accepted: 11/01/2019] [Indexed: 12/27/2022]
Abstract
Members of the mitochondrial carrier family (SLC25) provide the transport steps for amino acids, carboxylic acids, fatty acids, cofactors, inorganic ions, and nucleotides across the mitochondrial inner membrane and are crucial for many cellular processes. Here, we use new insights into the transport mechanism of the mitochondrial ADP/ATP carrier to examine the structure and function of other mitochondrial carriers. They all have a single substrate-binding site and two gates, which are present on either side of the membrane and involve salt-bridge networks. Transport is likely to occur by a common mechanism, in which the coordinated movement of six structural elements leads to the alternating opening and closing of the matrix or cytoplasmic side of the carriers.
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Affiliation(s)
- Jonathan J Ruprecht
- Medical Research Council (MRC) Mitochondrial Biology Unit, University of Cambridge, Cambridge Biomedical Campus, Cambridge, CB2 0XY, UK
| | - Edmund R S Kunji
- Medical Research Council (MRC) Mitochondrial Biology Unit, University of Cambridge, Cambridge Biomedical Campus, Cambridge, CB2 0XY, UK.
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9
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Ruprecht JJ, Kunji ER. Structural changes in the transport cycle of the mitochondrial ADP/ATP carrier. Curr Opin Struct Biol 2019; 57:135-144. [PMID: 31039524 PMCID: PMC6700394 DOI: 10.1016/j.sbi.2019.03.029] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2019] [Revised: 03/15/2019] [Accepted: 03/20/2019] [Indexed: 11/27/2022]
Abstract
The mitochondrial ADP/ATP carrier, also called adenine nucleotide translocase, accomplishes one of the most important transport activities in eukaryotic cells, importing ADP into the mitochondrial matrix for ATP synthesis, and exporting ATP to fuel cellular activities. In the transport cycle, the carrier changes between a cytoplasmic and matrix state, in which the central substrate binding site is alternately accessible to these compartments. A structure of a cytoplasmic state was known, but recently, a structure of a matrix-state in complex with bongkrekic acid was solved. Comparison of the two states explains the function of highly conserved sequence features and reveals that the transport mechanism is unique, involving the coordinated movement of six dynamic elements around a central translocation pathway.
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Affiliation(s)
- Jonathan J Ruprecht
- MRC Mitochondrial Biology Unit, University of Cambridge, Cambridge Biomedical Campus, Cambridge, CB2 0XY, UK.
| | - Edmund Rs Kunji
- MRC Mitochondrial Biology Unit, University of Cambridge, Cambridge Biomedical Campus, Cambridge, CB2 0XY, UK.
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10
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Villalobo A, González-Muñoz M, Berchtold MW. Proteins with calmodulin-like domains: structures and functional roles. Cell Mol Life Sci 2019; 76:2299-2328. [PMID: 30877334 PMCID: PMC11105222 DOI: 10.1007/s00018-019-03062-z] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Revised: 02/26/2019] [Accepted: 03/07/2019] [Indexed: 12/21/2022]
Abstract
The appearance of modular proteins is a widespread phenomenon during the evolution of proteins. The combinatorial arrangement of different functional and/or structural domains within a single polypeptide chain yields a wide variety of activities and regulatory properties to the modular proteins. In this review, we will discuss proteins, that in addition to their catalytic, transport, structure, localization or adaptor functions, also have segments resembling the helix-loop-helix EF-hand motifs found in Ca2+-binding proteins, such as calmodulin (CaM). These segments are denoted CaM-like domains (CaM-LDs) and play a regulatory role, making these CaM-like proteins sensitive to Ca2+ transients within the cell, and hence are able to transduce the Ca2+ signal leading to specific cellular responses. Importantly, this arrangement allows to this group of proteins direct regulation independent of other Ca2+-sensitive sensor/transducer proteins, such as CaM. In addition, this review also covers CaM-binding proteins, in which their CaM-binding site (CBS), in the absence of CaM, is proposed to interact with other segments of the same protein denoted CaM-like binding site (CLBS). CLBS are important regulatory motifs, acting either by keeping these CaM-binding proteins inactive in the absence of CaM, enhancing the stability of protein complexes and/or facilitating their dimerization via CBS/CLBS interaction. The existence of proteins containing CaM-LDs or CLBSs substantially adds to the enormous versatility and complexity of Ca2+/CaM signaling.
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Affiliation(s)
- Antonio Villalobo
- Department of Cancer Biology, Instituto de Investigaciones Biomédicas, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, Arturo Duperier 4, 28029, Madrid, Spain.
- Instituto de Investigaciones Sanitarias, Hospital Universitario La Paz, Edificio IdiPAZ, Paseo de la Castellana 261, 28046, Madrid, Spain.
| | - María González-Muñoz
- Department of Cancer Biology, Instituto de Investigaciones Biomédicas, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, Arturo Duperier 4, 28029, Madrid, Spain
| | - Martin W Berchtold
- Department of Biology, University of Copenhagen, 13 Universitetsparken, 2100, Copenhagen, Denmark.
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11
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Harborne SPD, Kunji ERS. Calcium-regulated mitochondrial ATP-Mg/P i carriers evolved from a fusion of an EF-hand regulatory domain with a mitochondrial ADP/ATP carrier-like domain. IUBMB Life 2018; 70:1222-1232. [PMID: 30281880 PMCID: PMC6283063 DOI: 10.1002/iub.1931] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Revised: 07/19/2018] [Accepted: 07/19/2018] [Indexed: 02/02/2023]
Abstract
The mitochondrial ATP-Mg/Pi carrier is responsible for the calcium-dependent regulation of adenosine nucleotide concentrations in the mitochondrial matrix, which allows mitochondria to respond to changing energy requirements of the cell. The carrier is expressed in mitochondria of fungi, plants and animals and belongs to the family of mitochondrial carriers. The carrier is unusual as it consists of three separate domains: (i) an N-terminal regulatory domain with four calcium-binding EF-hands similar to calmodulin, (ii) a loop domain containing an amphipathic α-helix and (iii) a mitochondrial carrier domain related to the mitochondrial ADP/ATP carrier. This striking example of three domains coming together from different origins to provide new functions represents an interesting quirk of evolution. In this review, we outline how the carrier was identified and how its physiological role was established with a focus on human isoforms. We exploit the sequence and structural information of the domains to explore the similarities and differences to their closest counterparts; mitochondrial ADP/ATP carriers and proteins with four EF-hands. We discuss how their combined function has led to a mechanism for calcium-regulated transport of adenosine nucleotides. Finally, we compare the ATP-Mg/Pi carrier with the mitochondrial aspartate/glutamate carrier, the only other mitochondrial carrier regulated by calcium, and we will argue that they have arisen by convergent rather than divergent evolution. © 2018 The Authors. IUBMB Life published by Wiley Periodicals, Inc. on behalf of International Union of Biochemistry and Molecular Biology, 70(12):1222-1232, 2018.
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Affiliation(s)
- Steven P. D. Harborne
- School of Biomedical Sciences and Astbury Centre for Structural Molecular BiologyUniversity of LeedsLeedsLS2 9JTUK
| | - Edmund R. S. Kunji
- Medical Research Council Mitochondrial Biology UnitUniversity of CambridgeCambridgeCB2 0XYUK
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12
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Ehmke N, Graul-Neumann L, Smorag L, Koenig R, Segebrecht L, Magoulas P, Scaglia F, Kilic E, Hennig AF, Adolphs N, Saha N, Fauler B, Kalscheuer VM, Hennig F, Altmüller J, Netzer C, Thiele H, Nürnberg P, Yigit G, Jäger M, Hecht J, Krüger U, Mielke T, Krawitz PM, Horn D, Schuelke M, Mundlos S, Bacino CA, Bonnen PE, Wollnik B, Fischer-Zirnsak B, Kornak U. De Novo Mutations in SLC25A24 Cause a Craniosynostosis Syndrome with Hypertrichosis, Progeroid Appearance, and Mitochondrial Dysfunction. Am J Hum Genet 2017; 101:833-843. [PMID: 29100093 DOI: 10.1016/j.ajhg.2017.09.016] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Accepted: 09/19/2017] [Indexed: 12/28/2022] Open
Abstract
Gorlin-Chaudhry-Moss syndrome (GCMS) is a dysmorphic syndrome characterized by coronal craniosynostosis and severe midface hypoplasia, body and facial hypertrichosis, microphthalmia, short stature, and short distal phalanges. Variable lipoatrophy and cutis laxa are the basis for a progeroid appearance. Using exome and genome sequencing, we identified the recurrent de novo mutations c.650G>A (p.Arg217His) and c.649C>T (p.Arg217Cys) in SLC25A24 in five unrelated girls diagnosed with GCMS. Two of the girls had pronounced neonatal progeroid features and were initially diagnosed with Wiedemann-Rautenstrauch syndrome. SLC25A24 encodes a mitochondrial inner membrane ATP-Mg/Pi carrier. In fibroblasts from affected individuals, the mutated SLC25A24 showed normal stability. In contrast to control cells, the probands' cells showed mitochondrial swelling, which was exacerbated upon treatment with hydrogen peroxide (H2O2). The same effect was observed after overexpression of the mutant cDNA. Under normal culture conditions, the mitochondrial membrane potential of the probands' fibroblasts was intact, whereas ATP content in the mitochondrial matrix was lower than that in control cells. However, upon H2O2 exposure, the membrane potential was significantly elevated in cells harboring the mutated SLC25A24. No reduction of mitochondrial DNA copy number was observed. These findings demonstrate that mitochondrial dysfunction with increased sensitivity to oxidative stress is due to the SLC25A24 mutations. Our results suggest that the SLC25A24 mutations induce a gain of pathological function and link mitochondrial ATP-Mg/Pi transport to the development of skeletal and connective tissue.
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Monné M, Daddabbo L, Giannossa LC, Nicolardi MC, Palmieri L, Miniero DV, Mangone A, Palmieri F. Mitochondrial ATP-Mg/phosphate carriers transport divalent inorganic cations in complex with ATP. J Bioenerg Biomembr 2017; 49:369-380. [PMID: 28695448 DOI: 10.1007/s10863-017-9721-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Accepted: 06/22/2017] [Indexed: 12/16/2022]
Abstract
The ATP-Mg/phosphate carriers (APCs) modulate the intramitochondrial adenine nucleotide pool size. In this study the concentration-dependent effects of Mg2+ and other divalent cations (Me2+) on the transport of [3H]ATP in liposomes reconstituted with purified human and Arabidopsis APCs (hAPCs and AtAPCs, respectively, including some lacking their N-terminal domains) have been investigated. The transport of Me2+ mediated by these proteins was also measured. In the presence of a low external concentration of [3H]ATP (12 μM) and increasing concentrations of Me2+, Mg2+ stimulated the activity (measured as initial transport rate of [3H]ATP) of hAPCs and decreased that of AtAPCs; Fe2+ and Zn2+ stimulated markedly hAPCs and moderately AtAPCs; Ca2+ and Mn2+ markedly AtAPCs and moderately hAPCs; and Cu2+ decreased the activity of both hAPCs and AtAPCs. All the Me2+-dependent effects correlated well with the amount of ATP-Me complex present. The transport of [14C]AMP, which has a much lower ability of complexation than ATP, was not affected by the presence of the Me2+ tested, except Cu2+. Furthermore, the transport of [3H]ATP catalyzed by the ATP/ADP carrier, which is known to transport only free ATP and ADP, was inhibited by all the Me2+ tested in an inverse relationship with the formation of the ATP-Me complex. Finally, direct measurements of Mg2+, Mn2+, Fe2+, Zn2+ and Cu2+ showed that they are cotransported with ATP by both hAPCs and AtAPCs. It is likely that in vivo APCs transport free ATP and ATP-Mg complex to different degrees, and probably trace amounts of other Me2+ in complex with ATP.
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Affiliation(s)
- Magnus Monné
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Via E. Orabona 4, 70125, Bari, Italy.,Department of Sciences, University of Basilicata, Via Ateneo Lucano 10, 85100, Potenza, Italy
| | - Lucia Daddabbo
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Via E. Orabona 4, 70125, Bari, Italy
| | | | - Maria Cristina Nicolardi
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Via E. Orabona 4, 70125, Bari, Italy
| | - Luigi Palmieri
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Via E. Orabona 4, 70125, Bari, Italy.,Institute of Biomembranes, Bioenergetics and Molecular Biotechnologies, Consiglio Nazionale delle Ricerche, 70126, Bari, Italy
| | - Daniela Valeria Miniero
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Via E. Orabona 4, 70125, Bari, Italy
| | - Annarosa Mangone
- Department of Chemistry, University of Bari, Via E. Orabona 4, 70126, Bari, Italy
| | - Ferdinando Palmieri
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Via E. Orabona 4, 70125, Bari, Italy. .,Institute of Biomembranes, Bioenergetics and Molecular Biotechnologies, Consiglio Nazionale delle Ricerche, 70126, Bari, Italy.
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Harborne SPD, King MS, Crichton PG, Kunji ERS. Calcium regulation of the human mitochondrial ATP-Mg/Pi carrier SLC25A24 uses a locking pin mechanism. Sci Rep 2017; 7:45383. [PMID: 28350015 PMCID: PMC5369052 DOI: 10.1038/srep45383] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Accepted: 02/22/2017] [Indexed: 12/18/2022] Open
Abstract
Mitochondrial ATP-Mg/Pi carriers import adenine nucleotides into the mitochondrial matrix and export phosphate to the cytosol. They are calcium-regulated to control the size of the matrix adenine nucleotide pool in response to cellular energetic demands. They consist of three domains: an N-terminal regulatory domain containing four calcium-binding EF-hands, a linker loop domain with an amphipathic α-helix and a C-terminal mitochondrial carrier domain for the transport of substrates. Here, we use thermostability assays to demonstrate that the carrier is regulated by calcium via a locking pin mechanism involving the amphipathic α-helix. When calcium levels in the intermembrane space are high, the N-terminus of the amphipathic α-helix is bound to a cleft in the regulatory domain, leading to substrate transport by the carrier domain. When calcium levels drop, the cleft closes, and the amphipathic α-helix is released to bind to the carrier domain via its C-terminus, locking the carrier in an inhibited state.
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Affiliation(s)
- Steven P. D. Harborne
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge Biomedical Campus, Wellcome Trust/MRC Building, Hills Road, Cambridge CB2 0XY, UK
- School of Biomedical Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, LS2 9JT, UK
| | - Martin S. King
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge Biomedical Campus, Wellcome Trust/MRC Building, Hills Road, Cambridge CB2 0XY, UK
| | - Paul G. Crichton
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge Biomedical Campus, Wellcome Trust/MRC Building, Hills Road, Cambridge CB2 0XY, UK
- Biomedical Research Centre, Norwich Medical School, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK
| | - Edmund R. S. Kunji
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge Biomedical Campus, Wellcome Trust/MRC Building, Hills Road, Cambridge CB2 0XY, UK
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Del Arco A, Contreras L, Pardo B, Satrustegui J. Calcium regulation of mitochondrial carriers. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2016; 1863:2413-21. [PMID: 27033520 DOI: 10.1016/j.bbamcr.2016.03.024] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Revised: 03/23/2016] [Accepted: 03/23/2016] [Indexed: 11/16/2022]
Abstract
Mitochondrial function is regulated by calcium. In addition to the long known effects of matrix Ca(2+), regulation of metabolite transport by extramitochondrial Ca(2+) represents an alternative Ca(2+)-dependent mechanism to regulate mitochondrial function. The Ca(2+) regulated mitochondrial transporters (CaMCs) are well suited for that role, as they contain long N-terminal extensions harboring EF-hand Ca(2+) binding domains facing the intermembrane space. They fall in two groups, the aspartate/glutamate exchangers, AGCs, major components of the NADH malate aspartate shuttle (MAS) and urea cycle, and the ATP-Mg(2+)/Pi exchangers or short CaMCs (APCs or SCaMCs). The AGCs are activated by relatively low Ca(2+) levels only slightly higher than resting Ca(2+), whereas all SCaMCs studied so far require strong Ca(2+) signals, above micromolar, for activation. In addition, AGCs are not strictly Ca(2+) dependent, being active even in Ca(2+)-free conditions. Thus, AGCs are well suited to respond to small Ca(2+) signals and that do not reach mitochondria. In contrast, ATP-Mg(2+)/Pi carriers are inactive in Ca(2+) free conditions and activation requires Ca(2+) signals that will also activate the calcium uniporter (MCU). By changing the net content of adenine nucleotides of the matrix upon activation, SCaMCs regulate the activity of the permeability transition pore, and the Ca(2+) retention capacity of mitochondria (CRC), two functions synergizing with those of the MCU. The different Ca(2+) activation properties of the two CaMCs are discussed in relation to their newly obtained structures. This article is part of a Special Issue entitled: Mitochondrial Channels edited by Pierre Sonveaux, Pierre Maechler and Jean-Claude Martinou.
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Affiliation(s)
- Araceli Del Arco
- Facultad de Ciencias Ambientales y Bioquímica, Centro RegionaI de Investigaciones Biomédicas, Universidad de Castilla la Mancha, Toledo 45071, Spain; CIBER de Enfermedades Raras (CIBERER), ISCIII, Madrid, Spain; Instituto de Investigaciones Sanitarias Fundación Jiménez Díaz (IIS-FJD), Madrid, Spain
| | - Laura Contreras
- Departamento de Biología Molecular, Centro de Biología Molecular Severo Ochoa, Universidad Autónoma de Madrid-Consejo Superior de Investigaciones Científicas, 28049 Madrid, Spain; CIBER de Enfermedades Raras (CIBERER), ISCIII, Madrid, Spain; Instituto de Investigaciones Sanitarias Fundación Jiménez Díaz (IIS-FJD), Madrid, Spain
| | - Beatriz Pardo
- Departamento de Biología Molecular, Centro de Biología Molecular Severo Ochoa, Universidad Autónoma de Madrid-Consejo Superior de Investigaciones Científicas, 28049 Madrid, Spain; CIBER de Enfermedades Raras (CIBERER), ISCIII, Madrid, Spain; Instituto de Investigaciones Sanitarias Fundación Jiménez Díaz (IIS-FJD), Madrid, Spain
| | - Jorgina Satrustegui
- Departamento de Biología Molecular, Centro de Biología Molecular Severo Ochoa, Universidad Autónoma de Madrid-Consejo Superior de Investigaciones Científicas, 28049 Madrid, Spain; CIBER de Enfermedades Raras (CIBERER), ISCIII, Madrid, Spain; Instituto de Investigaciones Sanitarias Fundación Jiménez Díaz (IIS-FJD), Madrid, Spain.
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16
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Palmieri F, Monné M. Discoveries, metabolic roles and diseases of mitochondrial carriers: A review. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2016; 1863:2362-78. [PMID: 26968366 DOI: 10.1016/j.bbamcr.2016.03.007] [Citation(s) in RCA: 172] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Revised: 02/29/2016] [Accepted: 03/01/2016] [Indexed: 12/25/2022]
Abstract
Mitochondrial carriers (MCs) are a superfamily of nuclear-encoded proteins that are mostly localized in the inner mitochondrial membrane and transport numerous metabolites, nucleotides, cofactors and inorganic anions. Their unique sequence features, i.e., a tripartite structure, six transmembrane α-helices and a three-fold repeated signature motif, allow MCs to be easily recognized. This review describes how the functions of MCs from Saccharomyces cerevisiae, Homo sapiens and Arabidopsis thaliana (listed in the first table) were discovered after the genome sequence of S. cerevisiae was determined in 1996. In the genomic era, more than 50 previously unknown MCs from these organisms have been identified and characterized biochemically using a method consisting of gene expression, purification of the recombinant proteins, their reconstitution into liposomes and transport assays (EPRA). Information derived from studies with intact mitochondria, genetic and metabolic evidence, sequence similarity, phylogenetic analysis and complementation of knockout phenotypes have guided the choice of substrates that were tested in the transport assays. In addition, the diseases associated to defects of human MCs have been briefly reviewed. This article is part of a Special Issue entitled: Mitochondrial Channels edited by Pierre Sonveaux, Pierre Maechler and Jean-Claude Martinou.
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Affiliation(s)
- Ferdinando Palmieri
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Via E. Orabona 4, 70125 Bari, Italy.
| | - Magnus Monné
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Via E. Orabona 4, 70125 Bari, Italy; Department of Sciences, University of Basilicata, Via Ateneo Lucano 10, 85100 Potenza, Italy
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17
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Ahmad K, Waris M, Hayat M. Prediction of Protein Submitochondrial Locations by Incorporating Dipeptide Composition into Chou's General Pseudo Amino Acid Composition. J Membr Biol 2016; 249:293-304. [PMID: 26746980 DOI: 10.1007/s00232-015-9868-8] [Citation(s) in RCA: 75] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Accepted: 12/30/2015] [Indexed: 12/15/2022]
Abstract
Mitochondrion is the key organelle of eukaryotic cell, which provides energy for cellular activities. Submitochondrial locations of proteins play crucial role in understanding different biological processes such as energy metabolism, program cell death, and ionic homeostasis. Prediction of submitochondrial locations through conventional methods are expensive and time consuming because of the large number of protein sequences generated in the last few decades. Therefore, it is intensively desired to establish an automated model for identification of submitochondrial locations of proteins. In this regard, the current study is initiated to develop a fast, reliable, and accurate computational model. Various feature extraction methods such as dipeptide composition (DPC), Split Amino Acid Composition, and Composition and Translation were utilized. In order to overcome the issue of biasness, oversampling technique SMOTE was applied to balance the datasets. Several classification learners including K-Nearest Neighbor, Probabilistic Neural Network, and support vector machine (SVM) are used. Jackknife test is applied to assess the performance of classification algorithms using two benchmark datasets. Among various classification algorithms, SVM achieved the highest success rates in conjunction with the condensed feature space of DPC, which are 95.20 % accuracy on dataset SML3-317 and 95.11 % on dataset SML3-983. The empirical results revealed that our proposed model obtained the highest results so far in the literatures. It is anticipated that our proposed model might be useful for future studies.
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Affiliation(s)
- Khurshid Ahmad
- Department of Computer Science, Abdul Wali Khan University Mardan, Mardan, Pakistan
| | - Muhammad Waris
- Department of Computer Science, Abdul Wali Khan University Mardan, Mardan, Pakistan
| | - Maqsood Hayat
- Department of Computer Science, Abdul Wali Khan University Mardan, Mardan, Pakistan.
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18
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Lorenz A, Lorenz M, Vothknecht UC, Niopek-Witz S, Neuhaus HE, Haferkamp I. In vitro analyses of mitochondrial ATP/phosphate carriers from Arabidopsis thaliana revealed unexpected Ca(2+)-effects. BMC PLANT BIOLOGY 2015; 15:238. [PMID: 26444389 PMCID: PMC4595200 DOI: 10.1186/s12870-015-0616-0] [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: 06/25/2015] [Accepted: 09/12/2015] [Indexed: 05/05/2023]
Abstract
BACKGROUND Adenine nucleotide/phosphate carriers (APCs) from mammals and yeast are commonly known to adapt the mitochondrial adenine nucleotide pool in accordance to cellular demands. They catalyze adenine nucleotide--particularly ATP-Mg--and phosphate exchange and their activity is regulated by calcium. Our current knowledge about corresponding proteins from plants is comparably limited. Recently, the three putative APCs from Arabidopsis thaliana were shown to restore the specific growth phenotype of APC yeast loss-of-function mutants and to interact with calcium via their N-terminal EF--hand motifs in vitro. In this study, we performed biochemical characterization of all three APC isoforms from A. thaliana to gain further insights into their functional properties. RESULTS Recombinant plant APCs were functionally reconstituted into liposomes and their biochemical characteristics were determined by transport measurements using radiolabeled substrates. All three plant APCs were capable of ATP, ADP and phosphate exchange, however, high preference for ATP-Mg, as shown for orthologous carriers, was not detectable. By contrast, the obtained data suggest that in the liposomal system the plant APCs rather favor ATP-Ca as substrate. Moreover, investigation of a representative mutant APC protein revealed that the observed calcium effects on ATP transport did not primarily/essentially involve Ca(2+)-binding to the EF-hand motifs in the N-terminal domain of the carrier. CONCLUSION Biochemical characteristics suggest that plant APCs can mediate net transport of adenine nucleotides and hence, like their pendants from animals and yeast, might be involved in the alteration of the mitochondrial adenine nucleotide pool. Although, ATP-Ca was identified as an apparent import substrate of plant APCs in vitro it is arguable whether ATP-Ca formation and thus the corresponding transport can take place in vivo.
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Affiliation(s)
- André Lorenz
- Cellular Physiology/Membrane Transport, University of Kaiserslautern, 67653, Kaiserslautern, Germany.
| | - Melanie Lorenz
- Cellular Physiology/Membrane Transport, University of Kaiserslautern, 67653, Kaiserslautern, Germany.
| | - Ute C Vothknecht
- Department of Biology I, Botany, LMU Munich, Großhaderner Str. 2, D-82152, Planegg-Martinsried, Germany.
| | - Sandra Niopek-Witz
- Plant Physiology, University of Kaiserslautern, 67653, Kaiserslautern, Germany.
| | - H Ekkehard Neuhaus
- Plant Physiology, University of Kaiserslautern, 67653, Kaiserslautern, Germany.
| | - Ilka Haferkamp
- Cellular Physiology/Membrane Transport, University of Kaiserslautern, 67653, Kaiserslautern, Germany.
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19
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Harborne SPD, Ruprecht JJ, Kunji ERS. Calcium-induced conformational changes in the regulatory domain of the human mitochondrial ATP-Mg/Pi carrier. BIOCHIMICA ET BIOPHYSICA ACTA 2015; 1847:1245-53. [PMID: 26164100 PMCID: PMC4562336 DOI: 10.1016/j.bbabio.2015.07.002] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/24/2015] [Revised: 06/15/2015] [Accepted: 07/06/2015] [Indexed: 12/21/2022]
Abstract
The mitochondrial ATP-Mg/Pi carrier imports adenine nucleotides from the cytosol into the mitochondrial matrix and exports phosphate. The carrier is regulated by the concentration of cytosolic calcium, altering the size of the adenine nucleotide pool in the mitochondrial matrix in response to energetic demands. The protein consists of three domains; (i) the N-terminal regulatory domain, which is formed of two pairs of fused calcium-binding EF-hands, (ii) the C-terminal mitochondrial carrier domain, which is involved in transport, and (iii) a linker region with an amphipathic α-helix of unknown function. The mechanism by which calcium binding to the regulatory domain modulates substrate transport in the carrier domain has not been resolved. Here, we present two new crystal structures of the regulatory domain of the human isoform 1. Careful analysis by SEC confirmed that although the regulatory domain crystallised as dimers, full-length ATP-Mg/Pi carrier is monomeric. Therefore, the ATP-Mg/Pi carrier must have a different mechanism of calcium regulation than the architecturally related aspartate/glutamate carrier, which is dimeric. The structure showed that an amphipathic α-helix is bound to the regulatory domain in a hydrophobic cleft of EF-hand 3/4. Detailed bioinformatics analyses of different EF-hand states indicate that upon release of calcium, EF-hands close, meaning that the regulatory domain would release the amphipathic α-helix. We propose a mechanism for ATP-Mg/Pi carriers in which the amphipathic α-helix becomes mobile upon release of calcium and could block the transport of substrates across the mitochondrial inner membrane.
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Affiliation(s)
- Steven P D Harborne
- The Medical Research Council, Mitochondrial Biology Unit, Cambridge Biomedical Campus, Wellcome Trust/MRC Building, Hills Road, Cambridge CB2 0XY, UK
| | - Jonathan J Ruprecht
- The Medical Research Council, Mitochondrial Biology Unit, Cambridge Biomedical Campus, Wellcome Trust/MRC Building, Hills Road, Cambridge CB2 0XY, UK
| | - Edmund R S Kunji
- The Medical Research Council, Mitochondrial Biology Unit, Cambridge Biomedical Campus, Wellcome Trust/MRC Building, Hills Road, Cambridge CB2 0XY, UK.
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20
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Run C, Yang Q, Liu Z, OuYang B, Chou JJ. Molecular Basis of MgATP Selectivity of the Mitochondrial SCaMC Carrier. Structure 2015; 23:1394-1403. [PMID: 26165595 DOI: 10.1016/j.str.2015.06.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Revised: 05/28/2015] [Accepted: 06/04/2015] [Indexed: 01/21/2023]
Abstract
The mitochondrial matrix is the supplier of cellular ATP. The short Ca(2+)-binding mitochondrial carrier (SCaMC) is one of the two mitochondrial carriers responsible for transporting ATP across the mitochondrial inner membrane. While the ADP/ATP carrier (AAC) accounts for the bulk ADP/ATP recycling in the matrix, the function of SCaMC is important for mitochondrial activities that depend on adenine nucleotides, such as gluconeogenesis and mitochondrial biogenesis. A key difference between SCaMC and AAC is that SCaMC selectively transports MgATP whereas AAC only transports free nucleotides. Here, we use a combination of nuclear magnetic resonance experiments and functional mutagenesis to investigate the structural basis of the MgATP selectivity in SCaMC. Our data revealed an MgATP binding site inside the transporter cavity, while identifying an aspartic acid residue that plays an important role in the higher selectivity for MgATP over free ATP.
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Affiliation(s)
- Changqing Run
- National Center for Protein Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai 200031, China; State Key Laboratory of Molecular Biology, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai 200031, China
| | - Qin Yang
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
| | - Zhijun Liu
- National Center for Protein Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai 200031, China
| | - Bo OuYang
- National Center for Protein Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai 200031, China; State Key Laboratory of Molecular Biology, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai 200031, China.
| | - James J Chou
- National Center for Protein Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai 200031, China; State Key Laboratory of Molecular Biology, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai 200031, China; Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA.
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21
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Functional characterization and organ distribution of three mitochondrial ATP-Mg/Pi carriers in Arabidopsis thaliana. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2015; 1847:1220-30. [PMID: 26140942 DOI: 10.1016/j.bbabio.2015.06.015] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 04/16/2015] [Revised: 06/15/2015] [Accepted: 06/29/2015] [Indexed: 11/22/2022]
Abstract
The Arabidopsis thaliana genome contains 58 membrane proteins belonging to the mitochondrial carrier family. Three members of this family, here named AtAPC1, AtAPC2, and AtAPC3, exhibit high structural similarities to the human mitochondrial ATP-Mg(2+)/phosphate carriers. Under normal physiological conditions the AtAPC1 gene was expressed at least five times more than the other two AtAPC genes in flower, leaf, stem, root and seedlings. However, in stress conditions the expression levels of AtAPC1 and AtAPC3 change. Direct transport assays with recombinant and reconstituted AtAPC1, AtAPC2 and AtAPC3 showed that they transport phosphate, AMP, ADP, ATP, adenosine 5'-phosphosulfate and, to a lesser extent, other nucleotides. AtAPC2 and AtAPC3 also had the ability to transport sulfate and thiosulfate. All three AtAPCs catalyzed a counter-exchange transport that was saturable and inhibited by pyridoxal-5'-phosphate. The transport activities of AtAPCs were also inhibited by the addition of EDTA or EGTA and stimulated by the addition of Ca(2+). Given that phosphate and sulfate can be recycled via their own specific carriers, these findings indicate that AtAPCs can catalyze net transfer of adenine nucleotides across the inner mitochondrial membrane in exchange for phosphate (or sulfate), and that this transport is regulated both at the transcriptional level and by Ca(2+).
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22
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Li L, Yu S, Xiao W, Li Y, Hu W, Huang L, Zheng X, Zhou S, Yang H. Protein submitochondrial localization from integrated sequence representation and SVM-based backward feature extraction. MOLECULAR BIOSYSTEMS 2015; 11:170-177. [PMID: 25335193 DOI: 10.1039/c4mb00340c] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Mitochondrion, a tiny energy factory, plays an important role in various biological processes of most eukaryotic cells. Mitochondrial defection is associated with a series of human diseases. Knowledge of the submitochondrial locations of proteins can help to reveal the biological functions of novel proteins, and understand the mechanisms underlying various biological processes occurring in the mitochondrion. However, experimental methods to determine protein submitochondrial locations are costly and time consuming. Thus it is essential to develop a fast and reliable computational method to predict protein submitochondrial locations. Here, we proposed a support vector machine (SVM) based approach for predicting protein submitochondrial locations. Information from the position-specific score matrix (PSSM), gene ontology (GO) and the protein feature (PROFEAT) was integrated into the principal features of this model. Then a recursive feature selection scheme was employed to select the optimal features. Finally, an SVM module was used to predict protein submitochondrial locations based on the optimal features. Through the jackknife cross-validation test, our method achieved an accuracy of 99.37% on benchmark dataset M317, and 100% on the other two datasets, M1105 and T86. These results indicate that our method is economic and effective for accurate prediction of the protein submitochondrial location.
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Affiliation(s)
- Liqi Li
- Department of General Surgery, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China.
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23
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Hajnóczky G, Booth D, Csordás G, Debattisti V, Golenár T, Naghdi S, Niknejad N, Paillard M, Seifert EL, Weaver D. Reliance of ER-mitochondrial calcium signaling on mitochondrial EF-hand Ca2+ binding proteins: Miros, MICUs, LETM1 and solute carriers. Curr Opin Cell Biol 2014; 29:133-41. [PMID: 24999559 PMCID: PMC4381426 DOI: 10.1016/j.ceb.2014.06.002] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2014] [Revised: 06/09/2014] [Accepted: 06/11/2014] [Indexed: 10/25/2022]
Abstract
Endoplasmic reticulum (ER) and mitochondria are functionally distinct with regard to membrane protein biogenesis and oxidative energy production, respectively, but cooperate in several essential cell functions, including lipid biosynthesis, cell signaling and organelle dynamics. The interorganellar cooperation requires local communication that can occur at the strategically positioned and dynamic associations between ER and mitochondria. Calcium is locally transferred from ER to mitochondria at the associations and exerts regulatory effects on numerous proteins. A common Ca(2+) sensing mechanism is the EF-hand Ca(2+) binding domain, many of which can be found in proteins of the mitochondria, including Miro1&2, MICU1,2&3, LETM1 and mitochondrial solute carriers. Recently, these proteins have triggered much interest and were described in reports with diverging conclusions. The present essay focuses on their shared features and established specific functions.
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Affiliation(s)
- György Hajnóczky
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, United States.
| | - David Booth
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, United States
| | - György Csordás
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, United States
| | - Valentina Debattisti
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, United States
| | - Tünde Golenár
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, United States
| | - Shamim Naghdi
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, United States
| | - Nima Niknejad
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, United States
| | - Melanie Paillard
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, United States
| | - Erin L Seifert
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, United States
| | - David Weaver
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, United States
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24
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Yu C, Lopez CA, Hu H, Xia Y, Freedman DS, Reddington AP, Daaboul GG, Ünlü MS, Genco CA. A high-throughput method to examine protein-nucleotide interactions identifies targets of the bacterial transcriptional regulatory protein fur. PLoS One 2014; 9:e96832. [PMID: 24811061 PMCID: PMC4014563 DOI: 10.1371/journal.pone.0096832] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2014] [Accepted: 04/13/2014] [Indexed: 11/19/2022] Open
Abstract
The Ferric uptake regulatory protein (Fur) is a transcriptional regulatory protein that functions to control gene transcription in response to iron in a number of pathogenic bacteria. In this study, we applied a label-free, quantitative and high-throughput analysis method, Interferometric Reflectance Imaging Sensor (IRIS), to rapidly characterize Fur-DNA interactions in vitro with predicted Fur binding sequences in the genome of Neisseria gonorrhoeae, the causative agent of the sexually transmitted disease gonorrhea. IRIS can easily be applied to examine multiple protein-protein, protein-nucleotide and nucleotide-nucleotide complexes simultaneously and demonstrated here that seventy percent of the predicted Fur boxes in promoter regions of iron-induced genes bound to Fur in vitro with a range of affinities as observed using this microarray screening technology. Combining binding data with mRNA expression levels in a gonococcal fur mutant strain allowed us to identify five new gonococcal genes under Fur-mediated direct regulation.
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Affiliation(s)
- Chunxiao Yu
- Department of Medicine, Section of Infectious Diseases, Boston University School of Medicine, Boston University, Boston, Massachusetts, United States of America
| | - Carlos A. Lopez
- Department of Electrical and Computer Engineering, Boston University, Boston, Massachusetts, United States of America
| | - Han Hu
- Bioinformatics Graduate Program, Boston University, Boston, Massachusetts, United States of America
| | - Yu Xia
- Bioinformatics Graduate Program, Boston University, Boston, Massachusetts, United States of America
| | - David S. Freedman
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts, United States of America
| | - Alexander P. Reddington
- Department of Electrical and Computer Engineering, Boston University, Boston, Massachusetts, United States of America
| | - George G. Daaboul
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts, United States of America
| | - M. Selim Ünlü
- Department of Electrical and Computer Engineering, Boston University, Boston, Massachusetts, United States of America
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts, United States of America
- Physics Department, Boston University, Boston, Massachusetts, United States of America
| | - Caroline Attardo Genco
- Department of Medicine, Section of Infectious Diseases, Boston University School of Medicine, Boston University, Boston, Massachusetts, United States of America
- Department of Microbiology, Boston University School of Medicine, Boston University, Boston, Massachusetts, United States of America
- * E-mail:
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25
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Yang Q, Brüschweiler S, Chou JJ. Purification, crystallization and preliminary X-ray diffraction of the N-terminal calmodulin-like domain of the human mitochondrial ATP-Mg/Pi carrier SCaMC1. Acta Crystallogr F Struct Biol Commun 2014; 70:68-71. [PMID: 24419621 PMCID: PMC3943107 DOI: 10.1107/s2053230x1303241x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Accepted: 11/27/2013] [Indexed: 12/14/2022] Open
Abstract
SCaMC is an ATP-Mg/Pi carrier protein located at the mitochondrial inner membrane. SCaMC has an unusual N-terminal Ca(2+)-binding domain (NTD) in addition to its characteristic six-helix transmembrane bundle. The NTD of human SCaMC1 (residues 1-193) was expressed and purified in order to study its role in Ca(2+)-regulated ATP-Mg/Pi transport mediated by its transmembrane domain. While Ca(2+)-bound NTD could be crystallized, the apo state resisted extensive crystallization trials. Selenomethionine-labeled Ca(2+)-bound NTD crystals, which belonged to space group P6(2)22 with one molecule per asymmetric unit, diffracted X-rays to 2.9 Å resolution.
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Affiliation(s)
- Qin Yang
- Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
| | - Sven Brüschweiler
- Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
| | - James J. Chou
- Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
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