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Scanga R, Scalise M, Marino N, Parisi F, Barca D, Galluccio M, Brunocilla C, Console L, Indiveri C. LAT1 (SLC7A5) catalyzes copper(histidinate) transport switching from antiport to uniport mechanism. iScience 2023; 26:107738. [PMID: 37692288 PMCID: PMC10492218 DOI: 10.1016/j.isci.2023.107738] [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: 04/27/2023] [Revised: 07/31/2023] [Accepted: 08/23/2023] [Indexed: 09/12/2023] Open
Abstract
LAT1 (SLC7A5) is one of the most studied membrane transporters due to its relevance to physiology in supplying essential amino acids to brain and fetus, and to pathology being linked to nervous or embryo alterations; moreover, LAT1 over-expression is always associated with cancer development. Thus, LAT1 is exploited as a pro-drug vehicle and as a target for anti-cancer therapy. We here report the identification of a new substrate with pathophysiological implications, i.e., Cu-histidinate, and an unconventional uniport mechanism exploited for the Cu-histidinate transport. Crystals of the monomeric species Cu(His)2 were obtained in our experimental conditions and the actual transport of the complex was evaluated by a combined strategy of bioinformatics, site-directed mutagenesis, radiolabeled transport, and mass spectrometry analysis. The LAT1-mediated transport of Cu(His)2 may have profound implications for both the treatment of copper dysmetabolism diseases, such as the rare Menkes disease, and of cancer as an alternative to platinum-based therapies.
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Affiliation(s)
- Raffaella Scanga
- Department DiBEST (Biologia, Ecologia, Scienze della Terra) Unit of Biochemistry and Molecular Biotechnology, University of Calabria, 87036 Arcavacata di Rende, Italy
| | - Mariafrancesca Scalise
- Department DiBEST (Biologia, Ecologia, Scienze della Terra) Unit of Biochemistry and Molecular Biotechnology, University of Calabria, 87036 Arcavacata di Rende, Italy
| | - Nadia Marino
- MAT-INLAB (Laboratorio di Materiali Molecolari Inorganici), Department of Chemistry and Chemical Technologies (CTC), University of Calabria—UNICAL, Via P. Bucci, 87036 Arcavacata di Rende, Italy
| | - Francesco Parisi
- MAT-INLAB (Laboratorio di Materiali Molecolari Inorganici), Department of Chemistry and Chemical Technologies (CTC), University of Calabria—UNICAL, Via P. Bucci, 87036 Arcavacata di Rende, Italy
| | - Donatella Barca
- Department DiBEST (Biologia, Ecologia e Scienze della Terra), 87036 Arcavacata di Rende, Italy
| | - Michele Galluccio
- Department DiBEST (Biologia, Ecologia, Scienze della Terra) Unit of Biochemistry and Molecular Biotechnology, University of Calabria, 87036 Arcavacata di Rende, Italy
| | - Chiara Brunocilla
- Department DiBEST (Biologia, Ecologia, Scienze della Terra) Unit of Biochemistry and Molecular Biotechnology, University of Calabria, 87036 Arcavacata di Rende, Italy
| | - Lara Console
- Department DiBEST (Biologia, Ecologia, Scienze della Terra) Unit of Biochemistry and Molecular Biotechnology, University of Calabria, 87036 Arcavacata di Rende, Italy
| | - Cesare Indiveri
- Department DiBEST (Biologia, Ecologia, Scienze della Terra) Unit of Biochemistry and Molecular Biotechnology, University of Calabria, 87036 Arcavacata di Rende, Italy
- CNR Institute of Biomembranes, Bioenergetics and Molecular Biotechnologies (IBIOM), 70126 Bari, Italy
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Incampo G, Giangregorio N, Gambacorta N, Nicolotti O, Pacifico C, Palmieri L, Tonazzi A. Praseodymium trivalent ion is an effective inhibitor of mitochondrial basic amino acids and carnitine/acylcarnitine carriers. BIOCHIMICA ET BIOPHYSICA ACTA. BIOENERGETICS 2022; 1863:148557. [PMID: 35367451 DOI: 10.1016/j.bbabio.2022.148557] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Revised: 03/18/2022] [Accepted: 03/25/2022] [Indexed: 06/14/2023]
Abstract
We herein report the identification of the lantanide praseodymium trivalent ion Pr3+ as inhibitor of mitochondrial transporters for basic amino acids and phylogenetically related carriers belonging to the Slc25 family. The inhibitory effect of Pr3+ has been tested using mitochondrial transporters reconstituted into liposomes being effective in the micromolar range, acting as a competitive inhibitor of the human basic amino acids carrier (BAC, Slc25A29), the human carnitine/acylcarnitine carrier (CAC, Slc25A20). Furthermore, we provide computational evidence that the complete inhibition of the transport activity of the recombinant proteins is due to the Pr3+ coordination to key acidic residues of the matrix salt bridge network. Besides being used as a first choice stop inhibitor for functional studies in vitro of mitochondrial carriers reconstituted in proteoliposomes, Pr3+ might also represent a useful tool for structural studies of the mitochondrial carrier family.
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Affiliation(s)
- Giovanna Incampo
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Via Orabona 4, 70125 Bari, Italy
| | - Nicola Giangregorio
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Via Orabona 4, 70125 Bari, Italy; CNR Institute of Biomembranes, Bioenergetics and Molecular Biotechnologies (IBIOM), Via Amendola 122/O, 70126 Bari, Italy
| | - Nicola Gambacorta
- Department of Pharmacy-Pharmaceutical Sciences, University of Bari, Via Orabona 4, 70125 Bari, Italy
| | - Orazio Nicolotti
- Department of Pharmacy-Pharmaceutical Sciences, University of Bari, Via Orabona 4, 70125 Bari, Italy
| | - Concetta Pacifico
- Department of Chemistry, University of Bari, Via Orabona 4, 70125 Bari, Italy
| | - Luigi Palmieri
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Via Orabona 4, 70125 Bari, Italy; CNR Institute of Biomembranes, Bioenergetics and Molecular Biotechnologies (IBIOM), Via Amendola 122/O, 70126 Bari, Italy
| | - Annamaria Tonazzi
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Via Orabona 4, 70125 Bari, Italy; CNR Institute of Biomembranes, Bioenergetics and Molecular Biotechnologies (IBIOM), Via Amendola 122/O, 70126 Bari, Italy.
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Effect of Copper on the Mitochondrial Carnitine/Acylcarnitine Carrier Via Interaction with Cys136 and Cys155. Possible Implications in Pathophysiology. Molecules 2020; 25:molecules25040820. [PMID: 32070004 PMCID: PMC7070283 DOI: 10.3390/molecules25040820] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Revised: 02/10/2020] [Accepted: 02/11/2020] [Indexed: 12/14/2022] Open
Abstract
The effect of copper on the mitochondrial carnitine/acylcarnitine carrier (CAC) was studied. Transport function was assayed as [3H]carnitine/carnitine antiport in proteoliposomes reconstituted with the native protein extracted from rat liver mitochondria or with the recombinant CAC over-expressed in E. coli. Cu2+ (as well as Cu+) strongly inhibited the native transporter. The inhibition was reversed by GSH (reduced glutathione) or by DTE (dithioerythritol). Dose-response analysis of the inhibition of the native protein was performed from which an IC50 of 1.6 µM for Cu2+ was derived. The mechanism of inhibition was studied by using the recombinant WT or Cys site-directed mutants of CAC. From the dose-response curve of the effect of Cu2+ on the recombinant protein, an IC50 of 0.28 µM was derived. Inhibition kinetics revealed a non-competitive type of inhibition by Cu2+. However, a substrate protection experiment indicated that the interaction of Cu2+ with the protein occurred in the vicinity of the substrate-binding site. Dose-response analysis on Cys mutants led to much higher IC50 values for the mutants C136S or C155S. The highest value was obtained for the C136/155S double mutant, indicating the involvement of both Cys residues in the interaction with Cu2+. Computational analysis performed on the WT CAC and on Cys mutants showed a pattern of the binding energy mostly overlapping the binding affinity derived from the dose-response analysis. All the data concur with bridging of Cu2+ with the two Cys residues, which blocks the conformational changes required for transport cycle.
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Scalise M, Console L, Galluccio M, Pochini L, Tonazzi A, Giangregorio N, Indiveri C. Exploiting Cysteine Residues of SLC Membrane Transporters as Targets for Drugs. SLAS DISCOVERY 2019; 24:867-881. [PMID: 31251685 DOI: 10.1177/2472555219856601] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The observation that cysteine is the top gainer amino acid during evolution attracted the attention of scientists dealing with protein chemistry. The thiol group of cysteine, indeed, is a potential site for several types of reactions with variable specificity and strength. This feature proved to be promising also in the field of membrane transporters that represent boundary proteins fundamental for cell homeostasis. These proteins are classified, according to the driving force for transport, in primary or secondary active transporters. Another frequently used classification is nowadays based on phylogenesis. Two major groups are identified that take into account both criteria: the ABC and the SLC transporters, the second being much more numerous. The cellular localization of the transporters makes them very attractive for drug design. Moreover, the presence of at least one cysteine residue in all the annotated SLC transporters, so far, highlights the possibility of using the thiol (SH) residue for covalent drug targeting. Even if a delay exists in this research field due to the scarce knowledge of structure/function relationships, the setup of novel experimental tools for studying SLC proteins of plasma and organelle membranes opens an important perspective in pharmacology.
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Affiliation(s)
- Mariafrancesca Scalise
- Department DiBEST (Biologia, Ecologia e Scienze della Terra) Unit of Biochemistry and Molecular Biotechnology, University of Calabria, Arcavacata di Rende, Italy
| | - Lara Console
- Department DiBEST (Biologia, Ecologia e Scienze della Terra) Unit of Biochemistry and Molecular Biotechnology, University of Calabria, Arcavacata di Rende, Italy
| | - Michele Galluccio
- Department DiBEST (Biologia, Ecologia e Scienze della Terra) Unit of Biochemistry and Molecular Biotechnology, University of Calabria, Arcavacata di Rende, Italy
| | - Lorena Pochini
- Department DiBEST (Biologia, Ecologia e Scienze della Terra) Unit of Biochemistry and Molecular Biotechnology, University of Calabria, Arcavacata di Rende, Italy
| | - Annamaria Tonazzi
- CNR Institute of Biomembranes, Bioenergetics and Molecular Biotechnology (IBIOM), Bari, Italy
| | - Nicola Giangregorio
- CNR Institute of Biomembranes, Bioenergetics and Molecular Biotechnology (IBIOM), Bari, Italy
| | - Cesare Indiveri
- Department DiBEST (Biologia, Ecologia e Scienze della Terra) Unit of Biochemistry and Molecular Biotechnology, University of Calabria, Arcavacata di Rende, Italy
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Giangregorio N, Tonazzi A, Console L, Galluccio M, Porcelli V, Indiveri C. Structure/function relationships of the human mitochondrial ornithine/citrulline carrier by Cys site-directed mutagenesis. Relevance to mercury toxicity. Int J Biol Macromol 2018; 120:93-99. [DOI: 10.1016/j.ijbiomac.2018.08.069] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Revised: 08/12/2018] [Accepted: 08/14/2018] [Indexed: 12/19/2022]
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Cobalt inhibits motility of axonal mitochondria and induces axonal degeneration in cultured dorsal root ganglion cells of rat. Cell Biol Toxicol 2017; 34:93-107. [PMID: 28656345 DOI: 10.1007/s10565-017-9402-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2017] [Accepted: 06/15/2017] [Indexed: 10/19/2022]
Abstract
Cobalt is a trace element that localizes in the human body as cobalamin, also known as vitamin B12. Excessive cobalt exposure induces a peripheral neuropathy, the mechanisms of which are yet to be elucidated. We investigated how cobalt may affect mitochondrial motility in primary cultures of rat dorsal root ganglion (DRG). We observed mitochondrial motility by time-lapse imaging after DsRed2 tagging via lentivirus, mitochondrial structure using transmission electron microscopy (TEM), and axonal swelling using immunocytochemical staining. The concentration of cobaltous ion (Co2+) required to significantly suppress mitochondrial motility is lower than that required to induce axonal swelling following a 24-h treatment. Exposure to relatively low concentrations of Co2+ for 48 h suppressed mitochondrial motility without leading to axonal swelling. TEM images indicated that Co2+ induces mitochondrial destruction. Our results show that destruction of the axonal mitochondria precedes the axonal degeneration induced by Co2+ exposure.
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Salazar A, Keusgen M, von Hagen J. Amino acids in the cultivation of mammalian cells. Amino Acids 2016; 48:1161-71. [PMID: 26832172 PMCID: PMC4833841 DOI: 10.1007/s00726-016-2181-8] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2016] [Accepted: 01/18/2016] [Indexed: 11/29/2022]
Abstract
Amino acids are crucial for the cultivation of mammalian cells. This importance of amino acids was realized soon after the development of the first cell lines, and a solution of a mixture of amino acids has been supplied to cultured cells ever since. The importance of amino acids is further pronounced in chemically defined mammalian cell culture media, making the consideration of their biological and chemical properties necessary. Amino acids concentrations have been traditionally adjusted to their cellular consumption rates. However, since changes in the metabolic equilibrium of amino acids can be caused by changes in extracellular concentrations, metabolomics in conjunction with flux balance analysis is being used in the development of culture media. The study of amino acid transporters is also gaining importance since they control the intracellular concentrations of these molecules and are influenced by conditions in cell culture media. A better understanding of the solubility, stability, dissolution kinetics, and interactions of these molecules is needed for an exploitation of these properties in the development of dry powdered chemically defined media for mammalian cells. Due to the complexity of these mixtures however, this has proven to be challenging. Studying amino acids in mammalian cell culture media will help provide a better understanding of how mammalian cells in culture interact with their environment. It would also provide insight into the chemical behavior of these molecules in solutions of complex mixtures, which is important in the understanding of the contribution of individual amino acids to protein structure.
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Affiliation(s)
- Andrew Salazar
- Institute of Pharmaceutical Chemistry, University of Marburg, 35032, Marburg, Germany.
- Biopharm Materials & Technologies R&D, Merck Lifescience, 64293, Darmstadt, Germany.
| | - Michael Keusgen
- Institute of Pharmaceutical Chemistry, University of Marburg, 35032, Marburg, Germany
| | - Jörg von Hagen
- Biopharm Materials & Technologies R&D, Merck Lifescience, 64293, Darmstadt, Germany
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The mitochondrial carnitine/acylcarnitine carrier is regulated by hydrogen sulfide via interaction with C136 and C155. Biochim Biophys Acta Gen Subj 2015; 1860:20-7. [PMID: 26459002 DOI: 10.1016/j.bbagen.2015.10.005] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Revised: 09/24/2015] [Accepted: 10/08/2015] [Indexed: 11/20/2022]
Abstract
BACKGROUND The carnitine/acylcarnitine carrier (CAC or CACT) mediates transport of acylcarnitines into mitochondria for the β-oxidation. CAC possesses Cys residues which respond to redox changes undergoing to SH/disulfide interconversion. METHODS The effect of H2S has been investigated on the [(3)H]carnitine/carnitine antiport catalyzed by recombinant or native CAC reconstituted in proteoliposomes. Site-directed mutagenesis was employed for identifying Cys reacting with H2S. RESULTS H2S led to transport inhibition, which was dependent on concentration, pH and time of incubation. Best inhibition with IC50 of 0.70 μM was observed at physiological pH after 30-60 min incubation. At longer times of incubation, inhibition was reversed. After oxidation of the carrier by O2, transport activity was rescued by H2S indicating that the inhibition/activation depends on the initial redox state of the protein. The observed effects were more efficient on the native rat liver transporter than on the recombinant protein. Only the protein containing both C136 and C155 responded to the reagent as the WT. While reduced responses were observed in the mutants containing C136 or C155. Multi-alignment of known mitochondrial carriers, highlighted that only the CAC possesses both Cys residues. This correlates well with the absence of effects of H2S on carriers which does not contain the Cys couple. CONCLUSIONS Altogether, these data demonstrate that H2S regulates the CAC by inhibiting or activating transport on the basis of the redox state of the protein. GENERAL SIGNIFICANCE CAC represents a specific target of H2S among mitochondrial carriers in agreement with the presence of a reactive Cys couple.
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Tonazzi A, Giangregorio N, Console L, Scalise M, La Russa D, Notaristefano C, Brunelli E, Barca D, Indiveri C. Mitochondrial carnitine/acylcarnitine transporter, a novel target of mercury toxicity. Chem Res Toxicol 2015; 28:1015-22. [PMID: 25849418 DOI: 10.1021/acs.chemrestox.5b00050] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The effect of Hg(2+) and CH3Hg(+) on the mitochondrial carnitine/acylcarnitine transporter (CACT) has been studied on the recombinant protein and on the CACT extracted from HeLa cells or Zebrafish and reconstituted in proteoliposomes. Transport was abolished upon treatment of the recombinant CACT in proteoliposomes by Hg(2+) or CH3Hg(+). Inhibition was reversed by the SH reducing agent 1,4-dithioerythritol, GSH, and N-acetylcysteine. IC50 for Hg(2+) and CH3Hg(+) of 90 nM and 137 nM, respectively, were measured by dose-response analyses. Inhibition was abolished in the C-less CACT mutant. Strong reduction of inhibition by both reagents was observed in the C136A and some reduction in the C155A mutants. Inhibition similar to that of the WT was observed in the C23V/C58V/C89S/C155V/C283S mutant, containing only C136. Optimal inhibition by Hg(2+)was found in the four replacement mutants C23V/C58V/C89S/C283S containing both C136 and C155 indicating cross-reaction of Hg(2+) with the two Cys residues. Inhibition kinetic analysis showed mixed inhibition by Hg(2+) or competitive inhibition by CH3Hg(+). HeLa cells or Zebrafish were treated with the more potent inhibitor. Ten micromolar HgCl2 caused clear impairment of viability of HeLa cells. The transport assay in proteoliposomes with CACT extracted from treated cells showed that the transporter was inactivated and that DTE rescued the activity. Nearly identical results were observed with Zebrafish upon extraction of the CACT from the liver of the treated animals that, indeed, showed accumulation of the mercurial compound.
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Affiliation(s)
- Annamaria Tonazzi
- †CNR Institute of Biomembranes and Bioenergetics, via Amendola 165/A, 70126 Bari, Italy.,‡Department of Bioscience, Biotechnology and Biopharmaceutics, University of Bari, Bari, Italy
| | - Nicola Giangregorio
- †CNR Institute of Biomembranes and Bioenergetics, via Amendola 165/A, 70126 Bari, Italy.,‡Department of Bioscience, Biotechnology and Biopharmaceutics, University of Bari, Bari, Italy
| | - Lara Console
- §Department DiBEST (Biologia, Ecologia, Scienze della Terra) Unit of Biochemistry and Molecular Biotechnology, University of Calabria, Via Bucci 4C, 87036 Arcavacata di Rende, Italy
| | - Mariafrancesca Scalise
- §Department DiBEST (Biologia, Ecologia, Scienze della Terra) Unit of Biochemistry and Molecular Biotechnology, University of Calabria, Via Bucci 4C, 87036 Arcavacata di Rende, Italy
| | - Daniele La Russa
- §Department DiBEST (Biologia, Ecologia, Scienze della Terra) Unit of Biochemistry and Molecular Biotechnology, University of Calabria, Via Bucci 4C, 87036 Arcavacata di Rende, Italy
| | - Caterina Notaristefano
- ‡Department of Bioscience, Biotechnology and Biopharmaceutics, University of Bari, Bari, Italy
| | - Elvira Brunelli
- §Department DiBEST (Biologia, Ecologia, Scienze della Terra) Unit of Biochemistry and Molecular Biotechnology, University of Calabria, Via Bucci 4C, 87036 Arcavacata di Rende, Italy
| | - Donatella Barca
- §Department DiBEST (Biologia, Ecologia, Scienze della Terra) Unit of Biochemistry and Molecular Biotechnology, University of Calabria, Via Bucci 4C, 87036 Arcavacata di Rende, Italy
| | - Cesare Indiveri
- †CNR Institute of Biomembranes and Bioenergetics, via Amendola 165/A, 70126 Bari, Italy.,§Department DiBEST (Biologia, Ecologia, Scienze della Terra) Unit of Biochemistry and Molecular Biotechnology, University of Calabria, Via Bucci 4C, 87036 Arcavacata di Rende, Italy
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Galluccio M, Pochini L, Peta V, Iannì M, Scalise M, Indiveri C. Functional and molecular effects of mercury compounds on the human OCTN1 cation transporter: C50 and C136 are the targets for potent inhibition. Toxicol Sci 2014; 144:105-13. [PMID: 25490951 DOI: 10.1093/toxsci/kfu259] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
The effect of mercury compounds has been tested on the organic cation transporter, hOCTN1. MeHg(+), Hg(2+), or Cd(2+) caused strong inhibition of transport. 1,4-Dithioerythritol (DTE), cysteine (Cys), and N-acetyl-l-cysteine reversed (NAC) the inhibition at different extents. 2-Aminoethyl methanethiosulfonate hydrobromide (MTSEA), a prototype SH reagent, exerted inhibition of transport similar to that observed for the mercurial agents. To investigate the mechanism of action of mercurials, mutants of hOCTN1 in which each of the Cys residues was substituted by Ala have been constructed, over-expressed in Escherichia coli, and purified. Tetraethylammonium chloride (TEA) uptake mediated by each mutant in proteoliposomes was comparable to that of wild type (WT). IC50 values of the WT and mutants for the mercury compounds were derived from dose-response analyses. The mutants C50A and C136A showed significant increase of IC50 indicating that the 2 Cys residues were involved in the interaction with the mercury compounds and inhibition of the transporter. The double mutant C50A/C136A was constructed; the lack of inhibition confirmed that the 2 Cys residues are the targets of mercury compounds. MTSEA showed similar behavior with respect to the mercurial reagents with the difference that increased IC50 was observed also in the C81A mutant. Similar results were obtained when transport was measured as acetylcholine uptake. Ethyl mercury (Thimerosal) inhibited hOCTN1 as well. C50A, C50A/C136A and, at very lower extent, C136A showed increased IC50 indicating that C50 was the major target of this mercury compound. The homology model of hOCTN1 was built using as template PiPT and validated by the experimental data on mutant proteins.
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Affiliation(s)
- Michele Galluccio
- Department DiBEST (Biologia, Ecologia, Scienze della Terra) Unit of Biochemistry and Molecular Biotechnology, Via Bucci 4C, University of Calabria, 87036 Arcavacata di Rende, Italy
| | - Lorena Pochini
- Department DiBEST (Biologia, Ecologia, Scienze della Terra) Unit of Biochemistry and Molecular Biotechnology, Via Bucci 4C, University of Calabria, 87036 Arcavacata di Rende, Italy
| | - Valentina Peta
- Department DiBEST (Biologia, Ecologia, Scienze della Terra) Unit of Biochemistry and Molecular Biotechnology, Via Bucci 4C, University of Calabria, 87036 Arcavacata di Rende, Italy
| | - Maria Iannì
- Department DiBEST (Biologia, Ecologia, Scienze della Terra) Unit of Biochemistry and Molecular Biotechnology, Via Bucci 4C, University of Calabria, 87036 Arcavacata di Rende, Italy
| | - Mariafrancesca Scalise
- Department DiBEST (Biologia, Ecologia, Scienze della Terra) Unit of Biochemistry and Molecular Biotechnology, Via Bucci 4C, University of Calabria, 87036 Arcavacata di Rende, Italy
| | - Cesare Indiveri
- Department DiBEST (Biologia, Ecologia, Scienze della Terra) Unit of Biochemistry and Molecular Biotechnology, Via Bucci 4C, University of Calabria, 87036 Arcavacata di Rende, Italy
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Pochini L, Scalise M, Galluccio M, Indiveri C. Membrane transporters for the special amino acid glutamine: structure/function relationships and relevance to human health. Front Chem 2014; 2:61. [PMID: 25157349 PMCID: PMC4127817 DOI: 10.3389/fchem.2014.00061] [Citation(s) in RCA: 175] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2014] [Accepted: 07/16/2014] [Indexed: 12/26/2022] Open
Abstract
Glutamine together with glucose is essential for body's homeostasis. It is the most abundant amino acid and is involved in many biosynthetic, regulatory and energy production processes. Several membrane transporters which differ in transport modes, ensure glutamine homeostasis by coordinating its absorption, reabsorption and delivery to tissues. These transporters belong to different protein families, are redundant and ubiquitous. Their classification, originally based on functional properties, has recently been associated with the SLC nomenclature. Function of glutamine transporters is studied in cells over-expressing the transporters or, more recently in proteoliposomes harboring the proteins extracted from animal tissues or over-expressed in microorganisms. The role of the glutamine transporters is linked to their transport modes and coupling with Na+ and H+. Most transporters share specificity for other neutral or cationic amino acids. Na+-dependent co-transporters efficiently accumulate glutamine while antiporters regulate the pools of glutamine and other amino acids. The most acknowledged glutamine transporters belong to the SLC1, 6, 7, and 38 families. The members involved in the homeostasis are the co-transporters B0AT1 and the SNAT members 1, 2, 3, 5, and 7; the antiporters ASCT2, LAT1 and 2. The last two are associated to the ancillary CD98 protein. Some information on regulation of the glutamine transporters exist, which, however, need to be deepened. No information at all is available on structures, besides some homology models obtained using similar bacterial transporters as templates. Some models of rat and human glutamine transporters highlight very similar structures between the orthologs. Moreover the presence of glycosylation and/or phosphorylation sites located at the extracellular or intracellular faces has been predicted. ASCT2 and LAT1 are over-expressed in several cancers, thus representing potential targets for pharmacological intervention.
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Affiliation(s)
- Lorena Pochini
- Department DiBEST (Biologia, Ecologia, Scienze della Terra) Unit of Biochemistry and Molecular Biotechnology, University of Calabria Arcavacata di Rende, Italy
| | - Mariafrancesca Scalise
- Department DiBEST (Biologia, Ecologia, Scienze della Terra) Unit of Biochemistry and Molecular Biotechnology, University of Calabria Arcavacata di Rende, Italy
| | - Michele Galluccio
- Department DiBEST (Biologia, Ecologia, Scienze della Terra) Unit of Biochemistry and Molecular Biotechnology, University of Calabria Arcavacata di Rende, Italy
| | - Cesare Indiveri
- Department DiBEST (Biologia, Ecologia, Scienze della Terra) Unit of Biochemistry and Molecular Biotechnology, University of Calabria Arcavacata di Rende, Italy
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Proteoliposomes as tool for assaying membrane transporter functions and interactions with xenobiotics. Pharmaceutics 2013; 5:472-97. [PMID: 24300519 PMCID: PMC3836619 DOI: 10.3390/pharmaceutics5030472] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Revised: 08/15/2013] [Accepted: 09/04/2013] [Indexed: 02/07/2023] Open
Abstract
Proteoliposomes represent a suitable and up to date tool for studying membrane transporters which physiologically mediate absorption, excretion, trafficking and reabsorption of nutrients and metabolites. Using recently developed reconstitution strategies, transporters can be inserted in artificial bilayers with the same orientation as in the cell membranes and in the absence of other interfering molecular systems. These methodologies are very suitable for studying kinetic parameters and molecular mechanisms. After the first applications on mitochondrial transporters, in the last decade, proteoliposomes obtained with optimized methodologies have been used for studying plasma membrane transporters and defining their functional and kinetic properties and structure/function relationships. A lot of information has been obtained which has clarified and completed the knowledge on several transporters among which the OCTN sub-family members, transporters for neutral amino acid, B0AT1 and ASCT2, and others. Transporters can mediate absorption of substrate-like derivatives or drugs, improving their bioavailability or can interact with these compounds or other xenobiotics, leading to side/toxic effects. Therefore, proteoliposomes have recently been used for studying the interaction of some plasma membrane and mitochondrial transporters with toxic compounds, such as mercurials, H2O2 and some drugs. Several mechanisms have been defined and in some cases the amino acid residues responsible for the interaction have been identified. The data obtained indicate proteoliposomes as a novel and potentially important tool in drug discovery.
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Pingitore P, Pochini L, Scalise M, Galluccio M, Hedfalk K, Indiveri C. Large scale production of the active human ASCT2 (SLC1A5) transporter in Pichia pastoris--functional and kinetic asymmetry revealed in proteoliposomes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1828:2238-46. [PMID: 23756778 DOI: 10.1016/j.bbamem.2013.05.034] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2013] [Revised: 05/28/2013] [Accepted: 05/31/2013] [Indexed: 12/11/2022]
Abstract
The human glutamine/neutral amino acid transporter ASCT2 (hASCT2) was over-expressed in Pichia pastoris and purified by Ni(2+)-chelating and gel filtration chromatography. The purified protein was reconstituted in liposomes by detergent removal with a batch-wise procedure. Time dependent [(3)H]glutamine/glutamine antiport was measured in proteoliposomes which was active only in the presence of external Na(+). Internal Na(+) slightly stimulated the antiport. Optimal activity was found at pH7.0. A substantial inhibition of the transport was observed by Cys, Thr, Ser, Ala, Asn and Met (≥70%) and by mercurials and methanethiosulfonates (≥80%). Heterologous antiport of [(3)H]glutamine with other neutral amino acids was also studied. The transporter showed asymmetric specificity for amino acids: Ala, Cys, Val, Met were only inwardly transported, while Gln, Ser, Asn, and Thr were transported bi-directionally. From kinetic analysis of [(3)H]glutamine/glutamine antiport Km values of 0.097 and 1.8mM were measured on the external and internal sides of proteoliposomes, respectively. The Km for Na(+) on the external side was 32mM. The homology structural model of the hASCT2 protein was built using the GltPh of Pyrococcus horikoshii as template. Cys395 was the only Cys residue externally exposed, thus being the potential target of SH reagents inhibition and, hence, potentially involved in the transport mechanism.
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Affiliation(s)
- Piero Pingitore
- Department BEST (Biologia, Ecologia, Scienze della Terra) Unit of Biochemistry and Molecular Biotechnology, University of Calabria, Via P. Bucci 4c, 87036 Arcavacata di Rende, Italy.
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Pochini L, Peta V, Indiveri C. Inhibition of the OCTN2 carnitine transporter by HgCl2and methylmercury in the proteoliposome experimental model: insights in the mechanism of toxicity. Toxicol Mech Methods 2012; 23:68-76. [DOI: 10.3109/15376516.2012.719166] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Randolph-Gips M, Srinivasan P. Modeling autism: a systems biology approach. J Clin Bioinforma 2012; 2:17. [PMID: 23043674 PMCID: PMC3507704 DOI: 10.1186/2043-9113-2-17] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2012] [Accepted: 08/09/2012] [Indexed: 12/13/2022] Open
Abstract
Autism is the fastest growing developmental disorder in the world today. The prevalence of autism in the US has risen from 1 in 2500 in 1970 to 1 in 88 children today. People with autism present with repetitive movements and with social and communication impairments. These impairments can range from mild to profound. The estimated total lifetime societal cost of caring for one individual with autism is $3.2 million US dollars. With the rapid growth in this disorder and the great expense of caring for those with autism, it is imperative for both individuals and society that techniques be developed to model and understand autism. There is increasing evidence that those individuals diagnosed with autism present with highly diverse set of abnormalities affecting multiple systems of the body. To this date, little to no work has been done using a whole body systems biology approach to model the characteristics of this disorder. Identification and modelling of these systems might lead to new and improved treatment protocols, better diagnosis and treatment of the affected systems, which might lead to improved quality of life by themselves, and, in addition, might also help the core symptoms of autism due to the potential interconnections between the brain and nervous system with all these other systems being modeled. This paper first reviews research which shows that autism impacts many systems in the body, including the metabolic, mitochondrial, immunological, gastrointestinal and the neurological. These systems interact in complex and highly interdependent ways. Many of these disturbances have effects in most of the systems of the body. In particular, clinical evidence exists for increased oxidative stress, inflammation, and immune and mitochondrial dysfunction which can affect almost every cell in the body. Three promising research areas are discussed, hierarchical, subgroup analysis and modeling over time. This paper reviews some of the systems disturbed in autism and suggests several systems biology research areas. Autism poses a rich test bed for systems biology modeling techniques.
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Affiliation(s)
- Mary Randolph-Gips
- Systems Engineering and Computer Engineering, University of Houston - Clear Lake, 2700 Bay Area Bvd, Houston, TX, 77058, USA.
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