1
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Ohse VA, Klotz LO, Priebs J. Copper Homeostasis in the Model Organism C. elegans. Cells 2024; 13:727. [PMID: 38727263 PMCID: PMC11083455 DOI: 10.3390/cells13090727] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2024] [Revised: 04/17/2024] [Accepted: 04/19/2024] [Indexed: 05/13/2024] Open
Abstract
Cellular and organismic copper (Cu) homeostasis is regulated by Cu transporters and Cu chaperones to ensure the controlled uptake, distribution and export of Cu ions. Many of these processes have been extensively investigated in mammalian cell culture, as well as in humans and in mammalian model organisms. Most of the human genes encoding proteins involved in Cu homeostasis have orthologs in the model organism, Caenorhabditis elegans (C. elegans). Starting with a compilation of human Cu proteins and their orthologs, this review presents an overview of Cu homeostasis in C. elegans, comparing it to the human system, thereby establishing the basis for an assessment of the suitability of C. elegans as a model to answer mechanistic questions relating to human Cu homeostasis.
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Affiliation(s)
| | - Lars-Oliver Klotz
- Nutrigenomics Section, Institute of Nutritional Sciences, Friedrich-Schiller-Universität Jena, 07743 Jena, Germany;
| | - Josephine Priebs
- Nutrigenomics Section, Institute of Nutritional Sciences, Friedrich-Schiller-Universität Jena, 07743 Jena, Germany;
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2
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Orlov IA, Sankova TP, Skvortsov AN, Klotchenko SA, Sakhenberg EI, Mekhova AA, Kiseleva IV, Ilyechova EY, Puchkova LV. Properties of recombinant extracellular N-terminal domain of human high-affinity copper transporter 1 (hNdCTR1) and its interactions with Cu(II) and Ag(I) ions. Dalton Trans 2023; 52:3403-3419. [PMID: 36815348 DOI: 10.1039/d2dt04060c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
High-affinity copper transporter 1 (CTR1) is a key link in the transfer of copper (Cu) from the extracellular environment to the cell. Violation in the control system of its expression, or mutations in this gene, cause a global copper imbalance. However, the mechanism of copper transfer via CTR1 remains unclear. It has been shown that transformed bacteria synthesizing the fused GB1-NdCTR become resistant to toxic silver ions. According to UV-Vis spectrophotometry and isothermal titration calorimetry, electrophoretically pure GB1-NdCTR specifically and reversibly binds copper and silver ions, and binding is associated with aggregation. Purified NdCTR1 forms SDS-resistant oligomers. The link between nontrivial properties of NdCTR1 and copper import mechanism from extracellular space, as well as potential chelating properties of NdCTR1, are discussed.
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Affiliation(s)
- Iurii A Orlov
- Research centre of advanced functional materials and laser communication systems, ADTS Institute, ITMO, University, 197101 St. Petersburg, Russia.
| | - Tatiana P Sankova
- Institute of Biomedical Systems and Biotechnology, Peter the Great St. Petersburg Polytechnic University, 195251 St. Petersburg, Russia
| | - Alexey N Skvortsov
- Institute of Biomedical Systems and Biotechnology, Peter the Great St. Petersburg Polytechnic University, 195251 St. Petersburg, Russia.,Laboratory of The Molecular Biology of Stem Cells, Institute of Cytology, RAS, 194064 St. Petersburg, Russia
| | - Sergey A Klotchenko
- Laboratory for the Development of Molecular Diagnostic Systems, Smorodintsev Research Institute of Influenza, 197376 St. Petersburg, Russia
| | - Elena I Sakhenberg
- Laboratory of cell protection mechanisms, Institute of Cytology, RAS, 194064 St. Petersburg, Russia
| | - Aleksandra A Mekhova
- Research centre of advanced functional materials and laser communication systems, ADTS Institute, ITMO, University, 197101 St. Petersburg, Russia. .,Institute of Biomedical Systems and Biotechnology, Peter the Great St. Petersburg Polytechnic University, 195251 St. Petersburg, Russia
| | - Irina V Kiseleva
- Department of Virology, Institute of Experimental Medicine, 197376 St. Petersburg, Russia
| | - Ekaterina Yu Ilyechova
- Research centre of advanced functional materials and laser communication systems, ADTS Institute, ITMO, University, 197101 St. Petersburg, Russia. .,Institute of Biomedical Systems and Biotechnology, Peter the Great St. Petersburg Polytechnic University, 195251 St. Petersburg, Russia.,Department of Molecular Genetics, Institute of Experimental Medicine, 197376 St. Petersburg, Russia
| | - Ludmila V Puchkova
- Research centre of advanced functional materials and laser communication systems, ADTS Institute, ITMO, University, 197101 St. Petersburg, Russia. .,Institute of Biomedical Systems and Biotechnology, Peter the Great St. Petersburg Polytechnic University, 195251 St. Petersburg, Russia.,Department of Molecular Genetics, Institute of Experimental Medicine, 197376 St. Petersburg, Russia
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3
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Schulte NB, Pushie MJ, Martinez A, Sendzik M, Escobedo M, Kuter K, Haas KL. Exploration of the Potential Role of Serum Albumin in the Delivery of Cu(I) to Ctr1. Inorg Chem 2023; 62:4021-4034. [PMID: 36826341 DOI: 10.1021/acs.inorgchem.2c03753] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/25/2023]
Abstract
Human serum albumin (HSA) is the major copper (Cu) carrier in blood. The majority of previous studies that have investigated Cu interactions with HSA have focused primarily on the Cu(II) oxidation state. Yet, cellular Cu uptake by the human copper transport protein (Ctr1), a plasma membrane-embedded protein responsible for Cu uptake into cells, requires Cu(I). Recent in vitro work has determined that reducing agents, such as the ascorbate present in blood, are sufficient to reduce the Cu(II)HSA complex to form Cu(I)HSA and that Cu(I) is bound to HSA with pM affinity. The biological accessibility of Cu(I)HSA suggests that HSA-bound Cu(I) may be an unappreciated form of Cu cargo and a key player in extracellular Cu trafficking. To better understand Cu trafficking by HSA, we sought to investigate the exchange of Cu(I) from HSA to a model peptide of the Cu-binding ectodomain of Ctr1. In this study, we used X-ray absorption near-edge spectroscopy to show that Cu(I) becomes more highly coordinated as increasing amounts of the Ctr1-14 model peptide are added to a solution of Cu(I)HSA. Extended X-ray absorption fine structure (EXAFS) spectroscopy was used to further characterize the interaction of Cu(I)HSA with Ctr1-14 by determining the ligands coordinating Cu(I) and their bond lengths. The EXAFS data support that some Cu(I) likely undergoes complete transfer from HSA to Ctr1-14. This finding of HSA interacting with and releasing Cu(I) to an ectodomain model peptide of Ctr1 suggests a mechanism by which HSA delivers Cu(I) to cells under physiological conditions.
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Affiliation(s)
- Natalie B Schulte
- Department of Chemistry, Duke University, Durham, North Carolina 27708, United States
| | - M Jake Pushie
- Department of Surgery, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E5, Canada
| | - Ana Martinez
- Department of Chemistry and Physics, Saint Mary's College, Notre Dame, Indiana 46556, United States
| | - Madison Sendzik
- Department of Chemistry and Physics, Saint Mary's College, Notre Dame, Indiana 46556, United States
| | - Maria Escobedo
- Department of Mathematics and Computer Science, Saint Mary's College, Notre Dame, Indiana 46556, United States
| | - Kristin Kuter
- Department of Mathematics and Computer Science, Saint Mary's College, Notre Dame, Indiana 46556, United States
| | - Kathryn L Haas
- Department of Chemistry, Duke University, Durham, North Carolina 27708, United States
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Endocytosis of nutrient transporters in fungi: The ART of connecting signaling and trafficking. Comput Struct Biotechnol J 2021; 19:1713-1737. [PMID: 33897977 PMCID: PMC8050425 DOI: 10.1016/j.csbj.2021.03.013] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2020] [Revised: 03/14/2021] [Accepted: 03/14/2021] [Indexed: 12/11/2022] Open
Abstract
Plasma membrane transporters play pivotal roles in the import of nutrients, including sugars, amino acids, nucleobases, carboxylic acids, and metal ions, that surround fungal cells. The selective removal of these transporters by endocytosis is one of the most important regulatory mechanisms that ensures a rapid adaptation of cells to the changing environment (e.g., nutrient fluctuations or different stresses). At the heart of this mechanism lies a network of proteins that includes the arrestin‐related trafficking adaptors (ARTs) which link the ubiquitin ligase Rsp5 to nutrient transporters and endocytic factors. Transporter conformational changes, as well as dynamic interactions between its cytosolic termini/loops and with lipids of the plasma membrane, are also critical during the endocytic process. Here, we review the current knowledge and recent findings on the molecular mechanisms involved in nutrient transporter endocytosis, both in the budding yeast Saccharomyces cerevisiae and in some species of the filamentous fungus Aspergillus. We elaborate on the physiological importance of tightly regulated endocytosis for cellular fitness under dynamic conditions found in nature and highlight how further understanding and engineering of this process is essential to maximize titer, rate and yield (TRY)-values of engineered cell factories in industrial biotechnological processes.
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Key Words
- AAs, amino acids
- ACT, amino Acid/Choline Transporter
- AP, adaptor protein
- APC, amino acid-polyamine-organocation
- Arg, arginine
- Arrestins
- Arts, arrestin‐related trafficking adaptors
- Asp, aspartic acid
- Aspergilli
- Biotechnology
- C, carbon
- C-terminus, carboxyl-terminus
- Cell factories
- Conformational changes
- Cu, copper
- DUBs, deubiquitinating enzymes
- EMCs, eisosome membrane compartments
- ER, endoplasmic reticulum
- ESCRT, endosomal sorting complex required for transport
- Endocytic signals
- Endocytosis
- Fe, iron
- Fungi
- GAAC, general amino acid control
- Glu, glutamic acid
- H+, proton
- IF, inward-facing
- LAT, L-type Amino acid Transporter
- LID, loop Interaction Domain
- Lys, lysine
- MCCs, membrane compartments containing the arginine permease Can1
- MCCs/eisosomes
- MCPs, membrane compartments of Pma1
- MFS, major facilitator superfamily
- MVB, multi vesicular bodies
- Met, methionine
- Metabolism
- Mn, manganese
- N, nitrogen
- N-terminus, amino-terminus
- NAT, nucleobase Ascorbate Transporter
- NCS1, nucleobase/Cation Symporter 1
- NCS2, nucleobase cation symporter family 2
- NH4+, ammonium
- Nutrient transporters
- OF, outward-facing
- PEST, proline (P), glutamic acid (E), serine (S), and threonine (T)
- PM, plasma membrane
- PVE, prevacuolar endosome
- Saccharomyces cerevisiae
- Signaling pathways
- Structure-function
- TGN, trans-Golgi network
- TMSs, transmembrane segments
- TORC1, target of rapamycin complex 1
- TRY, titer, rate and yield
- Trp, tryptophan
- Tyr, tyrosine
- Ub, ubiquitin
- Ubiquitylation
- VPS, vacuolar protein sorting
- W/V, weight per volume
- YAT, yeast Amino acid Transporter
- Zn, Zinc
- fAATs, fungal AA transporters
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5
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Mandal T, Kar S, Maji S, Sen S, Gupta A. Structural and Functional Diversity Among the Members of CTR, the Membrane Copper Transporter Family. J Membr Biol 2020; 253:459-468. [PMID: 32975619 DOI: 10.1007/s00232-020-00139-w] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Accepted: 09/04/2020] [Indexed: 12/19/2022]
Abstract
Copper is crucial for carrying out normal physiological functions in all higher life forms. Copper Transporter 1 (CTR1) is the high-affinity copper importer found in all eukaryotic organisms. The copper transporter family primarily comprises ~ six members (CTR1-6) and the related members share high sequence homology with CTR. However, with the exception of CTR1, not all six CTRs are present in every organism. Despite having a simple trimeric channel structure, CTR1 and other members exhibit some unique regulatory properties. In the present review, we attempt to understand the diversity and similarity of regulation and functioning of the members of this copper transporter family.
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Affiliation(s)
- Taniya Mandal
- Department of Biological Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, 741246, India
| | - Sumanta Kar
- Department of Biological Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, 741246, India
| | - Saptarshi Maji
- Department of Biological Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, 741246, India
| | - Samarpita Sen
- Department of Biological Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, 741246, India
| | - Arnab Gupta
- Department of Biological Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, 741246, India.
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6
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Pan W, Wang Y, Wang N. A new metal affinity NCTR 25 tag as a better alternative to the His-tag for the expression of recombinant fused proteins. Protein Expr Purif 2019; 164:105477. [PMID: 31419547 DOI: 10.1016/j.pep.2019.105477] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2019] [Revised: 07/20/2019] [Accepted: 08/11/2019] [Indexed: 12/18/2022]
Abstract
His-tagging is commonly used in fusion protein production, but the His-tag is usually prohibited in medicinal proteins and must be removed. A fragment (NCTR25-tag) truncated from the N-terminus of human copper transporter 1 was tested for feasibility as a replacement for the His-tag in fusion proteins. The NCTR25-tag and His-tag were separately fused to the transthyretin (TTR) protein, and the expression, affinity purification, refolding and stability of the two kinds of fusions were compared. NCTR25 fusion produced a 63% higher yield of the recombinant protein, which was purified by metal affinity chromatography with an efficiency similar to that of His-tagged protein. NCTR25-tag fusion had much less impact on the foldability, kinetic and thermodynamic stability of tetrameric TTR than His-tag fusion. When the tags were individually fused to enhanced green fluorescent protein (EGFP), NCTR25 fusion yielded 29-128% more product than His-EGFP. NCTR25-EGFP could be purified by metal affinity chromatography and showed better foldability than His-EGFP. Furthermore, tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) fusion with the third disulfide loop of TGF-α (TGF3L-TRAIL) fused with the NCTR25-tag retained the stability and superactivity of His-TGF3L-TRAIL. Therefore, the native tag NCTR25-tag is a feasible alternative to the His-tag in medicinal recombinant proteins.
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Affiliation(s)
- Weitong Pan
- Beijing Key Laboratory of New Drug Mechanisms and Pharmacological Evaluation Study, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, People's Republic of China
| | - Yan Wang
- Beijing Key Laboratory of New Drug Mechanisms and Pharmacological Evaluation Study, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, People's Republic of China.
| | - Nan Wang
- Beijing Key Laboratory of New Drug Mechanisms and Pharmacological Evaluation Study, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, People's Republic of China.
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7
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Pavlin M, Qasem Z, Sameach H, Gevorkyan-Airapetov L, Ritacco I, Ruthstein S, Magistrato A. Unraveling the Impact of Cysteine-to-Serine Mutations on the Structural and Functional Properties of Cu(I)-Binding Proteins. Int J Mol Sci 2019; 20:E3462. [PMID: 31337158 PMCID: PMC6679193 DOI: 10.3390/ijms20143462] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Revised: 07/09/2019] [Accepted: 07/11/2019] [Indexed: 02/03/2023] Open
Abstract
Appropriate maintenance of Cu(I) homeostasis is an essential requirement for proper cell function because its misregulation induces the onset of major human diseases and mortality. For this reason, several research efforts have been devoted to dissecting the inner working mechanism of Cu(I)-binding proteins and transporters. A commonly adopted strategy relies on mutations of cysteine residues, for which Cu(I) has an exquisite complementarity, to serines. Nevertheless, in spite of the similarity between these two amino acids, the structural and functional impact of serine mutations on Cu(I)-binding biomolecules remains unclear. Here, we applied various biochemical and biophysical methods, together with all-atom simulations, to investigate the effect of these mutations on the stability, structure, and aggregation propensity of Cu(I)-binding proteins, as well as their interaction with specific partner proteins. Among Cu(I)-binding biomolecules, we focused on the eukaryotic Atox1-ATP7B system, and the prokaryotic CueR metalloregulator. Our results reveal that proteins containing cysteine-to-serine mutations can still bind Cu(I) ions; however, this alters their stability and aggregation propensity. These results contribute to deciphering the critical biological principles underlying the regulatory mechanism of the in-cell Cu(I) concentration, and provide a basis for interpreting future studies that will take advantage of cysteine-to-serine mutations in Cu(I)-binding systems.
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Affiliation(s)
- Matic Pavlin
- CNR-IOM at SISSA, via Bonomea 265, 34135 Trieste, Italy
| | - Zena Qasem
- Department of Chemistry, Faculty of Exact Sciences, Bar Ilan University, Ramat-Gan 5290002, Israel
| | - Hila Sameach
- Department of Chemistry, Faculty of Exact Sciences, Bar Ilan University, Ramat-Gan 5290002, Israel
| | - Lada Gevorkyan-Airapetov
- Department of Chemistry, Faculty of Exact Sciences, Bar Ilan University, Ramat-Gan 5290002, Israel
| | - Ida Ritacco
- CNR-IOM at SISSA, via Bonomea 265, 34135 Trieste, Italy
| | - Sharon Ruthstein
- Department of Chemistry, Faculty of Exact Sciences, Bar Ilan University, Ramat-Gan 5290002, Israel.
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8
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Magistrato A, Pavlin M, Qasem Z, Ruthstein S. Copper trafficking in eukaryotic systems: current knowledge from experimental and computational efforts. Curr Opin Struct Biol 2019; 58:26-33. [PMID: 31176065 PMCID: PMC6863429 DOI: 10.1016/j.sbi.2019.05.002] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2019] [Revised: 04/16/2019] [Accepted: 05/02/2019] [Indexed: 01/16/2023]
Abstract
The main copper transporter, Ctr1, can transfer Cu(I) in the cell, through two different intracellular domains. Conformational flexibility of the copper metallochaperone Atox1 controls copper transfer mechanism in the cell. Each metal binding domain in ATP7B has a specific role.
Copper plays a vital role in fundamental cellular functions, and its concentration in the cell must be tightly regulated, as dysfunction of copper homeostasis is linked to severe neurological diseases and cancer. This review provides a compendium of current knowledge regarding the mechanism of copper transfer from the blood system to the Golgi apparatus; this mechanism involves the copper transporter hCtr1, the metallochaperone Atox1, and the ATPases ATP7A/B. We discuss key insights regarding the structural and functional properties of the hCtr1-Atox1-ATP7B cycle, obtained from diverse studies relying on distinct yet complementary biophysical, biochemical, and computational methods. We further address the mechanistic aspects of the cycle that continue to remain elusive. These knowledge gaps must be filled in order to be able to harness our understanding of copper transfer to develop therapeutic approaches with the capacity to modulate copper metabolism.
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Affiliation(s)
- Alessandra Magistrato
- National Research Council of Italy-IOM c/o International School for Advanced Studies (SISSA), via Bonomea 165, 34135, Trieste, Italy.
| | - Matic Pavlin
- National Research Council of Italy-IOM c/o International School for Advanced Studies (SISSA), via Bonomea 165, 34135, Trieste, Italy
| | - Zena Qasem
- The Chemistry Department, Faculty of Exact Sciences, Bar-Ilan University, 529002, Israel
| | - Sharon Ruthstein
- The Chemistry Department, Faculty of Exact Sciences, Bar-Ilan University, 529002, Israel.
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9
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Wezynfeld NE, Vileno B, Faller P. Cu(II) Binding to the N-Terminal Model Peptide of the Human Ctr2 Transporter at Lysosomal and Extracellular pH. Inorg Chem 2019; 58:7488-7498. [PMID: 31083932 DOI: 10.1021/acs.inorgchem.9b00711] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
It was shown that His3 of human copper transporter 1 (hCtr1) prompts the ATCUN-like Cu(II) coordination for model peptides of the hCtr1 N-terminus. Its high Cu(II) affinity is a potential driving force for the transfer of Cu(II) from extracellular Cu(II) carriers to hCtr1. Having a sequence similar to that of hCtr1, hCtr2 has been proposed as another human copper transporter. However, the N-terminal domain of hCtr2 is much shorter than that of hCtr1, with different copper binding motifs at its N-terminus. Employing a model peptide of the hCtr2 N-terminus, MAMHF-am, we demonstrated that His4 provides a unique pattern of Cu(II) complexes, involving Met sulfurs in their Cu(II) coordination sphere. The affinity of Cu(II) for MAMHF-am is a few orders of magnitude lower than that reported for the hCtr1 model peptides at the extracellular pH of 7.4, suggesting a maximal complementary role of Cu(II) binding to hCtr2 in the import of copper from the extracellular space to the cytoplasm. On the other hand, the ability of the hCtr2 model peptide to capture Cu(II) from amino acids and short peptides (potential degradation products of proteins) at pH 5.0 and the known predominant lysosomal localization of hCtr2 support an important potential role of the Cu(II)-hCtr2 interaction in the recovery of copper from lysosomes.
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Affiliation(s)
- Nina E Wezynfeld
- Institut de Chimie, UMR 7177 , CNRS-Université de Strasbourg , 4 rue Blaise Pascal , 67000 Strasbourg , France.,Institute of Biochemistry and Biophysics , Polish Academy of Sciences , Pawińskiego 5a , 02-106 Warsaw , Poland
| | - Bertrand Vileno
- Institut de Chimie, UMR 7177 , CNRS-Université de Strasbourg , 4 rue Blaise Pascal , 67000 Strasbourg , France.,French EPR Federation of Research (REseau NAtional de Rpe interDisciplinaire (RENARD) Fédération IR-RPE CNRS #3443) , 67081 Strasbourg , France
| | - Peter Faller
- Institut de Chimie, UMR 7177 , CNRS-Université de Strasbourg , 4 rue Blaise Pascal , 67000 Strasbourg , France
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10
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The Cu(II) affinity of the N-terminus of human copper transporter CTR1: Comparison of human and mouse sequences. J Inorg Biochem 2019; 182:230-237. [PMID: 29402466 DOI: 10.1016/j.jinorgbio.2018.01.011] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Revised: 01/08/2018] [Accepted: 01/19/2018] [Indexed: 11/20/2022]
Abstract
Copper Transporter 1 (CTR1) is a homotrimeric membrane protein providing the main route of copper transport into eukaryotic cells from the extracellular milieu. Its N-terminal extracellular domain, rich in His and Met residues, is considered responsible for directing copper into the transmembrane channel. Most of vertebrate CTR1 proteins contain the His residue in position three from N-terminus, creating a well-known Amino Terminal Cu(II)- and Ni(II)-Binding (ATCUN) site. CTR1 from humans, primates and many other species contains the Met-Asp-His (MDH) sequence, while some rodents including mouse have the Met-Asn-His (MNH) N-terminal sequence. CTR1 is thought to collect Cu(II) ions from blood copper transport proteins, including albumin, but previous reports indicated that the affinity of N-terminal peptide/domain of CTR1 is significantly lower than that of albumin, casting serious doubt on this aspect of CTR1 function. Using potentiometry and spectroscopic techniques we demonstrated that MDH-amide, a tripeptide model of human CTR1 N-terminus, binds Cu(II) with K of 1.3 × 1013 M-1 at pH 7.4, ~13 times stronger than Human Serum Albumin (HSA), and MNH-amide is even stronger, K of 3.2 × 1014 M-1 at pH 7.4. These results indicate that the N-terminus of CTR1 may serve as intermediate binding site during Cu(II) transfer from blood copper carriers to the transporter. MDH-amide, but not MNH-amide also forms a low abundance complex with non-ATCUN coordination involving the Met amine, His imidazole and Asp carboxylate. This species might assist Cu(II) relay down the peptide chain or its reduction to Cu(I), both steps necessary for the CTR1 function.
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11
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Yang Y, Zhu Y, Hu H, Cheng L, Liu M, Ma G, Yuan S, Cui P, Liu Y. Cuprous binding promotes interaction of copper transport protein hCTR1 with cell membranes. Chem Commun (Camb) 2019; 55:11107-11110. [DOI: 10.1039/c9cc04859f] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Cu(i) binding promotes the interaction of hCTR1 with cell membranes, which could initiate the cellular uptake of copper ions.
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Affiliation(s)
- Yang Yang
- CAS High Magnetic Field Laboratory
- Department of Chemistry
- University of Science and Technology of China
- Hefei Anhui
- China
| | - Yang Zhu
- CAS High Magnetic Field Laboratory
- Department of Chemistry
- University of Science and Technology of China
- Hefei Anhui
- China
| | - Hongze Hu
- CAS High Magnetic Field Laboratory
- Department of Chemistry
- University of Science and Technology of China
- Hefei Anhui
- China
| | - Lanjun Cheng
- CAS High Magnetic Field Laboratory
- Department of Chemistry
- University of Science and Technology of China
- Hefei Anhui
- China
| | - Manman Liu
- CAS High Magnetic Field Laboratory
- Department of Chemistry
- University of Science and Technology of China
- Hefei Anhui
- China
| | - Guolin Ma
- Institute of Biosciences and Technology
- College of Medicine
- Texas A&M University
- Houston
- USA
| | - Siming Yuan
- CAS High Magnetic Field Laboratory
- Department of Chemistry
- University of Science and Technology of China
- Hefei Anhui
- China
| | - Peixin Cui
- Key Laboratory of Soil Environment and Pollution Remediation
- Institute of Soil Science
- the Chinese Academy of Sciences
- Nanjing 210008
- China
| | - Yangzhong Liu
- CAS High Magnetic Field Laboratory
- Department of Chemistry
- University of Science and Technology of China
- Hefei Anhui
- China
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12
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Sanz A, Pike S, Khan MA, Carrió-Seguí À, Mendoza-Cózatl DG, Peñarrubia L, Gassmann W. Copper uptake mechanism of Arabidopsis thaliana high-affinity COPT transporters. PROTOPLASMA 2019; 256:161-170. [PMID: 30043153 DOI: 10.1007/s00709-018-1286-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Accepted: 07/11/2018] [Indexed: 05/24/2023]
Abstract
Copper (Cu) is an essential plant micronutrient. Under scarcity, Cu2+ is reduced to Cu+ and taken up through specific high-affinity transporters (COPTs). In Arabidopsis, the COPT family consists of six members, either located at the plasma membrane (COPT1, COPT2, and COPT6) or in internal membranes (COPT3 and COPT5). Cu uptake by COPT proteins has been mainly assessed through complementation studies in corresponding yeast mutants, but the mechanism of this transport has not been elucidated. To test whether Cu is incorporated by an electrogenic mechanism, electrophysiological changes induced by Cu addition were studied in Arabidopsis thaliana. Mutant (T-DNA insertion mutants, copt2-1 and copt5-2) and overexpressing lines (COPT1OE and COPT5OE) with altered expression of COPT transporters were compared to wild-type plants. No significant changes of the membrane potential (Em) were detected, regardless of genotype or Cu concentration supplied. In contrast, membrane depolarization was detected in response to iron supply in both wild-type and in mutant or transgenic plants. Similar results were obtained for trans-plant potentials (TPP). GFP fusions of the plasma membrane COPT2 and the internal COPT5 transporters were expressed in Xenopus laevis oocytes to potentiate Cu uptake signals, and the cRNA-injected oocytes were tested for electrical currents upon Cu addition using two-electrode voltage clamp. Results with oocytes confirmed those obtained in plants. Cu accumulation in injected oocytes was measured by ICP-OES, and a significant increase in Cu content with respect to controls occurred in oocytes expressing COPT2:GFP. The possible mechanisms driving this transport are discussed in this manuscript.
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Affiliation(s)
- Amparo Sanz
- Dpt de Biologia Vegetal, Universitat de València, c/ Dr Moliner 50, 46100-Burjassot, Valencia, Spain.
| | - Sharon Pike
- Division of Plant Sciences, CS Bond Life Sciences Center, and Interdisciplinary Plant Group, University of Missouri, 1201 Rollins St, Columbia, MO, 65211, USA
| | - Mather A Khan
- Division of Plant Sciences, CS Bond Life Sciences Center, and Interdisciplinary Plant Group, University of Missouri, 1201 Rollins St, Columbia, MO, 65211, USA
| | - Àngela Carrió-Seguí
- Dpt de Bioquímica i Biologia Molecular and ERI Biotecmed, Universitat de València, c/ Dr Moliner 50, 46100-Burjassot, Valencia, Spain
| | - David G Mendoza-Cózatl
- Division of Plant Sciences, CS Bond Life Sciences Center, and Interdisciplinary Plant Group, University of Missouri, 1201 Rollins St, Columbia, MO, 65211, USA
| | - Lola Peñarrubia
- Dpt de Bioquímica i Biologia Molecular and ERI Biotecmed, Universitat de València, c/ Dr Moliner 50, 46100-Burjassot, Valencia, Spain
| | - Walter Gassmann
- Division of Plant Sciences, CS Bond Life Sciences Center, and Interdisciplinary Plant Group, University of Missouri, 1201 Rollins St, Columbia, MO, 65211, USA
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13
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Fukai T, Ushio-Fukai M, Kaplan JH. Copper transporters and copper chaperones: roles in cardiovascular physiology and disease. Am J Physiol Cell Physiol 2018; 315:C186-C201. [PMID: 29874110 DOI: 10.1152/ajpcell.00132.2018] [Citation(s) in RCA: 97] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Copper (Cu) is an essential micronutrient but excess Cu is potentially toxic. Its important propensity to cycle between two oxidation states accounts for its frequent presence as a cofactor in many physiological processes through Cu-containing enzymes, including mitochondrial energy production (via cytochrome c-oxidase), protection against oxidative stress (via superoxide dismutase), and extracellular matrix stability (via lysyl oxidase). Since free Cu is potentially toxic, the bioavailability of intracellular Cu is tightly controlled by Cu transporters and Cu chaperones. Recent evidence reveals that these Cu transport systems play an essential role in the physiological responses of cardiovascular cells, including cell growth, migration, angiogenesis and wound repair. In response to growth factors, cytokines, and hypoxia, their expression, subcellular localization, and function are tightly regulated. Cu transport systems and their regulators have also been linked to various cardiovascular pathophysiologies such as hypertension, inflammation, atherosclerosis, diabetes, cardiac hypertrophy, and cardiomyopathy. A greater appreciation of the central importance of Cu transporters and Cu chaperones in cell signaling and gene expression in cardiovascular biology offers the possibility of identifying new therapeutic targets for cardiovascular disease.
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Affiliation(s)
- Tohru Fukai
- Vascular Biology Center, Medical College of Georgia at Augusta University , Augusta, Georgia.,Departments of Pharmacology and Toxicology, Medical College of Georgia at Augusta University , Augusta, Georgia.,Charlie Norwood Veterans Affairs Medical Center , Augusta Georgia
| | - Masuko Ushio-Fukai
- Vascular Biology Center, Medical College of Georgia at Augusta University , Augusta, Georgia.,Department of Medicine (Cardiology), Medical College of Georgia at Augusta University , Augusta, Georgia
| | - Jack H Kaplan
- Department of Biochemistry and Molecular Genetics, University of Illinois College of Medicine , Chicago, Illinois
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14
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Okada M, Kajimoto S, Nakabayashi T. Embedding a Metal-Binding Motif for Copper Transporter into a Lipid Bilayer by Cu(I) Binding. J Phys Chem B 2018; 122:6364-6370. [DOI: 10.1021/acs.jpcb.8b03179] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Mariko Okada
- Graduate School of Pharmaceutical Sciences, Tohoku University, Aoba-ku, Sendai 980-8578, Japan
| | - Shinji Kajimoto
- Graduate School of Pharmaceutical Sciences, Tohoku University, Aoba-ku, Sendai 980-8578, Japan
| | - Takakazu Nakabayashi
- Graduate School of Pharmaceutical Sciences, Tohoku University, Aoba-ku, Sendai 980-8578, Japan
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15
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Jiang L, Song D, Chen H, Zhang A, Wang H, Cheng Z. Pilot Study of 64CuCl₂ for PET Imaging of Inflammation. Molecules 2018; 23:molecules23020502. [PMID: 29495260 PMCID: PMC6017813 DOI: 10.3390/molecules23020502] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2018] [Revised: 02/18/2018] [Accepted: 02/20/2018] [Indexed: 11/16/2022] Open
Abstract
Copper(II) ion (Cu2+) is the essential element for numerous pathophysiological processes in vivo. Copper transporter 1 (CTR1) is mainly responsible for maintaining Cu2+ accumulation in cells, which has been found to be over-expressed in inflammatory tissues. Therefore, we explored the potential application of 64CuCl₂ for PET imaging of inflammation through targeting CTR1. The animal models of H₂O₂ induced muscle inflammation and lipopolysaccaharide induced lung inflammation were successfully established, then imaged by small animal PET (PET/CT) post-injection of 64CuCl₂, and PET images were quantitatively analyzed. H&E and immunohistochemical (IHC) staining and western blot experiments were performed for evaluating CTR1 levels in the inflammatory and control tissues. Both inflammatory muscle and lungs can be clearly imaged by PET. PET image quantitative analysis revealed that the inflammatory muscle and lungs showed significantly higher 64Cu accumulation than the controls, respectively (p < 0.05). Furthermore, IHC staining and western blot analysis demonstrated that compared with the controls, CTR1 expression was increased in both the inflammatory muscle and lungs, which was consistent with the levels of 64Cu2+ accumulation in these tissues. 64CuCl₂ can be used as a novel, simple, and highly promising PET tracer for CTR1 targeted imaging of inflammation.
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Affiliation(s)
- Lei Jiang
- Department of Nuclear Medicine, Shanghai Pulmonary Hospital, Tongji University School of Medicine, Shanghai 200433, China.
- Molecular Imaging Program at Stanford (MIPS), Department of Radiology and Bio-X Program, Canary Center at Stanford for Cancer Early Detection, Stanford University, Stanford, CA 94305-5484, USA.
| | - Dongli Song
- Institute of Clinical Science, Zhongshan Hospital, Fudan University, Shanghai 200032, China.
| | - Hao Chen
- Molecular Imaging Program at Stanford (MIPS), Department of Radiology and Bio-X Program, Canary Center at Stanford for Cancer Early Detection, Stanford University, Stanford, CA 94305-5484, USA.
| | - Ao Zhang
- CAS Key Laboratory of Receptor Research, Synthetic Organic & Medicinal Chemistry Laboratory (SOMCL), Shanghai Institute of Materia Medica, Chinese Academy of Sciences, No. 555 Zuchong Road, Pudong New Area, Shanghai 201203, China.
| | - Huoqiang Wang
- Department of Nuclear Medicine, Shanghai Pulmonary Hospital, Tongji University School of Medicine, Shanghai 200433, China.
| | - Zhen Cheng
- Molecular Imaging Program at Stanford (MIPS), Department of Radiology and Bio-X Program, Canary Center at Stanford for Cancer Early Detection, Stanford University, Stanford, CA 94305-5484, USA.
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16
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Kline CD, Gambill BF, Mayfield M, Lutsenko S, Blackburn NJ. pH-regulated metal-ligand switching in the HM loop of ATP7A: a new paradigm for metal transfer chemistry. Metallomics 2017; 8:729-33. [PMID: 27242196 DOI: 10.1039/c6mt00062b] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Cuproproteins such as PHM and DBM mature in late endosomal vesicles of the mammalian secretory pathway where changes in vesicle pH are employed for sorting and post-translational processing. Colocation with the P1B-type ATPase ATP7A suggests that the latter is the source of copper and supports a mechanism where selectivity in metal transfer is achieved by spatial colocation of partner proteins in their specific organelles or vesicles. In previous work we have suggested that a lumenal loop sequence located between trans-membrane helices TM1 and TM2 of the ATPase, and containing five histidines and four methionines, acts as an organelle-specific chaperone for metallation of the cuproproteins. The hypothesis posits that the pH of the vesicle regulates copper ligation and loop conformation via a mechanism which involves His to Met ligand switching induced by histidine protonation. Here we report the effect of pH on the HM loop copper coordination using X-ray absorption spectroscopy (XAS), and show via selenium substitution of the Met residues that the HM loop undergoes similar conformational switching to that found earlier for its partner PHM. We hypothesize that in the absence of specific chaperones, HM motifs provide a template for building a flexible, pH-sensitive transfer site whose structure and function can be regulated to accommodate the different active site structural elements and pH environments of its partner proteins.
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Affiliation(s)
- Chelsey D Kline
- Institute of Environmental Health, Oregon Health and Sciences University, 3181 SW Sam Jackson Park Road, Portland, Oregon 97239, USA.
| | - Benjamin F Gambill
- Institute of Environmental Health, Oregon Health and Sciences University, 3181 SW Sam Jackson Park Road, Portland, Oregon 97239, USA.
| | - Mary Mayfield
- Institute of Environmental Health, Oregon Health and Sciences University, 3181 SW Sam Jackson Park Road, Portland, Oregon 97239, USA.
| | - Svetlana Lutsenko
- Department of Physiology, The Johns Hopkins University, Baltimore, Maryland 21205, USA
| | - Ninian J Blackburn
- Institute of Environmental Health, Oregon Health and Sciences University, 3181 SW Sam Jackson Park Road, Portland, Oregon 97239, USA.
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17
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Abstract
At present, 64Cu(II) labeled tracers including 64CuCl2 have been widely applied in the research of molecular imaging and therapy. Human copper transporter 1 (hCTR1) is the major high affinity copper influx transporter in mammalian cells, and specially responsible for the transportation of Cu(I) not Cu(II). Thus, we investigated the feasible application of 64Cu(I) for PET imaging. 64Cu(II) was reduced to 64Cu(I) with the existence of sodium L-ascorbate, DL-Dithiothreitol or cysteine. Cell uptake and efflux assay was investigated using B16F10 and A375 cell lines, respectively. Small animal PET and biodistribution studies were performed in both B16F10 and A375 tumor-bearing mice. Compared with 64Cu(II), 64Cu(I) exhibited higher cellular uptake by melanoma, which testified CTR1 specially influx of Cu(I). However, due to oxidation reaction in vivo, no significant difference between 64Cu(I) and 64Cu(II) was observed through PET images and biodistribution. Additionally, radiation absorbed doses for major tissues of human were calculated based on the mouse biodistribution. Radiodosimetry calculations for 64/67Cu(I) and 64/67Cu(II) were similar, which suggested that although melanoma were with high radiation absorbed doses, high radioactivity accumulation by liver and kidney should be noticed for the further application. Thus, 64Cu(I) should be further studied to evaluate it as a PET imaging radiotracer.
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18
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Okada M, Miura T, Nakabayashi T. Comparison of extracellular Cys/Trp motif between Schizosaccharomyces pombe Ctr4 and Ctr5. J Inorg Biochem 2017; 169:97-105. [PMID: 28167404 DOI: 10.1016/j.jinorgbio.2017.01.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Revised: 01/07/2017] [Accepted: 01/20/2017] [Indexed: 11/19/2022]
Abstract
The reduction and binding of copper ions to the Cys/Trp motif, which is characterized by two cysteines and two tryptophans, in the extracellular N-terminal domain of the copper transporter (Ctr) protein of fungi are investigated using the model peptides of Ctr4 and Ctr5 from Schizosaccharomyces pombe. The Cys/Trp motif of Ctr5 can reduce Cu(II) and ligate Cu(I), which is the same as that of Ctr4 previously reported. Titration of Cu(II) and Cu(I) ions indicates that both the Cys/Trp motifs of Ctr4 and Ctr5 reduce two Cu(II) and bind two Cu(I) per one peptide. However, the coordination structure of the Cu(I)-peptide complex differs between Ctr4 and Ctr5. Cu(I) is bound to the Cys/Trp motif of Ctr5 via cysteine thiolate-Cu(I) bonds and cation-π interaction with tryptophan, as reported for Ctr4, and a histidine residue in the Cys/Trp motif of Ctr5 is suggested to interact with Cu(I) via its Nτ atom. Ctr4 and Ctr5 exhibit a heterotrimeric form within cell membranes and the copper transport mechanism of the Ctr4/Ctr5 heterotrimer is discussed along with quantitative evaluation of the Cu(I)-binding constant of the Cys/Trp motif.
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Affiliation(s)
- Mariko Okada
- Graduate School of Pharmaceutical Sciences, Tohoku University, Aoba-ku, Sendai 980-8578, Japan
| | - Takashi Miura
- Department of Pharmaceutical Sciences, International University of Health and Welfare, 2600-1 Kitakanemaru, Ohtawara, Tochigi 324-8501, Japan
| | - Takakazu Nakabayashi
- Graduate School of Pharmaceutical Sciences, Tohoku University, Aoba-ku, Sendai 980-8578, Japan.
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19
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Kaplan JH, Maryon EB. How Mammalian Cells Acquire Copper: An Essential but Potentially Toxic Metal. Biophys J 2016; 110:7-13. [PMID: 26745404 PMCID: PMC4805867 DOI: 10.1016/j.bpj.2015.11.025] [Citation(s) in RCA: 137] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Revised: 10/28/2015] [Accepted: 11/09/2015] [Indexed: 12/18/2022] Open
Abstract
Cu is an essential micronutrient, and its role in an array of critical physiological processes is receiving increasing attention. Among these are wound healing, angiogenesis, protection against reactive oxygen species, neurotransmitter synthesis, modulation of normal cell and tumor growth, and many others. Free Cu is absent inside cells, and a network of proteins has evolved to deliver this essential, but potentially toxic, metal ion to its intracellular target sites following uptake. Although the total body content is low (∼100 mg), dysfunction of proteins involved in Cu homeostasis results in several well-characterized human disease states. The initial step in cellular Cu handling is its transport across the plasma membrane, a subject of study for only about the last 25 years. This review focuses on the initial step in Cu homeostasis, the properties of the major protein, hCTR1, that mediates Cu uptake, and the status of our understanding of this highly specialized transport system. Although a high-resolution structure of the protein is still lacking, an array of biochemical and biophysical studies have provided a picture of how hCTR1 mediates Cu(I) transport and how Cu is delivered to the proteins in the intracellular milieu. Recent studies provide evidence that the transporter also plays a key protective role in the regulation of cellular Cu via regulatory endocytosis, lowering its surface expression, in response to elevated Cu loads.
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Affiliation(s)
- Jack H Kaplan
- Department of Biochemistry and Molecular Genetics, University of Illinois College of Medicine, Chicago, Illinois.
| | - Edward B Maryon
- Department of Biochemistry and Molecular Genetics, University of Illinois College of Medicine, Chicago, Illinois
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20
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Kahra D, Kovermann M, Wittung-Stafshede P. The C-Terminus of Human Copper Importer Ctr1 Acts as a Binding Site and Transfers Copper to Atox1. Biophys J 2016; 110:95-102. [PMID: 26745413 PMCID: PMC4805863 DOI: 10.1016/j.bpj.2015.11.016] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Revised: 11/10/2015] [Accepted: 11/10/2015] [Indexed: 11/19/2022] Open
Abstract
Uptake of copper (Cu) ions into human cells is mediated by the plasma membrane protein Ctr1 and is followed by Cu transfer to cytoplasmic Cu chaperones for delivery to Cu-dependent enzymes. The C-terminal cytoplasmic tail of Ctr1 is a 13-residue peptide harboring an HCH motif that is thought to interact with Cu. We here employ biophysical experiments under anaerobic conditions in peptide models of the Ctr1 C-terminus to deduce Cu-binding residues, Cu affinity, and the ability to release Cu to the cytoplasmic Cu chaperone Atox1. Based on NMR assignments and bicinchoninic acid competition experiments, we demonstrate that Cu interacts in a 1:1 stoichiometry with the HCH motif with an affinity, KD, of ∼10(-14) M. Removing either the Cys residue or the two His residues lowers the Cu-peptide affinity, but site specificity is retained. The C-terminal peptide and Atox1 do not interact in solution in the absence of Cu. However, as directly demonstrated at the residue level via NMR spectroscopy, Atox1 readily acquires Cu from the Cu-loaded peptide. We propose that Cu binding to the Ctr1 C-terminal tail regulates Cu transport into the cytoplasm such that the metal ion is only released to high-affinity Cu chaperones.
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Affiliation(s)
- Dana Kahra
- Chemistry Department, Umeå University, Umeå, Sweden
| | - Michael Kovermann
- Chemistry Department, Umeå University, Umeå, Sweden; Chemistry Department, University of Konstanz, Konstanz, Germany.
| | - Pernilla Wittung-Stafshede
- Chemistry Department, Umeå University, Umeå, Sweden; Department of Biology and Biological Engineering, Chalmers University of Technology, Gothenburg, Sweden.
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21
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Abstract
Copper (Cu) is indispensible for growth and development of human organisms. It is required for such fundamental and ubiquitous processes as respiration and protection against reactive oxygen species. Cu also enables catalytic activity of enzymes that critically contribute to the functional identity of many cells and tissues. Pigmentation, production of norepinephrine by the adrenal gland, the key steps in the formation of connective tissue, neuroendocrine signaling, wound healing - all these processes require Cu and depend on Cu entering the secretory pathway. To reach the Cu-dependent enzymes in a lumen of the trans-Golgi network and various vesicular compartments, Cu undertakes a complex journey crossing the extracellular and intracellular membranes and staying firmly on course while traveling in a cytosol. The proteins that assist Cu in this journey by mediating its entry, distribution, and export, have been identified. The accumulating data also indicate that the current model of cellular Cu homeostasis is still a "skeleton" that has to be fleshed out with many new details. This review summarizes recent data on the mechanisms responsible for Cu transfer to the secretory pathway. The emerging new concepts and gaps in our knowledge are discussed.
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Affiliation(s)
- Svetlana Lutsenko
- Department of Physiology, Johns Hopkins University School of Medicine, 725 N. Wolfe street, Baltimore, MD 21205, USA.
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22
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Bompiani KM, Tsai CY, Achatz FP, Liebig JK, Howell SB. Copper transporters and chaperones CTR1, CTR2, ATOX1, and CCS as determinants of cisplatin sensitivity. Metallomics 2016; 8:951-62. [PMID: 27157188 DOI: 10.1039/c6mt00076b] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The development of resistance to cisplatin (cDDP) is commonly accompanied by reduced drug uptake or increased efflux. Previous studies in yeast and murine embryonic fibroblasts have reported that the copper (Cu) transporters and chaperones participate in the uptake, efflux, and intracellular distribution of cDDP. However, there is conflicting data from studies in human cells. We used CRISPR-Cas9 genome editing to individually knock out the human copper transporters CTR1 and CTR2 and the copper chaperones ATOX1 and CCS. Isogenic knockout cell lines were generated in both human HEK-293T and ovarian carcinoma OVCAR8 cells. All knockout cell lines had slowed growth compared to parental cells, small changes in basal Cu levels, and varying sensitivities to Cu depending on the gene targeted. However, all of the knockouts demonstrated only modest 2 to 5-fold changes in cDDP sensitivity that did not differ from the range of sensitivities of 10 wild type clones grown from the same parental cell population. We conclude that, under basal conditions, loss of CTR1, CTR2, ATOX1, or CCS does not produce a change in cisplatin sensitivity that exceeds the variance found within the parental population, suggesting that they are not essential to the mechanism by which cDDP enters these cell lines and is transported to the nucleus.
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Affiliation(s)
- Kristin M Bompiani
- Moores Cancer Center, University of California, San Diego, 3855 Health Sciences Drive, Mail Code 0819, La Jolla, CA 92093, USA.
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23
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Dong Z, Guan L, Wang C, Xu H, Li Z, Li F. Reconstruction of a helical trimer by the second transmembrane domain of human copper transporter 2 in micelles and the binding of the trimer to silver. RSC Adv 2016. [DOI: 10.1039/c5ra24889b] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The second transmembrane domain of human copper transporter 2 (hCtr2-TMD2) forms a trimer with a weaker intermolecular interaction and a lower affinity for Ag(I) than hCtr1-TMD2 trimer.
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Affiliation(s)
- Zhe Dong
- State Key Laboratory of Supramolecular Structure and Materials
- Jilin University
- Changchun 130012
- P. R. China
| | - Liping Guan
- State Key Laboratory of Supramolecular Structure and Materials
- Jilin University
- Changchun 130012
- P. R. China
| | - Chunyu Wang
- State Key Laboratory of Supramolecular Structure and Materials
- Jilin University
- Changchun 130012
- P. R. China
| | - Haoran Xu
- Key Laboratory for Molecular Enzymology & Engineering
- The Ministry of Education
- Jilin University
- Changchun 130012
- P. R. China
| | - Zhengqiang Li
- Key Laboratory for Molecular Enzymology & Engineering
- The Ministry of Education
- Jilin University
- Changchun 130012
- P. R. China
| | - Fei Li
- State Key Laboratory of Supramolecular Structure and Materials
- Jilin University
- Changchun 130012
- P. R. China
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24
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Pushie MJ, Shaw K, Franz KJ, Shearer J, Haas KL. Model Peptide Studies Reveal a Mixed Histidine-Methionine Cu(I) Binding Site at the N-Terminus of Human Copper Transporter 1. Inorg Chem 2015; 54:8544-51. [PMID: 26258435 DOI: 10.1021/acs.inorgchem.5b01162] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Copper is a vital metal cofactor in enzymes that are essential to myriad biological processes. Cellular acquisition of copper is primarily accomplished through the Ctr family of plasma membrane copper transport proteins. Model peptide studies indicate that the human Ctr1 N-terminus binds to Cu(II) with high affinity through an amino terminal Cu(II), Ni(II) (ATCUN) binding site. Unlike typical ATCUN-type peptides, the Ctr1 peptide facilitates the ascorbate-dependent reduction of Cu(II) bound in its ATCUN site by virtue of an adjacent HH (bis-His) sequence in the peptide. It is likely that the Cu(I) coordination environment influences the redox behavior of Cu bound to this peptide; however, the identity and coordination geometry of the Cu(I) site has not been elucidated from previous work. Here, we show data from NMR, XAS, and structural modeling that sheds light on the identity of the Cu(I) binding site of a Ctr1 model peptide. The Cu(I) site includes the same bis-His site identified in previous work to facilitate ascorbate-dependent Cu(II) reduction. The data presented here are consistent with a rational mechanism by which Ctr1 provides coordination environments that facilitate Cu(II) reduction prior to Cu(I) transport.
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Affiliation(s)
- M Jake Pushie
- Department of Anatomy and Cell Biology, University of Saskatchewan , Saskatoon, Saskatchewan, Canada.,Canadian Light Source Incorporated, Saskatoon, Saskatchewan, Canada
| | - Katharine Shaw
- Department of Chemistry and Physics, Saint Mary's College , Notre Dame, Indiana 46556, United States
| | - Katherine J Franz
- Department of Chemistry, Duke University , Durham, North Carolina 27708, United States
| | - Jason Shearer
- Department of Chemistry, University of Nevada , Reno, Nevada 895030, United States
| | - Kathryn L Haas
- Department of Chemistry and Physics, Saint Mary's College , Notre Dame, Indiana 46556, United States
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25
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Tsai CY, Liebig JK, Tsigelny IF, Howell SB. The copper transporter 1 (CTR1) is required to maintain the stability of copper transporter 2 (CTR2). Metallomics 2015. [PMID: 26205368 DOI: 10.1039/c5mt00131e] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Mammalian cells have two influx Cu transporters that form trimers in membranes. CTR1 is the high affinity transporter that resides largely in the plasma membrane, and CTR2 is the low affinity transporter that is primarily associated with vesicular structures inside the cell. The major differences between CTR1 and CTR2 are that CTR1 contains a HIS/MET-rich domain N-terminal of the METS that participate in the first two stacked rings that form the pore, and a longer C-terminal tail that includes a Cu binding HIS-CYS-HIS (HCH) motif right at the end. It has been reported that CTR1 and CTR2 are physically associated with each other in the cell. We used the CRISPR-Cas9 technology to knock out either CTR1 or CTR2 in fully malignant HEK293T and OVCAR8 human ovarian cancer cells to investigate the interaction of CTR1 and CTR2. We report here that the level of CTR2 protein is markedly decreased in CTR1 knockout clones while the CTR2 transcript level remains unchanged. CTR2 was found to be highly ubiquitinated in the CTR1 knock out cells, and inhibition of the proteasome prevented the degradation of CTR2 when CTR1 was not present while inhibition of autophagy had no effect. Re-expression of CTR1 rescued CTR2 from degradation in the CTR1 knockout cells. We conclude that CTR1 is essential to maintain the stability of CTR2 and that in the absence of CTR1 CTR2 is degraded by the proteasome. This reinforces the concept that the functions of CTR1 and CTR2 are inter-dependent within the Cu homeostasis system.
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Affiliation(s)
- Cheng-Yu Tsai
- Moores Cancer Center, University of California, San Diego, 3855 Health Sciences Drive, Mail Code 0819, La Jolla, CA 92093-0819, USA.
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26
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Dong Z, Wang Y, Wang C, Xu H, Guan L, Li Z, Li F. Self-Assembly of the Second Transmembrane Domain of hCtr1 in Micelles and Interaction with Silver Ion. J Phys Chem B 2015; 119:8302-12. [PMID: 26061257 DOI: 10.1021/acs.jpcb.5b03744] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Human copper transporter 1 (hCtr1) transports copper and silver by a homotrimer. The protein contains three transmembrane domains in which the second transmembrane domain (TMD2) is a key component lining the central pore of the trimer. The MXXXM motif in the C-terminal end of TMD2 plays a significant role in the function of hCtr1. In this study, we characterized the structure and assembly of isolated TMD2 of hCtr1 in sodium dodecyl sulfate (SDS) micelles and the interaction of the micelle-bound peptide with silver ion using nuclear magnetic resonance, circular dichroism, isothermal titration calorimetry and electrophoresis techniques. We detected the formation of a trimer of the isolated hCtr1-TMD2 in SDS micelles and the binding of the trimer to Ag(I) by a chemical stoichiometry of 3:2 of peptide:Ag(I). We showed that either an intensive pretreatment of the TMD2 peptide by 1,1,1,3,3,3-hexafluoro-2-propanol solvent or a conversion from methionine to leucine in the MXXXM motif changes the aggregation structure of the peptide and decreases the binding affinity by 1 order of magnitude. Our results suggest that the intrinsic interaction of the second transmembrane domain itself may be closely associated with the formation of hCtr1 pore in cellular membranes, and two methionine residues in the MXXXM motif may be important for TMD2 both in the trimeric assembly and in a higher-affinity binding to Ag(I).
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Affiliation(s)
- Zhe Dong
- †State Key Laboratory of Supramolecular Structure and Materials, Jilin University, 2699 Qianjin Avenue, Changchun 130012, PR China
| | - Yunrui Wang
- †State Key Laboratory of Supramolecular Structure and Materials, Jilin University, 2699 Qianjin Avenue, Changchun 130012, PR China
| | - Chunyu Wang
- †State Key Laboratory of Supramolecular Structure and Materials, Jilin University, 2699 Qianjin Avenue, Changchun 130012, PR China
| | | | - Liping Guan
- †State Key Laboratory of Supramolecular Structure and Materials, Jilin University, 2699 Qianjin Avenue, Changchun 130012, PR China
| | | | - Fei Li
- †State Key Laboratory of Supramolecular Structure and Materials, Jilin University, 2699 Qianjin Avenue, Changchun 130012, PR China
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27
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Wang X, Jiang P, Wang P, Yang CS, Wang X, Feng Q. EGCG Enhances Cisplatin Sensitivity by Regulating Expression of the Copper and Cisplatin Influx Transporter CTR1 in Ovary Cancer. PLoS One 2015; 10:e0125402. [PMID: 25927922 PMCID: PMC4416002 DOI: 10.1371/journal.pone.0125402] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2015] [Accepted: 03/23/2015] [Indexed: 12/13/2022] Open
Abstract
Cisplatin is one of the first-line platinum-based chemotherapeutic agents for treatment of many types of cancer, including ovary cancer. CTR1 (copper transporter 1), a transmembrane solute carrier transporter, has previously been shown to increase the cellular uptake and sensitivity of cisplatin. It is hypothesized that increased CTR1 expression would enhance the sensitivity of cancer cells to cisplatin (cDDP). The present study demonstrates for the first time that (-)-epigallocatechin-3-gallate (EGCG), a major polyphenol from green tea, can enhance CTR1 mRNA and protein expression in ovarian cancer cells and xenograft mice. EGCG inhibits the rapid degradation of CTR1 induced by cDDP. The combination of EGCG and cDDP increases the accumulation of cDDP and DNA-Pt adducts, and subsequently enhances the sensitivity of ovarian cancer SKOV3 and OVCAR3 cells to the chemotherapeutic agent. In the OVCAR3 ovarian cancer xenograft nude mice model, the combination of the lower concentration of cDDP and EGCG strongly repressed the tumor growth and exhibited protective effect on the nephrotoxicity induced by cisplatin. Overall, these findings uncover a novel chemotherapy mechanism of EGCG as an adjuvant for the treatment of ovarian cancer.
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Affiliation(s)
- Xuemin Wang
- Department of Nutrition and Food Hygiene, Key Laboratory of Toxicology, School of Public Health, Nanjing Medical University, Nanjing, Jiangsu, China
- Beijing Research Institute for Nutritional Resources, Beijing, China
| | - Pan Jiang
- Department of Nutrition and Food Hygiene, Key Laboratory of Toxicology, School of Public Health, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Pengqi Wang
- Department of Nutrition and Food Hygiene, Key Laboratory of Toxicology, School of Public Health, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Chung S. Yang
- Department of Chemical Biology, Center for Cancer Prevention Research, Ernest Mario School of Pharmacy, Rutgers, the State University of New Jersey, Piscataway, New Jersey, United States of America
| | - Xuerong Wang
- Department of Pharmacology, School of Basic Medical Science, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Qing Feng
- Department of Nutrition and Food Hygiene, Key Laboratory of Toxicology, School of Public Health, Nanjing Medical University, Nanjing, Jiangsu, China
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Abstract
Metal ion assimilation is essential for all forms of life. However, organisms must properly control the availability of these nutrients within the cell to avoid inactivating proteins by mismetallation. To safeguard against an imbalance between supply and demand in eukaryotes, intracellular compartments contain metal transporters that load and unload metals. Although the vacuoles of Saccharomyces cerevisiae and Arabidopsis thaliana are well established locales for the storage of copper, zinc, iron, and manganese, related compartments are emerging as important mediators of metal homeostasis. Here we describe these compartments and review their metal transporter complement.
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Affiliation(s)
| | - Sabeeha S Merchant
- From the Department of Chemistry and Biochemistry and the Institute for Genomics and Proteomics, UCLA, Los Angeles, California 90095
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29
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Blackburn NJ, Yan N, Lutsenko S. Copper in Eukaryotes. BINDING, TRANSPORT AND STORAGE OF METAL IONS IN BIOLOGICAL CELLS 2014. [DOI: 10.1039/9781849739979-00524] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Copper is essential for normal growth and development of eukaryotic organisms. Numerous physiological processes rely on sufficient availability of copper: from indispensable reactions such as mitochondrial respiration to more highly specialized processes such as pigment development in a skin. Copper misbalance has been linked to a variety of metabolic and neurodegenerative disorders in humans. Complex cellular machinery has evolved to mediate copper uptake, compartmentalization and incorporation into target proteins. Extensive studies revealed a predominant utilization of methionines and histidines by copper handling molecules for copper capture at the extracellular surface and delivery to cuproenzymes in the lumen of cellular compartments, respectively. Cu(I) is a predominant form within the cell, and copper binding and distribution inside the cell at the cytosolic sites relies heavily on cysteines. The selectivity and directionality of copper transfer reactions is determined by thermodynamic and kinetic factors as well as spatial distribution of copper donors and acceptors. In this chapter, we review current structural and mechanistic data on copper transport and distribution in yeast and mammalian cells and highlight important issues and questions for future studies.
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Affiliation(s)
- Ninian J. Blackburn
- Institute of Environmental Health, Oregon Health and Sciences University Portland, OR 97239 USA
| | - Nan Yan
- Department of Physiology, The Johns Hopkins University School of Medicine Baltimore, MD 21205 USA
| | - Svetlana Lutsenko
- Department of Physiology, The Johns Hopkins University School of Medicine Baltimore, MD 21205 USA
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30
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Tsai CY, Larson CA, Safaei R, Howell SB. Molecular modulation of the copper and cisplatin transport function of CTR1 and its interaction with IRS-4. Biochem Pharmacol 2014; 90:379-87. [PMID: 24967972 DOI: 10.1016/j.bcp.2014.06.019] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Revised: 06/16/2014] [Accepted: 06/17/2014] [Indexed: 01/29/2023]
Abstract
The copper influx transporter CTR1 is also a major influx transporter for cisplatin (cDDP) in tumor cells. It influences the cytotoxicity of cDDP both in vivo and in vitro. Whereas Cu triggers internalization of CTR1 from the plasma membrane, cDDP does not. To investigate the mechanisms of these effects, myc-tagged forms of wild type hCTR1 and variants in which Y103 was converted to alanine, C189 was converted to serine, or the K178/K179 dilysine motif was converted to alanines were re-expressed in mouse embryo cells in which both alleles of CTR1 had been knocked out and also in HEK293T cells. The Y103A mutation and to a lesser extent the C189S mutation reduced internalization of CTR1 induced by Cu while the K178A/K179A had little effect. Both Y103 and C189 were required for Cu and cDDP transport whereas the K178/K179 motif was not. While Y103 lies in an YXXM motif that, when phosphorylated, is a potential docking site for phosphatidylinositol 3-kinase and other proteins involved in endocytosis, Western blot analysis of immunoprecipitated myc-CTR1, and proteomic analysis of peptides derived from CTR1, failed to identify any basal or Cu-induced phosphorylation. However, proteomic analysis did identify an interaction of CTR1 with IRS-4 and this was confirmed by co-immunoprecipitation from HEK cells expressing either FLAG-CTR1 or myc-CTR1. The interaction was greater in the Y103A-expressing cells. We conclude that Y103 is required for the internalization of hCTR1 in response to Cu, that this occurs by a mechanism other than phosphorylation and that mutation of Y103 modulates the interaction with IRS-4.
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Affiliation(s)
- Cheng-Yu Tsai
- Moores Cancer Center, University of California, San Diego, 3855 Health Sciences Drive, Mail Code 0819, La Jolla, CA 92093-0819, USA.
| | - Christopher A Larson
- Moores Cancer Center, University of California, San Diego, 3855 Health Sciences Drive, Mail Code 0819, La Jolla, CA 92093-0819, USA.
| | - Roohangiz Safaei
- Moores Cancer Center, University of California, San Diego, 3855 Health Sciences Drive, Mail Code 0819, La Jolla, CA 92093-0819, USA
| | - Stephen B Howell
- Moores Cancer Center, University of California, San Diego, 3855 Health Sciences Drive, Mail Code 0819, La Jolla, CA 92093-0819, USA; Department of Medicine, University of California, San Diego, 3855 Health Sciences Drive, Mail Code 0819, La Jolla, CA 92093-0819, USA.
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31
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Öhrvik H, Thiele DJ. How copper traverses cellular membranes through the mammalian copper transporter 1, Ctr1. Ann N Y Acad Sci 2014; 1314:32-41. [PMID: 24697869 PMCID: PMC4158275 DOI: 10.1111/nyas.12371] [Citation(s) in RCA: 93] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The copper transporter 1, Ctr1, is part of a major pathway for cellular copper (Cu) uptake in the intestinal epithelium, in hepatic and cardiac tissue, and likely in many other mammalian cells and tissues. Here, we summarize what is currently known about how extracellular Cu travels across the plasma membrane to enter the cytoplasm for intracellular distribution and for use by proteins and enzymes, the physiological roles of Ctr1, and its regulation. As a critical Cu importer, Ctr1 occupies a strategic position to exert a strong modifying influence on diseases and pathophysiological states caused by imbalances in Cu homeostasis. A more thorough understanding of the mechanisms that regulate Ctr1 abundance, trafficking, and function will provide new insights and opportunities for disease therapies.
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Affiliation(s)
- Helena Öhrvik
- Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, North Carolina 27708, USA
| | - Dennis J. Thiele
- Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, North Carolina 27708, USA
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32
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Liang ZD, Long Y, Chen HHW, Savaraj N, Kuo MT. Regulation of the high-affinity copper transporter (hCtr1) expression by cisplatin and heavy metals. J Biol Inorg Chem 2013; 19:17-27. [PMID: 24132751 PMCID: PMC3889686 DOI: 10.1007/s00775-013-1051-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2013] [Accepted: 10/03/2013] [Indexed: 01/11/2023]
Abstract
Platinum-based antitumor agents have been the mainstay in cancer chemotherapy for many human malignancies. Drug resistance is an important obstacle to achieving the maximal therapeutic efficacy of these drugs. Understanding how platinum drugs enter cells is of great importance in improving therapeutic efficacy. It has been demonstrated that human high-affinity copper transporter 1 (hCtr1) is involved in transporting cisplatin into cells to elicit cytotoxic effects, although other mechanisms may exist. In this communication, we demonstrate that cisplatin transcriptionally induces the expression of hCtr1 in time- and concentration-dependent manners. Cisplatin functions as a competitor for hCtr1-mediated copper transport, resulting in reduced cellular copper levels and leading to upregulated expression of Sp1, which is a positive regulator for hCtr1 expression. Thus, regulation of hCtr1 expression by cisplatin is an integral part of the copper homeostasis regulation system. We also demonstrate that Ag(I) and Zn(II), which are known to suppress hCtr1-mediated copper transport, can also induce hCtr1/Sp1 expression. In contrast, Cd(II), another inhibitor of copper transport, downregulates hCtr1 expression by suppressing Sp1 expression. Collectively, our results demonstrate diverse mechanisms of regulating copper metabolism by these heavy metals.
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Affiliation(s)
- Zheng Dong Liang
- Department of Translational Molecular Pathology (Route 2951), The University of Texas MD Anderson Cancer Center, 2130 W. Holcombe Blvd., Houston, TX 77030 USA
| | - Yan Long
- Department of Translational Molecular Pathology (Route 2951), The University of Texas MD Anderson Cancer Center, 2130 W. Holcombe Blvd., Houston, TX 77030 USA
| | - Helen H. W. Chen
- Department of Radiation Oncology, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Niramol Savaraj
- Hematology-Oncology Section, VA Medical Center, Miami, FL 33125 USA
| | - Macus Tien Kuo
- Department of Translational Molecular Pathology (Route 2951), The University of Texas MD Anderson Cancer Center, 2130 W. Holcombe Blvd., Houston, TX 77030 USA
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33
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Du X, Li H, Wang X, Liu Q, Ni J, Sun H. Kinetics and thermodynamics of metal binding to the N-terminus of a human copper transporter, hCTR1. Chem Commun (Camb) 2013; 49:9134-6. [PMID: 23962988 DOI: 10.1039/c3cc45360j] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The N-terminus of hCTR1 was demonstrated to bind three Cu(+) ions tightly (log K = 14.92) and reversibly via its Met-rich motifs. Ag(+) binds to the protein with the same stoichiometry but much lower affinities than Cu(+). The protein also coordinates two Cu(2+) ions through its ATCUN motif and His-rich motif with lower affinity. This study provides an insight into the selectivity of the transporter.
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Affiliation(s)
- Xiubo Du
- Department of Chemistry, The University of Hong Kong, Hong Kong, China.
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34
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Francis BR. Evolution of the genetic code by incorporation of amino acids that improved or changed protein function. J Mol Evol 2013; 77:134-58. [PMID: 23743924 DOI: 10.1007/s00239-013-9567-y] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Accepted: 05/25/2013] [Indexed: 12/31/2022]
Abstract
Fifty years have passed since the genetic code was deciphered, but how the genetic code came into being has not been satisfactorily addressed. It is now widely accepted that the earliest genetic code did not encode all 20 amino acids found in the universal genetic code as some amino acids have complex biosynthetic pathways and likely were not available from the environment. Therefore, the genetic code evolved as pathways for synthesis of new amino acids became available. One hypothesis proposes that early in the evolution of the genetic code four amino acids-valine, alanine, aspartic acid, and glycine-were coded by GNC codons (N = any base) with the remaining codons being nonsense codons. The other sixteen amino acids were subsequently added to the genetic code by changing nonsense codons into sense codons for these amino acids. Improvement in protein function is presumed to be the driving force behind the evolution of the code, but how improved function was achieved by adding amino acids has not been examined. Based on an analysis of amino acid function in proteins, an evolutionary mechanism for expansion of the genetic code is described in which individual coded amino acids were replaced by new amino acids that used nonsense codons differing by one base change from the sense codons previously used. The improved or altered protein function afforded by the changes in amino acid function provided the selective advantage underlying the expansion of the genetic code. Analysis of amino acid properties and functions explains why amino acids are found in their respective positions in the genetic code.
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Affiliation(s)
- Brian R Francis
- Department of Molecular Biology, University of Wyoming, Laramie, WY, 82071-3944, USA,
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35
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Maryon EB, Molloy SA, Ivy K, Yu H, Kaplan JH. Rate and regulation of copper transport by human copper transporter 1 (hCTR1). J Biol Chem 2013; 288:18035-46. [PMID: 23658018 DOI: 10.1074/jbc.m112.442426] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Human copper transporter 1 (hCTR1) is a homotrimer of a 190-amino acid monomer having three transmembrane domains believed to form a pore for copper permeation through the plasma membrane. The hCTR1-mediated copper transport mechanism is not well understood, nor has any measurement been made of the rate at which copper ions are transported by hCTR1. In this study, we estimated the rate of copper transport by the hCTR1 trimer in cultured cells using (64)Cu uptake assays and quantification of plasma membrane hCTR1. For endogenous hCTR1, we estimated a turnover number of about 10 ions/trimer/s. When overexpressed in HEK293 cells, a second transmembrane domain mutant of hCTR1 (H139R) had a 3-fold higher Km value and a 4-fold higher turnover number than WT. Truncations of the intracellular C-terminal tail and an AAA substitution of the putative metal-binding HCH C-terminal tripeptide (thought to be required for transport) also exhibited elevated transport rates and Km values when compared with WT hCTR1. Unlike WT hCTR1, H139R and the C-terminal mutants did not undergo regulatory endocytosis in elevated copper. hCTR1 mutants combining methionine substitutions that block transport (M150L,M154L) on the extracellular side of the pore and the high transport H139R or AAA intracellular side mutations exhibited the blocked transport of M150L,M154L, confirming that Cu(+) first interacts with the methionines during permeation. Our results show that hCTR1 elements on the intracellular side of the hCTR1 pore, including the carboxyl tail, are not essential for permeation, but serve to regulate the rate of copper entry.
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Affiliation(s)
- Edward B Maryon
- Department of Biochemistry and Molecular Genetics, University of Illinois College of Medicine, Chicago, IL 60607, USA
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36
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37
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Tsai CY, Finley JC, Ali SS, Patel HH, Howell SB. Copper influx transporter 1 is required for FGF, PDGF and EGF-induced MAPK signaling. Biochem Pharmacol 2012; 84:1007-13. [PMID: 22842628 DOI: 10.1016/j.bcp.2012.07.014] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2012] [Revised: 07/16/2012] [Accepted: 07/17/2012] [Indexed: 12/20/2022]
Abstract
Copper transporter 1 (CTR1) is the major copper (Cu) influx transporter in mammalian cells. We report here that CTR1 is required for the activation of signaling to the MAPK pathway by the ligands of three major receptor tyrosine kinases (RTK) including FGF, PDGF and EGF. Induction of Erk1/2 phosphorylation was compared in isogenic wild type CTR1(+/+) and CTR1(-/-) cells. Whereas all three ligands increased pErk1/2 in the CTR1(+/+) cells, they failed to do this in CTR1(-/-) cells. While FGF did not enhance the phosphorylation of AKT in the CTR1(+/+) cells, both PDGF and EGF increased pAKT in the CTR1(+/+) but not CTR1(-/-) cells. The deficit in Erk1/2 phosphorylation in the CTR1(-/-) cells was rescued by adding Cu to the medium, and it was induced in CTR1(+/+) cells by treatment with a Cu chelator. Intracellular Cu availability was reduced in the CTR1(-/-) cells as reflected by increased expression of the Cu chaperone CCS. The failure of RTK-induced signaling to both Erk1/2 and AKT suggested the presence of a Cu-dependent step upstream of Ras. The Cu-dependent enzyme SOD1 is responsible for generating the hydrogen peroxide in response to RTK activation that serves to inhibit phosphatases that normally limit RTK signaling. SOD1 activity was reduced by a factor of 17-fold in the CTR1(-/-) cells, and addition of hydrogen peroxide restored signaling. We conclude that Cu acquired from CTR1 is required for signaling in pathways regulated by RTKs that play major roles in development and cancer.
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Affiliation(s)
- Cheng-Yu Tsai
- The Moores Cancer Center, University of California, San Diego, La Jolla, CA 92093, USA
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38
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Hasan NM, Lutsenko S. Regulation of copper transporters in human cells. CURRENT TOPICS IN MEMBRANES 2012; 69:137-61. [PMID: 23046650 DOI: 10.1016/b978-0-12-394390-3.00006-9] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Copper is essential for normal growth and development of human organisms. The role of copper as a cofactor of important metabolic enzymes, such as cytochrome c oxidase, superoxide dismutase, lysyl oxidase, dopamine-β-hydroxylase, and many others, has been well established. In recent years, new regulatory roles of copper have emerged. Accumulating evidence points to the involvement of copper in lipid metabolism, antimicrobial defense, neuronal activity, resistance of tumor cells to platinum-based chemotherapeutic drugs, kinase-mediated signal transduction, and other essential cellular processes. For many of these processes, the precise mechanism of copper action remains to be established. Nevertheless, it is increasingly clear that many regulatory and signaling events are associated with changes in the intracellular localization and abundance of copper transporters, as well as distinct compartmentalization of copper itself. In this review, we discuss current data on regulation of the localization and abundance of copper transporters in response to metabolic and signaling events in human cells. Regulation by kinase-mediated phosphorylation will be addressed along with the emerging area of the redox-driven control of copper transport. We highlight mechanistic questions that await further testing.
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Affiliation(s)
- Nesrin M Hasan
- Department of Physiology, Johns Hopkins University, Baltimore, MD, USA
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