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Long Y, Zhu Z, Zhou Z, Yang C, Chao Y, Wang Y, Zhou Q, Wang MW, Qu Q. Structural insights into human zinc transporter ZnT1 mediated Zn 2+ efflux. EMBO Rep 2024:10.1038/s44319-024-00287-3. [PMID: 39390258 DOI: 10.1038/s44319-024-00287-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2024] [Revised: 09/06/2024] [Accepted: 09/18/2024] [Indexed: 10/12/2024] Open
Abstract
Zinc transporter 1 (ZnT1), the principal carrier of cytosolic zinc to the extracellular milieu, is important for cellular zinc homeostasis and resistance to zinc toxicity. Despite recent advancements in the structural characterization of various zinc transporters, the mechanism by which ZnTs-mediated Zn2+ translocation is coupled with H+ or Ca2+ remains unclear. To visualize the transport dynamics, we determined the cryo-electron microscopy (cryo-EM) structures of human ZnT1 at different functional states. ZnT1 dimerizes via extensive interactions between the cytosolic (CTD), the transmembrane (TMD), and the unique cysteine-rich extracellular (ECD) domains. At pH 7.5, both protomers adopt an outward-facing (OF) conformation, with Zn2+ ions coordinated at the TMD binding site by distinct compositions. At pH 6.0, ZnT1 complexed with Zn2+ exhibits various conformations [OF/OF, OF/IF (inward-facing), and IF/IF]. These conformational snapshots, together with biochemical investigation and molecular dynamic simulations, shed light on the mechanism underlying the proton-dependence of ZnT1 transport.
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Affiliation(s)
- Yonghui Long
- Shanghai Stomatological Hospital, School of Stomatology, Institutes of Biomedical Sciences, Fudan University, 200032, Shanghai, China
- Shanghai Key Laboratory of Medical Epigenetics, International Co-laboratory of Medical Epigenetics and Metabolism (Ministry of Science and Technology), Department of Systems Biology for Medicine, Fudan University, 200032, Shanghai, China
| | - Zhini Zhu
- Shanghai Stomatological Hospital, School of Stomatology, Institutes of Biomedical Sciences, Fudan University, 200032, Shanghai, China
- Shanghai Key Laboratory of Medical Epigenetics, International Co-laboratory of Medical Epigenetics and Metabolism (Ministry of Science and Technology), Department of Systems Biology for Medicine, Fudan University, 200032, Shanghai, China
| | - Zixuan Zhou
- Shanghai Stomatological Hospital, School of Stomatology, Institutes of Biomedical Sciences, Fudan University, 200032, Shanghai, China
- Shanghai Key Laboratory of Medical Epigenetics, International Co-laboratory of Medical Epigenetics and Metabolism (Ministry of Science and Technology), Department of Systems Biology for Medicine, Fudan University, 200032, Shanghai, China
| | - Chuanhui Yang
- Shanghai Stomatological Hospital, School of Stomatology, Institutes of Biomedical Sciences, Fudan University, 200032, Shanghai, China
- Shanghai Key Laboratory of Medical Epigenetics, International Co-laboratory of Medical Epigenetics and Metabolism (Ministry of Science and Technology), Department of Systems Biology for Medicine, Fudan University, 200032, Shanghai, China
| | - Yulin Chao
- Shanghai Stomatological Hospital, School of Stomatology, Institutes of Biomedical Sciences, Fudan University, 200032, Shanghai, China
- Shanghai Key Laboratory of Medical Epigenetics, International Co-laboratory of Medical Epigenetics and Metabolism (Ministry of Science and Technology), Department of Systems Biology for Medicine, Fudan University, 200032, Shanghai, China
| | - Yuwei Wang
- Shanghai Stomatological Hospital, School of Stomatology, Institutes of Biomedical Sciences, Fudan University, 200032, Shanghai, China
- Shanghai Key Laboratory of Medical Epigenetics, International Co-laboratory of Medical Epigenetics and Metabolism (Ministry of Science and Technology), Department of Systems Biology for Medicine, Fudan University, 200032, Shanghai, China
| | - Qingtong Zhou
- Department of Pharmacology, School of Basic Medical Sciences, Fudan University, 200032, Shanghai, China
| | - Ming-Wei Wang
- Research Center for Deepsea Bioresources, 572025, Sanya, Hainan, China
- School of Pharmacy, Hainan Medical University, 570228, Haikou, China
| | - Qianhui Qu
- Shanghai Stomatological Hospital, School of Stomatology, Institutes of Biomedical Sciences, Fudan University, 200032, Shanghai, China.
- Shanghai Key Laboratory of Medical Epigenetics, International Co-laboratory of Medical Epigenetics and Metabolism (Ministry of Science and Technology), Department of Systems Biology for Medicine, Fudan University, 200032, Shanghai, China.
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Mori H, Goji A, Hara M. Upregulation of Intracellular Zinc Ion Level after Differentiation of the Neural Stem/Progenitor Cells In Vitro with the Changes in Gene Expression of Zinc Transporters. Biol Trace Elem Res 2024; 202:4699-4714. [PMID: 38180597 DOI: 10.1007/s12011-023-04033-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Accepted: 12/18/2023] [Indexed: 01/06/2024]
Abstract
We measured the intracellular zinc ion concentration of murine fetal neural stem/progenitor cells (NSPCs) and that in the differentiated cells. The NSPCs cultured with 1.5 μM Zn2+ proliferated slightly faster than that in the zinc-deficient medium and the intracellular zinc concentration of the NSPCs and that of their differentiated cells (DCs) cultured with 1.5 μM Zn2+ was 1.34-fold and 2.00-fold higher than those in the zinc-deficient medium, respectively. The zinc transporter genes upregulated over the 3.5-fold change were Zip1, Zip4, Zip12, Zip13, ZnT1, ZnT8, and ZnT10 whereas the only downregulated one was Zip8 during the differentiation of NSPCs to DCs. The cell morphologies of both NSPCs and DCs in the low oxygen culture condition consisting of 2%O2 and 5%CO2, the high carbon dioxide condition consisting of 21%O2 and 10%CO2, and the normal condition consisting of 21%O2 and 5%CO2 were essentially the same each other. The expression of Zip4, Zip8, Zip12, and Zip14 was not drastically changed depending on the O2 and CO2 concentrations.
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Affiliation(s)
- Hideki Mori
- Department of Biological Chemistry, Graduate School of Science, Osaka Metropolitan University, 1-1 Gakuencho, Nakaku, Sakai, Osaka, 599-8531, Japan
| | - Akari Goji
- Department of Biological Chemistry, Graduate School of Science, Osaka Metropolitan University, 1-1 Gakuencho, Nakaku, Sakai, Osaka, 599-8531, Japan
| | - Masayuki Hara
- Department of Biological Chemistry, Graduate School of Science, Osaka Metropolitan University, 1-1 Gakuencho, Nakaku, Sakai, Osaka, 599-8531, Japan.
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3
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Li Y, Ma J, Wang R, Luo Y, Zheng S, Wang X. Zinc transporter 1 functions in copper uptake and cuproptosis. Cell Metab 2024; 36:2118-2129.e6. [PMID: 39111308 DOI: 10.1016/j.cmet.2024.07.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Revised: 05/05/2024] [Accepted: 07/09/2024] [Indexed: 09/06/2024]
Abstract
Copper (Cu) is a co-factor for several essential metabolic enzymes. Disruption of Cu homeostasis results in genetic diseases such as Wilson's disease. Here, we show that the zinc transporter 1 (ZnT1), known to export zinc (Zn) out of the cell, also mediates Cu2+ entry into cells and is required for Cu2+-induced cell death, cuproptosis. Structural analysis and functional characterization indicate that Cu2+ and Zn2+ share the same primary binding site, allowing Zn2+ to compete for Cu2+ uptake. Among ZnT members, ZnT1 harbors a unique inter-subunit disulfide bond that stabilizes the outward-open conformations of both protomers to facilitate efficient Cu2+ transport. Specific knockout of the ZnT1 gene in the intestinal epithelium caused the loss of Lgr5+ stem cells due to Cu deficiency. ZnT1, therefore, functions as a dual Zn2+ and Cu2+ transporter and potentially serves as a target for using Zn2+ in the treatment of Wilson's disease caused by Cu overload.
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Affiliation(s)
- Yehua Li
- National Institute of Biological Sciences, Beijing 102206, China
| | - Jiahao Ma
- Tsinghua Institute of Multidisciplinary Biomedical Research, Tsinghua University, Beijing 100084, China; National Institute of Biological Sciences, Beijing 102206, China
| | - Rui Wang
- Tsinghua Institute of Multidisciplinary Biomedical Research, Tsinghua University, Beijing 100084, China; National Institute of Biological Sciences, Beijing 102206, China
| | - Yuanhanyu Luo
- National Institute of Biological Sciences, Beijing 102206, China
| | - Sanduo Zheng
- Tsinghua Institute of Multidisciplinary Biomedical Research, Tsinghua University, Beijing 100084, China; National Institute of Biological Sciences, Beijing 102206, China.
| | - Xiaodong Wang
- Tsinghua Institute of Multidisciplinary Biomedical Research, Tsinghua University, Beijing 100084, China; National Institute of Biological Sciences, Beijing 102206, China.
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Swapna GVT, Dube N, Roth MJ, Montelione GT. Modeling Alternative Conformational States of Pseudo-Symmetric Solute Carrier Transporters using Methods from Machine Learning. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.07.15.603529. [PMID: 39071413 PMCID: PMC11275918 DOI: 10.1101/2024.07.15.603529] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/30/2024]
Abstract
The Solute Carrier (SLC) superfamily of integral membrane proteins function to transport a wide array of solutes across the plasma and organelle membranes. SLC proteins also function as important drug transporters and as viral receptors. Despite being classified as a single superfamily, SLC proteins do not share a single common fold classification; however, most belong to multi-pass transmembrane helical protein fold families. SLC proteins populate different conformational states during the solute transport process, including outward open, intermediate (occluded), and inward open conformational states. For some SLC fold families this structural "flipping" corresponds to swapping between conformations of their N-terminal and C-terminal symmetry-related sub-structures. Conventional AlphaFold2 or Evolutionary Scale Modeling methods typically generate models for only one of these multiple conformational states of SLC proteins. Here we describe a fast and simple approach for modeling multiple conformational states of SLC proteins using a combined ESM - AF2 process. The resulting multi-state models are validated by comparison with sequence-based evolutionary co-variance data (ECs) that encode information about contacts present in the various conformational states adopted by the protein. We also explored the impact of mutations on conformational distributions of SLC proteins modeled by AlphaFold2 using both conventional and enhanced sampling methods. This approach for modeling conformational landscapes of pseudo-symmetric SLC proteins is demonstrated for several integral membrane protein transporters, including SLC35F2 the receptor of a feline leukemia virus envelope protein required for viral entry into eukaryotic cells.
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Affiliation(s)
- G V T Swapna
- Dept. of Chemistry and Chemical Biology, Center for Biotechnology and Interdisciplinary Sciences, Rensselaer Polytechnic Institute, Troy, New York, 12180 USA
- Department of Pharmacology, Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, Piscataway NJ 08854 USA
| | - Namita Dube
- Dept. of Chemistry and Chemical Biology, Center for Biotechnology and Interdisciplinary Sciences, Rensselaer Polytechnic Institute, Troy, New York, 12180 USA
| | - Monica J Roth
- Department of Pharmacology, Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, Piscataway NJ 08854 USA
| | - Gaetano T Montelione
- Dept. of Chemistry and Chemical Biology, Center for Biotechnology and Interdisciplinary Sciences, Rensselaer Polytechnic Institute, Troy, New York, 12180 USA
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5
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Azzollini L, Prete DD, Wolf G, Klimek C, Saggioro M, Ricci F, Christodoulaki E, Wiedmer T, Ingles-Prieto A, Superti-Furga G, Scarabottolo L. Development of a live cell assay for the zinc transporter ZnT8. SLAS DISCOVERY : ADVANCING LIFE SCIENCES R & D 2024; 29:100166. [PMID: 38848895 DOI: 10.1016/j.slasd.2024.100166] [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: 01/30/2024] [Revised: 05/27/2024] [Accepted: 06/04/2024] [Indexed: 06/09/2024]
Abstract
Zinc is an essential trace element that is involved in many biological processes and in cellular homeostasis. In pancreatic β-cells, zinc is crucial for the synthesis, processing, and secretion of insulin, which plays a key role in glucose homeostasis and which deficiency is the cause of diabetes. The accumulation of zinc in pancreatic cells is regulated by the solute carrier transporter SLC30A8 (or Zinc Transporter 8, ZnT8), which transports zinc from cytoplasm in intracellular vesicles. Allelic variants of SLC30A8 gene have been linked to diabetes. Given the physiological intracellular localization of SLC30A8 in pancreatic β-cells and the ubiquitous endogenous expression of other Zinc transporters in different cell lines that could be used as cellular model for SLC30A8 recombinant over-expression, it is challenging to develop a functional assay to measure SLC30A8 activity. To achieve this goal, we have firstly generated a HEK293 cell line stably overexpressing SLC30A8, where the over-expression favors the partial localization of SLC30A8 on the plasma membrane. Then, we used the combination of this cell model, commercial FluoZin-3 cell permeant zinc dye and live cell imaging approach to follow zinc flux across SLC30A8 over-expressed on plasma membrane, thus developing a novel functional imaging- based assay specific for SLC30A8. Our novel approach can be further explored and optimized, paving the way for future small molecule medium-throughput screening.
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Affiliation(s)
- Lucia Azzollini
- Axxam SpA, Openzone, Via Meucci 3 20091 Bresso, Milan, Italy.
| | | | - Gernot Wolf
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria
| | - Christoph Klimek
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria
| | - Mattia Saggioro
- Axxam SpA, Openzone, Via Meucci 3 20091 Bresso, Milan, Italy
| | - Fernanda Ricci
- Axxam SpA, Openzone, Via Meucci 3 20091 Bresso, Milan, Italy
| | - Eirini Christodoulaki
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria
| | - Tabea Wiedmer
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria
| | - Alvaro Ingles-Prieto
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria
| | - Giulio Superti-Furga
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria; Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
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6
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Acevedo S, Segovia MF, de la Fuente-Ortega E. Emerging Perspectives in Zinc Transporter Research in Prostate Cancer: An Updated Review. Nutrients 2024; 16:2026. [PMID: 38999774 PMCID: PMC11243615 DOI: 10.3390/nu16132026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2024] [Revised: 06/18/2024] [Accepted: 06/19/2024] [Indexed: 07/14/2024] Open
Abstract
Dysregulation of zinc and zinc transporters families has been associated with the genesis and progression of prostate cancer. The prostate epithelium utilizes two types of zinc transporters, the ZIP (Zrt-, Irt-related Protein) and the ZnTs (Zinc Transporter), to transport zinc from the blood plasma to the gland lumen. ZIP transporters uptake zinc from extracellular space and organelle lumen, while ZnT transporters release zinc outside the cells or to organelle lumen. In prostate cancer, a commonly observed low zinc concentration in prostate tissue has been correlated with downregulations of certain ZIPs (e.g., ZIP1, ZIP2, ZIP3, ZIP14) and upregulations of specific ZnTs (e.g., ZnT1, ZnT9, ZnT10). These alterations may enable cancer cells to adapt to toxic high zinc levels. While zinc supplementation has been suggested as a potential therapy for this type of cancer, studies have yielded inconsistent results because some trials have indicated that zinc supplementation could exacerbate cancer risk. The reason for this discrepancy remains unclear, but given the high molecular and genetic variability present in prostate tumors, it is plausible that some zinc transporters-comprising 14 ZIP and 10 ZnT members-could be dysregulated in others patterns that promote cancer. From this perspective, this review highlights novel dysregulation, such as ZIP-Up/ZnT-Down, observed in prostate cancer cell lines for ZIP4, ZIP8, ZnT2, ZnT4, ZnT5, etc. Additionally, an in silico analysis of an available microarray from mouse models of prostate cancer (Nkx3.1;Pten) predicts similar dysregulation pattern for ZIP4, ZIP8, and ZnT2, which appear in early stages of prostate cancer progression. Furthermore, similar dysregulation patterns are supported by an in silico analysis of RNA-seq data from human cancer tumors available in cBioPortal. We discuss how these dysregulations of zinc transporters could impact zinc supplementation trials, particularly focusing on how the ZIP-Up/ZnT-Down dysregulation through various mechanisms might promote prostate cancer progression.
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Affiliation(s)
- Samantha Acevedo
- Laboratorio Estrés Celular y Enfermedades Crónicas No Transmisibles, Departamento de Ciencias Biomédicas, Facultad de Medicina, Universidad Católica del Norte, Larrondo 1281, Coquimbo 1781421, Chile
| | - María Fernanda Segovia
- Laboratorio Estrés Celular y Enfermedades Crónicas No Transmisibles, Departamento de Ciencias Biomédicas, Facultad de Medicina, Universidad Católica del Norte, Larrondo 1281, Coquimbo 1781421, Chile
| | - Erwin de la Fuente-Ortega
- Laboratorio Estrés Celular y Enfermedades Crónicas No Transmisibles, Departamento de Ciencias Biomédicas, Facultad de Medicina, Universidad Católica del Norte, Larrondo 1281, Coquimbo 1781421, Chile
- Centro de Investigación y Desarrollo Tecnológico en Algas y Otros Recursos Biológicos (CIDTA), Facultad de Ciencias del Mar, Universidad Católica del Norte, Coquimbo 1781421, Chile
- Núcleo de Investigación en Prevención y Tratamiento de Enfermedades Crónicas no Transmisibles (NiPTEC), Universidad Católica del Norte, Coquimbo 1781421, Chile
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7
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Sun C, He B, Gao Y, Wang X, Liu X, Sun L. Structural insights into the calcium-coupled zinc export of human ZnT1. SCIENCE ADVANCES 2024; 10:eadk5128. [PMID: 38669333 PMCID: PMC11051671 DOI: 10.1126/sciadv.adk5128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Accepted: 03/27/2024] [Indexed: 04/28/2024]
Abstract
Cellular zinc (Zn2+) homeostasis is essential to human health and is under tight regulations. Human zinc transporter 1 (hZnT1) is a plasma membrane-localized Zn2+ exporter belonging to the ZnT family, and its functional aberration is associated with multiple diseases. Here, we show that hZnT1 works as a Zn2+/Ca2+ exchanger. We determine the structure of hZnT1 using cryo-electron microscopy (cryo-EM) single particle analysis. hZnT1 adopts a homodimeric structure, and each subunit contains a transmembrane domain consisting of six transmembrane segments, a cytosolic domain, and an extracellular domain. The transmembrane region displays an outward-facing conformation. On the basis of structural and functional analysis, we propose a model for the hZnT1-mediated Zn2+/Ca2+ exchange. Together, these results facilitate our understanding of the biological functions of hZnT1 and provide a basis for further investigations of the ZnT family transporters.
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Affiliation(s)
- Chunqiao Sun
- Department of Neurology, The First Affiliated Hospital of USTC, MOE Key Laboratory for Membraneless Organelles and Cellular Dynamics, Hefei National Research Center for Physical Sciences at the Microscale, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230027, China
| | - Bangguo He
- Department of Neurology, The First Affiliated Hospital of USTC, MOE Key Laboratory for Membraneless Organelles and Cellular Dynamics, Hefei National Research Center for Physical Sciences at the Microscale, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230027, China
- Department of Hematology, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230001, China
| | - Yongxiang Gao
- Department of Neurology, The First Affiliated Hospital of USTC, MOE Key Laboratory for Membraneless Organelles and Cellular Dynamics, Hefei National Research Center for Physical Sciences at the Microscale, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230027, China
- Cryo-EM Center, Core Facility Center for Life Sciences, University of Science and Technology of China, Hefei 230027, China
| | - Xingbing Wang
- Department of Hematology, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230001, China
| | - Xin Liu
- Department of Neurology, The First Affiliated Hospital of USTC, MOE Key Laboratory for Membraneless Organelles and Cellular Dynamics, Hefei National Research Center for Physical Sciences at the Microscale, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230027, China
| | - Linfeng Sun
- Department of Neurology, The First Affiliated Hospital of USTC, MOE Key Laboratory for Membraneless Organelles and Cellular Dynamics, Hefei National Research Center for Physical Sciences at the Microscale, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230027, China
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8
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Bui HB, Inaba K. Structures, Mechanisms, and Physiological Functions of Zinc Transporters in Different Biological Kingdoms. Int J Mol Sci 2024; 25:3045. [PMID: 38474291 DOI: 10.3390/ijms25053045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2024] [Revised: 02/29/2024] [Accepted: 03/03/2024] [Indexed: 03/14/2024] Open
Abstract
Zinc transporters take up/release zinc ions (Zn2+) across biological membranes and maintain intracellular and intra-organellar Zn2+ homeostasis. Since this process requires a series of conformational changes in the transporters, detailed information about the structures of different reaction intermediates is required for a comprehensive understanding of their Zn2+ transport mechanisms. Recently, various Zn2+ transport systems have been identified in bacteria, yeasts, plants, and humans. Based on structural analyses of human ZnT7, human ZnT8, and bacterial YiiP, we propose updated models explaining their mechanisms of action to ensure efficient Zn2+ transport. We place particular focus on the mechanistic roles of the histidine-rich loop shared by several zinc transporters, which facilitates Zn2+ recruitment to the transmembrane Zn2+-binding site. This review provides an extensive overview of the structures, mechanisms, and physiological functions of zinc transporters in different biological kingdoms.
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Affiliation(s)
- Han Ba Bui
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan
- Department of Molecular and Chemical Life Sciences, Graduate School of Life Sciences, Tohoku University, Sendai 980-8577, Japan
- Medical Institute of Bioregulation, Kyushu University, Fukuoka 812-8582, Japan
| | - Kenji Inaba
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan
- Department of Molecular and Chemical Life Sciences, Graduate School of Life Sciences, Tohoku University, Sendai 980-8577, Japan
- Medical Institute of Bioregulation, Kyushu University, Fukuoka 812-8582, Japan
- Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan
- Core Research for Evolutional Science and Technology (CREST), Japan Agency for Medical Research and Development (AMED), Chiyoda-ku, Tokyo 100-0004, Japan
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9
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Maret W. Chemistry meets biology in the coordination dynamics of metalloproteins. J Inorg Biochem 2024; 251:112431. [PMID: 38016325 DOI: 10.1016/j.jinorgbio.2023.112431] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Revised: 11/10/2023] [Accepted: 11/14/2023] [Indexed: 11/30/2023]
Abstract
Metal sites in proteins are often presented in an idealized way that does not capture the intrinsic dynamic behavior of the protein or the extrinsic factors that affect changes in the coordination of the metal ion in biological space and time. The bioinorganic chemistry possible in healthy and diseased living organisms is limited by prevailing pH values, redox potentials, and availability and concentrations of metal ions and ligands. Changes in any of these parameters and protein-protein or protein-ligand interactions can result in differences in the type of metal ion bound, metal occupancy, and coordination number or geometry. This article addresses the plasticity and complexity of metal coordination in proteins when these parameters are considered. It uses three examples of zinc sites with sulfur donor atoms from cysteines in mammalian proteins: alcohol dehydrogenases, metallothioneins, and zinc transporters of the ZnT (SLC30A) family. Coordination dynamics of the metal sites in these proteins has different purposes; in alcohol dehydrogenases for the metal ion to perform its different roles in the catalytic cycle, in metallothioneins for serving as a metal buffer, and in ZnT zinc transporters for sensing metal ions and moving them through the protein and thus biological membranes. Defining the biological and chemical parameters that determine and affect coordination dynamics of metal ions in proteins will inform future investigations of metalloproteins.
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Affiliation(s)
- Wolfgang Maret
- Departments of Biochemistry and Nutritional Sciences, School of Life Course and Population Sciences, Faculty of Life Sciences and Medicine, King's College London, London SE1 9NH, UK.
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10
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Fan YG, Wu TY, Zhao LX, Jia RJ, Ren H, Hou WJ, Wang ZY. From zinc homeostasis to disease progression: Unveiling the neurodegenerative puzzle. Pharmacol Res 2024; 199:107039. [PMID: 38123108 DOI: 10.1016/j.phrs.2023.107039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/07/2023] [Revised: 11/16/2023] [Accepted: 12/10/2023] [Indexed: 12/23/2023]
Abstract
Zinc is a crucial trace element in the human body, playing a role in various physiological processes such as oxidative stress, neurotransmission, protein synthesis, and DNA repair. The zinc transporters (ZnTs) family members are responsible for exporting intracellular zinc, while Zrt- and Irt-like proteins (ZIPs) are involved in importing extracellular zinc. These processes are essential for maintaining cellular zinc homeostasis. Imbalances in zinc metabolism have been linked to the development of neurodegenerative diseases. Disruptions in zinc levels can impact the survival and activity of neurons, thereby contributing to the progression of neurodegenerative diseases through mechanisms like cell apoptosis regulation, protein phase separation, ferroptosis, oxidative stress, and neuroinflammation. Therefore, conducting a systematic review of the regulatory network of zinc and investigating the relationship between zinc dysmetabolism and neurodegenerative diseases can enhance our understanding of the pathogenesis of these diseases. Additionally, it may offer new insights and approaches for the treatment of neurodegenerative diseases.
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Affiliation(s)
- Yong-Gang Fan
- Key Laboratory of Medical Cell Biology of Ministry of Education, Key Laboratory of Major Chronic Diseases of Nervous System of Liaoning Province, Health Sciences Institute of China Medical University, Shenyang 110122, China.
| | - Ting-Yao Wu
- First Affiliated Hospital of Jinzhou Medical University, Jinzhou 121000, China
| | - Ling-Xiao Zhao
- Key Laboratory of Medical Cell Biology of Ministry of Education, Key Laboratory of Major Chronic Diseases of Nervous System of Liaoning Province, Health Sciences Institute of China Medical University, Shenyang 110122, China
| | - Rong-Jun Jia
- Key Laboratory of Medical Cell Biology of Ministry of Education, Key Laboratory of Major Chronic Diseases of Nervous System of Liaoning Province, Health Sciences Institute of China Medical University, Shenyang 110122, China
| | - Hang Ren
- Key Laboratory of Medical Cell Biology of Ministry of Education, Key Laboratory of Major Chronic Diseases of Nervous System of Liaoning Province, Health Sciences Institute of China Medical University, Shenyang 110122, China
| | - Wen-Jia Hou
- Key Laboratory of Medical Cell Biology of Ministry of Education, Key Laboratory of Major Chronic Diseases of Nervous System of Liaoning Province, Health Sciences Institute of China Medical University, Shenyang 110122, China
| | - Zhan-You Wang
- Key Laboratory of Medical Cell Biology of Ministry of Education, Key Laboratory of Major Chronic Diseases of Nervous System of Liaoning Province, Health Sciences Institute of China Medical University, Shenyang 110122, China.
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11
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Kambe T, Wagatsuma T. Metalation and activation of Zn 2+ enzymes via early secretory pathway-resident ZNT proteins. BIOPHYSICS REVIEWS 2023; 4:041302. [PMID: 38510844 PMCID: PMC10903440 DOI: 10.1063/5.0176048] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Accepted: 11/21/2023] [Indexed: 03/22/2024]
Abstract
Zinc (Zn2+), an essential trace element, binds to various proteins, including enzymes, transcription factors, channels, and signaling molecules and their receptors, to regulate their activities in a wide range of physiological functions. Zn2+ proteome analyses have indicated that approximately 10% of the proteins encoded by the human genome have potential Zn2+ binding sites. Zn2+ binding to the functional site of a protein (for enzymes, the active site) is termed Zn2+ metalation. In eukaryotic cells, approximately one-third of proteins are targeted to the endoplasmic reticulum; therefore, a considerable number of proteins mature by Zn2+ metalation in the early secretory pathway compartments. Failure to capture Zn2+ in these compartments results in not only the inactivation of enzymes (apo-Zn2+ enzymes), but also their elimination via degradation. This process deserves attention because many Zn2+ enzymes that mature during the secretory process are associated with disease pathogenesis. However, how Zn2+ is mobilized via Zn2+ transporters, particularly ZNTs, and incorporated in enzymes has not been fully elucidated from the cellular perspective and much less from the biophysical perspective. This review focuses on Zn2+ enzymes that are activated by Zn2+ metalation via Zn2+ transporters during the secretory process. Further, we describe the importance of Zn2+ metalation from the physiopathological perspective, helping to reveal the importance of understanding Zn2+ enzymes from a biophysical perspective.
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Affiliation(s)
- Taiho Kambe
- Division of Integrated Life Science, Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan
| | - Takumi Wagatsuma
- Division of Integrated Life Science, Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan
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12
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Yang L, Zhang X, Liu Q, Wen Y, Wang Q. Update on the ZNT8 epitope and its role in the pathogenesis of type 1 diabetes. Minerva Endocrinol (Torino) 2023; 48:447-458. [PMID: 38099391 DOI: 10.23736/s2724-6507.22.03723-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2023]
Abstract
Type 1 diabetes (T1D) is an organ-specific chronic autoimmune disease mediated by autoreactive T cells. ZnT8 is a pancreatic islet-specific zinc transporter that is mainly located in β cells. It not only participates in the synthesis, storage and secretion of insulin but also maintains the structural integrity of insulin. ZnT8 is the main autoantigen recognized by autoreactive CD8+ T cells in children and adults with T1D. This article summarizes the latest research results on the T lymphocyte epitope and B lymphocyte epitope of ZnT8 in the current literature. The structure and expression of ZnT8, the role of ZnT8 in insulin synthesis and its role in autoimmunity are reviewed. ZnT8 is the primary autoantigen of T1D and is specifically expressed in pancreatic islets. Thus, it is one of biomarkers for the diagnosis of T1D. It has broad prospects for further research on immunomodulators for the treatment of T1D.
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Affiliation(s)
- Liu Yang
- Department of Endocrinology, China-Japan Union Hospital of Jilin University, Changchun, China
| | - Xuejiao Zhang
- Department of Endocrinology, China-Japan Union Hospital of Jilin University, Changchun, China
| | - Qing Liu
- Department of Endocrinology, China-Japan Union Hospital of Jilin University, Changchun, China
| | - Yan Wen
- Department of Endocrinology, China-Japan Union Hospital of Jilin University, Changchun, China
| | - Qing Wang
- Department of Endocrinology, China-Japan Union Hospital of Jilin University, Changchun, China -
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13
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Hussein A, Fan S, Lopez-Redondo M, Kenney I, Zhang X, Beckstein O, Stokes DL. Energy coupling and stoichiometry of Zn 2+/H + antiport by the prokaryotic cation diffusion facilitator YiiP. eLife 2023; 12:RP87167. [PMID: 37906094 PMCID: PMC10617992 DOI: 10.7554/elife.87167] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2023] Open
Abstract
YiiP from Shewanella oneidensis is a prokaryotic Zn2+/H+ antiporter that serves as a model for the Cation Diffusion Facilitator (CDF) superfamily, members of which are generally responsible for homeostasis of transition metal ions. Previous studies of YiiP as well as related CDF transporters have established a homodimeric architecture and the presence of three distinct Zn2+ binding sites named A, B, and C. In this study, we use cryo-EM, microscale thermophoresis and molecular dynamics simulations to address the structural and functional roles of individual sites as well as the interplay between Zn2+ binding and protonation. Structural studies indicate that site C in the cytoplasmic domain is primarily responsible for stabilizing the dimer and that site B at the cytoplasmic membrane surface controls the structural transition from an inward facing conformation to an occluded conformation. Binding data show that intramembrane site A, which is directly responsible for transport, has a dramatic pH dependence consistent with coupling to the proton motive force. A comprehensive thermodynamic model encompassing Zn2+ binding and protonation states of individual residues indicates a transport stoichiometry of 1 Zn2+ to 2-3 H+ depending on the external pH. This stoichiometry would be favorable in a physiological context, allowing the cell to use the proton gradient as well as the membrane potential to drive the export of Zn2+.
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Affiliation(s)
- Adel Hussein
- Department of Biochemistry and Molecular Pharmacology, NYU School of MedicineNew YorkUnited States
| | - Shujie Fan
- Department of Physics, Arizona State UniversityTempeUnited States
| | - Maria Lopez-Redondo
- Department of Biochemistry and Molecular Pharmacology, NYU School of MedicineNew YorkUnited States
| | - Ian Kenney
- Department of Physics, Arizona State UniversityTempeUnited States
| | - Xihui Zhang
- Department of Biochemistry and Molecular Pharmacology, NYU School of MedicineNew YorkUnited States
| | - Oliver Beckstein
- Department of Physics, Arizona State UniversityTempeUnited States
| | - David L Stokes
- Department of Biochemistry and Molecular Pharmacology, NYU School of MedicineNew YorkUnited States
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14
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Bui HB, Watanabe S, Nomura N, Liu K, Uemura T, Inoue M, Tsutsumi A, Fujita H, Kinoshita K, Kato Y, Iwata S, Kikkawa M, Inaba K. Cryo-EM structures of human zinc transporter ZnT7 reveal the mechanism of Zn 2+ uptake into the Golgi apparatus. Nat Commun 2023; 14:4770. [PMID: 37553324 PMCID: PMC10409766 DOI: 10.1038/s41467-023-40521-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Accepted: 07/27/2023] [Indexed: 08/10/2023] Open
Abstract
Zinc ions (Zn2+) are vital to most cells, with the intracellular concentrations of Zn2+ being tightly regulated by multiple zinc transporters located at the plasma and organelle membranes. We herein present the 2.2-3.1 Å-resolution cryo-EM structures of a Golgi-localized human Zn2+/H+ antiporter ZnT7 (hZnT7) in Zn2+-bound and unbound forms. Cryo-EM analyses show that hZnT7 exists as a dimer via tight interactions in both the cytosolic and transmembrane (TM) domains of two protomers, each of which contains a single Zn2+-binding site in its TM domain. hZnT7 undergoes a TM-helix rearrangement to create a negatively charged cytosolic cavity for Zn2+ entry in the inward-facing conformation and widens the luminal cavity for Zn2+ release in the outward-facing conformation. An exceptionally long cytosolic histidine-rich loop characteristic of hZnT7 binds two Zn2+ ions, seemingly facilitating Zn2+ recruitment to the TM metal transport pathway. These structures permit mechanisms of hZnT7-mediated Zn2+ uptake into the Golgi to be proposed.
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Affiliation(s)
- Han Ba Bui
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Miyagi, 980-8577, Japan
- Department of Molecular and Chemical Life Sciences, Graduate School of Life Sciences, Tohoku University, Sendai, Miyagi, 980-8577, Japan
| | - Satoshi Watanabe
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Miyagi, 980-8577, Japan
- Department of Molecular and Chemical Life Sciences, Graduate School of Life Sciences, Tohoku University, Sendai, Miyagi, 980-8577, Japan
- Department of Chemistry, Graduate School of Science, Tohoku University, Sendai, Miyagi, 980-8578, Japan
| | - Norimichi Nomura
- Department of Cell Biology, Graduate School of Medicine, Kyoto University, Kyoto, 606-8501, Japan
| | - Kehong Liu
- Department of Cell Biology, Graduate School of Medicine, Kyoto University, Kyoto, 606-8501, Japan
| | - Tomoko Uemura
- Department of Cell Biology, Graduate School of Medicine, Kyoto University, Kyoto, 606-8501, Japan
| | - Michio Inoue
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Miyagi, 980-8577, Japan
| | - Akihisa Tsutsumi
- Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Hiroyuki Fujita
- Advanced Research Laboratory, Canon Medical Systems Corporation, Otawara, 324-8550, Japan
| | - Kengo Kinoshita
- Department of System Bioinformatics, Graduate School of Information Sciences, Tohoku University, Sendai, Miyagi, 980-8579, Japan
- Department of Integrative Genomics, Tohoku Medical Megabank Organization, Tohoku University, Sendai, Miyagi, 980-8573, Japan
| | - Yukinari Kato
- Graduate School of Medicine, Tohoku University, Sendai, 980-8575, Japan
| | - So Iwata
- Department of Cell Biology, Graduate School of Medicine, Kyoto University, Kyoto, 606-8501, Japan
| | - Masahide Kikkawa
- Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Kenji Inaba
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Miyagi, 980-8577, Japan.
- Department of Molecular and Chemical Life Sciences, Graduate School of Life Sciences, Tohoku University, Sendai, Miyagi, 980-8577, Japan.
- Department of Chemistry, Graduate School of Science, Tohoku University, Sendai, Miyagi, 980-8578, Japan.
- Medical Institute of Bioregulation, Kyushu University, Fukuoka, 812-8582, Japan.
- Core Research for Evolutional Science and Technology (CREST), Japan Agency for Medical Research and Development (AMED), Chiyoda-ku, Tokyo, Japan.
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15
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Hussein A, Fan S, Lopez-Redondo M, Kenney I, Zhang X, Beckstein O, Stokes DL. Energy Coupling and Stoichiometry of Zn 2+/H + Antiport by the Cation Diffusion Facilitator YiiP. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.23.529644. [PMID: 36865113 PMCID: PMC9980050 DOI: 10.1101/2023.02.23.529644] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/25/2023]
Abstract
YiiP is a prokaryotic Zn2+/H+ antiporter that serves as a model for the Cation Diffusion Facilitator (CDF) superfamily, members of which are generally responsible for homeostasis of transition metal ions. Previous studies of YiiP as well as related CDF transporters have established a homodimeric architecture and the presence of three distinct Zn2+ binding sites named A, B, and C. In this study, we use cryo-EM, microscale thermophoresis and molecular dynamics simulations to address the structural and functional roles of individual sites as well as the interplay between Zn2+ binding and protonation. Structural studies indicate that site C in the cytoplasmic domain is primarily responsible for stabilizing the dimer and that site B at the cytoplasmic membrane surface controls the structural transition from an inward facing conformation to an occluded conformation. Binding data show that intramembrane site A, which is directly responsible for transport, has a dramatic pH dependence consistent with coupling to the proton motive force. A comprehensive thermodynamic model encompassing Zn2+ binding and protonation states of individual residues indicates a transport stoichiometry of 1 Zn2+ to 2-3 H+ depending on the external pH. This stoichiometry would be favorable in a physiological context, allowing the cell to use the proton gradient as well as the membrane potential to drive the export of Zn2+.
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Affiliation(s)
- Adel Hussein
- Dept. of Cell Biology, NYU School of Medicine, New York, NY 10016 USA
| | - Shujie Fan
- Dept. of Physics, Arizona State University, Tempe AZ
| | | | - Ian Kenney
- Dept. of Physics, Arizona State University, Tempe AZ
| | - Xihui Zhang
- Dept. of Cell Biology, NYU School of Medicine, New York, NY 10016 USA
| | | | - David L Stokes
- Dept. of Cell Biology, NYU School of Medicine, New York, NY 10016 USA
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16
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Ray S, Gaudet R. Structures and coordination chemistry of transporters involved in manganese and iron homeostasis. Biochem Soc Trans 2023; 51:897-923. [PMID: 37283482 PMCID: PMC10330786 DOI: 10.1042/bst20210699] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 05/23/2023] [Accepted: 05/25/2023] [Indexed: 06/08/2023]
Abstract
A repertoire of transporters plays a crucial role in maintaining homeostasis of biologically essential transition metals, manganese, and iron, thus ensuring cell viability. Elucidating the structure and function of many of these transporters has provided substantial understanding into how these proteins help maintain the optimal cellular concentrations of these metals. In particular, recent high-resolution structures of several transporters bound to different metals enable an examination of how the coordination chemistry of metal ion-protein complexes can help us understand metal selectivity and specificity. In this review, we first provide a comprehensive list of both specific and broad-based transporters that contribute to cellular homeostasis of manganese (Mn2+) and iron (Fe2+ and Fe3+) in bacteria, plants, fungi, and animals. Furthermore, we explore the metal-binding sites of the available high-resolution metal-bound transporter structures (Nramps, ABC transporters, P-type ATPase) and provide a detailed analysis of their coordination spheres (ligands, bond lengths, bond angles, and overall geometry and coordination number). Combining this information with the measured binding affinity of the transporters towards different metals sheds light into the molecular basis of substrate selectivity and transport. Moreover, comparison of the transporters with some metal scavenging and storage proteins, which bind metal with high affinity, reveal how the coordination geometry and affinity trends reflect the biological role of individual proteins involved in the homeostasis of these essential transition metals.
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Affiliation(s)
- Shamayeeta Ray
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, U.S.A
| | - Rachelle Gaudet
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, U.S.A
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17
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Yadav GP, Wang H, Ouwendijk J, Cross S, Wang Q, Qin F, Verkade P, Zhu MX, Jiang QX. Chromogranin B (CHGB) is dimorphic and responsible for dominant anion channels delivered to cell surface via regulated secretion. Front Mol Neurosci 2023; 16:1205516. [PMID: 37435575 PMCID: PMC10330821 DOI: 10.3389/fnmol.2023.1205516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Accepted: 05/26/2023] [Indexed: 07/13/2023] Open
Abstract
Regulated secretion is conserved in all eukaryotes. In vertebrates granin family proteins function in all key steps of regulated secretion. Phase separation and amyloid-based storage of proteins and small molecules in secretory granules require ion homeostasis to maintain their steady states, and thus need ion conductances in granule membranes. But granular ion channels are still elusive. Here we show that granule exocytosis in neuroendocrine cells delivers to cell surface dominant anion channels, to which chromogranin B (CHGB) is critical. Biochemical fractionation shows that native CHGB distributes nearly equally in soluble and membrane-bound forms, and both reconstitute highly selective anion channels in membrane. Confocal imaging resolves granular membrane components including proton pumps and CHGB in puncta on the cell surface after stimulated exocytosis. High pressure freezing immuno-EM reveals a major fraction of CHGB at granule membranes in rat pancreatic β-cells. A cryo-EM structure of bCHGB dimer of a nominal 3.5 Å resolution delineates a central pore with end openings, physically sufficient for membrane-spanning and large single channel conductance. Together our data support that CHGB-containing (CHGB+) channels are characteristic of regulated secretion, and function in granule ion homeostasis near the plasma membrane or possibly in other intracellular processes.
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Affiliation(s)
- Gaya P. Yadav
- Departments of Microbiology and Cell Science and of Medicinal Chemistry, University of Florida, Gainesville, FL, United States
- Departments of Physiology and Biophysics, State University of New York at Buffalo, Buffalo, NY, United States
- Laboratory of Molecular Physiology and Biophysics, Hauptman-Woodward Medical Research Institute, Buffalo, NY, United States
| | - Haiyuan Wang
- Department of Integrative Biology and Pharmacology, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX, United States
| | - Joke Ouwendijk
- School of Biochemistry, University of Bristol, Bristol, United Kingdom
| | - Stephen Cross
- Wolfson Bioimaging facility, University of Bristol, Bristol, United Kingdom
| | - Qiaochu Wang
- Department of Integrative Biology and Pharmacology, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX, United States
| | - Feng Qin
- Departments of Physiology and Biophysics, State University of New York at Buffalo, Buffalo, NY, United States
| | - Paul Verkade
- School of Biochemistry, University of Bristol, Bristol, United Kingdom
| | - Michael X. Zhu
- Department of Integrative Biology and Pharmacology, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX, United States
| | - Qiu-Xing Jiang
- Departments of Microbiology and Cell Science and of Medicinal Chemistry, University of Florida, Gainesville, FL, United States
- Departments of Physiology and Biophysics, State University of New York at Buffalo, Buffalo, NY, United States
- Laboratory of Molecular Physiology and Biophysics, Hauptman-Woodward Medical Research Institute, Buffalo, NY, United States
- Cryo-EM Center, Laoshan Laboratory, Qingdao, Shandong, China
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18
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Abeyrathna SS, Abeyrathna NS, Basak P, Irvine GW, Zhang L, Meloni G. Plastic recognition and electrogenic uniport translocation of 1 st-, 2 nd-, and 3 rd-row transition and post-transition metals by primary-active transmembrane P 1B-2-type ATPase pumps. Chem Sci 2023; 14:6059-6078. [PMID: 37293658 PMCID: PMC10246665 DOI: 10.1039/d3sc00347g] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Accepted: 05/10/2023] [Indexed: 06/10/2023] Open
Abstract
Transmembrane P1B-type ATPase pumps catalyze the extrusion of transition metal ions across cellular lipid membranes to maintain essential cellular metal homeostasis and detoxify toxic metals. Zn(ii)-pumps of the P1B-2-type subclass, in addition to Zn2+, select diverse metals (Pb2+, Cd2+ and Hg2+) at their transmembrane binding site and feature promiscuous metal-dependent ATP hydrolysis in the presence of these metals. Yet, a comprehensive understanding of the transport of these metals, their relative translocation rates, and transport mechanism remain elusive. We developed a platform for the characterization of primary-active Zn(ii)-pumps in proteoliposomes to study metal selectivity, translocation events and transport mechanism in real-time, employing a "multi-probe" approach with fluorescent sensors responsive to diverse stimuli (metals, pH and membrane potential). Together with atomic-resolution investigation of cargo selection by X-ray absorption spectroscopy (XAS), we demonstrate that Zn(ii)-pumps are electrogenic uniporters that preserve the transport mechanism with 1st-, 2nd- and 3rd-row transition metal substrates. Promiscuous coordination plasticity, guarantees diverse, yet defined, cargo selectivity coupled to their translocation.
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Affiliation(s)
- Sameera S Abeyrathna
- Department of Chemistry and Biochemistry, The University of Texas at Dallas Richardson TX 75080 USA
| | - Nisansala S Abeyrathna
- Department of Chemistry and Biochemistry, The University of Texas at Dallas Richardson TX 75080 USA
| | - Priyanka Basak
- Department of Chemistry and Biochemistry, The University of Texas at Dallas Richardson TX 75080 USA
| | - Gordon W Irvine
- Department of Chemistry and Biochemistry, The University of Texas at Dallas Richardson TX 75080 USA
| | - Limei Zhang
- Department of Biochemistry and Redox Biology Center and the Nebraska Center for Integrated Biomolecular Communication, University of Nebraska-Lincoln Lincoln NE 68588 USA
| | - Gabriele Meloni
- Department of Chemistry and Biochemistry, The University of Texas at Dallas Richardson TX 75080 USA
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19
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Sharma G, Jafari M, Merz KM. Getting zinc into and out of cells. Methods Enzymol 2023; 687:263-278. [PMID: 37666635 DOI: 10.1016/bs.mie.2023.05.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/06/2023]
Abstract
Ion channels are specialized proteins located on the plasma membrane and control the movement of ions across the membrane. Zn ion plays an indispensable role as a structural constituent of various proteins, moreover, it plays an important dynamic role in cell signaling. In this chapter, we discuss computational insights into zinc efflux and influx mechanism through YiiP (from Escherichia coli and Shewanella oneidensis) and BbZIP (Bordetella bronchiseptica) transporters, respectively. Gaining knowledge about the mechanism of zinc transport at the molecular level can aid in developing treatments for conditions such as diabetes and cancer by manipulating extracellular and intracellular levels of zinc ions.
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Affiliation(s)
- Gaurav Sharma
- Department of Chemistry, Michigan State University, East Lansing, MI, United States
| | - Majid Jafari
- Department of Chemistry, Michigan State University, East Lansing, MI, United States
| | - Kenneth M Merz
- Department of Chemistry, Michigan State University, East Lansing, MI, United States; Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, United States.
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20
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Duan M, Zhang T. Expression, purification, and crystallization of the extracellular domain of a mammalian ZIP4. Methods Enzymol 2023; 687:49-65. [PMID: 37666638 DOI: 10.1016/bs.mie.2023.04.022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/06/2023]
Abstract
Zinc transporters are of vital importance in maintaining zinc homeostasis in all living organisms. In humans, ZIP4 is exclusive for dietary zinc uptake. Obtaining enough purified protein by heterologous expression is necessary for structural characterization to understand working mechanisms at the atomic level. However, due to the major obstacle in membrane protein expression, there is no structural information of the full-length human ZIP4 till now. A "divide and conquer" strategy has been applied to ZIP4 to study the extracellular domain (ECD) and the transmembrane domain separately, which has led to the first ECD structure in the entire ZIP family. In this chapter, we provide detailed protocols for the expression, purification, and crystallization of ZIP4-ECD from a mammalian species.
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Affiliation(s)
- Maoping Duan
- College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, P.R. China
| | - Tuo Zhang
- College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, P.R. China.
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21
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Sousa MS, Alves JL, Freitas JCS, Miraldo JN, Sampaio Dos Aidos FDS, Santos RM, Rosário LM, Quinta-Ferreira RM, Quinta-Ferreira ME, Matias CM. A model of zinc dynamics evoked by intense stimulation at the cleft of hippocampal mossy fiber synapses. Brain Res 2023; 1807:148322. [PMID: 36906226 DOI: 10.1016/j.brainres.2023.148322] [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: 09/16/2022] [Revised: 02/28/2023] [Accepted: 03/06/2023] [Indexed: 03/12/2023]
Abstract
Zinc is a transition metal that is particularly abundant in the mossy fibers of the hippocampal CA3 area. Despite the large number of studies about the zinc role in mossy fibers, the action of zinc in synaptic mechanisms is only partly known. The use of computational models can be a useful tool for this study. In a previous work, a model was developed to evaluate zinc dynamics at the mossy fiber synaptic cleft, following weak stimulation, insufficient to evoke zinc entry into postsynaptic neurons. For intense stimulation, cleft zinc effluxes must be considered. Therefore, the initial model was extended to include postsynaptic zinc effluxes based on the Goldman-Hodgkin-Katz current equation combined with Hodgkin and Huxley conductance changes. These effluxes occur through different postsynaptic escape routes, namely L- and N-types voltage-dependent calcium channels and NMDA receptors. For that purpose, various stimulations were assumed to induce high concentrations of cleft free zinc, named as intense (10 μM), very intense (100 μM) and extreme (500 μM). It was observed that the main postsynaptic escape routes of cleft zinc are the L-type calcium channels, followed by the NMDA receptor channels and by N-type calcium channels. However, their relative contribution for cleft zinc clearance was relatively small and decreased for higher amounts of zinc, most likely due to the blockade action of zinc in postsynaptic receptors and channels. Therefore, it can be concluded that the larger the zinc release, the more predominant the zinc uptake process will be in the cleft zinc clearance.
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Affiliation(s)
- Marta S Sousa
- Department of Physics, University of Coimbra, P-3004-516 Coimbra, Portugal; ESS-IPP - Superior School of Health - Polytechnic Institute of Porto, P-4200-072 Porto, Portugal; CNC- Center for Neuroscience and Cell Biology, University of Coimbra, P-3004-504 Coimbra, Portugal
| | - João L Alves
- CNC- Center for Neuroscience and Cell Biology, University of Coimbra, P-3004-504 Coimbra, Portugal; Department of Life Sciences, University of Coimbra, P-3004-516 Coimbra, Portugal
| | | | - João N Miraldo
- Department of Civil Engineering, University of Coimbra, P-3030-790 Coimbra, Portugal
| | - Fernando D S Sampaio Dos Aidos
- CNC- Center for Neuroscience and Cell Biology, University of Coimbra, P-3004-504 Coimbra, Portugal; CFisUC, Department of Physics, University of Coimbra, P-3004-516 Coimbra, Portugal
| | - Rosa M Santos
- CNC- Center for Neuroscience and Cell Biology, University of Coimbra, P-3004-504 Coimbra, Portugal; Department of Life Sciences, University of Coimbra, P-3004-516 Coimbra, Portugal
| | - Luís M Rosário
- CNC- Center for Neuroscience and Cell Biology, University of Coimbra, P-3004-504 Coimbra, Portugal; Department of Life Sciences, University of Coimbra, P-3004-516 Coimbra, Portugal
| | - Rosa M Quinta-Ferreira
- CIEPQPF - Research Centre of Chemical Process Engineering and Forest Products, Department of Chemical Engineering, University of Coimbra, P-3030-790 Coimbra, Portugal
| | - M Emília Quinta-Ferreira
- Department of Physics, University of Coimbra, P-3004-516 Coimbra, Portugal; CNC- Center for Neuroscience and Cell Biology, University of Coimbra, P-3004-504 Coimbra, Portugal
| | - Carlos M Matias
- CNC- Center for Neuroscience and Cell Biology, University of Coimbra, P-3004-504 Coimbra, Portugal; Dept. of Physics, UTAD- University of Trás-os-montes and Alto Douro, P-5000-801 Vila Real, Portugal.
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22
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Zhang S, Fu C, Luo Y, Xie Q, Xu T, Sun Z, Su Z, Zhou X. Cryo-EM structure of a eukaryotic zinc transporter at a low pH suggests its Zn 2+-releasing mechanism. J Struct Biol 2023; 215:107926. [PMID: 36464198 DOI: 10.1016/j.jsb.2022.107926] [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: 09/24/2022] [Revised: 11/10/2022] [Accepted: 11/28/2022] [Indexed: 12/04/2022]
Abstract
Zinc transporter 8 (ZnT8) is mainly expressed in pancreatic islet β cells and is responsible for H+-coupled uptake (antiport) of Zn2+ into the lumen of insulin secretory granules. Structures of human ZnT8 and its prokaryotic homolog YiiP have provided structural basis for constructing a plausible transport cycle for Zn2+. However, the mechanistic role that protons play in the transport process remains unclear. Here we present a lumen-facing cryo-EM structure of ZnT8 from Xenopus tropicalis (xtZnT8) in the presence of Zn2+ at a luminal pH (5.5). Compared to a Zn2+-bound xtZnT8 structure at a cytosolic pH (7.5), the low-pH structure displays an empty transmembrane Zn2+-binding site with a disrupted coordination geometry. Combined with a Zn2+-binding assay our data suggest that protons may disrupt Zn2+ coordination at the transmembrane Zn2+-binding site in the lumen-facing state, thus facilitating Zn2+ release from ZnT8 into the lumen.
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Affiliation(s)
- Senfeng Zhang
- Department of Integrated Traditional Chinese and Western Medicine, Rare Diseases Center, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China
| | - Chunting Fu
- Department of Integrated Traditional Chinese and Western Medicine, Rare Diseases Center, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China
| | - Yongbo Luo
- The State Key Laboratory of Biotherapy, Department of Geriatrics and National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China
| | - Qingrong Xie
- Department of Integrated Traditional Chinese and Western Medicine, Rare Diseases Center, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China
| | - Tong Xu
- Department of Integrated Traditional Chinese and Western Medicine, Rare Diseases Center, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China
| | - Ziyi Sun
- Department of Integrated Traditional Chinese and Western Medicine, Rare Diseases Center, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China.
| | - Zhaoming Su
- The State Key Laboratory of Biotherapy, Department of Geriatrics and National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China.
| | - Xiaoming Zhou
- Department of Integrated Traditional Chinese and Western Medicine, Rare Diseases Center, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China.
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23
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Guo Z, Kasinathan D, Merriman C, Nakayama M, Li H, Li H, Xu C, Wong GW, Yu L, Golson ML, Fu D. Cell-Surface Autoantibody Targets Zinc Transporter-8 (ZnT8) for In Vivo β-Cell Imaging and Islet-Specific Therapies. Diabetes 2023; 72:184-195. [PMID: 36448936 PMCID: PMC9876881 DOI: 10.2337/db22-0477] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/22/2022] [Accepted: 11/07/2022] [Indexed: 12/02/2022]
Abstract
Type 1 diabetes (T1D) is a disease in which autoimmune attacks are directed at the insulin-producing β-cell in the pancreatic islet. Autoantigens on the β-cell surface membrane are specific markers for molecular recognition and targets for engagement by autoreactive B lymphocytes, which produce islet cell surface autoantibody (ICSA) upon activation. We report the cloning of an ICSA (mAb43) that recognizes a major T1D autoantigen, ZnT8, with a subnanomolar binding affinity and conformation specificity. We demonstrate that cell-surface binding of mAb43 protects the extracellular epitope of ZnT8 against immunolabeling by serum ICSA from a patient with T1D. Furthermore, mAb43 exhibits in vitro and ex vivo specificity for islet cells, mirroring the exquisite specificity of islet autoimmunity in T1D. Systemic administration of mAb43 yields a pancreas-specific biodistribution in mice and islet homing of an mAb43-linked imaging payload through the pancreatic vasculature, thereby validating the in vivo specificity of mAb43. Identifying ZnT8 as a major antigenic target of ICSA allows for research into the molecular recognition and engagement of autoreactive B cells in the chronic phase of T1D progression. The in vivo islet specificity of mAb43 could be further exploited to develop in vivo imaging and islet-specific immunotherapies.
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Affiliation(s)
- Zheng Guo
- Department of Physiology, Johns Hopkins School of Medicine, Baltimore, MD
| | - Devi Kasinathan
- Department of Physiology, Johns Hopkins School of Medicine, Baltimore, MD
| | - Chengfeng Merriman
- Department of Physiology, Johns Hopkins School of Medicine, Baltimore, MD
| | - Maki Nakayama
- Barbara Davis Center for Diabetes, University of Colorado, Aurora, CO
| | - Hua Li
- Department of Structural Biology, Van Andel Institute, Grand Rapids, MI
| | - Huilin Li
- Department of Structural Biology, Van Andel Institute, Grand Rapids, MI
| | - Cheng Xu
- Department of Physiology, Johns Hopkins School of Medicine, Baltimore, MD
| | - G. William Wong
- Department of Physiology, Johns Hopkins School of Medicine, Baltimore, MD
| | - Liping Yu
- Barbara Davis Center for Diabetes, University of Colorado, Aurora, CO
| | - Maria L. Golson
- Division of Endocrinology, Diabetes, and Metabolism, Johns Hopkins School of Medicine, Baltimore, MD
| | - Dax Fu
- Department of Physiology, Johns Hopkins School of Medicine, Baltimore, MD
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24
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Escobar A, Styrpejko DJ, Ali S, Cuajungco MP. Transmembrane 163 (TMEM163) protein interacts with specific mammalian SLC30 zinc efflux transporter family members. Biochem Biophys Rep 2022; 32:101362. [PMID: 36204728 PMCID: PMC9530847 DOI: 10.1016/j.bbrep.2022.101362] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Revised: 09/11/2022] [Accepted: 09/26/2022] [Indexed: 11/06/2022] Open
Abstract
Recently, we reported that TMEM163 is a zinc efflux transporter that likely belongs to the mammalian solute carrier 30 (Slc30/ZnT) subfamily of the cation diffusion facilitator (CDF) protein superfamily. We hypothesized that human TMEM163 forms functional heterodimers with certain ZNT proteins based on their overlapping subcellular localization with TMEM163 and previous reports that some ZNT monomers interact with each other. In this study, we heterologously expressed individual constructs with a unique peptide tag containing TMEM163, ZNT1, ZNT2, ZNT3, and ZNT4 (negative control) or co-expressed TMEM163 with each ZNT in cultured cells for co-immunoprecipitation (co-IP) experiments. We also co-expressed TMEM163 with two different peptide tags as a positive co-IP control. Western blot analyses revealed that TMEM163 dimerizes with itself but that it also heterodimerizes with ZNT1, ZNT2, ZNT3, and ZNT4 proteins. Confocal microscopy revealed that TMEM163 and ZNT proteins partially co-localize in cells, suggesting that they exist as homodimers and heterodimers in their respective subcellular sites. Functional zinc flux assays using Fluozin-3 and Newport Green dyes show that TMEM163/ZNT heterodimers exhibit similar efflux function as TMEM163 homodimers. Cell surface biotinylation revealed that the plasma membrane localization of TMEM163 is not markedly influenced by ZNT co-expression. Overall, our results show that the interaction between TMEM163 and distinct ZNT proteins is physiologically relevant and that their heterodimerization may serve to increase the functional diversity of zinc effluxers within specific tissues or cell types. TMEM163 protein heterodimerizes with ZNT1, ZNT2, ZNT3 and ZNT4 zinc efflux transporters. Partial co-localization of TMEM163 and ZNT proteins in cells suggests distinct roles as homodimers and heterodimers. Zinc efflux activity of TMEM163 or ZNT protein homodimers did not differ from their TMEM163/ZNT heterodimer counterparts. TMEM163/ZNT heterodimerization attests to the role of TMEM163 as a bona fide SLC30 protein family member.
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Affiliation(s)
| | | | - Saima Ali
- Department of Biological Science, USA
| | - Math P. Cuajungco
- Department of Biological Science, USA,Center for Applied Biotechnology Studies, California State University Fullerton, CA, 92831, USA,Corresponding author. Department of Biological Science, California State University Fullerton, 800 North State College Blvd, Fullerton, CA, 92831, USA.
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25
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Willekens J, Runnels LW. Impact of Zinc Transport Mechanisms on Embryonic and Brain Development. Nutrients 2022; 14:2526. [PMID: 35745255 PMCID: PMC9231024 DOI: 10.3390/nu14122526] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Revised: 06/09/2022] [Accepted: 06/09/2022] [Indexed: 12/04/2022] Open
Abstract
The trace element zinc (Zn) binds to over ten percent of proteins in eukaryotic cells. Zn flexible chemistry allows it to regulate the activity of hundreds of enzymes and influence scores of metabolic processes in cells throughout the body. Deficiency of Zn in humans has a profound effect on development and in adults later in life, particularly in the brain, where Zn deficiency is linked to several neurological disorders. In this review, we will summarize the importance of Zn during development through a description of the outcomes of both genetic and early dietary Zn deficiency, focusing on the pathological consequences on the whole body and brain. The epidemiology and the symptomology of Zn deficiency in humans will be described, including the most studied inherited Zn deficiency disease, Acrodermatitis enteropathica. In addition, we will give an overview of the different forms and animal models of Zn deficiency, as well as the 24 Zn transporters, distributed into two families: the ZIPs and the ZnTs, which control the balance of Zn throughout the body. Lastly, we will describe the TRPM7 ion channel, which was recently shown to contribute to intestinal Zn absorption and has its own significant impact on early embryonic development.
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Affiliation(s)
| | - Loren W. Runnels
- Department of Pharmacology, Rutgers-Robert Wood Johnson Medical School, Piscataway, NJ 08854, USA;
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26
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Wang X, Wang C, Zhang Z, Shi G. Genome-wide Identification of Metal Tolerance Protein Genes in Peanut: Differential Expression in the Root of Two Contrasting Cultivars Under Metal Stresses. FRONTIERS IN PLANT SCIENCE 2022; 13:791200. [PMID: 35432419 PMCID: PMC9011049 DOI: 10.3389/fpls.2022.791200] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Accepted: 03/15/2022] [Indexed: 05/23/2023]
Abstract
Metal tolerance proteins (MTP) are Me2+/H+(K+) antiporters that play important roles in the transport of divalent cations in plants. However, their functions in peanut are unknown. In the present study, a total of 24 AhMTP genes were identified in peanut, which were divided into seven groups belonging to three substrate-specific clusters (Zn-CDFs, Zn/Fe-CDFs, and Mn-CDFs). All AhMTP genes underwent whole genome or segmental gene duplication events except AhMTP12. Most AhMTP members within the same subfamily or group generally have similar gene and protein structural characteristics. However, some genes, such as AhMTP1.3, AhMTP2.4, and AhMTP12, showed wide divergences. Most of AhMTP genes preferentially expressed in reproductive tissues, suggesting that these genes might play roles in metal transport during the pod and seed development stages. Excess metal exposure induced expressions for most of AhMTP genes in peanut roots depending on cultivars. By contrast, AhMTP genes in the root of Fenghua 1 were more sensitive to excess Fe, Cd, and Zn exposure than that of Silihong. Stepwise linear regression analysis showed that the percentage of Fe in shoots significantly and positively correlated with the expression of AhMTP4.1, AhMTP9.1, and AhMTPC4.1, but negatively correlated with that of AhMTPC2.1 and AhMTP12. The expression of AhMTP1.1 showed a significant and negative correlation with the percentage of Mn in shoots. The percentage of Zn in shoots was significantly and positively correlated with the expression of AhMTP2.1 but was negatively correlated with that of AhMTPC2.1. The differential responses of AhMTP genes to metal exposure might be, at least partially, responsible for the different metal translocation from roots to shoots between Fenghua 1 and Silihong.
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27
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Yin S, Duan M, Fang B, Zhao G, Leng X, Zhang T. Zinc homeostasis and regulation: Zinc transmembrane transport through transporters. Crit Rev Food Sci Nutr 2022; 63:7627-7637. [PMID: 35258351 DOI: 10.1080/10408398.2022.2048292] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The second abundant micronutrient, zinc, is attracting more and more attention for it performs essential functions in living organisms and bears close relationships with the occurrence of diseases. However, excess zinc is toxic to cells. Ensuring a balanced zinc state for organisms is essential. Zinc transporters, including ZIPs and ZnTs, are pivotal in regulating zinc homeostasis. Benefiting from zinc transporter structures determination and their transporting dynamic revelation, the clarification of detailed mechanisms of zinc trafficking and the maintenance of zinc homeostasis by transporters in the human body are getting more and more evident. The present review gives a detailed description of the structural basis of zinc transport through ZIP and ZnT, through which the molecular mechanism of zinc binding and transport was illustrated. Then the motive force that drives zinc transmembrane transport and finally a generalization for the regulation models of zinc transporters were summarized.
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Affiliation(s)
- Shuhua Yin
- Key Laboratory of Precision Nutrition and Food Quality, Ministry of Education, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, China
| | - Maoping Duan
- Key Laboratory of Precision Nutrition and Food Quality, Ministry of Education, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, China
| | - Bing Fang
- Department of Nutrition and Health, China Agricultural University, Beijing, China
| | - Guanghua Zhao
- Key Laboratory of Precision Nutrition and Food Quality, Ministry of Education, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, China
| | - Xiaojing Leng
- Key Laboratory of Precision Nutrition and Food Quality, Ministry of Education, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, China
| | - Tuo Zhang
- Key Laboratory of Precision Nutrition and Food Quality, Ministry of Education, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, China
- Department of Nutrition and Health, China Agricultural University, Beijing, China
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28
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del Alamo D, Sala D, Mchaourab HS, Meiler J. Sampling alternative conformational states of transporters and receptors with AlphaFold2. eLife 2022; 11:75751. [PMID: 35238773 PMCID: PMC9023059 DOI: 10.7554/elife.75751] [Citation(s) in RCA: 161] [Impact Index Per Article: 80.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Accepted: 03/02/2022] [Indexed: 11/13/2022] Open
Abstract
Equilibrium fluctuations and triggered conformational changes often underlie the functional cycles of membrane proteins. For example, transporters mediate the passage of molecules across cell membranes by alternating between inward- and outward-facing states, while receptors undergo intracellular structural rearrangements that initiate signaling cascades. Although the conformational plasticity of these proteins has historically posed a challenge for traditional de novo protein structure prediction pipelines, the recent success of AlphaFold2 (AF2) in CASP14 culminated in the modeling of a transporter in multiple conformations to high accuracy. Given that AF2 was designed to predict static structures of proteins, it remains unclear if this result represents an underexplored capability to accurately predict multiple conformations and/or structural heterogeneity. Here, we present an approach to drive AF2 to sample alternative conformations of topologically diverse transporters and G-protein-coupled receptors that are absent from the AF2 training set. Whereas models of most proteins generated using the default AF2 pipeline are conformationally homogeneous and nearly identical to one another, reducing the depth of the input multiple sequence alignments by stochastic subsampling led to the generation of accurate models in multiple conformations. In our benchmark, these conformations spanned the range between two experimental structures of interest, with models at the extremes of these conformational distributions observed to be among the most accurate (average template modeling score of 0.94). These results suggest a straightforward approach to identifying native-like alternative states, while also highlighting the need for the next generation of deep learning algorithms to be designed to predict ensembles of biophysically relevant states.
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Affiliation(s)
- Diego del Alamo
- Department of Molecular Physiology and Biophysics, Vanderbilt UniversityNashvilleUnited States
- Department of Chemistry, Vanderbilt UniversityNashvilleUnited States
| | - Davide Sala
- Institute for Drug Discovery, Leipzig UniversityLeipzigGermany
| | - Hassane S Mchaourab
- Department of Molecular Physiology and Biophysics, Vanderbilt UniversityNashvilleUnited States
| | - Jens Meiler
- Department of Chemistry, Vanderbilt UniversityNashvilleUnited States
- Institute for Drug Discovery, Leipzig UniversityLeipzigGermany
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29
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Sharma G, Merz KM. Mechanism of Zinc Transport through the Zinc Transporter YiiP. J Chem Theory Comput 2022; 18:2556-2568. [PMID: 35226479 DOI: 10.1021/acs.jctc.1c00927] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Zinc is an essential transition metal ion that plays as a structural, functional (catalytic), and a signaling molecule regulating cellular function. Unbalanced levels of zinc in cells can result in various pathological conditions. In the current work, all-atom molecular dynamics simulations were used to study the structure-function correlation between different YiiP states embedded in a lipid bilayer. This study enabled us to develop a hypothesis on the zinc efflux mechanism of YiiP. We have created six different models of YiiP representing the stages of the ion-transport process. We found that zinc ion plays a crucial role in restraining the transmembrane domains (TMDs) of the protein. In addition, H153, located in the TMD, has been proposed to guide the zinc ion toward the ZnA site of the YiiP transporter. Understanding the molecular-level Zn2+-transport process sheds light on the strategies affecting intracellular transition-metal ion concentrations in order to treat diseases like diabetes and cancer.
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Affiliation(s)
- Gaurav Sharma
- Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, United States
| | - Kenneth M Merz
- Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, United States.,Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824, United States
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30
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Kelleher SL, Alam S, Rivera OC, Barber-Zucker S, Zarivach R, Wagatsuma T, Kambe T, Soybel DI, Wright J, Lamendella R. Loss-of-function SLC30A2 mutants are associated with gut dysbiosis and alterations in intestinal gene expression in preterm infants. Gut Microbes 2022; 14:2014739. [PMID: 34965180 PMCID: PMC8726655 DOI: 10.1080/19490976.2021.2014739] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Accepted: 11/17/2021] [Indexed: 02/04/2023] Open
Abstract
Loss of Paneth cell (PC) function is implicated in intestinal dysbiosis, mucosal inflammation, and numerous intestinal disorders, including necrotizing enterocolitis (NEC). Studies in mouse models show that zinc transporter ZnT2 (SLC30A2) is critical for PC function, playing a role in granule formation, secretion, and antimicrobial activity; however, no studies have investigated whether loss of ZnT2 function is associated with dysbiosis, mucosal inflammation, or intestinal dysfunction in humans. SLC30A2 was sequenced in healthy preterm infants (26-37 wks; n = 75), and structural analysis and functional assays determined the impact of mutations. In human stool samples, 16S rRNA sequencing and RNAseq of bacterial and human transcripts were performed. Three ZnT2 variants were common (>5%) in this population: H346Q, f = 19%; L293R, f = 7%; and a previously identified compound substitution in Exon7, f = 16%). H346Q had no effect on ZnT2 function or beta-diversity. Exon7 impaired zinc transport and was associated with a fractured gut microbiome. Analysis of microbial pathways suggested diverse effects on nutrient metabolism, glycan biosynthesis and metabolism, and drug resistance, which were associated with increased expression of host genes involved in tissue remodeling. L293R caused profound ZnT2 dysfunction and was associated with overt gut dysbiosis. Microbial pathway analysis suggested effects on nucleotide, amino acid and vitamin metabolism, which were associated with the increased expression of host genes involved in inflammation and immune response. In addition, L293R was associated with reduced weight gain in the early postnatal period. This implicates ZnT2 as a novel modulator of mucosal homeostasis in humans and suggests that genetic variants in ZnT2 may affect the risk of mucosal inflammation and intestinal disease.
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MESH Headings
- Animals
- Bacteria/classification
- Bacteria/genetics
- Bacteria/isolation & purification
- Cation Transport Proteins/deficiency
- Cation Transport Proteins/genetics
- Dysbiosis/genetics
- Dysbiosis/metabolism
- Dysbiosis/microbiology
- Exons
- Female
- Gastrointestinal Microbiome
- Humans
- Infant, Newborn
- Infant, Newborn, Diseases/genetics
- Infant, Newborn, Diseases/metabolism
- Infant, Newborn, Diseases/microbiology
- Infant, Premature/metabolism
- Intestines/metabolism
- Intestines/microbiology
- Loss of Function Mutation
- Male
- Mice, Knockout
- Mutation
- Mutation, Missense
- Polysaccharides/metabolism
- Mice
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Affiliation(s)
- Shannon L Kelleher
- Department of Cellular and Molecular Physiology, Penn State Hershey College of Medicine, Hershey, Pennsylvania, USA
- Department of Pharmacology, Penn State Hershey College of Medicine, Hershey, Pennsylvania, USA
- Department of Surgery, Penn State Hershey College of Medicine, Hershey, Pennsylvania, USA
- Department of Biomedical and Nutritional Sciences, University of Massachusetts Lowell, Lowell, Massachusetts, USA
| | - Samina Alam
- Department of Cellular and Molecular Physiology, Penn State Hershey College of Medicine, Hershey, Pennsylvania, USA
- Department of Surgery, Penn State Hershey College of Medicine, Hershey, Pennsylvania, USA
| | - Olivia C Rivera
- Department of Cellular and Molecular Physiology, Penn State Hershey College of Medicine, Hershey, Pennsylvania, USA
- Department of Surgery, Penn State Hershey College of Medicine, Hershey, Pennsylvania, USA
| | - Shiran Barber-Zucker
- Department of Life Sciences, The National Institute for Biotechnology in the Negev and Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Raz Zarivach
- Department of Life Sciences, The National Institute for Biotechnology in the Negev and Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Takumi Wagatsuma
- The Division of Integrated Life Science, Graduate School of Biostudies, Kyoto University, Kyoto, Japan
| | - Taiho Kambe
- The Division of Integrated Life Science, Graduate School of Biostudies, Kyoto University, Kyoto, Japan
| | - David I Soybel
- Department of Surgery, Penn State Hershey College of Medicine, Hershey, Pennsylvania, USA
| | - Justin Wright
- Department of Biology, Juniata College, Huntingdon, Pennsylvania, USA
| | - Regina Lamendella
- Department of Biology, Juniata College, Huntingdon, Pennsylvania, USA
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31
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Fujishiro H, Kambe T. Manganese transport in mammals by zinc transporter family proteins, ZNT and ZIP. J Pharmacol Sci 2021; 148:125-133. [PMID: 34924116 DOI: 10.1016/j.jphs.2021.10.011] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Revised: 10/07/2021] [Accepted: 10/07/2021] [Indexed: 12/14/2022] Open
Abstract
Manganese (Mn) is an essential trace element required for various biological processes. However, excess Mn causes serious side effects in humans, including parkinsonism. Thus, elucidation of Mn homeostasis at the systemic, cellular, and molecular levels is important. Many metal transporters and channels can be involved in the transport and homeostasis of Mn, and an increasing body of evidence shows that several zinc (Zn) transporters belonging to the ZIP and ZNT families, specifically, ZNT10, ZIP8, and ZIP14, play pivotal roles in Mn metabolism. Mutations in the genes encoding these transporter proteins are associated with congenital disorders related to dysregulated Mn homeostasis in humans. Moreover, single nucleotide polymorphisms of ZIP8 are associated with multiple clinical phenotypes. In this review, we discuss the recent literature on the structural and biochemical features of ZNT10, ZIP8, and ZIP14, including transport mechanisms, regulation of expression, and pathophysiological functions. Because a disturbance in Mn homeostasis is closely associated with a variety of phenotypes and risk of human diseases, these transporters constitute a significant target for drug development. An understanding of the roles of these key transporters in Mn metabolism should provide new insights into pharmacological applications of their inhibitors and enhancers in human diseases.
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Affiliation(s)
- Hitomi Fujishiro
- Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Tokushima, 770-8514, Japan.
| | - Taiho Kambe
- Division of Integrated Life Science, Graduate School of Biostudies, Kyoto University, Kyoto, 606-8502, Japan.
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32
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Planeta Kepp K. Bioinorganic Chemistry of Zinc in Relation to the Immune System. Chembiochem 2021; 23:e202100554. [PMID: 34889510 DOI: 10.1002/cbic.202100554] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Revised: 12/09/2021] [Indexed: 01/18/2023]
Abstract
Zinc is well-known to have a central role in human inflammation and immunity and is itself an anti-inflammatory and antiviral agent. Despite its massively documented role in such processes, the underlying chemistry of zinc in relation to specific proteins and pathways of the immune system has not received much focus. This short review provides an overview of this topic, with emphasis on the structures of key proteins, zinc coordination chemistry, and probable mechanisms involved in zinc-based immunity, with some focus points for future chemical and biological research.
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Affiliation(s)
- Kasper Planeta Kepp
- DTU Chemistry, Technical University of Denmark, Building 206, 2800, Kongens Lyngby, Denmark
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33
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ZnT1 is a neuronal Zn 2+/Ca 2+ exchanger. Cell Calcium 2021; 101:102505. [PMID: 34871934 DOI: 10.1016/j.ceca.2021.102505] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2021] [Revised: 10/31/2021] [Accepted: 11/22/2021] [Indexed: 01/22/2023]
Abstract
Zinc transporter 1 (ZnT1; SLC30A1) is present in the neuronal plasma membrane, critically modulating NMDA receptor function and Zn2+ neurotoxicity. The mechanism mediating Zn2+ transport by ZnT1, however, has remained elusive. Here, we investigated ZnT1-dependent Zn2+ transport by measuring intracellular changes of this ion using the fluorescent indicator FluoZin-3. In primary mouse cortical neurons, which express ZnT1, transient addition of extracellular Zn2+ triggered a rise in cytosolic Zn2+, followed by its removal. Knockdown of ZnT1 by adeno associated viral (AAV)-short hairpin RNA (shZnT1) markedly increased rates of Zn2+ rise, and decreased rates of its removal, suggesting that ZnT1 is a primary route for Zn2+ efflux in neurons. Although Zn2+ transport by other members of the SLC30A family is dependent on pH gradients across cellular membranes, altered H+ gradients were not coupled to ZnT1-dependent transport. Removal of cytoplasmic Zn2+, against a large inward gradient during the initial loading phase, suggests that Zn2+ efflux requires a large driving force. We therefore asked if Ca2+ gradients across the membrane can facilitate Zn2+ efflux. Elimination of extracellular Ca2+ abolished Zn2+ efflux, while increased extracellular Ca2+ levels enhanced Zn2+ efflux. Intracellular Ca2+ rises, measured in GCaMP6 expressing neurons, closely paralleled cytoplasmic Zn2+ removal. Taken together, these results strongly suggest that ZnT1 functions as a Zn2+/Ca2+ exchanger, thereby regulating the transport of two ions of fundamental importance in neuronal signaling.
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34
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SLC-30A9 is required for Zn 2+ homeostasis, Zn 2+ mobilization, and mitochondrial health. Proc Natl Acad Sci U S A 2021; 118:2023909118. [PMID: 34433664 DOI: 10.1073/pnas.2023909118] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The trace element zinc is essential for many aspects of physiology. The mitochondrion is a major Zn2+ store, and excessive mitochondrial Zn2+ is linked to neurodegeneration. How mitochondria maintain their Zn2+ homeostasis is unknown. Here, we find that the SLC-30A9 transporter localizes on mitochondria and is required for export of Zn2+ from mitochondria in both Caenorhabditis elegans and human cells. Loss of slc-30a9 leads to elevated Zn2+ levels in mitochondria, a severely swollen mitochondrial matrix in many tissues, compromised mitochondrial metabolic function, reductive stress, and induction of the mitochondrial stress response. SLC-30A9 is also essential for organismal fertility and sperm activation in C. elegans, during which Zn2+ exits from mitochondria and acts as an activation signal. In slc-30a9-deficient neurons, misshapen mitochondria show reduced distribution in axons and dendrites, providing a potential mechanism for the Birk-Landau-Perez cerebrorenal syndrome where an SLC30A9 mutation was found.
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35
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Gu Y, Merriman C, Guo Z, Jia X, Wenzlau J, Li H, Li H, Rewers M, Yu L, Fu D. Novel autoantibodies to the β-cell surface epitopes of ZnT8 in patients progressing to type-1 diabetes. J Autoimmun 2021; 122:102677. [PMID: 34130115 PMCID: PMC9029399 DOI: 10.1016/j.jaut.2021.102677] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Revised: 05/26/2021] [Accepted: 05/29/2021] [Indexed: 11/22/2022]
Abstract
Type 1 diabetes (T1D) is a chronic autoimmune disease characterized by autoimmune destruction of insulin-producing β-cells in pancreatic islets. Seroconversions to islet autoantibodies (IAbs) precede the disease onset by many years, but the role of humoral autoimmunity in the disease initiation and progression are unclear. In the present study, we identified a new IAb directed to the extracellular epitopes of ZnT8 (ZnT8ec) in newly diagnosed patients with T1D, and demonstrated immunofluorescence staining of the surface of human β-cells by autoantibodies to ZnT8ec (ZnT8ecA). With the assay specificity set on 99th percentile of 336 healthy controls, the ZnT8ecA positivity rate was 23.6% (74/313) in patients with T1D. Moreover, 30 children in a longitudinal follow up of clinical T1D development were selected for sequential expression of four major IAbs (IAA, GADA, IA-2A and ZnT8icA). Among them, 10 children were ZnT8ecA positive. Remarkably, ZnT8ecA was the earliest IAb to appear in all 10 children. The identification of ZnT8ec as a cell surface target of humoral autoimmunity in the earliest phase of IAb responses opens a new avenue of investigation into the role of IAbs in the development of β-cell autoimmunity.
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Affiliation(s)
- Yong Gu
- Barbara Davis Center for Diabetes University of Colorado School of Medicine, Aurora, CO, USA
| | - Chengfeng Merriman
- Department of Physiology, Johns Hopkins School of Medicine, Baltimore, MD, USA
| | - Zheng Guo
- Department of Physiology, Johns Hopkins School of Medicine, Baltimore, MD, USA
| | - Xiaofan Jia
- Barbara Davis Center for Diabetes University of Colorado School of Medicine, Aurora, CO, USA
| | - Janet Wenzlau
- Barbara Davis Center for Diabetes University of Colorado School of Medicine, Aurora, CO, USA
| | - Hua Li
- Department of Structural Biology, Van Andel Institute, Grand Rapids, MI, USA
| | - Huilin Li
- Department of Structural Biology, Van Andel Institute, Grand Rapids, MI, USA
| | - Marian Rewers
- Barbara Davis Center for Diabetes University of Colorado School of Medicine, Aurora, CO, USA
| | - Liping Yu
- Barbara Davis Center for Diabetes University of Colorado School of Medicine, Aurora, CO, USA.
| | - Dax Fu
- Department of Physiology, Johns Hopkins School of Medicine, Baltimore, MD, USA.
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36
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Structure and function of an Arabidopsis thaliana sulfate transporter. Nat Commun 2021; 12:4455. [PMID: 34294705 PMCID: PMC8298490 DOI: 10.1038/s41467-021-24778-2] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Accepted: 07/01/2021] [Indexed: 02/06/2023] Open
Abstract
Plant sulfate transporters (SULTR) mediate absorption and distribution of sulfate (SO42-) and are essential for plant growth; however, our understanding of their structures and functions remains inadequate. Here we present the structure of a SULTR from Arabidopsis thaliana, AtSULTR4;1, in complex with SO42- at an overall resolution of 2.8 Å. AtSULTR4;1 forms a homodimer and has a structural fold typical of the SLC26 family of anion transporters. The bound SO42- is coordinated by side-chain hydroxyls and backbone amides, and further stabilized electrostatically by the conserved Arg393 and two helix dipoles. Proton and SO42- are co-transported by AtSULTR4;1 and a proton gradient significantly enhances SO42- transport. Glu347, which is ~7 Å from the bound SO42-, is required for H+-driven transport. The cytosolic STAS domain interacts with transmembrane domains, and deletion of the STAS domain or mutations to the interface compromises dimer formation and reduces SO42- transport, suggesting a regulatory function of the STAS domain.
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Lopez-Redondo M, Fan S, Koide A, Koide S, Beckstein O, Stokes DL. Zinc binding alters the conformational dynamics and drives the transport cycle of the cation diffusion facilitator YiiP. J Gen Physiol 2021; 153:212464. [PMID: 34254979 PMCID: PMC8282283 DOI: 10.1085/jgp.202112873] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Accepted: 06/14/2021] [Indexed: 11/20/2022] Open
Abstract
YiiP is a secondary transporter that couples Zn2+ transport to the proton motive force. Structural studies of YiiP from prokaryotes and Znt8 from humans have revealed three different Zn2+ sites and a conserved homodimeric architecture. These structures define the inward-facing and outward-facing states that characterize the archetypal alternating access mechanism of transport. To study the effects of Zn2+ binding on the conformational transition, we use cryo-EM together with molecular dynamics simulation to compare structures of YiiP from Shewanella oneidensis in the presence and absence of Zn2+. To enable single-particle cryo-EM, we used a phage-display library to develop a Fab antibody fragment with high affinity for YiiP, thus producing a YiiP/Fab complex. To perform MD simulations, we developed a nonbonded dummy model for Zn2+ and validated its performance with known Zn2+-binding proteins. Using these tools, we find that, in the presence of Zn2+, YiiP adopts an inward-facing conformation consistent with that previously seen in tubular crystals. After removal of Zn2+ with high-affinity chelators, YiiP exhibits enhanced flexibility and adopts a novel conformation that appears to be intermediate between inward-facing and outward-facing states. This conformation involves closure of a hydrophobic gate that has been postulated to control access to the primary transport site. Comparison of several independent cryo-EM maps suggests that the transition from the inward-facing state is controlled by occupancy of a secondary Zn2+ site at the cytoplasmic membrane interface. This work enhances our understanding of individual Zn2+ binding sites and their role in the conformational dynamics that govern the transport cycle.
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Affiliation(s)
- Maria Lopez-Redondo
- Skirball Institute of Biomolecular Medicine, Department of Cell Biology, New York University School of Medicine, New York, NY
| | - Shujie Fan
- Department of Physics, Arizona State University, Tempe, AZ
| | - Akiko Koide
- Perlmutter Cancer Center, Department of Medicine, New York University School of Medicine, New York, NY
| | - Shohei Koide
- Perlmutter Cancer Center, Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY
| | | | - David L Stokes
- Skirball Institute of Biomolecular Medicine, Department of Cell Biology, New York University School of Medicine, New York, NY
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Cotrim CA, Jarrott RJ, Whitten AE, Choudhury HG, Drew D, Martin JL. Heterologous Expression and Biochemical Characterization of the Human Zinc Transporter 1 (ZnT1) and Its Soluble C-Terminal Domain. Front Chem 2021; 9:667803. [PMID: 33996761 PMCID: PMC8120272 DOI: 10.3389/fchem.2021.667803] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2021] [Accepted: 03/31/2021] [Indexed: 11/13/2022] Open
Abstract
Human zinc transporter 1 (hZnT1) belongs to the cation diffusion facilitator (CDF) family. It plays a major role in transporting zinc (Zn2+) from the cytoplasm across the plasma membrane and into the extracellular space thereby protecting cells from Zn2+ toxicity. Through homology with other CDF family members, ZnT1 is predicted to contain a transmembrane region and a soluble C-terminal domain though little is known about its biochemistry. Here, we demonstrate that human ZnT1 and a variant can be produced by heterologous expression in Saccharomyces cerevisiae cells and purified in the presence of detergent and cholesteryl hemisuccinate. We show that the purified hZnT1 variant has Zn2+/H+ antiporter activity. Furthermore, we expressed, purified and characterized the soluble C-terminal domain of hZnT1 (hZnT1-CTD) in a bacterial expression system. We found that the hZnT1-CTD melting temperature increases at acidic pH, thus, we used an acetate buffer at pH 4.5 for purifications and concentration of the protein up to 12 mg/mL. Small-angle X-ray scattering analysis of hZnT1-CTD is consistent with the formation of a dimer in solution with a V-shaped core.
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Affiliation(s)
- Camila A. Cotrim
- Griffith Institute for Drug Discovery, Griffith University, Nathan, QLD, Australia
| | - Russell J. Jarrott
- Griffith Institute for Drug Discovery, Griffith University, Nathan, QLD, Australia
| | - Andrew E. Whitten
- Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW, Australia
| | - Hassanul G. Choudhury
- Institute for Molecular Bioscience, University of Queensland, St Lucia, QLD, Australia
| | - David Drew
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
| | - Jennifer L. Martin
- Griffith Institute for Drug Discovery, Griffith University, Nathan, QLD, Australia
- Vice-Chancellor's Unit, University of Wollongong, Wollongong, NSW, Australia
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Barber-Zucker S, Moran A, Zarivach R. Metal transport mechanism of the cation diffusion facilitator (CDF) protein family - a structural perspective on human CDF (ZnT)-related diseases. RSC Chem Biol 2021; 2:486-498. [PMID: 34458794 PMCID: PMC8341793 DOI: 10.1039/d0cb00181c] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Accepted: 12/26/2020] [Indexed: 11/21/2022] Open
Abstract
Divalent d-block metal cations (DDMCs) participate in many cellular functions; however, their accumulation in cells can be cytotoxic. The cation diffusion facilitator (CDF) family is a ubiquitous family of transmembrane DDMC exporters that ensures their homeostasis. Severe diseases, such as type II diabetes, Parkinson's and Alzheimer's disease, were linked to dysfunctional human CDF proteins, ZnT-1-10 (SLC30A1-10). Each member of the CDF family reduces the cytosolic concentration of a specific DDMC by transporting it from the cytoplasm to the extracellular environment or into intracellular compartments. This process is usually achieved by utilizing the proton motive force. In addition to their activity as DDMC transporters, CDFs also have other cellular functions such as the regulation of ion channels and enzymatic activity. The combination of structural and biophysical studies of different bacterial and eukaryotic CDF proteins led to significant progress in the understanding of the mutual interaction among CDFs and DDMCs, their involvement in ion binding and selectivity, conformational changes and the consequent transporting mechanisms. Here, we review these studies, provide our mechanistic interpretation of CDF proteins based on the current literature and relate the above to known human CDF-related diseases. Our analysis provides a common structure-function relationship to this important protein family and closes the gap between eukaryote and prokaryote CDFs.
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Affiliation(s)
- Shiran Barber-Zucker
- Department of Life Sciences, the National Institute for Biotechnology in the Negev and Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev P.O.B. 653 Beer Sheva 8410501 Israel +972-8-6472970 +972-8-6472970 +972-8-6428447 +972-8-6461999
| | - Arie Moran
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev P.O.B. 653 Beer Sheva 8410501 Israel
| | - Raz Zarivach
- Department of Life Sciences, the National Institute for Biotechnology in the Negev and Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev P.O.B. 653 Beer Sheva 8410501 Israel +972-8-6472970 +972-8-6472970 +972-8-6428447 +972-8-6461999
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40
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Catapano MC, Parsons DS, Kotuniak R, Mladěnka P, Bal W, Maret W. Probing the Structure and Function of the Cytosolic Domain of the Human Zinc Transporter ZnT8 with Nickel(II) Ions. Int J Mol Sci 2021; 22:2940. [PMID: 33799326 PMCID: PMC8000985 DOI: 10.3390/ijms22062940] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Revised: 03/08/2021] [Accepted: 03/09/2021] [Indexed: 11/30/2022] Open
Abstract
The human zinc transporter ZnT8 provides the granules of pancreatic β-cells with zinc (II) ions for assembly of insulin hexamers for storage. Until recently, the structure and function of human ZnTs have been modelled on the basis of the 3D structures of bacterial zinc exporters, which form homodimers with each monomer having six transmembrane α-helices harbouring the zinc transport site and a cytosolic domain with an α,β structure and additional zinc-binding sites. However, there are important differences in function as the bacterial proteins export an excess of zinc ions from the bacterial cytoplasm, whereas ZnT8 exports zinc ions into subcellular vesicles when there is no apparent excess of cytosolic zinc ions. Indeed, recent structural investigations of human ZnT8 show differences in metal binding in the cytosolic domain when compared to the bacterial proteins. Two common variants, one with tryptophan (W) and the other with arginine (R) at position 325, have generated considerable interest as the R-variant is associated with a higher risk of developing type 2 diabetes. Since the mutation is at the apex of the cytosolic domain facing towards the cytosol, it is not clear how it can affect zinc transport through the transmembrane domain. We expressed the cytosolic domain of both variants of human ZnT8 and have begun structural and functional studies. We found that (i) the metal binding of the human protein is different from that of the bacterial proteins, (ii) the human protein has a C-terminal extension with three cysteine residues that bind a zinc(II) ion, and (iii) there are small differences in stability between the two variants. In this investigation, we employed nickel(II) ions as a probe for the spectroscopically silent Zn(II) ions and utilised colorimetric and fluorimetric indicators for Ni(II) ions to investigate metal binding. We established Ni(II) coordination to the C-terminal cysteines and found differences in metal affinity and coordination in the two ZnT8 variants. These structural differences are thought to be critical for the functional differences regarding the diabetes risk. Further insight into the assembly of the metal centres in the cytosolic domain was gained from potentiometric investigations of zinc binding to synthetic peptides corresponding to N-terminal and C-terminal sequences of ZnT8 bearing the metal-coordinating ligands. Our work suggests the involvement of the C-terminal cysteines, which are part of the cytosolic domain, in a metal chelation and/or acquisition mechanism and, as now supported by the high-resolution structural work, provides the first example of metal-thiolate coordination chemistry in zinc transporters.
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Affiliation(s)
- Maria Carmen Catapano
- Departments of Biochemistry and Nutritional Sciences, School of Life Course Sciences, Faculty of Life Sciences and Medicine, King’s College London, Franklin-Wilkins Bldg, 150 Stamford St., London SE1 9NH, UK; (M.C.C.); (D.S.P.)
- Department of Analytical Chemistry, Faculty of Pharmacy in Hradec Králové, Charles University, Heyrovského 1203, 500 05 Hradec Králové, Czech Republic
| | - Douglas S. Parsons
- Departments of Biochemistry and Nutritional Sciences, School of Life Course Sciences, Faculty of Life Sciences and Medicine, King’s College London, Franklin-Wilkins Bldg, 150 Stamford St., London SE1 9NH, UK; (M.C.C.); (D.S.P.)
- Department of Radiology, Boston University School of Medicine, 670 Albany Street, Boston, MA 02118, USA
| | - Radosław Kotuniak
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106 Warsaw, Poland; (R.K.); (W.B.)
| | - Přemysl Mladěnka
- Department of Pharmacology and Toxicology, Faculty of Pharmacy in Hradec Králové, Charles University, Heyrovského 1203, 500 05 Hradec Králové, Czech Republic;
| | - Wojciech Bal
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106 Warsaw, Poland; (R.K.); (W.B.)
| | - Wolfgang Maret
- Departments of Biochemistry and Nutritional Sciences, School of Life Course Sciences, Faculty of Life Sciences and Medicine, King’s College London, Franklin-Wilkins Bldg, 150 Stamford St., London SE1 9NH, UK; (M.C.C.); (D.S.P.)
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41
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Sala D, Giachetti A, Rosato A. Insights into the Dynamics of the Human Zinc Transporter ZnT8 by MD Simulations. J Chem Inf Model 2021; 61:901-912. [PMID: 33508935 PMCID: PMC8023586 DOI: 10.1021/acs.jcim.0c01139] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Indexed: 02/07/2023]
Abstract
ZnT8 is a human zinc(II) transporter expressed at the membrane of secretory granules where it contributes to insulin storage importing zinc ions from the cytosol. In the human population, the two most common ZnT8 variants carry an arginine (R325) or a tryptophan (W325) in position 325. The former variant has the most efficient kinetics in zinc transport and has been correlated to a higher risk of developing insulin resistance. On the contrary, the W325 variant is less active and protects against type-2-diabetes. Here, we used molecular dynamics (MD) simulations to investigate the main differences between the R325 and W325 variants in the interaction with zinc(II) ions. Our simulations suggested that the position of the metal ion within the transport site was not the same for the two variants, underlying a different rearrangement of the transmembrane (TM) helices in the channel. The W325 variant featured a peculiar zinc environment not detected in the experimental structures. With respect to conformational dynamics, we observed that the R325 variant was significantly more flexible than W325, with the main role played by the transmembrane domain (TMD) and the C-terminal domain (CTD). This dynamics affected the packing of the TM helices and thus the channel accessibility from the cytosol. The dimer interface that keeps the two TM channels in contact became looser in both variants upon zinc binding to the transport site, suggesting that this may be an important step toward the switch from the inward- to the outward-facing state of the protein.
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Affiliation(s)
- Davide Sala
- Magnetic
Resonance Center (CERM), University of Florence, Via Luigi Sacconi 6, 50019 Sesto Fiorentino, Italy
| | - Andrea Giachetti
- Consorzio
Interuniversitario di Risonanze Magnetiche di Metallo Proteine, Via Luigi Sacconi 6, 50019 Sesto Fiorentino, Italy
| | - Antonio Rosato
- Magnetic
Resonance Center (CERM), University of Florence, Via Luigi Sacconi 6, 50019 Sesto Fiorentino, Italy
- Department
of Chemistry, University of Florence, Via della Lastruccia 3, 50019 Sesto Fiorentino, Italy
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42
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Styrpejko DJ, Cuajungco MP. Transmembrane 163 (TMEM163) Protein: A New Member of the Zinc Efflux Transporter Family. Biomedicines 2021; 9:biomedicines9020220. [PMID: 33670071 PMCID: PMC7926707 DOI: 10.3390/biomedicines9020220] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2020] [Revised: 02/17/2021] [Accepted: 02/17/2021] [Indexed: 12/27/2022] Open
Abstract
A growing body of evidence continues to demonstrate the vital roles that zinc and its transporters play on human health. The mammalian solute carrier 30 (SLC30) family, with ten current members, controls zinc efflux transport in cells. TMEM163, a recently reported zinc transporter, has similar characteristics in both predicted transmembrane domain structure and function to the cation diffusion facilitator (CDF) protein superfamily. This review discusses past and present data indicating that TMEM163 is a zinc binding protein that transports zinc in cells. We provide a brief background on TMEM163’s discovery, transport feature, protein interactome, and similarities, as well as differences, with known SLC30 (ZnT) protein family. We also examine recent reports that implicate TMEM163 directly or indirectly in various human diseases such as Parkinson’s disease, Mucolipidosis type IV and diabetes. Overall, the role of TMEM163 protein in zinc metabolism is beginning to be realized, and based on current evidence, we propose that it is likely a new CDF member belonging to mammalian SLC30 (ZnT) zinc efflux transporter proteins.
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Affiliation(s)
- Daniel J. Styrpejko
- Department of Biological Science, California State University Fullerton, Fullerton, CA 92831, USA;
| | - Math P. Cuajungco
- Department of Biological Science, California State University Fullerton, Fullerton, CA 92831, USA;
- Center for Applied Biotechnology Studies, California State University Fullerton, Fullerton, CA 92831, USA
- Correspondence:
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43
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Kambe T, Taylor KM, Fu D. Zinc transporters and their functional integration in mammalian cells. J Biol Chem 2021; 296:100320. [PMID: 33485965 PMCID: PMC7949119 DOI: 10.1016/j.jbc.2021.100320] [Citation(s) in RCA: 112] [Impact Index Per Article: 37.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 01/15/2021] [Accepted: 01/20/2021] [Indexed: 12/14/2022] Open
Abstract
Zinc is a ubiquitous biological metal in all living organisms. The spatiotemporal zinc dynamics in cells provide crucial cellular signaling opportunities, but also challenges for intracellular zinc homeostasis with broad disease implications. Zinc transporters play a central role in regulating cellular zinc balance and subcellular zinc distributions. The discoveries of two complementary families of mammalian zinc transporters (ZnTs and ZIPs) in the mid-1990s spurred much speculation on their metal selectivity and cellular functions. After two decades of research, we have arrived at a biochemical description of zinc transport. However, in vitro functions are fundamentally different from those in living cells, where mammalian zinc transporters are directed to specific subcellular locations, engaged in dedicated macromolecular machineries, and connected with diverse cellular processes. Hence, the molecular functions of individual zinc transporters are reshaped and deeply integrated in cells to promote the utilization of zinc chemistry to perform enzymatic reactions, tune cellular responsiveness to pathophysiologic signals, and safeguard cellular homeostasis. At present, the underlying mechanisms driving the functional integration of mammalian zinc transporters are largely unknown. This knowledge gap has motivated a shift of the research focus from in vitro studies of purified zinc transporters to in cell studies of mammalian zinc transporters in the context of their subcellular locations and protein interactions. In this review, we will outline how knowledge of zinc transporters has been accumulated from in-test-tube to in-cell studies, highlighting new insights and paradigm shifts in our understanding of the molecular and cellular basis of mammalian zinc transporter functions.
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Affiliation(s)
- Taiho Kambe
- Division of Integrated Life Science, Graduate School of Biostudies, Kyoto University, Kyoto, Japan
| | - Kathryn M Taylor
- School of Pharmacy and Pharmaceutical Sciences, Cardiff University, Cardiff, United Kingdom
| | - Dax Fu
- Department of Physiology, Johns Hopkins School of Medicine, Johns Hopkins University, Baltimore, Maryland, USA.
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44
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Krall RF, Tzounopoulos T, Aizenman E. The Function and Regulation of Zinc in the Brain. Neuroscience 2021; 457:235-258. [PMID: 33460731 DOI: 10.1016/j.neuroscience.2021.01.010] [Citation(s) in RCA: 61] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Revised: 01/05/2021] [Accepted: 01/08/2021] [Indexed: 12/31/2022]
Abstract
Nearly sixty years ago Fredrich Timm developed a histochemical technique that revealed a rich reserve of free zinc in distinct regions of the brain. Subsequent electron microscopy studies in Timm- stained brain tissue found that this "labile" pool of cellular zinc was highly concentrated at synaptic boutons, hinting a possible role for the metal in synaptic transmission. Although evidence for activity-dependent synaptic release of zinc would not be reported for another twenty years, these initial findings spurred decades of research into zinc's role in neuronal function and revealed a diverse array of signaling cascades triggered or regulated by the metal. Here, we delve into our current understanding of the many roles zinc plays in the brain, from influencing neurotransmission and sensory processing, to activating both pro-survival and pro-death neuronal signaling pathways. Moreover, we detail the many mechanisms that tightly regulate cellular zinc levels, including metal binding proteins and a large array of zinc transporters.
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Affiliation(s)
- Rebecca F Krall
- Department of Neurobiology, University of Pittsburgh School of Medicine, USA; Department of Otolaryngology, University of Pittsburgh School of Medicine, USA; Pittsburgh Hearing Research Center, University of Pittsburgh School of Medicine, USA; Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh School of Medicine, USA
| | - Thanos Tzounopoulos
- Department of Otolaryngology, University of Pittsburgh School of Medicine, USA; Pittsburgh Hearing Research Center, University of Pittsburgh School of Medicine, USA.
| | - Elias Aizenman
- Department of Neurobiology, University of Pittsburgh School of Medicine, USA; Pittsburgh Hearing Research Center, University of Pittsburgh School of Medicine, USA; Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh School of Medicine, USA.
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45
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Barber-Zucker S, Hall J, Froes A, Kolusheva S, MacMillan F, Zarivach R. The cation diffusion facilitator protein MamM's cytoplasmic domain exhibits metal-type dependent binding modes and discriminates against Mn 2. J Biol Chem 2020; 295:16614-16629. [PMID: 32967967 PMCID: PMC7864060 DOI: 10.1074/jbc.ra120.014145] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 09/11/2020] [Indexed: 12/20/2022] Open
Abstract
Cation diffusion facilitator (CDF) proteins are a conserved family of divalent transition metal cation transporters. CDF proteins are usually composed of two domains: the transmembrane domain, in which the metal cations are transported through, and a regulatory cytoplasmic C-terminal domain (CTD). Each CDF protein transports either one specific metal or multiple metals from the cytoplasm, and it is not known whether the CTD takes an active regulatory role in metal recognition and discrimination during cation transport. Here, the model CDF protein MamM, an iron transporter from magnetotactic bacteria, was used to probe the role of the CTD in metal recognition and selectivity. Using a combination of biophysical and structural approaches, the binding of different metals to MamM CTD was characterized. Results reveal that different metals bind distinctively to MamM CTD in terms of their binding sites, thermodynamics, and binding-dependent conformations, both in crystal form and in solution, which suggests a varying level of functional discrimination between CDF domains. Furthermore, these results provide the first direct evidence that CDF CTDs play a role in metal selectivity. We demonstrate that MamM's CTD can discriminate against Mn2+, supporting its postulated role in preventing magnetite formation poisoning in magnetotactic bacteria via Mn2+ incorporation.
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Affiliation(s)
- Shiran Barber-Zucker
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel; The National Institute for Biotechnology in the Negev, Ben-Gurion University of the Negev, Beer Sheva, Israel; Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Jenny Hall
- Henry Wellcome Unit for Biological EPR, School of Chemistry, University of East Anglia, Norwich, United Kingdom
| | - Afonso Froes
- Henry Wellcome Unit for Biological EPR, School of Chemistry, University of East Anglia, Norwich, United Kingdom
| | - Sofiya Kolusheva
- Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Fraser MacMillan
- Henry Wellcome Unit for Biological EPR, School of Chemistry, University of East Anglia, Norwich, United Kingdom.
| | - Raz Zarivach
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel; The National Institute for Biotechnology in the Negev, Ben-Gurion University of the Negev, Beer Sheva, Israel; Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, Beer Sheva, Israel.
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