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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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2
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Liu Y, Bafaro EM, Dempski RE. Single-molecule quantification of the oligomeric state of ZIP transporters in mammalian cells with fluorescence correlation spectroscopy. Methods Enzymol 2023; 687:103-137. [PMID: 37666629 DOI: 10.1016/bs.mie.2023.04.021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/06/2023]
Abstract
The SLC39 family of transporters, otherwise known as ZIPs for Zrt and Irt-like Proteins, function to increase cytosolic levels of transition metals. ZIP transporters have been identified at all phylogenetic levels and are members of the SoLute Carrier (SLC) superfamily. There are fourteen ZIP transporters encoded in the human genome. ZIP transmembrane proteins are expressed in the plasma membrane or membranes of intracellular organelles and have unique expression profiles across cell types. While direct structural efforts including x-ray crystallography, NMR and ab initio approaches have been effective tools in elucidating the structure of ZIPs, direct elucidation of the oligomeric state of these proteins is essential in understanding how wild type ZIP proteins function and whether mutations alter the oligomeric state of ZIPs. Unfortunately, several tools to quantify oligomeric states of proteins require overexpression of proteins which can lead to artifacts in experimental results. In contrast, fluorescence correlation spectroscopy (FCS) is a single-molecule technique which can be used to quantify the oligomeric state of transmembrane proteins. FCS takes advantage of the observation that the molecular brightness of a cluster of fluorescent molecules is directly proportional to the number of fluorescent molecules within the protein complex. This chapter describes how to implement FCS, focused on ZIP transporters, to quantify the oligomeric state of transmembrane in vivo. Included within this chapter are procedures to design constructs for experiments, transfection of mammalian cells as well as data acquisition and analysis. Taken together, FCS is a powerful mechanism to investigate the oligomeric state of proteins embedded within membranes of cells.
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Affiliation(s)
- Yuting Liu
- Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, Worcester, MA, United States
| | - Elizabeth M Bafaro
- Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, Worcester, MA, United States
| | - Robert E Dempski
- Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, Worcester, MA, United States.
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3
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Zhang T, Zhang Y, Sui D, Hu J. High-resolution structure of a mercury cross-linked ZIP metal transporter reveals delicate motions and metal relay for regulated zinc transport. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.20.537755. [PMID: 37131590 PMCID: PMC10153219 DOI: 10.1101/2023.04.20.537755] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Zrt-/Irt-like protein (ZIP) divalent metal transporters play a central role in maintaining trace element homeostasis. The prototypical ZIP from Bordetella bronchiseptica (BbZIP) is an elevator-type transporter, but the dynamic motions and detailed transport mechanism remain to be elucidated. Here, we report a high-resolution crystal structure of a mercury-crosslinked BbZIP variant at 1.95 Å, revealing an upward rotation of the transport domain in the new inward-facing conformation and a water-filled metal release channel that is divided into two parallel pathways by the previously disordered cytoplasmic loop. Mutagenesis and transport assays indicated that the newly identified high-affinity metal binding site in the primary pathway acts as a "metal sink" to reduce the transport rate. The discovery of a hinge motion around an extracellular axis allowed us to propose a sequential hinge-elevator-hinge movement of the transport domain to achieve alternating access. These findings provide key insights into the transport mechanisms and activity regulation.
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Affiliation(s)
- Tuo Zhang
- College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, 100083, China
- Department of Biochemistry & Molecular Biology, Michigan State University, MI 48824
| | - Yao Zhang
- Department of Biochemistry & Molecular Biology, Michigan State University, MI 48824
| | - Dexin Sui
- Department of Biochemistry & Molecular Biology, Michigan State University, MI 48824
| | - Jian Hu
- Department of Biochemistry & Molecular Biology, Michigan State University, MI 48824
- Department of Chemistry, Michigan State University, MI 48824
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4
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Hall AG, King JC. The Molecular Basis for Zinc Bioavailability. Int J Mol Sci 2023; 24:ijms24076561. [PMID: 37047530 PMCID: PMC10095312 DOI: 10.3390/ijms24076561] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Revised: 03/25/2023] [Accepted: 03/30/2023] [Indexed: 04/03/2023] Open
Abstract
Zinc is an essential micronutrient, and its deficiency is perhaps the most prevalent and least understood worldwide. Recent advances have expanded the understanding of zinc’s unique chemistry and molecular roles in a vast array of critical functions. However, beyond the concept of zinc absorption, few studies have explored the molecular basis of zinc bioavailability that determines the proportion of dietary zinc utilized in zinc-dependent processes in the body. The purpose of this review is to merge the concepts of zinc molecular biology and bioavailability with a focus on the molecular determinants of zinc luminal availability, absorption, transport, and utilization.
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5
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Heterologous Expression of Full-Length and Truncated Human ZIP4 Zinc Transporter in Saccharomyces cerevisiae. Biomolecules 2022; 12:biom12050726. [PMID: 35625653 PMCID: PMC9138318 DOI: 10.3390/biom12050726] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Revised: 05/12/2022] [Accepted: 05/13/2022] [Indexed: 02/01/2023] Open
Abstract
The human (h) transporter hZIP4 is the primary Zn2+ importer in the intestine. hZIP4 is also expressed in a variety of organs such as the pancreas and brain. Dysfunction of hZIP4 can result in the Zn2+ deficiency disease acrodermatitis enteropathica (AE). AE can disrupt digestive and immune system homeostasis. A limited number of hZIP4 expression strategies have hindered increasing knowledge about this essential transmembrane protein. Here, we report the heterologous expression of hZIP4 in Saccharomyces cerevisiae. Both a wild-type and a mutant S. cerevisiae strain, in which the endogenous Zn2+ transporters were deleted, were used to test the expression and localization of an hZIP4–GFP fusion protein. A full-length hZIP4–GFP and a truncated membrane-domain-only (mhZIP4–GFP) protein were observed to be present in the plasma membrane in yeast.
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6
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Zhang Z, Chen N, Zhang Z, Shi G. Genome-Wide Identification and Expression Profile Reveal Potential Roles of Peanut ZIP Family Genes in Zinc/Iron-Deficiency Tolerance. PLANTS 2022; 11:plants11060786. [PMID: 35336668 PMCID: PMC8950646 DOI: 10.3390/plants11060786] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Revised: 03/11/2022] [Accepted: 03/14/2022] [Indexed: 11/22/2022]
Abstract
Zinc/iron-regulated transporter-like protein (ZIP) family genes play crucial roles in metal uptake and transport in plants. However, little is known about their functions in peanut. Here, genome-wide analysis identified 30 peanut AhZIP genes that were divided into four classes. Most AhZIPs experienced whole-genome or segmental duplication. AhZIP proteins harbored 3–8 transmembrane domains and a typical ZIP domain, showing considerable homology with BbZIP from Bordetella bronchiseptica. Clustered AhZIPs generally share similar gene/protein structures; however, unique features were found in AhIRT1.2, AhZIP1.2, AhZIP3.5 and AhZIP7.8. RNA-seq data revealed that AhZIP2.1/2.2, AhZIP4.1/4.2 and AhZIP11.1/11.2 were highly and preferentially expressed in roots, nodule and reproductive tissues. RT-qPCR analysis indicated that transcriptional responses of AhZIPs to Fe/Zn deficiency are cultivar dependent. The expressions of AhIRT1.1, AhIRT1.2 and AhZIP6.1 were closely related to Fe uptake and translocation. AhIRT1.1 and AhZIP7.2 expression were significantly correlated with Zn accumulation. The expression of AhIRT1.1, AhIRT1.2, AhZIP3.6, AhZIP6.1 and AhZIP11.1 was associated with Mn uptake and translocation. The results confirmed that AhZIP genes play crucial roles in the uptake and transport of Fe, Zn and Mn in peanut, providing clues to further functionally characterize AhZIP genes in the future.
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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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8
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The Effects of Tetrapeptides Designed to Fit the Androgen Binding Site of ZIP9 on Myogenic and Osteogenic Cells. BIOLOGY 2021; 11:biology11010019. [PMID: 35053017 PMCID: PMC8772937 DOI: 10.3390/biology11010019] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/25/2021] [Revised: 12/19/2021] [Accepted: 12/22/2021] [Indexed: 12/30/2022]
Abstract
Simple Summary Pro-androgenic substances such as testosterone are often used to treat muscle- or bone-related disorders. Their interactions with the classical androgen receptor, however, can trigger a number of undesirable effects. It would therefore be of great benefit if the positive androgenic effects could be obtained by circumventing the classical androgen receptor. ZIP9 is a recently identified membrane-bound androgen receptor of physiological significance. Using in silico methods, we identified and verified the extracellular localization of its androgen binding site and designed small peptides that fit in it that do not interact with the AR. All peptides were found to be pro-androgenic; they stimulate mineralization in osteoblastic cells and myogenesis in myoblasts. Thus, these peptides might serve as testosterone surrogates in the treatment of osteogenic or myogenic disorders. Abstract ZIP9 is a recently identified membrane-bound androgen receptor of physiological significance that may mediate certain physiological responses to androgens. Using in silico methods, six tetrapeptides with the best docking properties at the testosterone binding site of ZIP9 were synthesized and further investigated. All tetrapeptides displaced T-BSA-FITC, a membrane-impermeable testosterone analog, from the surface of mouse myogenic L6 cells that express ZIP9 but not the classical androgen receptor (AR). Silencing the expression of ZIP9 with siRNA prevented this labeling. All tetrapeptides were found to be pro-androgenic; in L6 cells they stimulated the expression of myogenin, triggered activation of focal adhesion kinase, and prompted the fusion of L6 myocytes to syncytial myotubes. In human osteoblastic SAOS-2 cells that express AR and ZIP9, they reduced the expression of alkaline phosphatase and stimulated mineralization. These latter effects were prevented by silencing ZIP9 expression, indicating that the osteoblast/osteocyte conversion is exclusively mediated through ZIP9. Our results demonstrate that the synthetic tetrapeptides, by acting as ZIP9-specific androgens, have the potential to replace testosterone or testosterone analogs in the treatment of bone- or muscle-related disorders by circumventing the undesirable effects mediated through the classical AR.
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9
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Kim B, Kim HY, Lee WW. Zap70 Regulates TCR-Mediated Zip6 Activation at the Immunological Synapse. Front Immunol 2021; 12:687367. [PMID: 34394081 PMCID: PMC8358678 DOI: 10.3389/fimmu.2021.687367] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Accepted: 07/15/2021] [Indexed: 01/23/2023] Open
Abstract
The essential microelement zinc plays immunoregulatory roles via its ability to influence signaling pathways. Zinc deficiency impairs overall immune function and resultantly increases susceptibility to infection. Thus, zinc is considered as an immune-boosting supplement for populations with hypozincemia at high-risk for infection. Besides its role as a structural cofactor of many proteins, zinc also acts as an intracellular messenger in immune cell signaling. T-cell activation instructs zinc influx from extracellular and subcellular sources through the Zip6 and Zip8 zinc transporters, respectively. Increased cytoplasmic zinc participates in the regulation of T-cell responses by modifying activation signaling. However, the mechanism underlying the activation-dependent movement of zinc ions by Zip transporters in T cells remains elusive. Here, we demonstrate that Zip6, one of the most abundantly expressed Zip transporters in T cells, is mainly localized to lipid rafts in human T cells and is recruited into the immunological synapse in response to TCR stimulation. This was demonstrated through confocal imaging of the interaction between CD4+ T cells and antigen-presenting cells. Further, immunoprecipitation assays show that TCR triggering induces tyrosine phosphorylation of Zip6, which has at least three putative tyrosine motifs in its long cytoplasmic region, and this phosphorylation is coupled with its physical interaction with Zap70. Silencing Zip6 reduces zinc influx from extracellular sources and suppresses T-cell responses, suggesting an interaction between Zip6-mediated zinc influx and TCR activation. These results provide new insights into the mechanism through which Zip6-mediated zinc influx occurs in a TCR activation-dependent manner in human CD4+ T cells.
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Affiliation(s)
- Bonah Kim
- Laboratory of Autoimmunity and Inflammation (LAI), Department of Biomedical Sciences, BK21Plus Biomedical Science Project, Seoul National University College of Medicine, Seoul, South Korea
| | - Hee Young Kim
- Laboratory of Autoimmunity and Inflammation (LAI), Department of Biomedical Sciences, BK21Plus Biomedical Science Project, Seoul National University College of Medicine, Seoul, South Korea.,Department of Microbiology and Immunology, Seoul National University College of Medicine, Seoul, South Korea.,Institute of Infectious Diseases, Seoul National University College of Medicine, Seoul, South Korea
| | - Won-Woo Lee
- Laboratory of Autoimmunity and Inflammation (LAI), Department of Biomedical Sciences, BK21Plus Biomedical Science Project, Seoul National University College of Medicine, Seoul, South Korea.,Department of Microbiology and Immunology, Seoul National University College of Medicine, Seoul, South Korea.,Institute of Infectious Diseases, Seoul National University College of Medicine, Seoul, South Korea.,Cancer Research Institute and Ischemic/Hypoxic Disease Institute, Seoul National University College of Medicine, Seoul National University Hospital Biomedical Research Institute, Seoul, South Korea
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10
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Zhang C, Sui D, Zhang T, Hu J. Molecular Basis of Zinc-Dependent Endocytosis of Human ZIP4 Transceptor. Cell Rep 2021; 31:107582. [PMID: 32348750 PMCID: PMC7661102 DOI: 10.1016/j.celrep.2020.107582] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 02/03/2020] [Accepted: 04/07/2020] [Indexed: 12/05/2022] Open
Abstract
Nutrient transporters can be rapidly removed from the cell surface via substrate-stimulated endocytosis as a way to control nutrient influx, but the molecular underpinnings are not well understood. In this work, we focus on zinc-dependent endocytosis of human ZIP4 (hZIP4), a zinc transporter that is essential for dietary zinc uptake. Structure-guided mutagenesis and internalization assay reveal that hZIP4 per se acts as the exclusive zinc sensor, with the transport site’s being responsible for zinc sensing. In an effort of seeking sorting signal, a scan of the longest cytosolic loop (L2) leads to identification of a conserved Leu-Gln-Leu motif that is essential for endocytosis. Partial proteolysis of purified hZIP4 demonstrates a structural coupling between the transport site and the L2 upon zinc binding, which supports a working model of how zinc ions at physiological concentration trigger a conformation-dependent endocytosis of the zinc transporter. This work provides a paradigm on post-translational regulation of nutrient transporters. Cell surface expression of ZIP4, a transporter for intestinal zinc uptake, is regulated by zinc availability. Zhang et al. report that human ZIP4 acts as the exclusive zinc sensor in initiating the zinc-dependent endocytosis, and a cytosolic motif is essential for sorting signal formation, indicating that ZIP4 is a transceptor.
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Affiliation(s)
- Chi Zhang
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824, USA
| | - Dexin Sui
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824, USA
| | - Tuo Zhang
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824, USA
| | - Jian Hu
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824, USA; Department of Chemistry, Michigan State University, East Lansing, MI 48824, USA.
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11
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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: 99] [Impact Index Per Article: 33.0] [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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12
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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: 57] [Impact Index Per Article: 19.0] [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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13
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Thingholm TE, Rönnstrand L, Rosenberg PA. Why and how to investigate the role of protein phosphorylation in ZIP and ZnT zinc transporter activity and regulation. Cell Mol Life Sci 2020; 77:3085-3102. [PMID: 32076742 PMCID: PMC7391401 DOI: 10.1007/s00018-020-03473-3] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Revised: 01/13/2020] [Accepted: 01/28/2020] [Indexed: 12/20/2022]
Abstract
Zinc is required for the regulation of proliferation, metabolism, and cell signaling. It is an intracellular second messenger, and the cellular level of ionic, mobile zinc is strictly controlled by zinc transporters. In mammals, zinc homeostasis is primarily regulated by ZIP and ZnT zinc transporters. The importance of these transporters is underscored by the list of diseases resulting from changes in transporter expression and activity. However, despite numerous structural studies of the transporters revealing both zinc binding sites and motifs important for transporter function, the exact molecular mechanisms regulating ZIP and ZnT activities are still not clear. For example, protein phosphorylation was found to regulate ZIP7 activity resulting in the release of Zn2+ from intracellular stores leading to phosphorylation of tyrosine kinases and activation of signaling pathways. In addition, sequence analyses predict all 24 human zinc transporters to be phosphorylated suggesting that protein phosphorylation is important for regulation of transporter function. This review describes how zinc transporters are implicated in a number of important human diseases. It summarizes the current knowledge regarding ZIP and ZnT transporter structures and points to how protein phosphorylation seems to be important for the regulation of zinc transporter activity. The review addresses the need to investigate the role of protein phosphorylation in zinc transporter function and regulation, and argues for a pressing need to introduce quantitative phosphoproteomics to specifically target zinc transporters and proteins involved in zinc signaling. Finally, different quantitative phosphoproteomic strategies are suggested.
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Affiliation(s)
- T E Thingholm
- Department of Molecular Medicine, Cancer and Inflammation Research, University of Southern Denmark, J.B. Winsløws Vej 25, 3, 5000, Odense C, Denmark.
| | - L Rönnstrand
- Division of Translational Cancer Research, Lund University, Medicon Village, Building 404, Scheelevägen 2, Lund, Sweden
- Lund Stem Cell Center, Lund University, Medicon Village, Building 404, Scheelevägen 2, Lund, Sweden
- Division of Oncology, Skåne University Hospital, Lund, Sweden
| | - P A Rosenberg
- Department of Neurology and F.M. Kirby Neurobiology Center, Boston Children's Hospital, 300 Longwood Ave, Boston, MA, 02115, USA
- Department of Neurology and Program in Neuroscience, Harvard Medical School, Boston, MA, 02115, USA
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14
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Han JY, Choi TS, Heo CE, Son MK, Kim HI. Gas-phase conformations of intrinsically disordered proteins and their complexes with ligands: Kinetically trapped states during transfer from solution to the gas phase. MASS SPECTROMETRY REVIEWS 2019; 38:483-500. [PMID: 31021441 DOI: 10.1002/mas.21596] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Accepted: 04/10/2019] [Indexed: 06/09/2023]
Abstract
Flexible structures of intrinsically disordered proteins (IDPs) are crucial for versatile functions in living organisms, which involve interaction with diverse partners. Electrospray ionization ion mobility mass spectrometry (ESI-IM-MS) has been widely applied for structural characterization of apo-state and ligand-associated IDPs via two-dimensional separation in the gas phase. Gas-phase IDP structures have been regarded as kinetically trapped states originated from conformational features in solution. However, an implication of the states remains elusive in the structural characterization of IDPs, because it is unclear what structural property of IDPs is preserved. Recent studies have indicated that the conformational features of IDPs in solution are not fully reproduced in the gas phase. Nevertheless, the molecular interactions captured in the gas phase amplify the structural differences between IDP conformers. Therefore, an IDP conformational change that is not observed in solution is observable in the gas-phase structures obtained by ESI-IM-MS. Herein, we have presented up-to-date researches on the key implications of kinetically trapped states in the gas phase with a brief summary of the structural dynamics of IDPs in ESI-IM-MS.
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Affiliation(s)
- Jong Yoon Han
- Department of Chemistry, Korea University, Seoul, 02841, Republic of Korea
| | - Tae Su Choi
- Department of Chemistry, Korea University, Seoul, 02841, Republic of Korea
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA, 92093
| | - Chae Eun Heo
- Department of Chemistry, Korea University, Seoul, 02841, Republic of Korea
| | - Myung Kook Son
- Department of Chemistry, Korea University, Seoul, 02841, Republic of Korea
| | - Hugh I Kim
- Department of Chemistry, Korea University, Seoul, 02841, Republic of Korea
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15
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The histidine-rich loop in the extracellular domain of ZIP4 binds zinc and plays a role in zinc transport. Biochem J 2019; 476:1791-1803. [PMID: 31164399 DOI: 10.1042/bcj20190108] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Revised: 05/28/2019] [Accepted: 05/31/2019] [Indexed: 02/04/2023]
Abstract
The Zrt-/Irt-like protein (ZIP) family mediates zinc influx from extracellular space or intracellular vesicles/organelles, playing a central role in systemic and cellular zinc homeostasis. Out of the 14 family members encoded in human genome, ZIP4 is exclusively responsible for zinc uptake from dietary food and dysfunctional mutations of ZIP4 cause a life-threatening genetic disorder, Acrodermatitis Enteropathica (AE). About half of the missense AE-causing mutations occur within the large N-terminal extracellular domain (ECD), and our previous study has shown that ZIP4-ECD is crucial for optimal zinc uptake but the underlying mechanism has not been clarified. In this work, we examined zinc binding to the isolated ZIP4-ECD from Pteropus Alecto (black fruit bat) and located zinc-binding sites with a low micromolar affinity within a histidine-rich loop ubiquitously present in ZIP4 proteins. Zinc binding to this protease-susceptible loop induces a small and highly localized structural perturbation. Mutagenesis and functional study on human ZIP4 by using an improved cell-based zinc uptake assay indicated that the histidine residues within this loop are not involved in preselection of metal substrate but play a role in promoting zinc transport. The possible function of the histidine-rich loop as a metal chaperone facilitating zinc binding to the transport site and/or a zinc sensor allosterically regulating the transport machinery was discussed. This work helps to establish the structure/function relationship of ZIP4 and also sheds light on other metal transporters and metalloproteins with clustered histidine residues.
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16
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Bafaro EM, Maciejewski MW, Hoch JC, Dempski RE. Concomitant disorder and high-affinity zinc binding in the human zinc- and iron-regulated transport protein 4 intracellular loop. Protein Sci 2019; 28:868-880. [PMID: 30793391 DOI: 10.1002/pro.3591] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Revised: 01/21/2019] [Accepted: 02/13/2019] [Indexed: 12/27/2022]
Abstract
The human zinc- and iron-regulated transport protein 4 (hZIP4) protein is the major plasma membrane protein responsible for the uptake of zinc in the body, and as such it plays a key role in cellular zinc homeostasis. hZIP4 plasma membrane levels are regulated through post-translational modification of its large, disordered, histidine-rich cytosolic loop (ICL2) in response to intracellular zinc concentrations. Here, structural characteristics of the isolated disordered loop region, both in the absence and presence of zinc, were investigated using nuclear magnetic resonance (NMR) spectroscopy. NMR chemical shifts, coupling constants and temperature coefficients of the apoprotein, are consistent with a random coil with minor propensities for transient polyproline Type II helices and β-strand in regions implicated in post-translational modifications. The ICL2 protein remains disordered upon zinc binding, which induces exchange broadening. Paramagnetic relaxation enhancement experiments reveal that the histidine-rich region in the apoprotein makes transient tertiary contacts with predicted post-translational modification sites. The residue-specific data presented here strengthen the relationship between hZIP4 post-translational modifications, which impact its role in cellular zinc homeostasis, and zinc sensing by the intracellular loop. Furthermore, the zinc sensing mechanism employed by the ICL2 protein demonstrates that high-affinity interactions can occur in the presence of conformational disorder.
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Affiliation(s)
- Elizabeth M Bafaro
- Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, Worcester, Massachusetts 01609
| | - Mark W Maciejewski
- Department of Molecular Biology and Biophysics, UConn Health, Farmington, Connecticut 06030
| | - Jeffrey C Hoch
- Department of Molecular Biology and Biophysics, UConn Health, Farmington, Connecticut 06030
| | - Robert E Dempski
- Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, Worcester, Massachusetts 01609
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17
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Bulldan A, Malviya VN, Upmanyu N, Konrad L, Scheiner-Bobis G. Testosterone/bicalutamide antagonism at the predicted extracellular androgen binding site of ZIP9. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2017; 1864:2402-2414. [PMID: 28943399 DOI: 10.1016/j.bbamcr.2017.09.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Revised: 09/19/2017] [Accepted: 09/20/2017] [Indexed: 10/18/2022]
Abstract
ZIP9 is a Zn2+ transporter, testosterone receptor, and mediator of signaling events through G-proteins. Despite these pivotal properties, however, its physiological and pathophysiological significance has not yet been comprehensively addressed. Using a cell line that lacks the classical androgen receptor we show that ZIP9-mediated phosphorylation of Erk1/2, CREB, or ATF-1 and expression of claudin-5 and zonula occludens-1 by testosterone can be completely antagonized by bicalutamide (Casodex), an anti-androgen of significant clinical impact. Computational modeling and docking experiments with ZIP9 reveal typical characteristics of ZIP transporters and an extracellular binding site for testosterone capable of accommodating bicalutamide. The presence of this site is verified by our demonstration that the membrane-impermeable testosterone analogue T-BSA-FITC labels the membrane only when ZIP9 is expressed and that this labeling is completely prevented by bicalutamide. The study connects structural features of ZIP9 to its functions and indicates a possible relevance of ZIP9 as a pharmacological target.
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Affiliation(s)
- Ahmed Bulldan
- Institute for Veterinary-Physiology and -Biochemistry, School of Veterinary Medicine, Justus-Liebig-University, Giessen, Germany
| | | | - Neha Upmanyu
- Institute for Veterinary-Physiology and -Biochemistry, School of Veterinary Medicine, Justus-Liebig-University, Giessen, Germany
| | - Lutz Konrad
- Department of Obstetrics and Gynecology, Faculty of Medicine, Justus-Liebig-University, Giessen, Germany
| | - Georgios Scheiner-Bobis
- Institute for Veterinary-Physiology and -Biochemistry, School of Veterinary Medicine, Justus-Liebig-University, Giessen, Germany.
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18
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Bafaro E, Liu Y, Xu Y, Dempski RE. The emerging role of zinc transporters in cellular homeostasis and cancer. Signal Transduct Target Ther 2017; 2:17029. [PMID: 29218234 PMCID: PMC5661630 DOI: 10.1038/sigtrans.2017.29] [Citation(s) in RCA: 149] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Revised: 04/21/2017] [Accepted: 04/25/2017] [Indexed: 12/21/2022] Open
Abstract
Zinc is an essential micronutrient that plays a role in the structural or enzymatic functions of many cellular proteins. Cellular zinc homeostasis involves the opposing action of two families of metal transporters: the ZnT (SLC30) family that functions to reduce cytoplasmic zinc concentrations and the ZIP (SLC39) family that functions to increase cytoplasmic zinc concentrations. Fluctuations in intracellular zinc levels mediated by these transporter families affect signaling pathways involved in normal cell development, growth, differentiation and death. Consequently, changes in zinc transporter localization and function resulting in zinc dyshomeostasis have pathophysiological effects. Zinc dyshomeostasis has been implicated in the progression of cancer. Here we review recent progress toward understanding the structural basis for zinc transport by ZnT and ZIP family proteins, as well as highlight the roles of zinc as a signaling molecule in physiological conditions and in various cancers. As zinc is emerging as an important signaling molecule in the development and progression of cancer, the ZnT and ZIP transporters that regulate cellular zinc homeostasis are promising candidates for targeted cancer therapy.
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Affiliation(s)
- Elizabeth Bafaro
- Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, Worcester, Massachusetts, USA
| | - Yuting Liu
- Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, Worcester, Massachusetts, USA
| | - Yan Xu
- Department of Obstetrics and Gynecology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Robert E Dempski
- Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, Worcester, Massachusetts, USA
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19
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Fernández-Martín KG, Alvarez-Sánchez ME, Arana-Argáez VE, Alvarez-Sánchez LC, Lara-Riegos JC, Torres-Romero JC. Genome-wide identification, in silico characterization and expression analysis of ZIP-like genes from Trichomonas vaginalis in response to Zinc and Iron. Biometals 2017; 30:663-675. [PMID: 28733845 DOI: 10.1007/s10534-017-0034-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2017] [Accepted: 07/12/2017] [Indexed: 01/29/2023]
Abstract
Trace elements such as Zinc and Iron are essential components of metalloproteins and serve as cofactors or structural elements for enzymes involved in several important biological processes in almost all organisms. Because either excess or insufficient levels of Zn and Fe can be harmful for the cells, the homeostatic levels of these trace minerals must be tightly regulated. The Zinc regulated transporter, Iron regulated transporter-like Proteins (ZIP) comprise a diverse family, with several paralogues in diverse organisms and are considered essential for the Zn and Fe uptake and homeostasis. Zn and Fe has been shown to regulate expression of proteins involved in metabolism and pathogenicity mechanisms in the protozoan pathogen Trichomonas vaginalis, in contrast high concentrations of these elements were also found to be toxic for T. vaginalis trophozoites. Nevertheless, Zn and Fe uptake and homeostasis mechanisms is not yet clear in this parasite. We performed a genome-wide analysis and localized the 8 members of the ZIP gene family in T. vaginalis (TvZIP1-8). The bioinformatic programs predicted that the TvZIP proteins are highly conserved and show similar properties to the reported in other ZIP orthologues. The expression patterns of TvZIP1, 3, 5 and 7 were diminished in presence of Zinc, while the rest of the TvZIP genes showed an unchanged profile in this condition. In addition, TvZIP2 and TvZIP4 showed a differential expression pattern in trophozoites growth under different Iron conditions. These results suggest that TvZIP genes encode membrane transporters that may be responsible for the Zn and Fe acquisition in T. vaginalis.
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Affiliation(s)
- K G Fernández-Martín
- Laboratorio de Bioquímica y Genética Molecular, Facultad de Química de la Universidad Autónoma de Yucatán, Calle 43 No. 613 x C. 90 Col. Inalámbrica, 97069, Mérida, Yucatán, Mexico
| | - M E Alvarez-Sánchez
- Posgrado en Ciencias Genómicas, Universidad Autónoma de la Ciudad de México (UACM), San Lorenzo # 290, Col. Del Valle, 03100, Ciudad de México, Mexico
| | - V E Arana-Argáez
- Laboratorio de Farmacología, Facultad de Química de la Universidad Autónoma de Yucatán, Calle 43 No. 613 x C. 90 Col. Inalámbrica, 97069, Mérida, Yucatán, Mexico
| | - L C Alvarez-Sánchez
- Laboratorio de Virología, Centro de Investigaciones Regionales "Dr, Hideyo Noguchi" de la Universidad Autónoma de Yucatán, Calle 43 s/n x C. 90 Col. Inalámbrica, 97069, Mérida, Yucatán, Mexico
| | - J C Lara-Riegos
- Laboratorio de Bioquímica y Genética Molecular, Facultad de Química de la Universidad Autónoma de Yucatán, Calle 43 No. 613 x C. 90 Col. Inalámbrica, 97069, Mérida, Yucatán, Mexico
| | - J C Torres-Romero
- Laboratorio de Bioquímica y Genética Molecular, Facultad de Química de la Universidad Autónoma de Yucatán, Calle 43 No. 613 x C. 90 Col. Inalámbrica, 97069, Mérida, Yucatán, Mexico.
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20
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Hashimoto A, Nakagawa M, Tsujimura N, Miyazaki S, Kizu K, Goto T, Komatsu Y, Matsunaga A, Shirakawa H, Narita H, Kambe T, Komai M. Properties of Zip4 accumulation during zinc deficiency and its usefulness to evaluate zinc status: a study of the effects of zinc deficiency during lactation. Am J Physiol Regul Integr Comp Physiol 2016; 310:R459-68. [DOI: 10.1152/ajpregu.00439.2015] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Accepted: 12/18/2015] [Indexed: 11/22/2022]
Abstract
Systemic and cellular zinc homeostasis is elaborately controlled by ZIP and ZnT zinc transporters. Therefore, detailed characterization of their expression properties is of importance. Of these transporter proteins, Zip4 functions as the primarily important transporter to control systemic zinc homeostasis because of its indispensable function of zinc absorption in the small intestine. In this study, we closely investigated Zip4 protein accumulation in the rat small intestine in response to zinc status using an anti-Zip4 monoclonal antibody that we generated and contrasted this with the zinc-responsive activity of the membrane-bound alkaline phosphatase (ALP). We found that Zip4 accumulation is more rapid in response to zinc deficiency than previously thought. Accumulation increased in the jejunum as early as 1 day following a zinc-deficient diet. In the small intestine, Zip4 protein expression was higher in the jejunum than in the duodenum and was accompanied by reduction of ALP activity, suggesting that the jejunum can become zinc deficient more easily. Furthermore, by monitoring Zip4 accumulation levels and ALP activity in the duodenum and jejunum, we reasserted that zinc deficiency during lactation may transiently alter plasma glucose levels in the offspring in a sex-specific manner, without affecting homeostatic control of zinc metabolism. This confirms that zinc nutrition during lactation is extremely important for the health of the offspring. These results reveal that rapid Zip4 accumulation provides a significant conceptual advance in understanding the molecular basis of systemic zinc homeostatic control, and that properties of Zip4 protein accumulation are useful to evaluate zinc status closely.
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Affiliation(s)
- Ayako Hashimoto
- The Division of Integrated Life Science, Graduate School of Biostudies, Kyoto University, Kyoto, Japan
| | - Miki Nakagawa
- Department of Science of Food Function and Health, Graduate School of Agricultural Science, Tohoku University, Sendai, Japan
| | - Natsuki Tsujimura
- Department of Science of Food Function and Health, Graduate School of Agricultural Science, Tohoku University, Sendai, Japan
| | - Shiho Miyazaki
- The Division of Integrated Life Science, Graduate School of Biostudies, Kyoto University, Kyoto, Japan
| | - Kumiko Kizu
- Department of Life and Living, Osaka Seikei College, Osaka, Japan; and
| | - Tomoko Goto
- Department of Science of Food Function and Health, Graduate School of Agricultural Science, Tohoku University, Sendai, Japan
| | - Yusuke Komatsu
- Department of Science of Food Function and Health, Graduate School of Agricultural Science, Tohoku University, Sendai, Japan
| | - Ayu Matsunaga
- Department of Food Science, Kyoto Women's University, Kyoto, Japan
| | - Hitoshi Shirakawa
- Department of Science of Food Function and Health, Graduate School of Agricultural Science, Tohoku University, Sendai, Japan
| | - Hiroshi Narita
- Department of Food Science, Kyoto Women's University, Kyoto, Japan
| | - Taiho Kambe
- The Division of Integrated Life Science, Graduate School of Biostudies, Kyoto University, Kyoto, Japan
| | - Michio Komai
- Department of Science of Food Function and Health, Graduate School of Agricultural Science, Tohoku University, Sendai, Japan
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21
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Antala S, Ovchinnikov S, Kamisetty H, Baker D, Dempski RE. Computation and Functional Studies Provide a Model for the Structure of the Zinc Transporter hZIP4. J Biol Chem 2015; 290:17796-17805. [PMID: 25971965 PMCID: PMC4505028 DOI: 10.1074/jbc.m114.617613] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2014] [Revised: 04/24/2015] [Indexed: 11/06/2022] Open
Abstract
Members of the Zrt and Irt protein (ZIP) family are a central participant in transition metal homeostasis as they function to increase the cytosolic concentration of zinc and/or iron. However, the lack of a crystal structure hinders elucidation of the molecular mechanism of ZIP proteins. Here, we employed GREMLIN, a co-evolution-based contact prediction approach in conjunction with the Rosetta structure prediction program to construct a structural model of the human (h) ZIP4 transporter. The predicted contact data are best fit by modeling hZIP4 as a dimer. Mutagenesis of residues that comprise a central putative hZIP4 transmembrane transition metal coordination site in the structural model alter the kinetics and specificity of hZIP4. Comparison of the hZIP4 dimer model to all known membrane protein structures identifies the 12-transmembrane monomeric Piriformospora indica phosphate transporter (PiPT), a member of the major facilitator superfamily (MFS), as a likely structural homolog.
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Affiliation(s)
- Sagar Antala
- Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, Worcester, Massachusetts 01609
| | - Sergey Ovchinnikov
- Howard Hughes Medical Institute, University of Washington, Seattle, Washington 98195; Department of Biochemistry, University of Washington, Seattle, Washington 98195; Molecular and Cellular Biology Program, University of Washington, Seattle, Washington 98195
| | - Hetunandan Kamisetty
- Howard Hughes Medical Institute, University of Washington, Seattle, Washington 98195; Department of Biochemistry, University of Washington, Seattle, Washington 98195
| | - David Baker
- Howard Hughes Medical Institute, University of Washington, Seattle, Washington 98195; Department of Biochemistry, University of Washington, Seattle, Washington 98195
| | - Robert E Dempski
- Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, Worcester, Massachusetts 01609.
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