1
|
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: 95] [Impact Index Per Article: 31.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [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.
Collapse
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.
| |
Collapse
|
2
|
Murata Y, Yoshida M, Sakamoto N, Morimoto S, Watanabe T, Namba K. Iron uptake mediated by the plant-derived chelator nicotianamine in the small intestine. J Biol Chem 2020; 296:100195. [PMID: 33334885 PMCID: PMC7948497 DOI: 10.1074/jbc.ra120.015861] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Revised: 11/28/2020] [Accepted: 12/14/2020] [Indexed: 11/06/2022] Open
Abstract
Iron is an essential metal for all living organisms that is absorbed in the intestinal cells as a heme-chelated or free form. It is unclear how important plant-derived chelators, such as nicotianamine (NA), an organic small molecule that is ubiquitous in crops, vegetables, and various other foods, contribute to iron bioavailability in mammals. We performed electrophysiological assays with Xenopus laevis oocytes and radioactive tracer experiments with Caco-2 cells. The findings revealed that the proton-coupled amino acid transporter SLC36A1 (PAT1) transports iron in the form of NA-Fe (II) complex in vitro. Decreased expression of hPAT1 by RNA interference in Caco-2 cells reduced the uptake of NA-59Fe (II) complex. The uptake of inorganic 59Fe (II) was relatively unaffected. These results imply that PAT1 transports iron as a NA-Fe (II) complex. The rate of 59Fe absorption in the spleen, liver, and kidney was higher when mice were orally administered NA-59Fe (II) compared with free 59Fe (II). The profile of site-specific PAT1 expression in the mouse intestine coincided with those of NA and iron contents, which were the highest in the proximal jejunum. Orally administered NA-59Fe (II) complex in mice was detected in the proximal jejunum by thin layer chromatography. In contrast, much less 59Fe (or NA) was detected in the duodenum, where the divalent metal transporter SLC11A2 (DMT1) absorbs free Fe (II). The collective results revealed the role of PAT1 in NA-Fe (II) absorption in the intestine and potential implication of NA in iron uptake in mammals.
Collapse
Affiliation(s)
- Yoshiko Murata
- Bioorganic Research Institute, Suntory Foundation for Life Sciences, Soraku-gun, Kyoto, Japan.
| | - Masami Yoshida
- Bioorganic Research Institute, Suntory Foundation for Life Sciences, Soraku-gun, Kyoto, Japan
| | - Naho Sakamoto
- Bioorganic Research Institute, Suntory Foundation for Life Sciences, Soraku-gun, Kyoto, Japan
| | - Shiho Morimoto
- Bioorganic Research Institute, Suntory Foundation for Life Sciences, Soraku-gun, Kyoto, Japan
| | - Takehiro Watanabe
- Bioorganic Research Institute, Suntory Foundation for Life Sciences, Soraku-gun, Kyoto, Japan
| | - Kosuke Namba
- Graduate School of Pharmaceutical Science, Tokushima University, Tokushima, Japan
| |
Collapse
|
3
|
Horning KJ, Joshi P, Nitin R, Balachandran RC, Yanko FM, Kim K, Christov P, Aschner M, Sulikowski GA, Weaver CD, Bowman AB. Identification of a selective manganese ionophore that enables nonlethal quantification of cellular manganese. J Biol Chem 2020; 295:3875-3890. [PMID: 32047113 PMCID: PMC7086026 DOI: 10.1074/jbc.ra119.009781] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2019] [Revised: 02/11/2020] [Indexed: 01/14/2023] Open
Abstract
Available assays for measuring cellular manganese (Mn) levels require cell lysis, restricting longitudinal experiments and multiplexed outcome measures. Conducting a screen of small molecules known to alter cellular Mn levels, we report here that one of these chemicals induces rapid Mn efflux. We describe this activity and the development and implementation of an assay centered on this small molecule, named manganese-extracting small molecule (MESM). Using inductively-coupled plasma-MS, we validated that this assay, termed here "manganese-extracting small molecule estimation route" (MESMER), can accurately assess Mn in mammalian cells. Furthermore, we found evidence that MESM acts as a Mn-selective ionophore, and we observed that it has increased rates of Mn membrane transport, reduced cytotoxicity, and increased selectivity for Mn over calcium compared with two established Mn ionophores, calcimycin (A23187) and ionomycin. Finally, we applied MESMER to test whether prior Mn exposures subsequently affect cellular Mn levels. We found that cells receiving continuous, elevated extracellular Mn accumulate less Mn than cells receiving equally-elevated Mn for the first time for 24 h, indicating a compensatory cellular homeostatic response. Use of the MESMER assay versus a comparable detergent lysis-based assay, cellular Fura-2 Mn extraction assay, reduced the number of cells and materials required for performing a similar but cell lethality-based experiment to 25% of the normally required sample size. We conclude that MESMER can accurately quantify cellular Mn levels in two independent cells lines through an ionophore-based mechanism, maintaining cell viability and enabling longitudinal assessment within the same cultures.
Collapse
Affiliation(s)
- Kyle J. Horning
- Vanderbilt Brain Institute, Vanderbilt University, Nashville, Tennessee 37232
| | - Piyush Joshi
- Vanderbilt Brain Institute, Vanderbilt University, Nashville, Tennessee 37232
| | - Rachana Nitin
- Vanderbilt Brain Institute, Vanderbilt University, Nashville, Tennessee 37232
| | | | - Frank M. Yanko
- School of Health Sciences, Purdue University, West Lafayette, Indiana 47907
| | - Kwangho Kim
- Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee 37232,Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37235
| | - Plamen Christov
- Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee 37232
| | - Michael Aschner
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York 10461
| | - Gary A. Sulikowski
- Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee 37232,Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37235,Department of Pharmacology, Vanderbilt University, Nashville, Tennessee 37212
| | - C. David Weaver
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37235,Department of Pharmacology, Vanderbilt University, Nashville, Tennessee 37212
| | - Aaron B. Bowman
- Vanderbilt Brain Institute, Vanderbilt University, Nashville, Tennessee 37232,School of Health Sciences, Purdue University, West Lafayette, Indiana 47907, To whom correspondence should be addressed:
Purdue University, 550 Stadium Mall Dr., HAMP 1173A, West Lafayette, IN 47907-2051. E-mail:
| |
Collapse
|
4
|
Li L, Bertram S, Kaplan J, Jia X, Ward DM. The mitochondrial iron exporter genes MMT1 and MMT2 in yeast are transcriptionally regulated by Aft1 and Yap1. J Biol Chem 2020; 295:1716-1726. [PMID: 31896574 PMCID: PMC7008362 DOI: 10.1074/jbc.ra119.011154] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Revised: 12/30/2019] [Indexed: 12/12/2022] Open
Abstract
Budding yeast (Saccharomyces cerevisiae) responds to low cytosolic iron by up-regulating the expression of iron import genes; iron import can reflect iron transport into the cytosol or mitochondria. Mmt1 and Mmt2 are nuclearly encoded mitochondrial proteins that export iron from the mitochondria into the cytosol. Here we report that MMT1 and MMT2 expression is transcriptionally regulated by two pathways: the low-iron-sensing transcription factor Aft1 and the oxidant-sensing transcription factor Yap1. We determined that MMT1 and MMT2 expression is increased under low-iron conditions and decreased when mitochondrial iron import is increased through overexpression of the high-affinity mitochondrial iron importer Mrs3. Moreover, loss of iron-sulfur cluster synthesis induced expression of MMT1 and MMT2 We show that exposure to the oxidant H2O2 induced MMT1 expression but not MMT2 expression and identified the transcription factor Yap1 as being involved in oxidant-mediated MMT1 expression. We defined Aft1- and Yap1-dependent transcriptional sites in the MMT1 promoter that are necessary for low-iron- or oxidant-mediated MMT1 expression. We also found that the MMT2 promoter contains domains that are important for regulating its expression under low-iron conditions, including an upstream region that appears to partially repress expression under low-iron conditions. Our findings reveal that MMT1 and MMT2 are induced under low-iron conditions and that the low-iron regulator Aft1 is required for this induction. We further uncover an Aft1-binding site in the MMT1 promoter sufficient for inducing MMT1 transcription and identify an MMT2 promoter region required for low iron induction.
Collapse
Affiliation(s)
- Liangtao Li
- Department of Pathology, Division of Microbiology and Immunology, University of Utah School of Medicine, Salt Lake City, Utah 84132
| | - Sophie Bertram
- Department of Pathology, Division of Microbiology and Immunology, University of Utah School of Medicine, Salt Lake City, Utah 84132
| | - Jerry Kaplan
- Department of Pathology, Division of Microbiology and Immunology, University of Utah School of Medicine, Salt Lake City, Utah 84132
| | - Xuan Jia
- Department of Pathology, Division of Microbiology and Immunology, University of Utah School of Medicine, Salt Lake City, Utah 84132
| | - Diane M Ward
- Department of Pathology, Division of Microbiology and Immunology, University of Utah School of Medicine, Salt Lake City, Utah 84132.
| |
Collapse
|
5
|
Bozzi AT, McCabe AL, Barnett BC, Gaudet R. Transmembrane helix 6b links proton and metal release pathways and drives conformational change in an Nramp-family transition metal transporter. J Biol Chem 2019; 295:1212-1224. [PMID: 31882536 DOI: 10.1074/jbc.ra119.011336] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Revised: 12/10/2019] [Indexed: 12/15/2022] Open
Abstract
The natural resistance-associated macrophage protein (Nramp) family encompasses transition metal and proton cotransporters that are present in many organisms from bacteria to humans. Recent structures of Deinococcus radiodurans Nramp (DraNramp) in multiple conformations revealed the intramolecular rearrangements required for alternating access of the metal-binding site to the external or cytosolic environment. Here, using recombinant proteins and metal transport and cysteine accessibility assays, we demonstrate that two parallel cytoplasm-accessible networks of conserved hydrophilic residues in DraNramp, one lining the wide intracellular vestibule for metal release and the other forming a narrow proton transport pathway, are essential for metal transport. We further show that mutagenic or posttranslational modifications of transmembrane helix (TM) 6b, which structurally links these two pathways, impede normal conformational cycling and metal transport. TM6b contains two highly conserved histidines, His232 and His237 We found that different mutagenic perturbations of His232, just below the metal-binding site along the proton exit route, differentially affect DraNramp's conformational state, suggesting that His232 serves as a pivot point for conformational changes. In contrast, any replacement of His237, lining the metal exit route, locked the transporter in a transport-inactive outward-closed state. We conclude that these two histidines, and TM6b more broadly, help trigger the bulk rearrangement of DraNramp to the inward-open state upon metal binding and facilitate return of the empty transporter to an outward-open state upon metal release.
Collapse
Affiliation(s)
- Aaron T Bozzi
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts 02138
| | - Anne L McCabe
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts 02138
| | - Benjamin C Barnett
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts 02138
| | - Rachelle Gaudet
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts 02138
| |
Collapse
|
6
|
Steimle BL, Smith FM, Kosman DJ. The solute carriers ZIP8 and ZIP14 regulate manganese accumulation in brain microvascular endothelial cells and control brain manganese levels. J Biol Chem 2019; 294:19197-19208. [PMID: 31699897 DOI: 10.1074/jbc.ra119.009371] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Revised: 10/29/2019] [Indexed: 12/29/2022] Open
Abstract
Manganese supports numerous neuronal functions but in excess is neurotoxic. Consequently, regulation of manganese flux at the blood-brain barrier (BBB) is critical to brain homeostasis. However, the molecular pathways supporting the transcellular trafficking of divalent manganese ions within the microvascular capillary endothelial cells (BMVECs) that constitute the BBB have not been examined. In this study, we have determined that ZIP8 and ZIP14 (Zrt- and Irt-like proteins 8 and 14) support Mn2+ uptake by BMVECs and that neither DMT1 nor an endocytosis-dependent pathway play any significant role in Mn2+ uptake. Specifically, siRNA-mediated knockdown of ZIP8 and ZIP14 coincided with a decrease in manganese uptake, and kinetic analyses revealed that manganese uptake depends on pH and bicarbonate and is up-regulated by lipopolysaccharide, all biochemical markers of ZIP8 or ZIP14 activity. Mn2+ uptake also was associated with cell-surface membrane presentation of ZIP8 and ZIP14, as indicated by membrane protein biotinylation. Importantly, surface ZIP8 and ZIP14 biotinylation and Mn2+-uptake experiments together revealed that these transporters support manganese uptake at both the apical, blood and basal, brain sides of BMVECs. This indicated that in the BMVECs of the BBB, these two transporters support a bidirectional Mn2+ flux. We conclude that BMVECs play a critical role in controlling manganese homeostasis in the brain.
Collapse
Affiliation(s)
- Brittany L Steimle
- Department of Biochemistry, State University of New York at Buffalo, Jacobs School of Medicine and Biomedical Sciences, Buffalo, New York 14203
| | - Frances M Smith
- Department of Biochemistry, State University of New York at Buffalo, Jacobs School of Medicine and Biomedical Sciences, Buffalo, New York 14203
| | - Daniel J Kosman
- Department of Biochemistry, State University of New York at Buffalo, Jacobs School of Medicine and Biomedical Sciences, Buffalo, New York 14203
| |
Collapse
|
7
|
Merriman C, Fu D. Down-regulation of the islet-specific zinc transporter-8 (ZnT8) protects human insulinoma cells against inflammatory stress. J Biol Chem 2019; 294:16992-17006. [PMID: 31591269 DOI: 10.1074/jbc.ra119.010937] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Revised: 10/04/2019] [Indexed: 12/31/2022] Open
Abstract
Zinc transporter-8 (ZnT8) primarily functions as a zinc-sequestrating transporter in the insulin-secretory granules (ISGs) of pancreatic β-cells. Loss-of-function mutations in ZnT8 are associated with protection against type-2 diabetes (T2D), but the protective mechanism is unclear. Here, we developed an in-cell ZnT8 assay to track endogenous ZnT8 responses to metabolic and inflammatory stresses applied to human insulinoma EndoC-βH1 cells. Unexpectedly, high glucose and free fatty acids did not alter cellular ZnT8 levels, but proinflammatory cytokines acutely, reversibly, and gradually down-regulated ZnT8. Approximately 50% of the cellular ZnT8 was localized to the endoplasmic reticulum (ER), which was the primary target of the cytokine-mediated ZnT8 down-regulation. Transcriptome profiling of cytokine-exposed β-cells revealed an adaptive unfolded protein response (UPR) including a marked immunoproteasome activation that coordinately degraded ZnT8 and insulin over a 1,000-fold cytokine concentration range. RNAi-mediated ZnT8 knockdown protected cells against cytokine cytotoxicity, whereas inhibiting immunoproteasomes blocked cytokine-induced ZnT8 degradation and triggered a transition of the adaptive UPR to cell apoptosis. Hence, cytokine-induced down-regulation of the ER ZnT8 level promotes adaptive UPR, acting as a protective mechanism that decongests the ER burden of ZnT8 to protect β-cells from proapoptotic UPR during chronic low-grade inflammation.
Collapse
Affiliation(s)
- Chengfeng Merriman
- Department of Physiology, Johns Hopkins School of Medicine, Baltimore, Maryland 21205
| | - Dax Fu
- Department of Physiology, Johns Hopkins School of Medicine, Baltimore, Maryland 21205
| |
Collapse
|
8
|
Gupta S, Merriman C, Petzold CJ, Ralston CY, Fu D. Water molecules mediate zinc mobility in the bacterial zinc diffusion channel ZIPB. J Biol Chem 2019; 294:13327-13335. [PMID: 31320477 DOI: 10.1074/jbc.ra119.009239] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Revised: 07/17/2019] [Indexed: 11/06/2022] Open
Abstract
Regulated ion diffusion across biological membranes is vital for cell function. In a nanoscale ion channel, the active role of discrete water molecules in modulating hydrodynamic behaviors of individual ions is poorly understood because of the technical challenge of tracking water molecules through the channel. Here we report the results of a hydroxyl radical footprinting analysis of the zinc-selective channel ZIPB from the Gram-negative bacterium, Bordetella bronchiseptica Irradiating ZIPB by microsecond X-ray pulses activated water molecules to form covalent hydroxyl radical adducts at nearby residues, which were identified by bottom-up proteomics to detect residues that interact either with zinc or water in response to zinc binding. We found a series of residues exhibiting reciprocal changes in water accessibility attributed to alternating zinc and water binding. Mapping these residues to the previously reported crystal structure of ZIPB, we identified a water-reactive pathway that superimposed on a zinc translocation pathway consisting of two binuclear metal centers and an interim zinc-binding site. The cotranslocation of zinc and water suggested that pore-lining residues undergo a mode switch between zinc coordination and water binding to confer zinc mobility. The unprecedented details of water-mediated zinc transport identified here highlight an essential role of solvated waters in driving zinc coordination dynamics and transmembrane crossing.
Collapse
Affiliation(s)
- Sayan Gupta
- Berkeley Center for Structural Biology, Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720
| | - Chengfeng Merriman
- Department of Physiology, Johns Hopkins School of Medicine, Baltimore, Maryland 21205
| | - Christopher J Petzold
- Biological Systems Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720; Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720
| | - Corie Y Ralston
- Berkeley Center for Structural Biology, Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720
| | - Dax Fu
- Department of Physiology, Johns Hopkins School of Medicine, Baltimore, Maryland 21205.
| |
Collapse
|
9
|
Hu YM, Boehm DM, Chung H, Wilson S, Bird AJ. Zinc-dependent activation of the Pho8 alkaline phosphatase in Schizosaccharomyces pombe. J Biol Chem 2019; 294:12392-12404. [PMID: 31239353 DOI: 10.1074/jbc.ra119.007371] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2019] [Revised: 06/20/2019] [Indexed: 01/23/2023] Open
Abstract
Genome-wide analyses have revealed that during metal ion starvation, many cells undergo programmed changes in their transcriptome or proteome that lower the levels of abundant metalloproteins, conserving metal ions for more critical functions. Here we investigated how changes in cellular zinc status affect the expression and activity of the zinc-requiring Pho8 alkaline phosphatase from fission yeast (Schizosaccharomyces pombe). In S. pombe, Pho8 is a membrane-tethered and processed glycoprotein that resides in the vacuole. Using alkaline phosphatase activity assays along with various biochemical analyses, we found that Pho8 is active when zinc is plentiful and inactive when zinc is limited. Although Pho8 activity depended on zinc, we also found that higher levels of pho8 mRNAs and Pho8 protein accumulate in zinc-deficient cells. To gain a better understanding of the inverse relationship between pho8 mRNA levels and Pho8 activity, we examined the effects of zinc on the stability and processing of the Pho8 protein. We show that Pho8 is processed regardless of zinc status and that mature Pho8 accumulates under all conditions. We also noted that alkaline phosphatase activity is rapidly restored when zinc is resupplied to cells, even in the presence of the protein synthesis inhibitor cycloheximide. Our results suggest that S. pombe cells maintain inactive pools of Pho8 proteins under low-zinc conditions and that these pools facilitate rapid restoration of Pho8 activity when zinc ions become available.
Collapse
Affiliation(s)
- Ya-Mei Hu
- Department of Human Nutrition, Ohio State University, Columbus, Ohio 43210
| | - Derek M Boehm
- Department of Molecular Genetics, Ohio State University, Columbus, Ohio 43210
| | - Hak Chung
- Ohio State University Interdisciplinary Nutrition Program, Ohio State University, Columbus, Ohio 43210
| | - Stevin Wilson
- Department of Molecular Genetics, Ohio State University, Columbus, Ohio 43210
| | - Amanda J Bird
- Department of Human Nutrition, Ohio State University, Columbus, Ohio 43210; Department of Molecular Genetics, Ohio State University, Columbus, Ohio 43210; Center for RNA Biology, Ohio State University, Columbus, Ohio 43210.
| |
Collapse
|
10
|
Robinson AE, Lowe JE, Koh EI, Henderson JP. Uropathogenic enterobacteria use the yersiniabactin metallophore system to acquire nickel. J Biol Chem 2018; 293:14953-14961. [PMID: 30108176 DOI: 10.1074/jbc.ra118.004483] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Revised: 08/10/2018] [Indexed: 12/21/2022] Open
Abstract
Invasive Gram-negative bacteria often express multiple virulence-associated metal ion chelators to combat host-mediated metal deficiencies. Escherichia coli, Klebsiella, and Yersinia pestis isolates encoding the Yersinia high pathogenicity island (HPI) secrete yersiniabactin (Ybt), a metallophore originally shown to chelate iron ions during infection. However, our recent demonstration that Ybt also scavenges copper ions during infection led us to question whether it might be capable of retrieving other metals as well. Here, we find that uropathogenic E. coli also use Ybt to bind extracellular nickel ions. Using quantitative MS, we show that the canonical metal-Ybt import pathway internalizes the resulting Ni-Ybt complexes, extracts the nickel, and releases metal-free Ybt back to the extracellular space. We find that E. coli and Klebsiella direct the nickel liberated from this pathway to intracellular nickel enzymes. Thus, Ybt may provide access to nickel that is inaccessible to the conserved NikABCDE permease system. Nickel should be considered alongside iron and copper as a plausible substrate for Ybt-mediated metal import by enterobacteria during human infections.
Collapse
Affiliation(s)
- Anne E Robinson
- From the Division of Infectious Diseases, Department of Internal Medicine, Department of Molecular Microbiology, Center for Women's Infectious Diseases Research, Washington University, St. Louis, Missouri, 63110
| | - Jessica E Lowe
- From the Division of Infectious Diseases, Department of Internal Medicine, Department of Molecular Microbiology, Center for Women's Infectious Diseases Research, Washington University, St. Louis, Missouri, 63110
| | - Eun-Ik Koh
- From the Division of Infectious Diseases, Department of Internal Medicine, Department of Molecular Microbiology, Center for Women's Infectious Diseases Research, Washington University, St. Louis, Missouri, 63110
| | - Jeffrey P Henderson
- From the Division of Infectious Diseases, Department of Internal Medicine, Department of Molecular Microbiology, Center for Women's Infectious Diseases Research, Washington University, St. Louis, Missouri, 63110
| |
Collapse
|
11
|
Abstract
This 11th Thematic Metals in Biology Thematic Series deals with copper, a transition metal with a prominent role in biochemistry. Copper is a very versatile element, and both deficiencies and excesses can be problematic. The five Minireviews in this series deal with several aspects of copper homeostasis in microorganisms and mammals and the role of this metal in two enzymes, copper-only superoxide dismutase and cytochrome c oxidase.
Collapse
Affiliation(s)
- F Peter Guengerich
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146.
| |
Collapse
|
12
|
Neupane DP, Avalos D, Fullam S, Roychowdhury H, Yukl ET. Mechanisms of zinc binding to the solute-binding protein AztC and transfer from the metallochaperone AztD. J Biol Chem 2017; 292:17496-17505. [PMID: 28887302 DOI: 10.1074/jbc.m117.804799] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Revised: 08/16/2017] [Indexed: 01/22/2023] Open
Abstract
Bacteria can acquire the essential metal zinc from extremely zinc-limited environments by using ATP-binding cassette (ABC) transporters. These transporters are critical virulence factors, relying on specific and high-affinity binding of zinc by a periplasmic solute-binding protein (SBP). As such, the mechanisms of zinc binding and release among bacterial SBPs are of considerable interest as antibacterial drug targets. Zinc SBPs are characterized by a flexible loop near the high-affinity zinc-binding site. The function of this structure is not always clear, and its flexibility has thus far prevented structural characterization by X-ray crystallography. Here, we present intact structures for the zinc-specific SBP AztC from the bacterium Paracoccus denitrificans in the zinc-bound and apo-states. A comparison of these structures revealed that zinc loss prompts significant structural rearrangements, mediated by the formation of a sodium-binding site in the apo-structure. We further show that the AztC flexible loop has no impact on zinc-binding affinity, stoichiometry, or protein structure, yet is essential for zinc transfer from the metallochaperone AztD. We also found that 3 His residues in the loop appear to temporarily coordinate zinc and then convey it to the high-affinity binding site. Thus, mutation of any of these residues to Ala abrogated zinc transfer from AztD. Our structural and mechanistic findings conclusively identify a role for the AztC flexible loop in zinc acquisition from the metallochaperone AztD, yielding critical insights into metal binding by AztC from both solution and AztD. These proteins are highly conserved in human pathogens, making this work potentially useful for the development of novel antibiotics.
Collapse
Affiliation(s)
- Durga P Neupane
- From the Department of Chemistry and Biochemistry, New Mexico State University, Las Cruces, New Mexico 88003
| | - Dante Avalos
- From the Department of Chemistry and Biochemistry, New Mexico State University, Las Cruces, New Mexico 88003
| | - Stephanie Fullam
- From the Department of Chemistry and Biochemistry, New Mexico State University, Las Cruces, New Mexico 88003
| | - Hridindu Roychowdhury
- From the Department of Chemistry and Biochemistry, New Mexico State University, Las Cruces, New Mexico 88003
| | - Erik T Yukl
- From the Department of Chemistry and Biochemistry, New Mexico State University, Las Cruces, New Mexico 88003
| |
Collapse
|
13
|
Sankari S, O'Brian MR. The Bradyrhizobium japonicum Ferrous Iron Transporter FeoAB Is Required for Ferric Iron Utilization in Free Living Aerobic Cells and for Symbiosis. J Biol Chem 2016; 291:15653-62. [PMID: 27288412 PMCID: PMC4957049 DOI: 10.1074/jbc.m116.734129] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Revised: 06/07/2016] [Indexed: 01/02/2023] Open
Abstract
The bacterium Bradyrhizobium japonicum USDA110 does not synthesize siderophores for iron utilization in aerobic environments, and the mechanism of iron uptake within symbiotic soybean root nodules is unknown. An mbfA bfr double mutant defective in iron export and storage activities cannot grow aerobically in very high iron medium. Here, we found that this phenotype was suppressed by loss of function mutations in the feoAB operon encoding ferrous (Fe(2+)) iron uptake proteins. Expression of the feoAB operon genes was elevated under iron limitation, but mutants defective in either gene were unable to grow aerobically over a wide external ferric (Fe(3+)) iron (FeCl3) concentration range. Thus, FeoAB accommodates iron acquisition under iron limited and iron replete conditions. Incorporation of radiolabel from either (55)Fe(2+) or (59)Fe(3+) into cells was severely defective in the feoA and feoB strains, suggesting Fe(3+) reduction to Fe(2+) prior to traversal across the cytoplasmic membrane by FeoAB. The feoA or feoB deletion strains elicited small, ineffective nodules on soybean roots, containing few bacteria and lacking nitrogen fixation activity. A feoA(E40K) mutant contained partial iron uptake activity in culture that supported normal growth and established an effective symbiosis. The feoA(E40K) strain had partial iron uptake activity in situ within nodules and in isolated cells, indicating that FeoAB is the iron transporter in symbiosis. We conclude that FeoAB supports iron acquisition under limited conditions of soil and in the iron-rich environment of a symbiotic nodule.
Collapse
Affiliation(s)
- Siva Sankari
- From the Department of Biochemistry, State University of New York, Buffalo, New York 14214
| | - Mark R O'Brian
- From the Department of Biochemistry, State University of New York, Buffalo, New York 14214
| |
Collapse
|
14
|
Patel SJ, Lewis BE, Long JE, Nambi S, Sassetti CM, Stemmler TL, Argüello JM. Fine-tuning of Substrate Affinity Leads to Alternative Roles of Mycobacterium tuberculosis Fe2+-ATPases. J Biol Chem 2016; 291:11529-39. [PMID: 27022029 DOI: 10.1074/jbc.m116.718239] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2016] [Indexed: 11/06/2022] Open
Abstract
Little is known about iron efflux transporters within bacterial systems. Recently, the participation of Bacillus subtilis PfeT, a P1B4-ATPase, in cytoplasmic Fe(2+) efflux has been proposed. We report here the distinct roles of mycobacterial P1B4-ATPases in the homeostasis of Co(2+) and Fe(2+) Mutation of Mycobacterium smegmatis ctpJ affects the homeostasis of both ions. Alternatively, an M. tuberculosis ctpJ mutant is more sensitive to Co(2+) than Fe(2+), whereas mutation of the homologous M. tuberculosis ctpD leads to Fe(2+) sensitivity but no alterations in Co(2+) homeostasis. In vitro, the three enzymes are activated by both Fe(2+) and Co(2+) and bind 1 eq of either ion at their transport site. However, equilibrium binding affinities and activity kinetics show that M. tuberculosis CtpD has higher affinity for Fe(2+) and twice the Fe(2+)-stimulated activity than the CtpJs. These parameters are paralleled by a lower activation and affinity for Co(2+) Analysis of Fe(2+) and Co(2+) binding to CtpD by x-ray absorption spectroscopy shows that both ions are five- to six-coordinate, constrained within oxygen/nitrogen environments with similar geometries. Mutagenesis studies suggest the involvement of invariant Ser, His, and Glu residues in metal coordination. Interestingly, replacement of the conserved Cys at the metal binding pocket leads to a large reduction in Fe(2+) but not Co(2+) binding affinity. We propose that CtpJ ATPases participate in the control of steady state Fe(2+) levels. CtpD, required for M. tuberculosis virulence, is a high affinity Fe(2+) transporter involved in the rapid response to iron dyshomeostasis generated upon redox stress.
Collapse
Affiliation(s)
- Sarju J Patel
- From the Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, Worcester, Massachusetts 01609
| | - Brianne E Lewis
- Department of Pharmaceutical Sciences, Wayne State University, Detroit, Michigan 48201
| | - Jarukit E Long
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, Massachusetts 01655, and
| | - Subhalaxmi Nambi
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, Massachusetts 01655, and
| | - Christopher M Sassetti
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, Massachusetts 01655, and Howard Hughes Medical Institute, Chevy Chase, Maryland 20815
| | - Timothy L Stemmler
- Department of Pharmaceutical Sciences, Wayne State University, Detroit, Michigan 48201
| | - José M Argüello
- From the Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, Worcester, Massachusetts 01609,
| |
Collapse
|
15
|
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] [What about the content of this article? (0)] [Affiliation(s)] [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.
Collapse
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.
| |
Collapse
|
16
|
Abstract
The possibility of a “post-antibiotic era” in the 21st century, in which common infections may kill, has prompted research into radically new antimicrobials. CO-releasing molecules (CORMs), mostly metal carbonyl compounds, originally developed for therapeutic CO delivery in animals, are potent antimicrobial agents. Certain CORMs inhibit growth and respiration, reduce viability, and release CO to intracellular hemes, as predicted, but their actions are more complex, as revealed by transcriptomic datasets and modeling. Progress is hindered by difficulties in detecting CO release intracellularly, limited understanding of the biological chemistry of CO reactions with non-heme targets, and the cytotoxicity of some CORMs to mammalian cells.
Collapse
Affiliation(s)
- Lauren K Wareham
- From the Department of Molecular Biology and Biotechnology, The University of Sheffield, Sheffield S10 2TN, United Kingdom
| | - Robert K Poole
- From the Department of Molecular Biology and Biotechnology, The University of Sheffield, Sheffield S10 2TN, United Kingdom
| | - Mariana Tinajero-Trejo
- From the Department of Molecular Biology and Biotechnology, The University of Sheffield, Sheffield S10 2TN, United Kingdom
| |
Collapse
|