1
|
Mahim A, Petering DH. Zinc trafficking to apo-Zn-proteins 2. Cellular interplay of proteome, metallothionein, and glutathione. Metallomics 2022; 14:mfac081. [PMID: 36214409 PMCID: PMC9646480 DOI: 10.1093/mtomcs/mfac081] [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] [Received: 08/12/2022] [Accepted: 10/07/2022] [Indexed: 11/12/2022]
Abstract
A recent study investigated the impact of glutathione (GSH) on the transfer of zinc (Zn) from proteome to apo-carbonic anhydrase. Here, we probed the requirement of glutathione for zinc trafficking in LLC-PK1 pig kidney epithelial cells. Depletion of GSH by at least 95% left cells viable and able to divide and synthesize Zn-proteins at the control rate over a 48-h period. Loss of GSH stimulated the accumulation of 2.5x the normal concentration of cellular Zn. According to gel filtration chromatography, differential centrifugal filtration, and spectrofluorimetry with TSQ, the extra Zn was distributed between the proteome and metallothionein (MT). To test the functionality of proteome and/or MT as sources of Zn for the constitution of Zn-proteins, GSH-deficient cells were incubated with CaEDTA to isolate them from their normal source of nutrient Zn. Control cells plus CaEDTA stopped dividing; GSH-depleted cells plus CaEDTA continued to divide at ∼40% the rate of GSH deficient cells. Evidently, proteome and/or MT served as a functional source of Zn for generating Zn-proteins. In vitro insertion of Zn bound to proteome into apo-carbonic anhydrase occurred faster at larger concentrations of Zn bound to proteome. These results support the hypothesis that enhanced transport of Zn into cells drives the conversion of apo-Zn-proteins to Zn-proteins by mass action. Similar results were also obtained with human Jurkat T lymphocyte epithelial cells. This study reveals a powerful new model for studying the chemistry of Zn trafficking, including transport processes, involvement of intermediate binding sites, and constitution of Zn-proteins.
Collapse
Affiliation(s)
- Afsana Mahim
- PPD, Biopharmaceutical Department, Middleton WI, USA
| | - David H Petering
- Department of Chemistry and Biochemistry, University of Wisconsin-Milwaukee, 3210 N. Cramer, Milwaukee, Wisconsin 53201, USA
| |
Collapse
|
2
|
López-Solís L, Companys E, Puy J, Blindauer CA, Galceran J. Direct determination of free Zn concentration in samples of biological interest. Anal Chim Acta 2022; 1229:340195. [DOI: 10.1016/j.aca.2022.340195] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Revised: 06/25/2022] [Accepted: 07/19/2022] [Indexed: 11/01/2022]
|
3
|
Mahim A, Karim M, Petering DH. Zinc trafficking 1. Probing the roles of proteome, metallothionein, and glutathione. Metallomics 2021; 13:6362609. [PMID: 34472617 DOI: 10.1093/mtomcs/mfab055] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Accepted: 08/18/2021] [Indexed: 11/13/2022]
Abstract
The cellular trafficking pathways that conduct zinc to its sites of binding in functional proteins remain largely unspecified. In this study, the hypothesis was investigated that nonspecific proteomic binding sites serve as intermediates in zinc trafficking. Proteome from pig kidney LLC-PK1 cells contains a large concentration of such sites, displaying an average conditional stability constant of 1010-11, that are dependent on sulfhydryl ligands to achieve high-affinity binding of zinc. As a result, the proteome competes effectively with induced metallothionein for Zn2+ upon exposure of cells to extracellular Zn2+ or during in vitro direct competition. The reaction of added Zn2+ bound to proteome with apo-carbonic anhydrase was examined as a potential model for intracellular zinc trafficking. The extent of this reaction was inversely dependent upon proteome concentration and under cellular conditions thought to be negligible. The rate of reaction was strictly first order in both Zn2+ and apo-carbonic anhydrase, and also considered to be insignificant in cells. Adding the low molecular weight fraction of cell supernatant to the proteome markedly enhanced the speed of this reaction, a phenomenon dependent on the presence of glutathione (GSH). In agreement, inclusion of GSH accelerated the reaction in a concentration-dependent manner. The implications of abundant high-affinity binding sites for Zn2+ within the proteome are considered in relation to their interaction with GSH in the efficient delivery of Zn2+ to functional binding sites and in the operation of fluorescent zinc sensors as a tool to observe zinc trafficking.
Collapse
Affiliation(s)
- Afsana Mahim
- Department of Chemistry and Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
| | - Mohammad Karim
- Department of Cell and Gene Therapy, PPD, Middleton, WI, USA
| | - David H Petering
- Department of Chemistry and Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
| |
Collapse
|
4
|
Theoretical Three-Dimensional Zinc Complexes with Glutathione, Amino Acids and Flavonoids. STRESSES 2021. [DOI: 10.3390/stresses1030011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Zinc plays an important role in the regulation of many cellular functions; it is a signaling molecule involved in the transduction of several cascades in response to intra and extracellular stimuli. Labile zinc is a small fraction of total intracellular zinc, that is loosely bound to proteins and is easily interchangeable. At the cellular level, several molecules can bind labile zinc and promote its passage across lipophilic membranes. Such molecules are known as ionophores. Several of these compounds are known in the scientific literature, but most of them can be harmful to human health and are therefore not allowed for medical use. We here performed a theoretical three-dimensional study of known zinc ionophores, together with a computational energetic study and propose that some dietary flavonoids, glutathione and amino acids could form zinc complexes and facilitate the transport of zinc, with the possible biological implications and potential health benefits of these natural compounds. The study is based on obtaining a molecular conformational structure of the zinc complexes with the lowest possible energy content. The discovery of novel substances that act as zinc ionophores is an attractive research topic that offers exciting opportunities in medicinal chemistry. We propose that these novel complexes could be promising candidates for drug design to provide new solutions for conditions and diseases related to zinc deficiency or impairment derived from the dysregulation of this important metal.
Collapse
|
5
|
Ghazvini Zadeh EH, Huang Z, Xia J, Li D, Davidson HW, Li WH. ZIGIR, a Granule-Specific Zn 2+ Indicator, Reveals Human Islet α Cell Heterogeneity. Cell Rep 2021; 32:107904. [PMID: 32668245 DOI: 10.1016/j.celrep.2020.107904] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 05/04/2020] [Accepted: 06/23/2020] [Indexed: 02/07/2023] Open
Abstract
Numerous mammalian cells contain abundant Zn2+ in their secretory granules, yet available Zn2+ sensors lack the desired specificity and sensitivity for imaging granular Zn2+. We developed a fluorescent zinc granule indicator, ZIGIR, that possesses numerous desired properties for live cell imaging, including >100-fold fluorescence enhancement, membrane permeability, and selective enrichment to acidic granules. The combined advantages endow ZIGIR with superior sensitivity and specificity for imaging granular Zn2+. ZIGIR enables separation of heterogenous β cells based on their insulin content and sorting of mouse islets into pure α cells and β cells. In human islets, ZIGIR facilitates sorting of endocrine cells into highly enriched α cells and β cells, reveals unexpectedly high Zn2+ activity in the somatostatin granule of some δ cells, and uncovers variation in the glucagon content among human α cells. We expect broad applications of ZIGIR for studying Zn2+ biology and Zn2+-rich secretory granules and for engineering β cells with high insulin content for treating diabetes.
Collapse
Affiliation(s)
- Ebrahim H Ghazvini Zadeh
- Departments of Cell Biology and Biochemistry, University of Texas Southwestern Medical Center, 6000 Harry Hines Blvd., Dallas, TX 75390-9039, USA
| | - ZhiJiang Huang
- Departments of Cell Biology and Biochemistry, University of Texas Southwestern Medical Center, 6000 Harry Hines Blvd., Dallas, TX 75390-9039, USA
| | - Jing Xia
- Departments of Cell Biology and Biochemistry, University of Texas Southwestern Medical Center, 6000 Harry Hines Blvd., Dallas, TX 75390-9039, USA; Department of Biological Sciences, The University of Texas at Dallas, Richardson, TX, USA
| | - Daliang Li
- Departments of Cell Biology and Biochemistry, University of Texas Southwestern Medical Center, 6000 Harry Hines Blvd., Dallas, TX 75390-9039, USA
| | - Howard W Davidson
- Barbara Davis Center for Diabetes, University of Colorado Denver Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Wen-Hong Li
- Departments of Cell Biology and Biochemistry, University of Texas Southwestern Medical Center, 6000 Harry Hines Blvd., Dallas, TX 75390-9039, USA.
| |
Collapse
|
6
|
Zastrow ML, Huang Z, Lippard SJ. HaloTag-Based Hybrid Targetable and Ratiometric Sensors for Intracellular Zinc. ACS Chem Biol 2020; 15:396-406. [PMID: 31917534 DOI: 10.1021/acschembio.9b00872] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
We report a new series of small molecule-protein hybrid zinc sensors that combine genetic targetability with the spectroscopic profile of synthetic fluorophores. We functionalized the zinc sensor ZinPyr-1 (ZP1) with a chloroalkane linker (ZP1-12Cl) that reacts specifically with the engineered protein HaloTag. The resulting construct, ZP1-HaloTag, binds zinc ions with a threefold fluorescence enhancement. Through exploitation of the protein synthesis machinery of live cells, the HaloTag protein component was expressed, and the ZP1-HaloTag hybrid was assembled upon bath application of ZP1-12Cl. After fusion of HaloTag with targeting peptides or proteins, the resulting hybrid sensor could be directed to specific subcellular locales, including the nucleus, mitochondrial outer membrane, and endoplasmic reticulum. Furthermore, HaloTag was linked with the red fluorescent protein mCherry, permitting formation of a two-fluorophore system that provides not only targetable but also ratiometric sensing of cellular zinc. This system reversibly detects both exogenous and endogenous mobile Zn2+ in response to reactive nitrogen species in live HeLa cells. HaloTag-based hybrid zinc sensors offer new opportunities for visualizing and quantifying biological mobile zinc at discrete subcellular compartments.
Collapse
Affiliation(s)
- Melissa L Zastrow
- Department of Chemistry , Massachusetts Institute of Technology , Cambridge , Massachusetts 02139 , United States
| | - Zhen Huang
- Department of Chemistry , Massachusetts Institute of Technology , Cambridge , Massachusetts 02139 , United States
| | - Stephen J Lippard
- Department of Chemistry , Massachusetts Institute of Technology , Cambridge , Massachusetts 02139 , United States
| |
Collapse
|
7
|
Abstract
The cellular constitution of Zn-proteins and Zn-dependent signaling depend on the capacity of Zn2+ to find specific binding sites in the face of a plethora of other high affinity ligands. The most prominent of these is metallothionein (MT). It serves as a storage site for Zn2+ under various conditions, and has chemical properties that support a dynamic role for MT in zinc trafficking. Consistent with these characteristics, changing the availability of zinc for cells and tissues causes rapid alteration of zinc bound to MT. Nevertheless, zinc trafficking occurs in metallothionein-null animals and cells, hypothetically making use of proteomic binding sites to mediate the intracellular movements of zinc. Like metallothionein, the proteome contains a large concentration of proteins that strongly coordinate zinc. In this environment, free Zn2+ may be of little significance. Instead, this review sets forth the basis for the hypothesis that components of the proteome and MT jointly provide the platform for zinc trafficking.
Collapse
Affiliation(s)
- David H Petering
- Department of Chemistry and Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, WI 53217, USA.
| | - Afsana Mahim
- Department of Chemistry and Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, WI 53217, USA.
| |
Collapse
|