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Munzone A, Pujol M, Tamhankar A, Joseph C, Mazurenko I, Réglier M, Jannuzzi SAV, Royant A, Sicoli G, DeBeer S, Orio M, Simaan AJ, Decroos C. Integrated Experimental and Theoretical Investigation of Copper Active Site Properties of a Lytic Polysaccharide Monooxygenase from Serratia marcescens. Inorg Chem 2024; 63:11063-11078. [PMID: 38814816 DOI: 10.1021/acs.inorgchem.4c00602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2024]
Abstract
In this paper, we employed a multidisciplinary approach, combining experimental techniques and density functional theory (DFT) calculations to elucidate key features of the copper coordination environment of the bacterial lytic polysaccharide monooxygenase (LPMO) from Serratia marcescens (SmAA10). The structure of the holo-enzyme was successfully obtained by X-ray crystallography. We then determined the copper(II) binding affinity using competing ligands and observed that the affinity of the histidine brace ligands for copper is significantly higher than previously described. UV-vis, advanced electron paramagnetic resonance (EPR), and X-ray absorption spectroscopy (XAS) techniques, including high-energy resolution fluorescence detected (HERFD) XAS, were further used to gain insight into the copper environment in both the Cu(II) and Cu(I) redox states. The experimental data were successfully rationalized by DFT models, offering valuable information on the electronic structure and coordination geometry of the copper center. Finally, the Cu(II)/Cu(I) redox potential was determined using two different methods at ca. 350 mV vs NHE and rationalized by DFT calculations. This integrated approach not only advances our knowledge of the active site properties of SmAA10 but also establishes a robust framework for future studies of similar enzymatic systems.
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Affiliation(s)
- Alessia Munzone
- Aix Marseille Univ, CNRS, Centrale Méditerranée, iSm2, Marseille 13013, France
| | - Manon Pujol
- Aix Marseille Univ, CNRS, Centrale Méditerranée, iSm2, Marseille 13013, France
| | - Ashish Tamhankar
- Max Planck Institute for Chemical Energy Conversion, Stiftstr. 34-36, Mülheim an der Ruhr 45470, Germany
| | - Chris Joseph
- Max Planck Institute for Chemical Energy Conversion, Stiftstr. 34-36, Mülheim an der Ruhr 45470, Germany
| | | | - Marius Réglier
- Aix Marseille Univ, CNRS, Centrale Méditerranée, iSm2, Marseille 13013, France
| | - Sergio A V Jannuzzi
- Max Planck Institute for Chemical Energy Conversion, Stiftstr. 34-36, Mülheim an der Ruhr 45470, Germany
| | - Antoine Royant
- Université Grenoble Alpes, CNRS, CEA, Institut de Biologie Structurale (IBS), Grenoble 38000, France
- European Synchrotron Radiation Facility, Grenoble 38043, France
| | - Giuseppe Sicoli
- LASIRE UMR CNRS 8516, Université de Lille, Villeneuve-d'Arcy 59655, France
| | - Serena DeBeer
- Max Planck Institute for Chemical Energy Conversion, Stiftstr. 34-36, Mülheim an der Ruhr 45470, Germany
| | - Maylis Orio
- Aix Marseille Univ, CNRS, Centrale Méditerranée, iSm2, Marseille 13013, France
| | - A Jalila Simaan
- Aix Marseille Univ, CNRS, Centrale Méditerranée, iSm2, Marseille 13013, France
| | - Christophe Decroos
- Aix Marseille Univ, CNRS, Centrale Méditerranée, iSm2, Marseille 13013, France
- Department of Integrative Structural Biology, Université de Strasbourg, CNRS, INSERM, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Illkirch 67400, France
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2
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Jiang Z, Zhang C, Wang X, Ling Z, Chen Y, Guo Z, Liu Z. A Small-Molecule Ratiometric Photoacoustic Probe for the High-Spatiotemporal-Resolution Imaging of Copper(II) Dynamics in the Mouse Brain. Angew Chem Int Ed Engl 2024; 63:e202318340. [PMID: 38303099 DOI: 10.1002/anie.202318340] [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: 11/30/2023] [Revised: 01/22/2024] [Accepted: 02/01/2024] [Indexed: 02/03/2024]
Abstract
Copper dysmetabolism is associated with various neurodegenerative disorders, making high-spatiotemporal-resolution imaging of Cu2+ in the brain essential for understanding the underlying pathophysiological processes. Nevertheless, the current probes encounter obstacles in crossing the blood-brain barrier (BBB) and providing high-spatial-resolution in deep tissues. Herein, we present a photoacoustic probe capable of imaging Cu2+ dynamics in the mouse brain with high-spatiotemporal-resolution. The probe demonstrates selective ratiometric and reversible responses to Cu2+ , while also efficiently crossing the BBB. Using the probe as the imaging agent, we successfully visualized Cu2+ in the brain of Parkinson's disease (PD) model mouse with a remarkable micron-level resolution. The imaging results revealed a significant increase in Cu2+ levels in the cerebral cortex as PD progresses, highlighting the close association between Cu2+ alternations in the region and the disease. We also demonstrated that the probe can be used to monitor changes in Cu2+ distribution in the PD model mouse brain during L-dopa intervention. Mechanism studies suggest that the copper dyshomeostasis in the PD mouse brain was dominated by the expression levels of divalent metal transporter 1. The application of our probe in imaging Cu2+ dynamics in the mouse brain offers valuable insights into the copper-related molecular mechanisms underlying neurodegenerative diseases.
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Affiliation(s)
- Zhiyong Jiang
- College of Materials Science and Engineering, College of Science, Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, Nanjing Forestry University, Nanjing, 210037, China
- State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210093, China
| | - Changli Zhang
- School of Environmental Science, Nanjing Xiaozhuang University, Nanjing, 211171, China
| | - Xiaoqing Wang
- College of Materials Science and Engineering, College of Science, Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, Nanjing Forestry University, Nanjing, 210037, China
| | - Zongxin Ling
- Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, National Clinical Research Center for Infectious Diseases, the, First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, 310003, China
| | - Yuncong Chen
- State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210093, China
| | - Zijian Guo
- State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210093, China
| | - Zhipeng Liu
- College of Materials Science and Engineering, College of Science, Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, Nanjing Forestry University, Nanjing, 210037, China
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3
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Angeltveit CF, Várnai A, Eijsink VGH, Horn SJ. Enhancing enzymatic saccharification yields of cellulose at high solid loadings by combining different LPMO activities. BIOTECHNOLOGY FOR BIOFUELS AND BIOPRODUCTS 2024; 17:39. [PMID: 38461298 PMCID: PMC10924376 DOI: 10.1186/s13068-024-02485-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2024] [Accepted: 02/24/2024] [Indexed: 03/11/2024]
Abstract
BACKGROUND The polysaccharides in lignocellulosic biomass hold potential for production of biofuels and biochemicals. However, achieving efficient conversion of this resource into fermentable sugars faces challenges, especially when operating at industrially relevant high solid loadings. While it is clear that combining classical hydrolytic enzymes and lytic polysaccharide monooxygenases (LPMOs) is necessary to achieve high saccharification yields, exactly how these enzymes synergize at high solid loadings remains unclear. RESULTS An LPMO-poor cellulase cocktail, Celluclast 1.5 L, was spiked with one or both of two fungal LPMOs from Thermothielavioides terrestris and Thermoascus aurantiacus, TtAA9E and TaAA9A, respectively, to assess their impact on cellulose saccharification efficiency at high dry matter loading, using Avicel and steam-exploded wheat straw as substrates. The results demonstrate that LPMOs can mitigate the reduction in saccharification efficiency associated with high dry matter contents. The positive effect of LPMO inclusion depends on the type of feedstock and the type of LPMO and increases with the increasing dry matter content and reaction time. Furthermore, our results show that chelating free copper, which may leak out of the active site of inactivated LPMOs during saccharification, with EDTA prevents side reactions with in situ generated H2O2 and the reductant (ascorbic acid). CONCLUSIONS This study shows that sustaining LPMO activity is vital for efficient cellulose solubilization at high substrate loadings. LPMO cleavage of cellulose at high dry matter loadings results in new chain ends and thus increased water accessibility leading to decrystallization of the substrate, all factors making the substrate more accessible to cellulase action. Additionally, this work highlights the importance of preventing LPMO inactivation and its potential detrimental impact on all enzymes in the reaction.
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Affiliation(s)
- Camilla F Angeltveit
- Faculty of Chemistry, Biotechnology, and Food Science, Norwegian University of Life Sciences (NMBU), Ås, Norway
| | - Anikó Várnai
- Faculty of Chemistry, Biotechnology, and Food Science, Norwegian University of Life Sciences (NMBU), Ås, Norway
| | - Vincent G H Eijsink
- Faculty of Chemistry, Biotechnology, and Food Science, Norwegian University of Life Sciences (NMBU), Ås, Norway
| | - Svein J Horn
- Faculty of Chemistry, Biotechnology, and Food Science, Norwegian University of Life Sciences (NMBU), Ås, Norway.
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Puentes-Díaz N, Chaparro D, Reyes-Marquez V, Morales-Morales D, Flores-Gaspar A, Alí-Torres J. Computational Evaluation of the Potential Pharmacological Activity of Salen-Type Ligands in Alzheimer's Disease. J Alzheimers Dis 2024; 99:S383-S396. [PMID: 37483007 DOI: 10.3233/jad-230542] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/25/2023]
Abstract
Background Alzheimer's disease (AD) is the most common form of dementia representing from 60% to 70% of the cases globally. It is a multifactorial disease that, among its many pathological characteristics, has been found to provoke the metal ion dysregulation in the brain, along with an increase in the oxidative stress. There is proof that metallic complexes formed by the amyloid-β peptide (Aβ) and extraneuronal copper can catalyze the production of reactive oxygen species, leading to an increase in oxidative stress, promoting neuronal death. Due to this interaction, bioavailable copper has become an important redox active target to consider within the search protocols of multifunctional agents for AD's treatment. Objective In this study, we examined by using bioinformatics and electronic structure calculations the potential application of 44 salen-type copper chelating ligands and 12 further proposed molecules as possible multifunctional agents in the context of AD. Methods The candidates were evaluated by combining bioinformatic tools and electronic structure calculations, which allowed us to classify the molecules as potential antioxidants, redistributor-like compounds, and the newly proposed suppressor mechanism. Results This evaluation demonstrate that salen-type ligands exhibit properties suitable for interfering in the chain of copper-induced oxidative stress reactions present in AD and potential redistributor and suppressor activity for copper ions. Finally, a novel set of plausible candidates is proposed and evaluated. Conclusion According to the evaluated criteria, a subset of 13 salen-type candidates was found to exhibit promissory pharmacological properties in the AD framework and were classified according to three plausible action mechanisms.
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Affiliation(s)
- Nicolás Puentes-Díaz
- Departamento de Química, Universidad Nacionalde Colombia -Sede Bogotá, Bogotá, Colombia
| | - Diego Chaparro
- Departamento de Química, Universidad Nacionalde Colombia -Sede Bogotá, Bogotá, Colombia
- Departamento de Química, Universidad Militar Nueva Granada, Cajicá, Colombia
| | - Viviana Reyes-Marquez
- Departamentode Ciencias Químico-Biológicas, Universidad de Sonora, Luis Encinas y Rosales S/N, Hermosillo, México
| | - David Morales-Morales
- Instituto de Química, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, Ciudad de México, México
| | - Areli Flores-Gaspar
- Departamento de Química, Universidad Militar Nueva Granada, Cajicá, Colombia
| | - Jorge Alí-Torres
- Departamento de Química, Universidad Nacionalde Colombia -Sede Bogotá, Bogotá, Colombia
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Puentes-Díaz N, Chaparro D, Morales-Morales D, Alí-Torres J, Flores-Gaspar A. Pincer Ligands as Multifunctional Agents for Alzheimer's Copper Dysregulation and Oxidative Stress: A Computational Evaluation. Chempluschem 2023; 88:e202300405. [PMID: 37756039 DOI: 10.1002/cplu.202300405] [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: 07/30/2023] [Revised: 09/22/2023] [Accepted: 09/26/2023] [Indexed: 09/28/2023]
Abstract
Alzheimer's disease (AD) is the most common form of dementia worldwide, affecting millions of people around the globe. AD is characterized by different pathologies being beta-amyloid (Aβ) plaque formation, metal ion dysregulation, and oxidative stress (OS) central topics under investigation. Copper-Aβ complexes have been shown to induce catalytic hydrogen peroxide formation and increase OS in the brain leading to neuronal death. Pincer-type compounds are tridentate ligands that coordinate metals in a planar fashion whose properties can be tuned via group substitutions, giving rise to many possibilities in catalysis and drug discovery. In this work we evaluated the potential pharmaceutical activity of 26 pincer compounds in AD's copper ion-related oxidative stress framework. In this sense, four key aspects were considered: 1) Lipinski's rule of five, 2) blood-brain barrier permeation, 3) standard reduction potential (SRP) of the formed copper complexes, and 4) the ligand's affinity towards copper cations. The evaluation of these criteria was performed by means of bioinformatic tools and electronic structure calculations at the DFT level of theory. Our results suggest that two compounds from this set are potential antioxidant agents, whereas five of them are promissory distributor-like compounds in the context of AD.
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Affiliation(s)
- Nicolás Puentes-Díaz
- Department of Chemistry, Universidad Nacional de Colombia, Av. Cra. 30 #45-03, Bogotá
| | - Diego Chaparro
- Department of Chemistry, Universidad Nacional de Colombia, Av. Cra. 30 #45-03, Bogotá
- Department of Chemistry, Universidad Militar Nueva Granada, Kilómetro 2, vía Cajicá-Zipaquira, costado oriental, Cajicá, Colombia
| | - David Morales-Morales
- Institute of Chemistry, Universidad Nacional Autónoma de México, Ciudad de México, 04510, Mexico
| | - Jorge Alí-Torres
- Department of Chemistry, Universidad Nacional de Colombia, Av. Cra. 30 #45-03, Bogotá
| | - Areli Flores-Gaspar
- Department of Chemistry, Universidad Militar Nueva Granada, Kilómetro 2, vía Cajicá-Zipaquira, costado oriental, Cajicá, Colombia
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6
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Behar AE, Maayan G. A Peptoid-Chelator Selective to Cu 2+ That Can Extract Copper from Metallothionein-2 and Lead to the Production of ROS. Antioxidants (Basel) 2023; 12:2031. [PMID: 38136151 PMCID: PMC10741037 DOI: 10.3390/antiox12122031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2023] [Revised: 11/13/2023] [Accepted: 11/16/2023] [Indexed: 12/24/2023] Open
Abstract
Copper is an essential metal ion that is involved in critical cellular processes, but which can also exhibit toxic effects through its ability to catalyze reactive oxygen species (ROS) formation. Dysregulation of copper homeostasis has been implicated in the progression of several diseases, including cancer. A novel therapeutic approach, extensively studied in recent years, is to capitalize on the increased copper uptake and dependency exhibited by cancer cells and to promote copper-associated ROS production within the tumor microenvironment, leading to the apoptosis of cancer cells. Such an effect can be achieved by selectively chelating copper from copper-bearing metalloproteins in cancer cells, thereby forming a copper-chelator complex that produces ROS and, through this, induces oxidative stress and initiates apoptosis. Herein, we describe a peptoid chelator, TB, that is highly suitable to carry this task. Peptoids are N-substituted glycine oligomers that can be efficiently synthesized on a solid support and are also biocompatible; thus, they are considered promising drug candidates. We show, by rigorous spectroscopic techniques, that TB is not only selective for Cu(II) ions, but can also effectively extract copper from metallothionein-2, and the formed complex CuTB can promote ROS production. Our findings present a promising first example for the future development of peptoid-based chelators for applications in anti-cancer chelation therapy, highlighting the potential for the prospect of peptoid chelators as therapeutics.
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Affiliation(s)
| | - Galia Maayan
- Schulich Faculty of Chemistry, Technion-Israel Institute of Technology Technion City, Haifa 3200008, Israel
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7
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Diep P, Kell B, Yakunin A, Hilfinger A, Mahadevan R. Quantifying metal-binding specificity of CcNikZ-II from Clostridium carboxidivorans in the presence of competing metal ions. Anal Biochem 2023; 676:115182. [PMID: 37355028 DOI: 10.1016/j.ab.2023.115182] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2023] [Revised: 04/25/2023] [Accepted: 05/08/2023] [Indexed: 06/26/2023]
Abstract
Many proteins bind transition metal ions as cofactors to carry out their biological functions. Despite binding affinities for divalent transition metal ions being predominantly dictated by the Irving-Williams series for wild-type proteins, in vivo metal ion binding specificity is ensured by intracellular mechanisms that regulate free metal ion concentrations. However, a growing area of biotechnology research considers the use of metal-binding proteins in vitro to purify specific metal ions from wastewater, where specificity is dictated by the protein's metal binding affinities. A goal of metalloprotein engineering is to modulate these affinities to improve a protein's specificity towards a particular metal; however, the quantitative relationship between the affinities and the equilibrium metal-bound protein fractions depends on the underlying binding mechanisms. Here we demonstrate a high-throughput intrinsic tryptophan fluorescence quenching method to validate binding models in multi-metal solutions for CcNikZ-II, a nickel-binding protein from Clostridium carboxidivorans. Using our validated models, we quantify the relationship between binding affinity and specificity in different classes of metal-binding models for CcNikZ-II. We further illustrate the potential relevance of data-informed models to predicting engineering targets for improved specificity.
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Affiliation(s)
- Patrick Diep
- BioZone Centre for Applied Bioscience and Bioengineering, Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, ON, Canada; Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA, USA.
| | - Brayden Kell
- Department of Physics, University of Toronto, Toronto, ON, Canada; Department of Chemical and Physical Sciences, University of Toronto Mississauga, Mississauga, ON, Canada; Department of Molecular Biosciences, Northwestern University, Evanston, IL, USA; NSF-Simons Center for Quantitative Biology, Northwestern University, Evanston, IL, USA
| | - Alexander Yakunin
- BioZone Centre for Applied Bioscience and Bioengineering, Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, ON, Canada; Centre for Environmental Biotechnology, School of Natural Sciences, Bangor University, Bangor, Gwynedd, UK
| | - Andreas Hilfinger
- Department of Physics, University of Toronto, Toronto, ON, Canada; Department of Chemical and Physical Sciences, University of Toronto Mississauga, Mississauga, ON, Canada; Department of Mathematics, University of Toronto, Toronto, ON, Canada; Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada
| | - Radhakrishnan Mahadevan
- BioZone Centre for Applied Bioscience and Bioengineering, Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, ON, Canada; Institute for Biomedical Engineering, University of Toronto, Toronto, ON, Canada
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8
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Maares M, Haupt A, Schüßler C, Kulike-Koczula M, Hackler J, Keil C, Mohr I, Schomburg L, Süssmuth RD, Zischka H, Merle U, Haase H. A fluorometric assay to determine labile copper(II) ions in serum. Sci Rep 2023; 13:12807. [PMID: 37550465 PMCID: PMC10406877 DOI: 10.1038/s41598-023-39841-9] [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: 04/19/2023] [Accepted: 07/31/2023] [Indexed: 08/09/2023] Open
Abstract
Labile copper(II) ions (Cu2+) in serum are considered to be readily available for cellular uptake and to constitute the biologically active Cu2+ species in the blood. It might also be suitable to reflect copper dyshomeostasis during diseases such as Wilson's disease (WD) or neurological disorders. So far, no direct quantification method has been described to determine this small Cu2+ subset. This study introduces a fluorometric high throughput assay using the novel Cu2+ binding fluoresceine-peptide sensor FP4 (Kd of the Cu2+-FP4-complex 0.38 pM) to determine labile Cu2+ in human and rat serum. Using 96 human serum samples, labile Cu2+was measured to be 0.14 ± 0.05 pM, showing no correlation with age or other serum trace elements. No sex-specific differences in labile Cu2+ concentrations were noted, in contrast to the total copper levels in serum. Analysis of the effect of drug therapy on labile Cu2+ in the sera of 19 patients with WD showed a significant decrease in labile Cu2+ following copper chelation therapy, suggesting that labile Cu2+ may be a specific marker of disease status and that the assay could be suitable for monitoring treatment progress.
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Affiliation(s)
- Maria Maares
- Department of Food Chemistry and Toxicology, Technische Universität Berlin, Straße des 17. Juni 135, 10623, Berlin, Germany
- TraceAge-DFG Research Unit on Interactions of Essential Trace Elements in Healthy and Diseased Elderly, Potsdam-Berlin-Jena, Germany
| | - Alessia Haupt
- Department of Food Chemistry and Toxicology, Technische Universität Berlin, Straße des 17. Juni 135, 10623, Berlin, Germany
| | - Christoph Schüßler
- Department of Food Chemistry and Toxicology, Technische Universität Berlin, Straße des 17. Juni 135, 10623, Berlin, Germany
- TraceAge-DFG Research Unit on Interactions of Essential Trace Elements in Healthy and Diseased Elderly, Potsdam-Berlin-Jena, Germany
| | - Marcel Kulike-Koczula
- Department of Organic and Biological Chemistry, Technische Universität Berlin, Straße des 17. Juni 135, 10623, Berlin, Germany
| | - Julian Hackler
- TraceAge-DFG Research Unit on Interactions of Essential Trace Elements in Healthy and Diseased Elderly, Potsdam-Berlin-Jena, Germany
- Institute for Experimental Endocrinology, Berlin Institute of Health, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, 10115, Berlin, Germany
| | - Claudia Keil
- Department of Food Chemistry and Toxicology, Technische Universität Berlin, Straße des 17. Juni 135, 10623, Berlin, Germany
| | - Isabelle Mohr
- Department of Internal Medicine IV, University Hospital Heidelberg, 69120, Heidelberg, Germany
| | - Lutz Schomburg
- TraceAge-DFG Research Unit on Interactions of Essential Trace Elements in Healthy and Diseased Elderly, Potsdam-Berlin-Jena, Germany
- Institute for Experimental Endocrinology, Berlin Institute of Health, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, 10115, Berlin, Germany
| | - Roderich D Süssmuth
- Department of Organic and Biological Chemistry, Technische Universität Berlin, Straße des 17. Juni 135, 10623, Berlin, Germany
| | - Hans Zischka
- Institute of Molecular Toxicology and Pharmacology, Helmholtz Center Munich, German Research Center for Environmental Health, Ingolstaedter Landstrasse 1, 85764, Neuherberg, Germany
- School of Medicine, Institute of Toxicology and Environmental Hygiene, Technical University Munich, Biedersteiner Strasse 29, 80802, Munich, Germany
| | - Uta Merle
- Department of Internal Medicine IV, University Hospital Heidelberg, 69120, Heidelberg, Germany
| | - Hajo Haase
- Department of Food Chemistry and Toxicology, Technische Universität Berlin, Straße des 17. Juni 135, 10623, Berlin, Germany.
- TraceAge-DFG Research Unit on Interactions of Essential Trace Elements in Healthy and Diseased Elderly, Potsdam-Berlin-Jena, Germany.
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9
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Zimmeter K, Vileno B, Platas-Iglesias C, Vinjamuri B, Sour A, Faller P. Derivatization of the Peptidic Xxx-Zzz-His Motif toward a Ligand with Attomolar Cu II Affinity under Maintaining High Selectivity and Fast Redox Silencing. Inorg Chem 2023. [PMID: 37269299 DOI: 10.1021/acs.inorgchem.3c00480] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Cu chelation in biological systems is of interest as a tool to study the metabolism of this essential metal or for applications in the case of diseases with a systemic or local Cu overload, such as Wilson's or Alzheimer's disease. The choice of the chelating agent must meet several criteria. Among others, affinities and kinetics of metal binding and related metal selectivity are important parameters of the chelators to consider. Here, we report on the synthesis and characterization of Cu-binding properties of two ligands, L1 and L2, derivatives of the well-known peptidic CuII-binding motif Xxx-Zzz-His (also called ATCUN), where CuII is bound to the N-terminal amine, two amidates, and the imidazole. In either L, the N-terminal amine was replaced with a pyridine, and for L2, one amide was replaced with an amine compared to Xxx-Zzz-His. In particular, L2 showed several interesting features, including a CuII-binding affinity with a log KDapp = -16.0 similar to that of EDTA and stronger than all reported ATCUN peptides. L2 showed high selectivity for CuII over ZnII and other essential metal ions, even under the challenging conditions of the presence of human serum albumin. Further, L2 showed fast and efficient CuII redox silencing qualities and CuII-L2 was stable in the presence of mM GSH concentrations. Benefitting the fact that L2 can be easily elongated on its peptide part by standard SPPS to add other functions, L2 has attractive properties as a CuII chelator for application in biological systems.
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Affiliation(s)
- Katharina Zimmeter
- Institut de Chimie (UMR 7177), Université de Strasbourg, CNRS, 4 Rue Blaise Pascal, 67000 Strasbourg, France
| | - Bertrand Vileno
- Institut de Chimie (UMR 7177), Université de Strasbourg, CNRS, 4 Rue Blaise Pascal, 67000 Strasbourg, France
| | - Carlos Platas-Iglesias
- Departamento de Química Fundamental, Universidade da Coruña, Campus da Zapateira, Rúa da Fraga 10, 15008 A Coruña, Spain
| | - Bharath Vinjamuri
- Institut de Chimie (UMR 7177), Université de Strasbourg, CNRS, 4 Rue Blaise Pascal, 67000 Strasbourg, France
| | - Angélique Sour
- Institut de Chimie (UMR 7177), Université de Strasbourg, CNRS, 4 Rue Blaise Pascal, 67000 Strasbourg, France
| | - Peter Faller
- Institut de Chimie (UMR 7177), Université de Strasbourg, CNRS, 4 Rue Blaise Pascal, 67000 Strasbourg, France
- Institut Universitaire de France (IUF), 1 rue Descartes, 75231 Paris, France
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10
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Schulte NB, Pushie MJ, Martinez A, Sendzik M, Escobedo M, Kuter K, Haas KL. Exploration of the Potential Role of Serum Albumin in the Delivery of Cu(I) to Ctr1. Inorg Chem 2023; 62:4021-4034. [PMID: 36826341 DOI: 10.1021/acs.inorgchem.2c03753] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/25/2023]
Abstract
Human serum albumin (HSA) is the major copper (Cu) carrier in blood. The majority of previous studies that have investigated Cu interactions with HSA have focused primarily on the Cu(II) oxidation state. Yet, cellular Cu uptake by the human copper transport protein (Ctr1), a plasma membrane-embedded protein responsible for Cu uptake into cells, requires Cu(I). Recent in vitro work has determined that reducing agents, such as the ascorbate present in blood, are sufficient to reduce the Cu(II)HSA complex to form Cu(I)HSA and that Cu(I) is bound to HSA with pM affinity. The biological accessibility of Cu(I)HSA suggests that HSA-bound Cu(I) may be an unappreciated form of Cu cargo and a key player in extracellular Cu trafficking. To better understand Cu trafficking by HSA, we sought to investigate the exchange of Cu(I) from HSA to a model peptide of the Cu-binding ectodomain of Ctr1. In this study, we used X-ray absorption near-edge spectroscopy to show that Cu(I) becomes more highly coordinated as increasing amounts of the Ctr1-14 model peptide are added to a solution of Cu(I)HSA. Extended X-ray absorption fine structure (EXAFS) spectroscopy was used to further characterize the interaction of Cu(I)HSA with Ctr1-14 by determining the ligands coordinating Cu(I) and their bond lengths. The EXAFS data support that some Cu(I) likely undergoes complete transfer from HSA to Ctr1-14. This finding of HSA interacting with and releasing Cu(I) to an ectodomain model peptide of Ctr1 suggests a mechanism by which HSA delivers Cu(I) to cells under physiological conditions.
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Affiliation(s)
- Natalie B Schulte
- Department of Chemistry, Duke University, Durham, North Carolina 27708, United States
| | - M Jake Pushie
- Department of Surgery, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E5, Canada
| | - Ana Martinez
- Department of Chemistry and Physics, Saint Mary's College, Notre Dame, Indiana 46556, United States
| | - Madison Sendzik
- Department of Chemistry and Physics, Saint Mary's College, Notre Dame, Indiana 46556, United States
| | - Maria Escobedo
- Department of Mathematics and Computer Science, Saint Mary's College, Notre Dame, Indiana 46556, United States
| | - Kristin Kuter
- Department of Mathematics and Computer Science, Saint Mary's College, Notre Dame, Indiana 46556, United States
| | - Kathryn L Haas
- Department of Chemistry, Duke University, Durham, North Carolina 27708, United States
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11
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Pham TL, Fazliev S, Baur P, Comba P, Thomas F. An Engineered β-Hairpin Peptide Forming Thermostable Complexes with Zn II , Ni II , and Cu II through a His 3 Site. Chembiochem 2023; 24:e202200588. [PMID: 36445805 PMCID: PMC10107957 DOI: 10.1002/cbic.202200588] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Revised: 11/28/2022] [Accepted: 11/28/2022] [Indexed: 11/30/2022]
Abstract
The three-dimensional structure of a peptide, which determines its function, can denature at elevated temperatures, in the presence of chaotropic reagents, or in organic solvents. These factors limit the applicability of peptides. Herein, we present an engineered β-hairpin peptide containing a His3 site that forms complexes with ZnII , NiII , and CuII . Circular dichroism spectroscopy shows that the peptide-metal complexes exhibit melting temperatures up to 80 °C and remain folded in 6 M guanidine hydrochloride as well as in organic solvents. Intrinsic fluorescence titration experiments were used to determine the dissociation constants of metal binding in the nano- to sub-nanomolar range. The coordination geometry of the peptide-CuII complex was studied by EPR spectroscopy, and a distorted square planar coordination geometry with weak interactions to axial ligands was revealed. Due to their impressive stability, the presented peptide-metal complexes open up interesting fields of application, such as the development of a new class of peptide-metal catalysts for stereoselective organic synthesis or the directed design of extremophilic β-sheet peptides.
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Affiliation(s)
- Truc Lam Pham
- Institute of Organic Chemistry, Heidelberg University, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany
| | - Sunnatullo Fazliev
- Institute of Organic Chemistry, Heidelberg University, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany.,Institute of Inorganic Chemistry, Heidelberg University, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany
| | - Philipp Baur
- Institute of Inorganic Chemistry, Heidelberg University, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany
| | - Peter Comba
- Institute of Inorganic Chemistry, Heidelberg University, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany.,Interdisciplinary Center for Scientific Computing (IWR), Heidelberg University, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany
| | - Franziska Thomas
- Institute of Organic Chemistry, Heidelberg University, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany
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12
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The Extracellular Electron Transport Pathway Reduces Copper for Sensing by the CopRS Two-Component System under Anaerobic Conditions in Listeria monocytogenes. J Bacteriol 2023; 205:e0039122. [PMID: 36622231 PMCID: PMC9879103 DOI: 10.1128/jb.00391-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The renowned antimicrobial activity of copper stems in part from its ability to undergo redox cycling between Cu1+/2+ oxidation states. Bacteria counter copper toxicity with a network of sensors that often include two-component signaling systems to direct transcriptional responses. As in typical two-component systems, ligand binding by the extracellular domain of the membrane bound copper sensor component leads to phosphorylation and activation of the cognate response regulator transcription factor. In Listeria monocytogenes, the plasmid-borne CopRS two-component system upregulates both copper resistance and lipoprotein remodeling genes upon copper challenge, but the oxidation state of copper bound by CopS is unknown. Herein, we show CopS utilizes a triad of key residues (His-His-Phe) that are predicted to be at the dimerization interface and that are analogous with the Escherichia coli CusS copper sensor to specifically bind Cu1+/Ag1+ and activate CopR transcription. We demonstrate Cu2+ only induces CopRS if first reduced by electron transport systems, as strains lacking menaquinone carriers were unable to respond to Cu2+. The flavin-dependent extracellular electron transport system (EET) was the main mechanism for metal reduction, capable of either generating inducing ligand (Cu2+ to Cu1+) or removing it by precipitation (Ag1+ to Ag0). We show that EET flux is directly proportional to the rate of Cu2+ reduction and that since EET activity is low under oxygenated conditions when a competing respiratory chain is operating, CopRS signaling in turn is activated only under anaerobic conditions. EET metal reduction thus sensitizes cells to copper while providing resistance to silver under anaerobic growth. IMPORTANCE Two-component extracellular copper sensing from the periplasm of Gram-negative bacteria has been well studied, but copper detection at the cell surface of the Gram-positive L. monocytogenes is less understood. Collectively, our results show that EET is most active under anaerobic conditions and reduces Cu2+ and Ag1+ to, respectively, generate or remove the monovalent ligands that directly bind to CopS and lead to the induction of lipoprotein remodeling genes. This reducing activity regulates CopRS signaling and links the upregulation of copper resistance genes with increasing EET flux. Our studies provide insight into how a two-component copper sensing system is integrated into a model monoderm Firmicute to take cues from the electron transport chain activity.
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13
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Osman D, Robinson NJ. Protein metalation in a nutshell. FEBS Lett 2023; 597:141-150. [PMID: 36124565 PMCID: PMC10087151 DOI: 10.1002/1873-3468.14500] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Revised: 09/15/2022] [Accepted: 09/15/2022] [Indexed: 01/14/2023]
Abstract
Metalation, the acquisition of metals by proteins, must avoid mis-metalation with tighter binding metals. This is illustrated by four selected proteins that require different metals: all show similar ranked orders of affinity for bioavailable metals, as described in a universal affinity series (the Irving-Williams series). Crucially, cellular protein metalation occurs in competition with other metal binding sites. The strength of this competition defines the intracellular availability of each metal: its magnitude has been estimated by calibrating a cells' set of DNA-binding, metal-sensing, transcriptional regulators. This has established that metal availabilities (as free energies for forming metal complexes) are maintained to the inverse of the universal series. The tightest binding metals are least available. With these availabilities, correct metalation is achieved.
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Affiliation(s)
- Deenah Osman
- Department of Biosciences, University of Durham, UK.,Department of Chemistry, University of Durham, UK
| | - Nigel J Robinson
- Department of Biosciences, University of Durham, UK.,Department of Chemistry, University of Durham, UK
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14
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Gupta S, Ward CL, Perera SS, Gowan CT, Dittrich TM, Allen MJ, McElmurry SP, Kodanko JJ. Development of a Highly Selective Ni(II) Chelator in Aqueous Solution. Inorg Chem 2022; 61:19492-19501. [PMID: 36414257 PMCID: PMC10391596 DOI: 10.1021/acs.inorgchem.2c03441] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The design, synthesis, and characterization of a novel Ni(II) chelator SG-20 is reported. SG-20 is selective in binding to Ni(II) versus other metal ions including Cu(II), Fe(II), Co(II), and Zn(II). At pH = 7.1, SG-20 binds Ni(II) with a Kd = 7.0 ± 0.4 μM. Job analysis indicates that SG-20 binds to both Ni(II) and Cu(II) with a 1:1 stoichiometry. Affinity of SG-20 for Ni(II) is pH dependent and decreases upon lowering to pH 4.0. A green solid was isolated from the reaction of SG-20 with NiCl2·6H2O in MeOH and characterized by X-ray photoelectron spectroscopy (XPS), electronic absorption and infrared (IR) spectroscopies, and mass spectrometry. Collectively, XPS and IR analysis revealed Ni-N and Ni-O interactions and a shift in C-O asymmetric and symmetric stretches consistent with Ni binding. Attempts to crystalize a mononuclear complex were unsuccessful, likely due to the Ni-SG-20 complex being in equilibrium with higher order species in solution. However, reaction of SG-20 with NiCl2·6H2O in water followed by slow evaporation yielded green crystals that were characterized by electronic absorption spectroscopy (λmax = 260 nm) and X-ray crystallography. These analyses revealed that SG-20 supports formation of a complex cluster containing six SG-20 ligands, 15 Ni(II), and three Na(I) centers, with two distinct types of Ni atoms in its outer and inner core. The nine Ni atoms present in the inner core were bound by oxo and carbonate bridges, whereas the six Ni atoms present in its outer shell were bound to N, O, and S donor atoms derived from SG-20. Overall, X-ray crystallographic analysis revealed that two chelator arms of SG-20 bind to one Ni(II) ion with an axial aqua ligand, whereas the third arm is free to interact with Ni ions within the central cluster, supporting the goal of Ni capture.
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Affiliation(s)
- Sayak Gupta
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, United States
| | - Cassandra L Ward
- Lumigen Instrument Center, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, United States
| | - S Sameera Perera
- Lumigen Instrument Center, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, United States
| | - Conor T Gowan
- Department of Civil and Environmental Engineering, Wayne State University, 5050 Anthony Wayne Dr, Detroit, Michigan 48202, United States
| | - Timothy M Dittrich
- Department of Civil and Environmental Engineering, Wayne State University, 5050 Anthony Wayne Dr, Detroit, Michigan 48202, United States
| | - Matthew J Allen
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, United States
| | - Shawn P McElmurry
- Department of Civil and Environmental Engineering, Wayne State University, 5050 Anthony Wayne Dr, Detroit, Michigan 48202, United States
| | - Jeremy J Kodanko
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, United States
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15
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Walencik PK. The redox-active Cu-FomA complex: the mode that provides coordination of Cu II/Cu I ions during the reduction/oxidation cycle. Dalton Trans 2022; 51:15515-15529. [PMID: 36165635 DOI: 10.1039/d2dt02398a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Colorectal cancer (CRC) is the third most commonly diagnosed form of cancer worldwide. Recent studies have indicated a strong correlation between microbial imbalance and the development of CRC. An abundance of Fusobacterium nucleatum, an anaerobic Gram-negative bacterium, has been considered a biomarker of CRC progression. Several investigations have also proposed that binding copper ions to various bacterial proteins enhances the CuII + e- ⇄ CuI redox cycle, which consequently promotes uncontrolled production of reactive oxygen species (ROS) and propels colorectal carcinogenesis. In this work, a multidisciplinary approach was applied to study the molecular relation of copper with the peptide models of FomA, a protein expressed by Fusobacterium nucleatum. The main goal was to investigate all the factors that tune the CuII + e- ⇄ CuI equilibrium. A linear peptide Fom1 (Ac-KGHGNGEEGTPTVHNE-NH2) and cyclic peptide Fom2 (cyclo-(KGHGNGEEGTPTVHNE)) were used as ligands. The coordination of CuI was deduced from the NMR data. The conditional dissociation constants KcondD defined the stability of CuI complexes. The electrochemical activity of CuII and CuI compounds was analysed using cyclic voltammetry. A quasi-reversible redox conversion CuII-peptide + e- ⇄ CuI-peptide was revealed for all studied systems. In the presence of ascorbic acid (HAsc), CuII complexes were immediately reduced to CuI species; however, their re-oxidation was kinetically sluggish. The HAsc-induced redox cycle provoked the metal-catalyzed oxidation (MCO) effect. That in the end prevented coordination of the re-appearing CuII ion to its initial binding site. The toxicity of the FomA-CuII/CuI complexes and their role in CRC progression were briefly discussed.
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Affiliation(s)
- Paulina K Walencik
- Faculty of Chemistry, University of Wroclaw, F. Joliot-Curie 14, 50-383 Wroclaw, Poland.
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16
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Xu J, Cotruvo JA. Reconsidering the czcD (NiCo) Riboswitch as an Iron Riboswitch. ACS BIO & MED CHEM AU 2022; 2:376-385. [PMID: 35996475 PMCID: PMC9389577 DOI: 10.1021/acsbiomedchemau.1c00069] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
![]()
Recent work has proposed
a new mechanism of bacterial iron regulation:
riboswitches that undergo a conformational change in response to FeII. The czcD (NiCo) riboswitch was initially
proposed to be specific for NiII and CoII, but
we recently showed via a czcD-based fluorescent sensor
that FeII is also a plausible physiological ligand for
this riboswitch class. Here, we provide direct evidence that this
riboswitch class responds to FeII. Isothermal titration
calorimetry studies of the native czcD riboswitches
from three organisms show no response to MnII, a weak response
to ZnII, and similar dissociation constants (∼1
μM) and conformational responses for FeII, CoII, and NiII. Only the iron response is in the physiological
concentration regime; the riboswitches’ responses to CoII, NiII, and ZnII require 103-, 105-, and 106-fold higher “free”
metal ion concentrations, respectively, than the typical availability
of those metal ions in cells. By contrast, the “Sensei”
RNA, recently claimed to be an iron-specific riboswitch, exhibits
no response to FeII. Our results demonstrate that iron
responsiveness is a conserved property of czcD riboswitches
and clarify that this is the only family of iron-responsive riboswitch
identified to date, setting the stage for characterization of their
physiological function.
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Affiliation(s)
- Jiansong Xu
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Center for RNA Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Joseph A. Cotruvo
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Center for RNA Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
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17
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Hu M, Zhang X, Hu C, Teng T, Tang QZ. A brief overview about the adipokine: Isthmin-1. Front Cardiovasc Med 2022; 9:939757. [PMID: 35958402 PMCID: PMC9360543 DOI: 10.3389/fcvm.2022.939757] [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: 05/09/2022] [Accepted: 06/30/2022] [Indexed: 11/24/2022] Open
Abstract
Isthmin-1 is a secreted protein with multiple capability; however, it truly attracts our attention since the definition as an adipokine in 2021, which exerts indispensable roles in various pathophysiological processes through the endocrine or autocrine manners. In this review, we summarize recent knowledge of isthmin-1, including its distribution, structure, receptor and potential function.
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Affiliation(s)
- Min Hu
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, China
- Hubei Key Laboratory of Metabolic and Chronic Diseases, Wuhan, China
| | - Xin Zhang
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, China
- Hubei Key Laboratory of Metabolic and Chronic Diseases, Wuhan, China
| | - Can Hu
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, China
- Hubei Key Laboratory of Metabolic and Chronic Diseases, Wuhan, China
| | - Teng Teng
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, China
- Hubei Key Laboratory of Metabolic and Chronic Diseases, Wuhan, China
| | - Qi-Zhu Tang
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, China
- Hubei Key Laboratory of Metabolic and Chronic Diseases, Wuhan, China
- *Correspondence: Qi-Zhu Tang
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18
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Vaccaro FA, Drennan CL. The role of nucleoside triphosphate hydrolase metallochaperones in making metalloenzymes. Metallomics 2022; 14:6575898. [PMID: 35485745 PMCID: PMC9164220 DOI: 10.1093/mtomcs/mfac030] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2022] [Accepted: 04/07/2022] [Indexed: 11/13/2022]
Abstract
Metalloenzymes catalyze a diverse set of challenging chemical reactions that are essential for life. These metalloenzymes rely on a wide range of metallocofactors, from single metal ions to complicated metallic clusters. Incorporation of metal ions and metallocofactors into apo-proteins often requires the assistance of proteins known as metallochaperones. Nucleoside triphosphate hydrolases (NTPases) are one important class of metallochaperones and are found widely distributed throughout the domains of life. These proteins use the binding and hydrolysis of nucleoside triphosphates, either adenosine triphosphate (ATP) or guanosine triphosphate (GTP), to carry out highly specific and regulated roles in the process of metalloenzyme maturation. Here, we review recent literature on NTPase metallochaperones and describe the current mechanistic proposals and available structural data. By using representative examples from each type of NTPase, we also illustrate the challenges in studying these complicated systems. We highlight open questions in the field and suggest future directions. This minireview is part of a special collection of articles in memory of Professor Deborah Zamble, a leader in the field of nickel biochemistry.
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Affiliation(s)
- Francesca A Vaccaro
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA, USA
| | - Catherine L Drennan
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA, USA.,Department of Biology, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA, USA.,Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA, USA
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19
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Roy M, Nath AK, Pal I, Dey SG. Second Sphere Interactions in Amyloidogenic Diseases. Chem Rev 2022; 122:12132-12206. [PMID: 35471949 DOI: 10.1021/acs.chemrev.1c00941] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Amyloids are protein aggregates bearing a highly ordered cross β structural motif, which may be functional but are mostly pathogenic. Their formation, deposition in tissues and consequent organ dysfunction is the central event in amyloidogenic diseases. Such protein aggregation may be brought about by conformational changes, and much attention has been directed toward factors like metal binding, post-translational modifications, mutations of protein etc., which eventually affect the reactivity and cytotoxicity of the associated proteins. Over the past decade, a global effort from different groups working on these misfolded/unfolded proteins/peptides has revealed that the amino acid residues in the second coordination sphere of the active sites of amyloidogenic proteins/peptides cause changes in H-bonding pattern or protein-protein interactions, which dramatically alter the structure and reactivity of these proteins/peptides. These second sphere effects not only determine the binding of transition metals and cofactors, which define the pathology of some of these diseases, but also change the mechanism of redox reactions catalyzed by these proteins/peptides and form the basis of oxidative damage associated with these amyloidogenic diseases. The present review seeks to discuss such second sphere modifications and their ramifications in the etiopathology of some representative amyloidogenic diseases like Alzheimer's disease (AD), type 2 diabetes mellitus (T2Dm), Parkinson's disease (PD), Huntington's disease (HD), and prion diseases.
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Affiliation(s)
- Madhuparna Roy
- School of Chemical Sciences, Indian Association for the Cultivation of Science, 2A & 2B, Raja S. C. Mullick Road, Jadavpur, Kolkata 700032, India
| | - Arnab Kumar Nath
- School of Chemical Sciences, Indian Association for the Cultivation of Science, 2A & 2B, Raja S. C. Mullick Road, Jadavpur, Kolkata 700032, India
| | - Ishita Pal
- School of Chemical Sciences, Indian Association for the Cultivation of Science, 2A & 2B, Raja S. C. Mullick Road, Jadavpur, Kolkata 700032, India
| | - Somdatta Ghosh Dey
- School of Chemical Sciences, Indian Association for the Cultivation of Science, 2A & 2B, Raja S. C. Mullick Road, Jadavpur, Kolkata 700032, India
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20
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Abstract
SignificanceZinc deficiency in the human population, a major public health concern, can also be a consequence of nutritional deficiency in protein uptake. The discovery that tryptophan metabolites 3-hydroxykynurenine and xanthurenic acid are major zinc-binding ligands in insect cells establishes the kynurenine pathway as a regulator of systemic zinc homeostasis. Many biological processes influenced by zinc and the kynurenine pathway, including the regulation of innate and acquired immune responses to viral infections, have not been studied in light of the direct molecular links revealed in this study.
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21
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Petit GA, Hong Y, Djoko KY, Whitten AE, Furlong EJ, McCoy AJ, Gulbis JM, Totsika M, Martin JL, Halili MA. The suppressor of copper sensitivity protein C from Caulobacter crescentus is a trimeric disulfide isomerase that binds copper(I) with subpicomolar affinity. ACTA CRYSTALLOGRAPHICA SECTION D STRUCTURAL BIOLOGY 2022; 78:337-352. [PMID: 35234148 PMCID: PMC8900818 DOI: 10.1107/s2059798322000729] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Accepted: 01/21/2022] [Indexed: 11/10/2022]
Abstract
The characterization of the suppressor of copper sensitivity protein C from C. crescentus is reported. The introduction of disulfide bonds into periplasmic proteins is a critical process in many Gram-negative bacteria. The formation and regulation of protein disulfide bonds have been linked to the production of virulence factors. Understanding the different pathways involved in this process is important in the development of strategies to disarm pathogenic bacteria. The well characterized disulfide bond-forming (DSB) proteins play a key role by introducing or isomerizing disulfide bonds between cysteines in substrate proteins. Curiously, the suppressor of copper sensitivity C proteins (ScsCs), which are part of the bacterial copper-resistance response, share structural and functional similarities with DSB oxidase and isomerase proteins, including the presence of a catalytic thioredoxin domain. However, the oxidoreductase activity of ScsC varies with its oligomerization state, which depends on a poorly conserved N-terminal domain. Here, the structure and function of Caulobacter crescentus ScsC (CcScsC) have been characterized. It is shown that CcScsC binds copper in the copper(I) form with subpicomolar affinity and that its isomerase activity is comparable to that of Escherichia coli DsbC, the prototypical dimeric bacterial isomerase. It is also reported that CcScsC functionally complements trimeric Proteus mirabilis ScsC (PmScsC) in vivo, enabling the swarming of P. mirabilis in the presence of copper. Using mass photometry and small-angle X-ray scattering (SAXS) the protein is demonstrated to be trimeric in solution, like PmScsC, and not dimeric like EcDsbC. The crystal structure of CcScsC was also determined at a resolution of 2.6 Å, confirming the trimeric state and indicating that the trimerization results from interactions between the N-terminal α-helical domains of three CcScsC protomers. The SAXS data analysis suggested that the protomers are dynamic, like those of PmScsC, and are able to sample different conformations in solution.
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22
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Walke G, Aupič J, Kashoua H, Janoš P, Meron S, Shenberger Y, Qasem Z, Gevorkyan-Airapetov L, Magistrato A, Ruthstein S. Dynamical interplay between the human high-affinity copper transporter hCtr1 and its cognate metal ion. Biophys J 2022; 121:1194-1204. [PMID: 35202609 PMCID: PMC9034245 DOI: 10.1016/j.bpj.2022.02.033] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 10/12/2021] [Accepted: 02/17/2022] [Indexed: 11/02/2022] Open
Abstract
Abnormal cellular copper levels have been clearly implicated in genetic diseases, cancer, and neurodegeneration. Ctr1, a high affinity copper transporter, is an homotrimeric integral membrane protein that provides the main route for cellular copper uptake. Together with a sophisticated copper transport system, Ctr1 regulates Cu(I) metabolism in eukaryotes. Despite its pivotal role in normal cell function, the molecular mechanism of copper uptake and transport via Ctr1 remains elusive. In this study, electron paramagnetic resonance (EPR), UV-visible spectroscopy, and all-atom simulations were employed to explore Cu(I) binding to full-length human Ctr1 (hCtr1), thereby elucidating how metal binding at multiple distinct sites affects the hCtr1 conformational dynamics. We demonstrate that each hCtr1 monomer binds up to 5 Cu(I) ions and that progressive Cu(I) binding triggers a marked structural rearrangement in the hCtr1 C-terminal region. The observed Cu(I)-induced conformational remodelling suggests that the C-terminal region may play a dual role, serving both as a channel gate and as a shuttle mediating the delivery of Cu ions from the extracellular hCtr1 selectivity filter to intracellular metallochaperones. Our findings thus contribute to a more complete understanding of the mechanism of hCtr1-mediated Cu(I) uptake and provide a conceptual basis for developing mechanism-based therapeutics for treating pathological conditions linked to de-regulated copper metabolism.
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Affiliation(s)
- Gulshan Walke
- Department of Chemistry and the Institute of Nanotechnology and Advanced Materials (BINA), Bar-Ilan University, Ramat-Gan, Israel, 5290002
| | - Jana Aupič
- Department National Research Council of Italy (CNR) - Institute of Material (IOM) c/o International School for Advanced Studies (SISSA), via Bonomea 265, 34136 Trieste, Italy
| | - Hadeel Kashoua
- Department of Chemistry and the Institute of Nanotechnology and Advanced Materials (BINA), Bar-Ilan University, Ramat-Gan, Israel, 5290002
| | - Pavel Janoš
- Department National Research Council of Italy (CNR) - Institute of Material (IOM) c/o International School for Advanced Studies (SISSA), via Bonomea 265, 34136 Trieste, Italy
| | - Shelly Meron
- Department of Chemistry and the Institute of Nanotechnology and Advanced Materials (BINA), Bar-Ilan University, Ramat-Gan, Israel, 5290002
| | - Yulia Shenberger
- Department of Chemistry and the Institute of Nanotechnology and Advanced Materials (BINA), Bar-Ilan University, Ramat-Gan, Israel, 5290002
| | - Zena Qasem
- Department of Chemistry and the Institute of Nanotechnology and Advanced Materials (BINA), Bar-Ilan University, Ramat-Gan, Israel, 5290002
| | - Lada Gevorkyan-Airapetov
- Department of Chemistry and the Institute of Nanotechnology and Advanced Materials (BINA), Bar-Ilan University, Ramat-Gan, Israel, 5290002
| | - Alessandra Magistrato
- Department National Research Council of Italy (CNR) - Institute of Material (IOM) c/o International School for Advanced Studies (SISSA), via Bonomea 265, 34136 Trieste, Italy.
| | - Sharon Ruthstein
- Department of Chemistry and the Institute of Nanotechnology and Advanced Materials (BINA), Bar-Ilan University, Ramat-Gan, Israel, 5290002.
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23
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López C, Delmonti J, Bonomo RA, Vila AJ. Deciphering the evolution of metallo-β-lactamases: a journey from the test tube to the bacterial periplasm. J Biol Chem 2022; 298:101665. [PMID: 35120928 DOI: 10.1016/j.jbc.2022.101665] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Revised: 01/13/2022] [Accepted: 01/16/2022] [Indexed: 12/20/2022] Open
Abstract
Understanding the evolution of metallo-β-lactamases (MBLs) is fundamental to deciphering the mechanistic basis of resistance to carbapenems in pathogenic and opportunistic bacteria. Presently, these MBL producing pathogens are linked to high rates of morbidity and mortality worldwide. However, the study of the biochemical and biophysical features of MBLs in vitro provides an incomplete picture of their evolutionary potential, since this limited and artificial environment disregards the physiological context where evolution and selection take place. Herein, we describe recent efforts aimed to address the evolutionary traits acquired by different clinical variants of MBLs in conditions mimicking their native environment (the bacterial periplasm) and considering whether they are soluble or membrane-bound proteins. This includes addressing the metal content of MBLs within the cell under zinc starvation conditions, and the context provided by different bacterial hosts that result in particular resistance phenotypes. Our analysis highlights recent progress bridging the gap between in vitro and in-cell studies.
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Affiliation(s)
- Carolina López
- Instituto de Biología Molecular y Celular de Rosario (IBR, CONICET-UNR), S2000EXF Rosario, Argentina
| | - Juliana Delmonti
- Instituto de Biología Molecular y Celular de Rosario (IBR, CONICET-UNR), S2000EXF Rosario, Argentina
| | - Robert A Bonomo
- Research Service, Veterans Affairs Northeast Ohio Healthcare System, Cleveland, Ohio, USA; Departments of Medicine, Pharmacology, Molecular Biology and Microbiology, Biochemistry, and Proteomics and Bioinformatics, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA; Medical Service and GRECC, Veterans Affairs Northeast Ohio Healthcare System, Cleveland, Ohio, USA; CWRU-Cleveland VAMC Center for Antimicrobial Resistance and Epidemiology (Case VA CARES), Cleveland, Ohio, USA
| | - Alejandro J Vila
- Instituto de Biología Molecular y Celular de Rosario (IBR, CONICET-UNR), S2000EXF Rosario, Argentina; CWRU-Cleveland VAMC Center for Antimicrobial Resistance and Epidemiology (Case VA CARES), Cleveland, Ohio, USA; Area Biofísica, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, S2002LRK Rosario, Argentina.
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24
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Yu L, Cao Q, Chen W, Yang N, Yang CG, Ji Q, Wu M, Bae T, Lan L. A novel copper-sensing two-component system for inducing Dsb gene expression in bacteria. Sci Bull (Beijing) 2022; 67:198-212. [PMID: 36546013 DOI: 10.1016/j.scib.2021.03.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Revised: 01/15/2021] [Accepted: 03/01/2021] [Indexed: 01/06/2023]
Abstract
In nature, bacteria must sense copper and tightly regulate gene expression to evade copper toxicity. Here, we identify a new copper-responsive two-component system named DsbRS in the important human pathogen Pseudomonas aeruginosa; in this system, DsbS is a sensor histidine kinase, and DsbR, its cognate response regulator, directly induces the transcription of genes involved in protein disulfide bond formation (Dsb) (i.e., the dsbDEG operon and dsbB). In the absence of copper, DsbS acts as a phosphatase toward DsbR, thus blocking the transcription of Dsb genes. In the presence of copper, the metal ion directly binds to the sensor domain of DsbS, and the Cys82 residue plays a critical role in this process. The copper-binding behavior appears to inhibit the phosphatase activity of DsbS, leading to the activation of DsbR. The copper resistance of the dsbRS knock-out mutant is restored by the ectopic expression of the dsbDEG operon, which is a DsbRS major target. Strikingly, cognates of the dsbRS-dsbDEG pair are widely distributed across eubacteria. In addition, a DsbR-binding site, which contains the consensus sequence 5'-TTA-N8-TTAA-3', is detected in the promoter region of dsbDEG homologs in these species. These findings suggest that the regulation of Dsb genes by DsbRS represents a novel mechanism by which bacterial cells cope with copper stress.
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Affiliation(s)
- Liang Yu
- University of Chinese Academy of Sciences, Beijing 100049, China; State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Qiao Cao
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Weizhong Chen
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Nana Yang
- University of Chinese Academy of Sciences, Beijing 100049, China; State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Cai-Guang Yang
- University of Chinese Academy of Sciences, Beijing 100049, China; State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China; School of Pharmaceutical Science and Technology, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou 310024, China
| | - Quanjiang Ji
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Min Wu
- Department of Biomedical Sciences, University of North Dakota, Grand Forks ND 58203-9037, USA
| | - Taeok Bae
- Department of Microbiology and Immunology, Indiana University School of Medicine-Northwest, Gary IN 46408, USA
| | - Lefu Lan
- University of Chinese Academy of Sciences, Beijing 100049, China; State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China; School of Pharmaceutical Science and Technology, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou 310024, China; NMPA Key Laboratory for Testing Technology of Pharmaceutical Microbiology, Shanghai Institute for Food and Drug Control, Shanghai 201203, China.
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25
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Abstract
The functions, purposes, and roles of metallothioneins have been the subject of speculations since the discovery of the protein over 60 years ago. This article guides through the history of investigations and resolves multiple contentions by providing new interpretations of the structure-stability-function relationship. It challenges the dogma that the biologically relevant structure of the mammalian proteins is only the one determined by X-ray diffraction and NMR spectroscopy. The terms metallothionein and thionein are ambiguous and insufficient to understand biological function. The proteins need to be seen in their biological context, which limits and defines the chemistry possible. They exist in multiple forms with different degrees of metalation and types of metal ions. The homoleptic thiolate coordination of mammalian metallothioneins is important for their molecular mechanism. It endows the proteins with redox activity and a specific pH dependence of their metal affinities. The proteins, therefore, also exist in different redox states of the sulfur donor ligands. Their coordination dynamics allows a vast conformational landscape for interactions with other proteins and ligands. Many fundamental signal transduction pathways regulate the expression of the dozen of human metallothionein genes. Recent advances in understanding the control of cellular zinc and copper homeostasis are the foundation for suggesting that mammalian metallothioneins provide a highly dynamic, regulated, and uniquely biological metal buffer to control the availability, fluctuations, and signaling transients of the most competitive Zn(II) and Cu(I) ions in cellular space and time.
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Affiliation(s)
- Artur Krężel
- Department of Chemical Biology, Faculty of Biotechnology, University of Wrocław, Wrocław 50-383, Poland
| | - Wolfgang Maret
- Departments of Biochemistry and Nutritional Sciences, School of Life Course Sciences, Faculty of Life Sciences and Medicine, King's College London, London SE1 9NH, U.K
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26
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Cziferszky M, Truong D, Hartinger CG, Gust R. Determination of Relative Stabilities of Metal-Peptide Bonds in the Gas Phase. Chemistry 2021; 27:16401-16406. [PMID: 34554615 PMCID: PMC9298285 DOI: 10.1002/chem.202102385] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Indexed: 11/09/2022]
Abstract
Understanding binding site preferences in biological systems as well as affinities to binding partners is a crucial aspect in metallodrug development. We here present a mass spectrometry‐based method to compare relative stabilities of metal‐peptide adducts in the gas phase. Angiotensin 1 and substance P were used as model peptides. Incubation with isostructural N‐heterocyclic carbene (NHC) complexes of RuII, OsII, RhIII, and IrIII led to the formation of various adducts, which were subsequently studied by energy‐resolved fragmentation experiments. The gas‐phase stability of the metal‐peptide bonds depended on the metal and the binding partner. Of the four complexes used, the OsII derivative bound strongest to Met, while RuII formed the most stable coordination bond with His. RhIII was identified as the weakest peptide binder and IrIII formed peptide adducts with intermediate stability. Probing these intrinsic gas‐phase properties can help in the interpretation of biological activities and the design of site‐specific protein binding metal complexes.
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Affiliation(s)
- Monika Cziferszky
- Department of Chemistry and Pharmacy, Institute of Pharmacy, University of Innsbruck, Innrain 80-82, A-6020, Innsbruck, Austria
| | - Dianna Truong
- School of Chemical Sciences, University of Auckland Private Bag, 92019, Auckland 1142, New Zealand
| | - Christian G Hartinger
- School of Chemical Sciences, University of Auckland Private Bag, 92019, Auckland 1142, New Zealand
| | - Ronald Gust
- Department of Chemistry and Pharmacy, Institute of Pharmacy, University of Innsbruck, Innrain 80-82, A-6020, Innsbruck, Austria
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27
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Chen L, Li N, Zhang M, Sun M, Bian J, Yang B, Li Z, Wang J, Li F, Shi X, Wang Y, Yuan F, Zou P, Shan C, Wang J. APEX2-based Proximity Labeling of Atox1 Identifies CRIP2 as a Nuclear Copper-binding Protein that Regulates Autophagy Activation. Angew Chem Int Ed Engl 2021; 60:25346-25355. [PMID: 34550632 DOI: 10.1002/anie.202108961] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Revised: 08/25/2021] [Indexed: 01/05/2023]
Abstract
Mammalian cell nuclei contain copper, and cancer cells are known to accumulate aberrantly high copper levels, yet the mechanisms underlying nuclear accumulation and copper's broader functional significance remain poorly understood. Here, by combining APEX2-based proximity labeling focused on the copper chaperone Atox1 with mass spectrometry we identified a previously unrecognized nuclear copper binding protein, Cysteine-rich protein 2 (CRIP2), that interacts with Atox1 in the nucleus. We show that Atox1 transfers copper to CRIP2, which induces a change in CRIP2's secondary structure that ultimately promotes its ubiquitin-mediated proteasomal degradation. Finally, we demonstrate that depletion of CRIP2-as well as copper-induced CRIP2 degradation-elevates ROS levels and activates autophagy in H1299 cells. Thus, our study establishes that CRIP2 as an autophagic suppressor protein and implicates CRIP2-mediated copper metabolism in the activation of autophagy in cancer cells.
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Affiliation(s)
- Lin Chen
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Chemical Biology, School of Pharmaceutical Sciences, Peking University, Beijing, 100191, China
| | - Na Li
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Chemical Biology, School of Pharmaceutical Sciences, Peking University, Beijing, 100191, China
| | - Meiqi Zhang
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Chemical Biology, School of Pharmaceutical Sciences, Peking University, Beijing, 100191, China
| | - Mingming Sun
- State Key Laboratory of Medicinal Chemical Biology, College of Pharmacy, Nankai University, Tianjin, 300071, China
| | - Jiaxuan Bian
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Chemical Biology, School of Pharmaceutical Sciences, Peking University, Beijing, 100191, China
| | - Bo Yang
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Chemical Biology, School of Pharmaceutical Sciences, Peking University, Beijing, 100191, China
| | - Zhengcunxiao Li
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Chemical Biology, School of Pharmaceutical Sciences, Peking University, Beijing, 100191, China
| | - Jiayu Wang
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Chemical Biology, School of Pharmaceutical Sciences, Peking University, Beijing, 100191, China
| | - Fei Li
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Chemical Biology, School of Pharmaceutical Sciences, Peking University, Beijing, 100191, China
| | - Xiaomeng Shi
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Chemical Biology, School of Pharmaceutical Sciences, Peking University, Beijing, 100191, China
| | - Yuan Wang
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Chemical Biology, School of Pharmaceutical Sciences, Peking University, Beijing, 100191, China
| | - Feng Yuan
- College of Chemistry and Molecular Engineering, Synthetic and Functional Biomolecules Center, Beijing National Laboratory for Molecular Sciences, Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, Peking University, Beijing, 100871, China
| | - Peng Zou
- College of Chemistry and Molecular Engineering, Synthetic and Functional Biomolecules Center, Beijing National Laboratory for Molecular Sciences, Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, Peking University, Beijing, 100871, China
| | - Changliang Shan
- State Key Laboratory of Medicinal Chemical Biology, College of Pharmacy, Nankai University, Tianjin, 300071, China
| | - Jing Wang
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Chemical Biology, School of Pharmaceutical Sciences, Peking University, Beijing, 100191, China
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28
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Chen L, Li N, Zhang M, Sun M, Bian J, Yang B, Li Z, Wang J, Li F, Shi X, Wang Y, Yuan F, Zou P, Shan C, Wang J. APEX2‐based Proximity Labeling of Atox1 Identifies CRIP2 as a Nuclear Copper‐binding Protein that Regulates Autophagy Activation. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202108961] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Lin Chen
- State Key Laboratory of Natural and Biomimetic Drugs Department of Chemical Biology School of Pharmaceutical Sciences Peking University Beijing 100191 China
| | - Na Li
- State Key Laboratory of Natural and Biomimetic Drugs Department of Chemical Biology School of Pharmaceutical Sciences Peking University Beijing 100191 China
| | - Meiqi Zhang
- State Key Laboratory of Natural and Biomimetic Drugs Department of Chemical Biology School of Pharmaceutical Sciences Peking University Beijing 100191 China
| | - Mingming Sun
- State Key Laboratory of Medicinal Chemical Biology College of Pharmacy Nankai University Tianjin 300071 China
| | - Jiaxuan Bian
- State Key Laboratory of Natural and Biomimetic Drugs Department of Chemical Biology School of Pharmaceutical Sciences Peking University Beijing 100191 China
| | - Bo Yang
- State Key Laboratory of Natural and Biomimetic Drugs Department of Chemical Biology School of Pharmaceutical Sciences Peking University Beijing 100191 China
| | - Zhengcunxiao Li
- State Key Laboratory of Natural and Biomimetic Drugs Department of Chemical Biology School of Pharmaceutical Sciences Peking University Beijing 100191 China
| | - Jiayu Wang
- State Key Laboratory of Natural and Biomimetic Drugs Department of Chemical Biology School of Pharmaceutical Sciences Peking University Beijing 100191 China
| | - Fei Li
- State Key Laboratory of Natural and Biomimetic Drugs Department of Chemical Biology School of Pharmaceutical Sciences Peking University Beijing 100191 China
| | - Xiaomeng Shi
- State Key Laboratory of Natural and Biomimetic Drugs Department of Chemical Biology School of Pharmaceutical Sciences Peking University Beijing 100191 China
| | - Yuan Wang
- State Key Laboratory of Natural and Biomimetic Drugs Department of Chemical Biology School of Pharmaceutical Sciences Peking University Beijing 100191 China
| | - Feng Yuan
- College of Chemistry and Molecular Engineering Synthetic and Functional Biomolecules Center Beijing National Laboratory for Molecular Sciences Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education Peking University Beijing 100871 China
| | - Peng Zou
- College of Chemistry and Molecular Engineering Synthetic and Functional Biomolecules Center Beijing National Laboratory for Molecular Sciences Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education Peking University Beijing 100871 China
| | - Changliang Shan
- State Key Laboratory of Medicinal Chemical Biology College of Pharmacy Nankai University Tianjin 300071 China
| | - Jing Wang
- State Key Laboratory of Natural and Biomimetic Drugs Department of Chemical Biology School of Pharmaceutical Sciences Peking University Beijing 100191 China
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29
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Behar AE, Sabater L, Baskin M, Hureau C, Maayan G. A Water-Soluble Peptoid Chelator that Can Remove Cu 2+ from Amyloid-β Peptides and Stop the Formation of Reactive Oxygen Species Associated with Alzheimer's Disease. Angew Chem Int Ed Engl 2021; 60:24588-24597. [PMID: 34510664 DOI: 10.1002/anie.202109758] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Revised: 09/01/2021] [Indexed: 12/25/2022]
Abstract
Cu bound to amyloid-β (Aβ) peptides can act as a catalyst for the formation of reactive oxygen species (ROS), leading to neuropathologic degradation associated with Alzheimer's disease (AD). An excellent therapeutic approach is to use a chelator that can selectively remove Cu from Cu-Aβ. This chelator should compete with Zn2+ ions (Zn) that are present in the synaptic cleft while forming a nontoxic Cu complex. Herein we describe P3, a water-soluble peptidomimetic chelator that selectively removes Cu2+ from Cu-Aβ in the presence of Zn and prevent the formation of ROS even in a reductive environment. We demonstrate, based on extensive spectroscopic analysis, that although P3 extracts Zn from Cu,Zn-Aβ faster than it removes Cu, the formed Zn complexes are kinetic products that further dissociate, while CuP3 is formed as an exclusive stable thermodynamic product. Our unique findings, combined with the bioavailability of peptoids, make P3 an excellent drug candidate in the context of AD.
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Affiliation(s)
- Anastasia E Behar
- Schulich Faculty of Chemistry, Technion-Israel Institute of Technology, Technion City, 3200008, Haifa, Israel
| | - Laurent Sabater
- CNRS, LCC (Laboratoire de Chimie de Coordination), 205 route de Narbonne, 31077, Toulouse, France.,Université de Toulouse, 31077, Toulouse, France
| | - Maria Baskin
- Schulich Faculty of Chemistry, Technion-Israel Institute of Technology, Technion City, 3200008, Haifa, Israel
| | - Christelle Hureau
- CNRS, LCC (Laboratoire de Chimie de Coordination), 205 route de Narbonne, 31077, Toulouse, France.,Université de Toulouse, 31077, Toulouse, France
| | - Galia Maayan
- Schulich Faculty of Chemistry, Technion-Israel Institute of Technology, Technion City, 3200008, Haifa, Israel
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30
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Behar AE, Sabater L, Baskin M, Hureau C, Maayan G. A Water‐Soluble Peptoid Chelator that Can Remove Cu
2+
from Amyloid‐β Peptides and Stop the Formation of Reactive Oxygen Species Associated with Alzheimer's Disease. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202109758] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Anastasia E. Behar
- Schulich Faculty of Chemistry Technion—Israel Institute of Technology Technion City 3200008 Haifa Israel
| | - Laurent Sabater
- CNRS LCC (Laboratoire de Chimie de Coordination) 205 route de Narbonne 31077 Toulouse France
- Université de Toulouse 31077 Toulouse France
| | - Maria Baskin
- Schulich Faculty of Chemistry Technion—Israel Institute of Technology Technion City 3200008 Haifa Israel
| | - Christelle Hureau
- CNRS LCC (Laboratoire de Chimie de Coordination) 205 route de Narbonne 31077 Toulouse France
- Université de Toulouse 31077 Toulouse France
| | - Galia Maayan
- Schulich Faculty of Chemistry Technion—Israel Institute of Technology Technion City 3200008 Haifa Israel
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31
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Wang D, Li Y, Zheng Y, Hsieh YSY. Recent Advances in Screening Methods for the Functional Investigation of Lytic Polysaccharide Monooxygenases. Front Chem 2021; 9:653754. [PMID: 33912540 PMCID: PMC8072006 DOI: 10.3389/fchem.2021.653754] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Accepted: 02/12/2021] [Indexed: 01/22/2023] Open
Abstract
Lytic polysaccharide monooxygenase (LPMO) is a newly discovered and widely studied enzyme in recent years. These enzymes play a key role in the depolymerization of sugar-based biopolymers (including cellulose, hemicellulose, chitin and starch), and have a positive significance for biomass conversion. LPMO is a copper-dependent enzyme that can oxidize and cleave glycosidic bonds in cellulose and other polysaccharides. Their mechanism of action depends on the correct coordination of copper ions in the active site. There are still difficulties in the analysis of LPMO activity, which often requires multiple methods to be used in concert. In this review, we discussed various LPMO activity analysis methods reported so far, including mature mass spectrometry, chromatography, labeling, and indirect measurements, and summarized the advantages, disadvantages and applicability of different methods.
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Affiliation(s)
- Damao Wang
- College of Food Science, Southwest University, Chongqing, China
| | - Yanping Li
- College of Food Science, Southwest University, Chongqing, China
| | - Yuting Zheng
- College of Food Science, Southwest University, Chongqing, China
| | - Yves S Y Hsieh
- Division of Glycoscience, Department of Chemistry, School of Engineering Sciences in Chemistry, Biotechnology and Health, Royal Institute of Technology (KTH), AlbaNova University Centre, Stockholm, Sweden.,School of Pharmacy, College of Pharmacy, Taipei Medical University, Taipei, Taiwan.,Genomics Research Center, Academia Sinica, Taipei, Taiwan
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32
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Principles and practice of determining metal-protein affinities. Biochem J 2021; 478:1085-1116. [PMID: 33710331 PMCID: PMC7959690 DOI: 10.1042/bcj20200838] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Revised: 02/05/2021] [Accepted: 02/11/2021] [Indexed: 01/02/2023]
Abstract
Metal ions play many critical roles in biology, as structural and catalytic cofactors, and as cell regulatory and signalling elements. The metal–protein affinity, expressed conveniently by the metal dissociation constant, KD, describes the thermodynamic strength of a metal–protein interaction and is a key parameter that can be used, for example, to understand how proteins may acquire metals in a cell and to identify dynamic elements (e.g. cofactor binding, changing metal availabilities) which regulate protein metalation in vivo. Here, we outline the fundamental principles and practical considerations that are key to the reliable quantification of metal–protein affinities. We review a selection of spectroscopic probes which can be used to determine protein affinities for essential biological transition metals (including Mn(II), Fe(II), Co(II), Ni(II), Cu(I), Cu(II) and Zn(II)) and, using selected examples, demonstrate how rational probe selection combined with prudent experimental design can be applied to determine accurate KD values.
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33
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Mattocks JA, Tirsch JL, Cotruvo JA. Determination of affinities of lanthanide-binding proteins using chelator-buffered titrations. Methods Enzymol 2021; 651:23-61. [PMID: 33888205 DOI: 10.1016/bs.mie.2021.01.044] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The recent discoveries of the first proteins that bind lanthanides as part of their biological function not only are relevant to the emerging field of lanthanide-dependent biology, but also hold promise to revolutionize the technologically critical rare earths industry. Although protocols to assess the thermodynamics of metal-protein interactions are well established for "traditional" metal ions in biology, the characterization of lanthanide-binding proteins presents a challenge to biochemists due to the lanthanides' Lewis acidity, propensity for hydrolysis, and high-affinity complexes with biological ligands. These properties necessitate the preparation of metal stock solutions with very low buffered "free" metal concentrations (e.g., femtomolar to nanomolar) for such determinations. Herein we describe several protocols to overcome these challenges. First, we present standardization methods for the preparation of chelator-buffered solutions of lanthanide ions with easily calculated free metal concentrations. We also describe how these solutions can be used in concert with analytical methods including UV-visible spectrophotometry, circular dichroism spectroscopy, Förster resonance energy transfer (FRET), and sensitized terbium luminescence, in order to accurately determine dissociation constants (Kds) of lanthanide-protein complexes. Finally, we highlight how application of these methods to lanthanide-binding proteins, such as lanmodulin, has yielded insights into selective recognition of lanthanides in biology. We anticipate that these protocols will facilitate discovery and characterization of additional native lanthanide-binding proteins, will motivate the understanding of their biological context, and will prompt their applications in biotechnology.
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Affiliation(s)
- Joseph A Mattocks
- Department of Chemistry, The Pennsylvania State University, University Park, Philadelphia, PA, United States
| | - Jonathan L Tirsch
- Department of Chemistry, The Pennsylvania State University, University Park, Philadelphia, PA, United States
| | - Joseph A Cotruvo
- Department of Chemistry, The Pennsylvania State University, University Park, Philadelphia, PA, United States.
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34
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Calculating metalation in cells reveals CobW acquires Co II for vitamin B 12 biosynthesis while related proteins prefer Zn II. Nat Commun 2021; 12:1195. [PMID: 33608553 PMCID: PMC7895991 DOI: 10.1038/s41467-021-21479-8] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Accepted: 01/25/2021] [Indexed: 02/01/2023] Open
Abstract
Protein metal-occupancy (metalation) in vivo has been elusive. To address this challenge, the available free energies of metals have recently been determined from the responses of metal sensors. Here, we use these free energy values to develop a metalation-calculator which accounts for inter-metal competition and changing metal-availabilities inside cells. We use the calculator to understand the function and mechanism of GTPase CobW, a predicted CoII-chaperone for vitamin B12. Upon binding nucleotide (GTP) and MgII, CobW assembles a high-affinity site that can obtain CoII or ZnII from the intracellular milieu. In idealised cells with sensors at the mid-points of their responses, competition within the cytosol enables CoII to outcompete ZnII for binding CobW. Thus, CoII is the cognate metal. However, after growth in different [CoII], CoII-occupancy ranges from 10 to 97% which matches CobW-dependent B12 synthesis. The calculator also reveals that related GTPases with comparable ZnII affinities to CobW, preferentially acquire ZnII due to their relatively weaker CoII affinities. The calculator is made available here for use with other proteins.
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35
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Portelinha J, Duay SS, Yu SI, Heilemann K, Libardo MDJ, Juliano SA, Klassen JL, Angeles-Boza AM. Antimicrobial Peptides and Copper(II) Ions: Novel Therapeutic Opportunities. Chem Rev 2021; 121:2648-2712. [PMID: 33524257 DOI: 10.1021/acs.chemrev.0c00921] [Citation(s) in RCA: 48] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The emergence of new pathogens and multidrug resistant bacteria is an important public health issue that requires the development of novel classes of antibiotics. Antimicrobial peptides (AMPs) are a promising platform with great potential for the identification of new lead compounds that can combat the aforementioned pathogens due to their broad-spectrum antimicrobial activity and relatively low rate of resistance emergence. AMPs of multicellular organisms made their debut four decades ago thanks to ingenious researchers who asked simple questions about the resistance to bacterial infections of insects. Questions such as "Do fruit flies ever get sick?", combined with pioneering studies, have led to an understanding of AMPs as universal weapons of the immune system. This review focuses on a subclass of AMPs that feature a metal binding motif known as the amino terminal copper and nickel (ATCUN) motif. One of the metal-based strategies of hosts facing a pathogen, it includes wielding the inherent toxicity of copper and deliberately trafficking this metal ion into sites of infection. The sudden increase in the concentration of copper ions in the presence of ATCUN-containing AMPs (ATCUN-AMPs) likely results in a synergistic interaction. Herein, we examine common structural features in ATCUN-AMPs that exist across species, and we highlight unique features that deserve additional attention. We also present the current state of knowledge about the molecular mechanisms behind their antimicrobial activity and the methods available to study this promising class of AMPs.
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Affiliation(s)
- Jasmin Portelinha
- Department of Chemistry, University of Connecticut, 55 North Eagleville Road, Storrs, Connecticut 06269, United States
| | - Searle S Duay
- Department of Chemistry, University of Connecticut, 55 North Eagleville Road, Storrs, Connecticut 06269, United States.,Chemistry Department, Adamson University, 900 San Marcelino Street, Ermita, Manila 1000, Philippines
| | - Seung I Yu
- Department of Molecular and Cell Biology, University of Connecticut, 91 North Eagleville Road, Storrs, Connecticut 06269, United States
| | - Kara Heilemann
- Department of Chemistry, University of Connecticut, 55 North Eagleville Road, Storrs, Connecticut 06269, United States
| | - M Daben J Libardo
- Department of Chemistry, University of Connecticut, 55 North Eagleville Road, Storrs, Connecticut 06269, United States
| | - Samuel A Juliano
- Department of Chemistry, University of Connecticut, 55 North Eagleville Road, Storrs, Connecticut 06269, United States
| | - Jonathan L Klassen
- Department of Molecular and Cell Biology, University of Connecticut, 91 North Eagleville Road, Storrs, Connecticut 06269, United States
| | - Alfredo M Angeles-Boza
- Department of Chemistry, University of Connecticut, 55 North Eagleville Road, Storrs, Connecticut 06269, United States.,Institute of Material Science, University of Connecticut, 55 North Eagleville Road, Storrs, Connecticut 06269, United States
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Osman D, Cooke A, Young TR, Deery E, Robinson NJ, Warren MJ. The requirement for cobalt in vitamin B 12: A paradigm for protein metalation. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2021; 1868:118896. [PMID: 33096143 PMCID: PMC7689651 DOI: 10.1016/j.bbamcr.2020.118896] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 10/13/2020] [Accepted: 10/14/2020] [Indexed: 12/20/2022]
Abstract
Vitamin B12, cobalamin, is a cobalt-containing ring-contracted modified tetrapyrrole that represents one of the most complex small molecules made by nature. In prokaryotes it is utilised as a cofactor, coenzyme, light sensor and gene regulator yet has a restricted role in assisting only two enzymes within specific eukaryotes including mammals. This deployment disparity is reflected in another unique attribute of vitamin B12 in that its biosynthesis is limited to only certain prokaryotes, with synthesisers pivotal in establishing mutualistic microbial communities. The core component of cobalamin is the corrin macrocycle that acts as the main ligand for the cobalt. Within this review we investigate why cobalt is paired specifically with the corrin ring, how cobalt is inserted during the biosynthetic process, how cobalt is made available within the cell and explore the cellular control of cobalt and cobalamin levels. The partitioning of cobalt for cobalamin biosynthesis exemplifies how cells assist metalation.
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Affiliation(s)
- Deenah Osman
- Department of Biosciences, Durham University, Durham DH1 3LE, UK; Department of Chemistry, Durham University, Durham DH1 3LE, UK.
| | - Anastasia Cooke
- School of Biosciences, University of Kent, Canterbury, Kent CT2 7NJ, UK.
| | - Tessa R Young
- Department of Biosciences, Durham University, Durham DH1 3LE, UK; Department of Chemistry, Durham University, Durham DH1 3LE, UK.
| | - Evelyne Deery
- School of Biosciences, University of Kent, Canterbury, Kent CT2 7NJ, UK.
| | - Nigel J Robinson
- Department of Biosciences, Durham University, Durham DH1 3LE, UK; Department of Chemistry, Durham University, Durham DH1 3LE, UK.
| | - Martin J Warren
- School of Biosciences, University of Kent, Canterbury, Kent CT2 7NJ, UK; Quadram Institute Bioscience, Norwich Research Park, Norwich NR4 7UQ, UK; Biomedical Research Centre, University of East Anglia, Norwich NR4 7TJ, UK.
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The Two-Component System CopRS Maintains Subfemtomolar Levels of Free Copper in the Periplasm of Pseudomonas aeruginosa Using a Phosphatase-Based Mechanism. mSphere 2020; 5:5/6/e01193-20. [PMID: 33361129 PMCID: PMC7763554 DOI: 10.1128/msphere.01193-20] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Copper is a micronutrient required as cofactor in redox enzymes. When free, copper is toxic, mismetallating proteins and generating damaging free radicals. Two-component systems control periplasmic Cu+ homeostasis in Gram-negative bacteria. In characterized systems such as Escherichia coli CusRS, upon Cu+ binding to the periplasmic sensing region of CusS, a cytoplasmic phosphotransfer domain of the sensor phosphorylates the response regulator CusR. This drives the expression of efflux transporters, chaperones, and redox enzymes to ameliorate metal toxic effects. Here, we show that the Pseudomonas aeruginosa two-component sensor histidine kinase CopS exhibits a Cu-dependent phosphatase activity that maintains CopR in a nonphosphorylated state when the periplasmic Cu levels are below the activation threshold of CopS. Upon Cu+ binding to the sensor, the phosphatase activity is blocked and the phosphorylated CopR activates transcription of the CopRS regulon. Supporting the model, mutagenesis experiments revealed that the ΔcopS strain exhibits maximal expression of the CopRS regulon, lower intracellular Cu+ levels, and increased Cu tolerance compared to wild-type cells. The invariant phosphoacceptor residue His235 of CopS was not required for the phosphatase activity itself but was necessary for its Cu dependency. To sense the metal, the periplasmic domain of CopS binds two Cu+ ions at its dimeric interface. Homology modeling of CopS based on CusS structure (four Ag+ binding sites) clearly supports the different binding stoichiometries in the two systems. Interestingly, CopS binds Cu+/2+ with 3 × 10−14 M affinity, pointing to the absence of free (hydrated) Cu+/2+ in the periplasm. IMPORTANCE Copper is a micronutrient required as cofactor in redox enzymes. When free, copper is toxic, mismetallating proteins and generating damaging free radicals. Consequently, copper overload is a strategy that eukaryotic cells use to combat pathogens. Bacteria have developed copper-sensing transcription factors to control copper homeostasis. The cell envelope is the first compartment that has to cope with copper stress. Dedicated two-component systems control the periplasmic response to metal overload. This paper shows that the sensor kinase of the copper-sensing two-component system present in Pseudomonadales exhibits a signal-dependent phosphatase activity controlling the activation of its cognate response regulator, distinct from previously described periplasmic Cu sensors. Importantly, the data show that the system is activated by copper levels compatible with the absence of free copper in the cell periplasm. These observations emphasize the diversity of molecular mechanisms that have evolved in bacteria to manage the copper cellular distribution.
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Taher R, de Rosny E. A structure-function study of ZraP and ZraS provides new insights into the two-component system Zra. Biochim Biophys Acta Gen Subj 2020; 1865:129810. [PMID: 33309686 DOI: 10.1016/j.bbagen.2020.129810] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 11/16/2020] [Accepted: 12/07/2020] [Indexed: 11/19/2022]
Abstract
BACKGROUND Zra belongs to the envelope stress response (ESR) two-component systems (TCS). It is atypical because of its third periplasmic repressor partner (ZraP), in addition to its histidine kinase sensor protein (ZraS) and its response regulator (ZraR) components. Furthermore, although it is activated by Zn2+, it is not involved in zinc homeostasis or protection against zinc toxicity. Here, we mainly focus on ZraS but also provide information on ZraP. METHODS The purified periplasmic domain of ZraS and ZraP were characterized using biophysical and biochemical technics: multi-angle laser light scattering (MALLS), circular dichroism (CD), differential scanning fluorescence (DSF), inductively coupled plasma atomic emission spectroscopy (ICP-AES), cross-linking and small-angle X-ray scattering (SAXS). In-vivo experiments were carried out to determine the redox state of the cysteine residue in ZraP and the consequences for the cell of an over-activation of the Zra system. RESULTS We show that ZraS binds one Zn2+ molecule with high affinity resulting in conformational changes of the periplasmic domain, consistent with a triggering function of the metal ion. We also demonstrate that, in the periplasm, the only cysteine residue of ZraP is at least partially reduced. Using SAXS, we conclude that the previously determined X-ray structure is different from the structure in solution. CONCLUSION Our results allow us to propose a general mechanism for the Zra system activation and to compare it to the homologous Cpx system. GENERAL SIGNIFICANCE We bring new input on the so far poorly described Zra system and notably on ZraS.
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Affiliation(s)
- Raleb Taher
- Univ. Grenoble Alpes, CEA, CNRS, IBS, Metalloproteins Unit, F-38000 Grenoble, France; University of California, Irvine, Medical Science Building B, CA 92697, United States of America
| | - Eve de Rosny
- Univ. Grenoble Alpes, CEA, CNRS, IBS, Metalloproteins Unit, F-38000 Grenoble, France.
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Diep P, Mahadevan R, Yakunin AF. A microplate screen to estimate metal-binding affinities of metalloproteins. Anal Biochem 2020; 609:113836. [PMID: 32750358 DOI: 10.1016/j.ab.2020.113836] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 06/16/2020] [Accepted: 06/17/2020] [Indexed: 11/16/2022]
Abstract
Solute-binding proteins (SBPs) from ATP-binding cassette (ABC) transporters play crucial roles across all forms of life in transporting compounds against chemical gradients. Some SBPs have evolved to scavenge metal substrates from the environment with nanomolar and micromolar affinities (KD). There exist well established techniques like isothermal titration calorimetry for thoroughly studying these metalloprotein interactions with metal ions, but they are low-throughput. For protein libraries comprised of many metalloprotein homologues and mutants, and for collections of buffer conditions and potential ligands, the throughput of these techniques is paramount. In this study, we describe an improved method termed the microITFQ-LTA and validated it using CjNikZ, a well-characterized nickel-specific SBP (Ni-BP) from Campylobacter jejuni. We then demonstrated how the microITFQ-LTA can be designed to screen through a small collection of buffers and ligands to elucidate the binding profile of a putative Ni-BP from Clostridium carboxidivorans that we call CcSBPII. Through this study, we showed CcSBPII can bind to various metal ions with KD ranged over 3 orders of magnitude. In the presence of l-histidine, CcSBPII could bind to Ni2+ over 2000-fold more tightly, which was 11.6-fold tighter than CjNikZ given the same ligand.
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Affiliation(s)
- Patrick Diep
- BioZone Centre for Applied Bioscience and Bioengineering, Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario, Canada.
| | - Radhakrishnan Mahadevan
- BioZone Centre for Applied Bioscience and Bioengineering, Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario, Canada; Institute of Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada
| | - Alexander F Yakunin
- BioZone Centre for Applied Bioscience and Bioengineering, Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario, Canada; Centre for Environmental Biotechnology, School of Natural Sciences, Bangor University, Bangor, United Kingdom
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40
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Lange JL, Davey PRWJ, Ma MT, White JM, Morgenstern A, Bruchertseifer F, Blower PJ, Paterson BM. An octadentate bis(semicarbazone) macrocycle: a potential chelator for lead and bismuth radiopharmaceuticals. Dalton Trans 2020; 49:14962-14974. [PMID: 33079111 DOI: 10.1039/d0dt02673e] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
A variant of 1,4,7,10-tetraazacyclododecane (cyclen) bearing two semicarbazone pendant groups has been prepared. The octadentate ligand forms complexes with Bi3+ and Pb2+. X-ray crystallography showed that the neutral ligand provides an eight-coordinate environment for both metal ions and intermolecular hydrogen bond interactions have influenced the coordination environments of both complexes in the solid state. NMR spectroscopy revealed a fluxional environment for both complexes. The ligand was radiolabeled with the α-emitting radioactive isotope 213Bi3+, which is used in systemic targeted radiotherapy. The resulting complex was stable in serum for at least 90 min (two decay half-lives). The Pb2+ complex has reasonably fast kinetics of formation (t1/2 = 20 min) at 25 °C and pH 7.4. The Bi3+ and Pb2+ complexes show kinetic stability in 1.2 M HCl (half-lives of 214 min and 47 min, respectively). This is the first description of a macrocycle bearing semicarbazone pendant groups and its utility in coordinating main group metals, specifically those with radiotherapeutic potential.
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Affiliation(s)
- Jaclyn L Lange
- School of Biomedical Engineering and Imaging Sciences, King's College London, St Thomas' Hospital, London SE1 7EH, UK
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41
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Andrei A, Öztürk Y, Khalfaoui-Hassani B, Rauch J, Marckmann D, Trasnea PI, Daldal F, Koch HG. Cu Homeostasis in Bacteria: The Ins and Outs. MEMBRANES 2020; 10:E242. [PMID: 32962054 PMCID: PMC7558416 DOI: 10.3390/membranes10090242] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/22/2020] [Revised: 09/11/2020] [Accepted: 09/15/2020] [Indexed: 12/16/2022]
Abstract
Copper (Cu) is an essential trace element for all living organisms and used as cofactor in key enzymes of important biological processes, such as aerobic respiration or superoxide dismutation. However, due to its toxicity, cells have developed elaborate mechanisms for Cu homeostasis, which balance Cu supply for cuproprotein biogenesis with the need to remove excess Cu. This review summarizes our current knowledge on bacterial Cu homeostasis with a focus on Gram-negative bacteria and describes the multiple strategies that bacteria use for uptake, storage and export of Cu. We furthermore describe general mechanistic principles that aid the bacterial response to toxic Cu concentrations and illustrate dedicated Cu relay systems that facilitate Cu delivery for cuproenzyme biogenesis. Progress in understanding how bacteria avoid Cu poisoning while maintaining a certain Cu quota for cell proliferation is of particular importance for microbial pathogens because Cu is utilized by the host immune system for attenuating pathogen survival in host cells.
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Affiliation(s)
- Andreea Andrei
- Institut für Biochemie und Molekularbiologie, ZBMZ, Medizinische Fakultät, Albert-Ludwigs Universität Freiburg; Stefan Meier Str. 17, 79104 Freiburg, Germany; (A.A.); (Y.O.); (J.R.); (D.M.)
- Fakultät für Biologie, Albert-Ludwigs Universität Freiburg; Schänzlestrasse 1, 79104 Freiburg, Germany
| | - Yavuz Öztürk
- Institut für Biochemie und Molekularbiologie, ZBMZ, Medizinische Fakultät, Albert-Ludwigs Universität Freiburg; Stefan Meier Str. 17, 79104 Freiburg, Germany; (A.A.); (Y.O.); (J.R.); (D.M.)
| | | | - Juna Rauch
- Institut für Biochemie und Molekularbiologie, ZBMZ, Medizinische Fakultät, Albert-Ludwigs Universität Freiburg; Stefan Meier Str. 17, 79104 Freiburg, Germany; (A.A.); (Y.O.); (J.R.); (D.M.)
| | - Dorian Marckmann
- Institut für Biochemie und Molekularbiologie, ZBMZ, Medizinische Fakultät, Albert-Ludwigs Universität Freiburg; Stefan Meier Str. 17, 79104 Freiburg, Germany; (A.A.); (Y.O.); (J.R.); (D.M.)
| | | | - Fevzi Daldal
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19104, USA;
| | - Hans-Georg Koch
- Institut für Biochemie und Molekularbiologie, ZBMZ, Medizinische Fakultät, Albert-Ludwigs Universität Freiburg; Stefan Meier Str. 17, 79104 Freiburg, Germany; (A.A.); (Y.O.); (J.R.); (D.M.)
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Hunsaker EW, McAuliffe KJ, Franz KJ. Fluconazole analogues with metal-binding motifs impact metal-dependent processes and demonstrate antifungal activity in Candida albicans. J Biol Inorg Chem 2020; 25:729-745. [PMID: 32542530 PMCID: PMC7415656 DOI: 10.1007/s00775-020-01796-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Accepted: 05/25/2020] [Indexed: 12/28/2022]
Abstract
Azole antifungals are an important class of antifungal drugs due to their low cost, ability to be administered orally, and broad-spectrum activity. However, their widespread and long-term use have given rise to adaptation mechanisms that render these compounds less effective against common fungal pathogens, including Candida albicans. New antifungals are desperately needed as drug-resistant strains become more prevalent. We recently showed that copper supplementation potentiates the activity of the azole antifungal fluconazole against the opportunistic fungal pathogen C. albicans. Here, we report eight new azole analogues derived from fluconazole in which one triazole group has been replaced with a metal-binding group, a strategy designed to enhance potentiation of azole antifungal activity by copper. The bioactivity of all eight compounds was tested and compared to that of fluconazole. Three of the analogues showed activity against C. albicans and two had lower levels of trailing growth. One compound, Flu-TSCZ, was found to impact the levels, speciation, and bioavailability of cellular metals.
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Affiliation(s)
- Elizabeth W Hunsaker
- Department of Chemistry, French Family Science Center, Duke University, 124 Science Drive, Durham, NC, 27708, USA
| | - Katherine J McAuliffe
- Department of Chemistry, French Family Science Center, Duke University, 124 Science Drive, Durham, NC, 27708, USA
| | - Katherine J Franz
- Department of Chemistry, French Family Science Center, Duke University, 124 Science Drive, Durham, NC, 27708, USA.
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D'Amato A, Ghosh P, Costabile C, Della Sala G, Izzo I, Maayan G, De Riccardis F. Peptoid-based siderophore mimics as dinuclear Fe 3+ chelators. Dalton Trans 2020; 49:6020-6029. [PMID: 32319496 DOI: 10.1039/d0dt00689k] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
A practical synthesis of preorganized tripodal enterobactin/corynebactin-type ligands (consisting of a C3-symmetric macrocyclic peptoid core, three catecholamide coordinating units, and C2, C4, and C6 spacers) is reported. The formation of complexes with Fe3+ was investigated by spectrophotometric (UV-Vis) and spectrometric (ESI, negative ionization mode) methods and corroborated by theoretical (DFT) calculations. Preliminary studies revealed the intricate interplay between the conformational chirality of cyclic trimeric peptoids and metal coordination geometry of mononuclear species similar to that of natural catechol-based siderophores. Experimental results demonstrated the unexpected formation of unique dinuclear Fe3+ complexes.
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Affiliation(s)
- Assunta D'Amato
- Department of Chemistry and Biology "A. Zambelli", University of Salerno, Via Giovanni Paolo II, 132, Fisciano, SA 84084, Italy.
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Tarrant E, P Riboldi G, McIlvin MR, Stevenson J, Barwinska-Sendra A, Stewart LJ, Saito MA, Waldron KJ. Copper stress in Staphylococcus aureus leads to adaptive changes in central carbon metabolism. Metallomics 2020; 11:183-200. [PMID: 30443649 PMCID: PMC6350627 DOI: 10.1039/c8mt00239h] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Copper toxicity has been a long-term selection pressure on bacteria due to its presence in the environment and its use as an antimicrobial agent by grazing protozoa, by phagocytic cells of the immune system, and in man-made medical and commercial products. There is recent evidence that exposure to increased copper stress may have been a key driver in the evolution and spread of methicillin-resistant Staphylococcus aureus, a globally important pathogen that causes significant mortality and morbidity worldwide. Yet it is unclear how S. aureus physiology is affected by copper stress or how it adapts in order to be able to grow in the presence of excess copper. Here, we have determined quantitatively how S. aureus alters its proteome during growth under copper stress conditions, comparing this adaptive response in two different types of growth regime. We found that the adaptive response involves induction of the conserved copper detoxification system as well as induction of enzymes of central carbon metabolism, with only limited induction of proteins involved in the oxidative stress response. Further, we identified a protein that binds copper inside S. aureus cells when stressed by copper excess. This copper-binding enzyme, a glyceraldehyde-3-phosphate dehydrogenase essential for glycolysis, is inhibited by copper in vitro and inside S. aureus cells. Together, our data demonstrate that copper stress leads to the inhibition of glycolysis in S. aureus, and that the bacterium adapts to this stress by altering its central carbon utilisation pathways.
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Affiliation(s)
- Emma Tarrant
- Institute for Cell & Molecular Biosciences, Faculty of Medical Sciences, Newcastle University, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK.
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45
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Abstract
Iron is essential for nearly every organism, and mismanagement of its intracellular concentrations (either deficiency or excess) contributes to diminished virulence in human pathogens, necessitating intricate metalloregulatory mechanisms. To date, although several metal-responsive riboswitches have been identified in bacteria, none has been shown to respond to FeII. The czcD riboswitch, present in numerous human gut microbiota and pathogens, was recently shown to respond to NiII and CoII but thought not to respond to FeII, on the basis of aerobic, in vitro assays; its function in vivo is not well understood. We constructed a fluorescent sensor using this riboswitch fused to the RNA aptamer, Spinach2. When assayed anaerobically, the resulting sensor responds in vitro to FeII, as well as to MnII, CoII, NiII, and ZnII, but only in the cases of FeII and MnII do the apparent Kd values (0.4 and 11 μM, respectively) fall within the range of labile metal concentrations maintained by known metalloregulators. We also show that the sensor-which is, to the best of our knowledge, the first reversible genetically encoded fluorescent sensor for FeII-responds to iron in Escherichia coli cells. Finally, we demonstrate that the putative metal exporters directly downstream of two czcD riboswitches efficiently rescue iron toxicity in a heterologous expression system. Together, our results indicate that iron merits consideration as a plausible physiological ligand for czcD riboswitches, although a response to general metal stress cannot be ruled out at present.
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Affiliation(s)
- Jiansong Xu
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Joseph A Cotruvo
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
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46
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Abstract
It has been reported that Cu(II) ions in human blood are bound mainly to serum albumin (HSA), ceruloplasmin (CP), alpha-2-macroglobulin (α2M) and His, however, data for α2M are very limited and the thermodynamics and kinetics of the copper distribution are not known. We have applied a new LC-ICP MS-based approach for direct determination of Cu(II)-binding affinities of HSA, CP and α2M in the presence of competing Cu(II)-binding reference ligands including His. The ligands affected both the rate of metal release from Cu•HSA complex and the value of KD. Slow release and KD = 0.90 pM was observed with nitrilotriacetic acid (NTA), whereas His showed fast release and substantially lower KD = 34.7 fM (50 mM HEPES, 50 mM NaCl, pH 7.4), which was explained with formation of ternary His•Cu•HSA complex. High mM concentrations of EDTA were not able to elicit metal release from metallated CP at pH 7.4 and therefore it was impossible to determine the KD value for CP. In contrast to earlier inconclusive evidence, we show that α2M does not bind Cu(II) ions. In the human blood serum ~75% of Cu(II) ions are in a nonexchangeable manner bound to CP and the rest exchangeable copper is in an equilibrium between HSA (~25%) and Cu(II)-His-Xaa ternary complexes (~0.2%).
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47
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Reilley DJ, Hennefarth MR, Alexandrova AN. The Case for Enzymatic Competitive Metal Affinity Methods. ACS Catal 2020; 10:2298-2307. [PMID: 34012720 PMCID: PMC8130888 DOI: 10.1021/acscatal.9b04831] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- David J Reilley
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 607 Charles E. Young Drive East, Los Angeles, CA 90095-1569, USA
| | - Matthew R Hennefarth
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 607 Charles E. Young Drive East, Los Angeles, CA 90095-1569, USA
| | - Anastassia N Alexandrova
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 607 Charles E. Young Drive East, Los Angeles, CA 90095-1569, USA
- California NanoSystems Institute, University of California, Los Angeles, 570 Westwood Plaza, Los Angeles, California 90095-1569, USA
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Exploring the role of the various methionine residues in the Escherichia coli CusB adapter protein. PLoS One 2019; 14:e0219337. [PMID: 31465444 PMCID: PMC6715271 DOI: 10.1371/journal.pone.0219337] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Accepted: 08/15/2019] [Indexed: 11/29/2022] Open
Abstract
The dissemination of resistant pathogenic microbes has become one of the most challenging problems that modern medicine has faced. Developing novel drugs based on new molecular targets that previously were not targeted, is therefore the highest priority in antibiotics research. One approach that has been recently suggested is to inhibit copper transporters in prokaryotic systems. Copper is required for many biological pathways, but sometimes it can harm the cell. Pathogenic systems have a highly sophisticated copper-regulation network; therefore, a better understanding of how this network operates at the molecular level should assist in developing the next generation of antibiotics. The CusB protein is part of the CusCBA periplasmic Cu(I) efflux system in Gram-negative bacteria, and was recently reported to play a key role in the functioning of the whole CusCBA system, in which conformational changes as well as the assembly/disassembly process control the opening of the transporter. More knowledge of the underlying mechanism is needed to attain a full understanding of CusB functioning, which is associated with targeting specific and crucial residues in CusB. Here, we combine in-vitro structural measurements, which use EPR spectroscopy and UV-Vis measurements, with cell experiments to explore the role of the various methionine residues in CusB. We targeted two methionine residues (M227 and M241) that are essential for the proper functioning of CusB.
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Subedi P, Paxman JJ, Wang G, Ukuwela AA, Xiao Z, Heras B. The Scs disulfide reductase system cooperates with the metallochaperone CueP in Salmonella copper resistance. J Biol Chem 2019; 294:15876-15888. [PMID: 31444272 DOI: 10.1074/jbc.ra119.010164] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Revised: 08/21/2019] [Indexed: 12/31/2022] Open
Abstract
The human pathogen Salmonella enterica serovar Typhimurium (S Typhimurium) contains a complex disulfide bond (Dsb) catalytic machinery. This machinery encompasses multiple Dsb thiol-disulfide oxidoreductases that mediate oxidative protein folding and a less-characterized suppressor of copper sensitivity (scs) gene cluster, associated with increased tolerance to copper. To better understand the function of the Salmonella Scs system, here we characterized two of its key components, the membrane protein ScsB and the periplasmic protein ScsC. Our results revealed that these two proteins form a redox pair in which the electron transfer from the periplasmic domain of ScsB (n-ScsB) to ScsC is thermodynamically driven. We also demonstrate that the Scs reducing pathway remains separate from the Dsb oxidizing pathways and thereby avoids futile redox cycles. Additionally, we provide new insight into the molecular mechanism underlying Scs-mediated copper tolerance in Salmonella We show that both ScsB and ScsC can bind toxic copper(I) with femtomolar affinities and transfer it to the periplasmic copper metallochaperone CueP. Our results indicate that the Salmonella Scs machinery has evolved a dual mode of action, capable of transferring reducing power to the oxidizing periplasm and protecting against copper stress by cooperating with the cue regulon, a major copper resistance mechanism in Salmonella. Overall, these findings expand our understanding of the functional diversity of Dsb-like systems, ranging from those mediating oxidative folding of proteins required for infection to those contributing to defense mechanisms against oxidative stress and copper toxicity, critical traits for niche adaptation and survival.
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Affiliation(s)
- Pramod Subedi
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Kingsbury Drive, Bundoora, Victoria 3083, Australia
| | - Jason J Paxman
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Kingsbury Drive, Bundoora, Victoria 3083, Australia
| | - Geqing Wang
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Kingsbury Drive, Bundoora, Victoria 3083, Australia
| | - Ashwinie A Ukuwela
- School of Chemistry and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Zhiguang Xiao
- School of Chemistry and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, Victoria 3010, Australia.,Melbourne Dementia Research Centre, Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, Victoria 3052, Australia
| | - Begoña Heras
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Kingsbury Drive, Bundoora, Victoria 3083, Australia
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Walke G, Ruthstein S. Does the ATSM-Cu(II) Biomarker Integrate into the Human Cellular Copper Cycle? ACS OMEGA 2019; 4:12278-12285. [PMID: 31460344 PMCID: PMC6681976 DOI: 10.1021/acsomega.9b01748] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Accepted: 07/04/2019] [Indexed: 06/10/2023]
Abstract
Hypoxia is commonly encountered in the tumor microenvironment and drives proliferation, angiogenesis, and resistance to therapy. Imaging of hypoxia is important in many disease states in oncology, cardiology, and neurology. Finding clinically approved imaging biomarkers for hypoxia has proved challenging. Candidate biomarkers have shown low uptake into tumors and low signal to background ratios that adversely affect imaging quality. Copper complexes have been identified as potential biomarkers for hypoxia owing to their redox ability. Active uptake of copper complexes into cells could ensure selectivity and high sensitivity. We explored the reactivity and selectivity of the ATSM-Cu(II) biomarker to proteins that are involved in the copper cycle using electron paramagnetic resonance (EPR) spectroscopy and UV-vis measurements. We show that the affinity of the ATSM-Cu(II) complex to proteins in the copper cycle is low and the cell probably does not actively uptake ATSM-Cu(II).
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