1
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Chivers PT, Basak P, Maroney MJ. One His, two His…the emerging roles of histidine in cellular nickel trafficking. J Inorg Biochem 2024; 259:112668. [PMID: 39053077 DOI: 10.1016/j.jinorgbio.2024.112668] [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: 04/29/2024] [Revised: 07/15/2024] [Accepted: 07/16/2024] [Indexed: 07/27/2024]
Abstract
Biological environments present a complex array of metal-binding ligands. Metal-binding proteins have been the overwhelming focus of study because of their important and well-defined biological roles. Consequently, the presence of functional low molecular weight (LMW) metal-ligand complexes has been overlooked in terms of their roles in metallobiochemistry, particularly within cells. Recent studies in microbial systems have illuminated the different roles of L-histidine in nickel uptake, gene expression, and metalloenzyme maturation. In this focused critical review, these roles are surveyed in the context of the coordination chemistry of Ni(II) ions and the amino acid histidine, and the physico-chemical properties of nickel complexes of histidine. These complexes are fundamentally important to cellular metal homeostasis and further work is needed to fully define their contributions.
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Affiliation(s)
- Peter T Chivers
- Departments of Biosciences and Chemistry, University of Durham, Durham DH1 3LE, UK
| | - Priyanka Basak
- Department of Chemistry, University of Massachusetts, Amherst, MA 01002, United States of America
| | - Michael J Maroney
- Department of Chemistry, University of Massachusetts, Amherst, MA 01002, United States of America.
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2
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Sieg JP. A Divalent Metal Cation-Metabolite Interaction Model Reveals Cation Buffering and Speciation. Biochemistry 2024; 63:1709-1717. [PMID: 38975737 DOI: 10.1021/acs.biochem.4c00125] [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: 07/09/2024]
Abstract
I present the perspective that the divalent metalome and the metabolome can be modeled as a network of chelating interactions instead of separate entities. I review progress in understanding the complex cellular environment, in particular recent contributions to modeling metabolite-Mg2+ interactions. I then demonstrate a simple extension of these strategies based approximately on intracellular Escherichia coli concentrations. This model is composed of four divalent metal cations with a range of cellular concentrations and physical properties (Mg2+, Ca2+, Mn2+, and Zn2+), eight representative metabolites, and interaction constants. I applied this model to predict the speciation of divalent metal cations between free and metabolite-chelated species. This approach reveals potentially beneficial properties, including maintenance of free divalent metal cations at biologically relevant concentrations, buffering of free divalent metal cations, and enrichment of functional metabolite-chelated species. While currently limited by available interaction coefficients, this modeling strategy can be generalized to more complex systems. In summary, biochemists should consider the potential of cellular metabolites to form chelating interactions with divalent metal cations.
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Affiliation(s)
- Jacob P Sieg
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Department of Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
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3
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Shi H, Fu Y, Kodyte V, Andreas A, Sachla AJ, Miller K, Shrestha R, Helmann JD, Glasfeld A, Ahuja S. Structural basis for transcription activation through cooperative recruitment of MntR. RESEARCH SQUARE 2024:rs.3.rs-4657015. [PMID: 39070638 PMCID: PMC11275975 DOI: 10.21203/rs.3.rs-4657015/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/30/2024]
Abstract
The manganese transport regulator (MntR) from B. subtilis is a dual regulatory protein that responds to heightened Mn2+ availability in the cell by both repressing the expression of uptake transporters and activating the expression of efflux proteins. Recent work indicates that, in its role as an activator, MntR binds several sites upstream of the genes encoding Mn2+ exporters, leading to a cooperative response to manganese. Here, we use cryo-EM to explore the molecular basis of gene activation by MntR and report a structure of four MntR dimers bound to four 18-base pair sites across an 84-base pair regulatory region of the mneP promoter. Our structures, along with solution studies including mass photometry and in vivo transcription assays, reveal that MntR dimers employ polar and non-polar contacts to bind cooperatively to an array of low-affinity DNA-binding sites. These results reveal the molecular basis for cooperativity in the activation of manganese efflux.
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Affiliation(s)
- Haoyuan Shi
- Department of Chemistry, Reed College, Portland, Oregon 97202, USA
- Current address: Department of Chemical Pharmacology & Biochemistry, Oregon Health & Science University, Portland, OR 97239
| | - Yu Fu
- Department of Chemistry, Reed College, Portland, Oregon 97202, USA
- Current address: Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| | - Vilmante Kodyte
- Department of Chemistry, Reed College, Portland, Oregon 97202, USA
| | - Amelie Andreas
- Department of Chemistry, Reed College, Portland, Oregon 97202, USA
| | - Ankita J. Sachla
- Department of Microbiology, Cornell University, Ithaca, NY 14853-8101
| | - Keiki Miller
- Department of Chemistry, Reed College, Portland, Oregon 97202, USA
| | | | - John D. Helmann
- Department of Microbiology, Cornell University, Ithaca, NY 14853-8101
| | - Arthur Glasfeld
- Department of Chemistry, Reed College, Portland, Oregon 97202, USA
| | - Shivani Ahuja
- Department of Chemistry, Reed College, Portland, Oregon 97202, USA
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4
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Shi H, Fu Y, Kodyte V, Andreas A, Sachla AJ, Miller K, Shrestha R, Helmann JD, Glasfeld A, Ahuja S. Structural basis for transcription activation through cooperative recruitment of MntR. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.28.601288. [PMID: 38979284 PMCID: PMC11230367 DOI: 10.1101/2024.06.28.601288] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/10/2024]
Abstract
The manganese transport regulator (MntR) from B. subtilis is a dual regulatory protein that responds to heightened Mn 2+ availability in the cell by both repressing the expression of uptake transporters and activating the expression of efflux proteins. Recent work indicates that, in its role as an activator, MntR binds several sites upstream of the genes encoding Mn 2+ exporters, leading to a cooperative response to manganese. Here, we use cryo-EM to explore the molecular basis of gene activation by MntR and report a structure of four MntR dimers bound to four 18-base pair sites across an 84-base pair regulatory region of the mneP promoter. Our structures, along with solution studies including mass photometry and in vivo transcription assays, reveal that MntR dimers employ polar and non-polar contacts to bind cooperatively to an array of low-affinity DNA-binding sites. These results reveal the molecular basis for cooperativity in the activation of manganese efflux.
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5
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Krämer U. Metal Homeostasis in Land Plants: A Perpetual Balancing Act Beyond the Fulfilment of Metalloproteome Cofactor Demands. ANNUAL REVIEW OF PLANT BIOLOGY 2024; 75:27-65. [PMID: 38277698 DOI: 10.1146/annurev-arplant-070623-105324] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2024]
Abstract
One of life's decisive innovations was to harness the catalytic power of metals for cellular chemistry. With life's expansion, global atmospheric and biogeochemical cycles underwent dramatic changes. Although initially harmful, they permitted the evolution of multicellularity and the colonization of land. In land plants as primary producers, metal homeostasis faces heightened demands, in part because soil is a challenging environment for nutrient balancing. To avoid both nutrient metal limitation and metal toxicity, plants must maintain the homeostasis of metals within tighter limits than the homeostasis of other minerals. This review describes the present model of protein metalation and sketches its transfer from unicellular organisms to land plants as complex multicellular organisms. The inseparable connection between metal and redox homeostasis increasingly draws our attention to more general regulatory roles of metals. Mineral co-option, the use of nutrient or other metals for functions other than nutrition, is an emerging concept beyond that of nutritional immunity.
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Affiliation(s)
- Ute Krämer
- Molecular Genetics and Physiology of Plants, Ruhr University Bochum, Bochum, Germany;
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6
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Kwiatos N, Waldron KJ. In a state of flux: new insight into the transport processes that maintain bacterial metal homeostasis. J Bacteriol 2024; 206:e0014624. [PMID: 38712925 PMCID: PMC11112988 DOI: 10.1128/jb.00146-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/08/2024] Open
Abstract
A new study by Nies et al. (J Bacteriol 206:e00080-24, 2024, https://doi.org/10.1128/jb.00080-24) provides a rich, quantitative data set of zinc accumulation by cells of Cupriavidus metallidurans, including of mutant bacterial strains lacking import or efflux genes, and comparison of zinc accumulation by cells previously starved of metal with those of zinc-replete cells. The data surprisingly demonstrate the concomitant activity of both active metal import and metal efflux systems. They present a flow equilibrium model to describe zinc homeostasis in bacteria.
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Affiliation(s)
- Natalia Kwiatos
- Laboratory of Metalloprotein Biology, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland
| | - Kevin J. Waldron
- Laboratory of Metalloprotein Biology, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland
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7
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Rohaun SK, Sethu R, Imlay JA. Microbes vary strategically in their metalation of mononuclear enzymes. Proc Natl Acad Sci U S A 2024; 121:e2401738121. [PMID: 38743623 PMCID: PMC11127058 DOI: 10.1073/pnas.2401738121] [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: 01/25/2024] [Accepted: 04/15/2024] [Indexed: 05/16/2024] Open
Abstract
Studies have determined that nonredox enzymes that are cofactored with Fe(II) are the most oxidant-sensitive targets inside Escherichia coli. These enzymes use Fe(II) cofactors to bind and activate substrates. Because of their solvent exposure, the metal can be accessed and oxidized by reactive oxygen species, thereby inactivating the enzyme. Because these enzymes participate in key physiological processes, the consequences of stress can be severe. Accordingly, when E. coli senses elevated levels of H2O2, it induces both a miniferritin and a manganese importer, enabling the replacement of the iron atom in these enzymes with manganese. Manganese does not react with H2O2 and thereby preserves enzyme activity. In this study, we examined several diverse microbes to identify the metal that they customarily integrate into ribulose-5-phosphate 3-epimerase, a representative of this enzyme family. The anaerobe Bacteroides thetaiotaomicron, like E. coli, uses iron. In contrast, Bacillus subtilis and Lactococcus lactis use manganese, and Saccharomyces cerevisiae uses zinc. The latter organisms are therefore well suited to the oxidizing environments in which they dwell. Similar results were obtained with peptide deformylase, another essential enzyme of the mononuclear class. Strikingly, heterologous expression experiments show that it is the metal pool within the organism, rather than features of the protein itself, that determine which metal is incorporated. Further, regardless of the source organism, each enzyme exhibits highest turnover with iron and lowest turnover with zinc. We infer that the intrinsic catalytic properties of the metal cannot easily be retuned by evolution of the polypeptide.
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Affiliation(s)
| | | | - James A. Imlay
- Department of Microbiology, University of Illinois, Urbana, IL61801
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8
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Choi Y, Koh J, Cha SS, Roe JH. Activation of zinc uptake regulator by zinc binding to three regulatory sites. Nucleic Acids Res 2024; 52:4185-4197. [PMID: 38349033 PMCID: PMC11077047 DOI: 10.1093/nar/gkae079] [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] [Received: 06/15/2023] [Revised: 01/23/2024] [Accepted: 02/05/2024] [Indexed: 05/09/2024] Open
Abstract
Zur is a Fur-family metalloregulator that is widely used to control zinc homeostasis in bacteria. In Streptomyces coelicolor, Zur (ScZur) acts as both a repressor for zinc uptake (znuA) gene and an activator for zinc exporter (zitB) gene. Previous structural studies revealed three zinc ions specifically bound per ScZur monomer; a structural one to allow dimeric architecture and two regulatory ones for DNA-binding activity. In this study, we present evidence that Zur contains a fourth specific zinc-binding site with a key histidine residue (H36), widely conserved among actinobacteria, for regulatory function. Biochemical, genetic, and calorimetric data revealed that H36 is critical for hexameric binding of Zur to the zitB zurbox and further binding to its upstream region required for full activation. A comprehensive thermodynamic model demonstrated that the DNA-binding affinity of Zur to both znuA and zitB zurboxes is remarkably enhanced upon saturation of all three regulatory zinc sites. The model also predicts that the strong coupling between zinc binding and DNA binding equilibria of Zur drives a biphasic activation of the zitB gene in response to a wide concentration change of zinc. Similar mechanisms may be pertinent to other metalloproteins, expanding their response spectrum through binding multiple regulatory metals.
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Affiliation(s)
- Yunchan Choi
- Laboratory of Molecular Microbiology, School of Biological Sciences, College of Natural Science, Seoul National University, Seoul 08826, Republic of Korea
| | - Junseock Koh
- Laboratory of Biophysical Chemistry, School of Biological Sciences, College of Natural Science, Seoul National University, Seoul 08826, Republic of Korea
| | - Sun-Shin Cha
- Protein Research Laboratory, Department of Chemistry and Nanoscience, Ewha Womans University, Seoul 03760, Republic of Korea
| | - Jung-Hye Roe
- Laboratory of Molecular Microbiology, School of Biological Sciences, College of Natural Science, Seoul National University, Seoul 08826, Republic of Korea
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9
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Jensen GC, Janis MK, Nguyen HN, David OW, Zastrow ML. Fluorescent Protein-Based Sensors for Detecting Essential Metal Ions across the Tree of Life. ACS Sens 2024; 9:1622-1643. [PMID: 38587931 PMCID: PMC11073808 DOI: 10.1021/acssensors.3c02695] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/10/2024]
Abstract
Genetically encoded fluorescent metal ion sensors are powerful tools for elucidating metal dynamics in living systems. Over the last 25 years since the first examples of genetically encoded fluorescent protein-based calcium indicators, this toolbox of probes has expanded to include other essential and non-essential metal ions. Collectively, these tools have illuminated fundamental aspects of metal homeostasis and trafficking that are crucial to fields ranging from neurobiology to human nutrition. Despite these advances, much of the application of metal ion sensors remains limited to mammalian cells and tissues and a limited number of essential metals. Applications beyond mammalian systems and in vivo applications in living organisms have primarily used genetically encoded calcium ion sensors. The aim of this Perspective is to provide, with the support of historical and recent literature, an updated and critical view of the design and use of fluorescent protein-based sensors for detecting essential metal ions in various organisms. We highlight the historical progress and achievements with calcium sensors and discuss more recent advances and opportunities for the detection of other essential metal ions. We also discuss outstanding challenges in the field and directions for future studies, including detecting a wider variety of metal ions, developing and implementing a broader spectral range of sensors for multiplexing experiments, and applying sensors to a wider range of single- and multi-species biological systems.
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Affiliation(s)
- Gary C Jensen
- Department of Chemistry, University of Houston, Houston, Texas 77204, United States
| | - Makena K Janis
- Department of Chemistry, University of Houston, Houston, Texas 77204, United States
| | - Hazel N Nguyen
- Department of Chemistry, University of Houston, Houston, Texas 77204, United States
| | - Ogonna W David
- Department of Chemistry, University of Houston, Houston, Texas 77204, United States
| | - Melissa L Zastrow
- Department of Chemistry, University of Houston, Houston, Texas 77204, United States
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10
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Kim M, Le MT, Fan L, Campbell C, Sen S, Capdevila DA, Stemmler TL, Giedroc DP. Characterization of the Zinc Uptake Repressor (Zur) from Acinetobacter baumannii. Biochemistry 2024; 63:660-670. [PMID: 38385972 PMCID: PMC11019503 DOI: 10.1021/acs.biochem.3c00679] [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: 02/23/2024]
Abstract
Bacterial cells tightly regulate the intracellular concentrations of essential transition metal ions by deploying a panel of metal-regulated transcriptional repressors and activators that bind to operator-promoter regions upstream of regulated genes. Like other zinc uptake regulator (Zur) proteins, Acinetobacter baumannii Zur represses transcription of its regulon when ZnII is replete and binds more weakly to DNA when ZnII is limiting. Previous studies established that Zur proteins are homodimeric and harbor at least two metal sites per protomer or four per dimer. CdII X-ray absorption spectroscopy (XAS) of the Cd2Zn2 AbZur metalloderivative with CdII bound to the allosteric sites reveals a S(N/O)3 first coordination shell. Site-directed mutagenesis suggests that H89 and C100 from the N-terminal DNA binding domain and H107 and E122 from the C-terminal dimerization domain comprise the regulatory metal site. KZn for this allosteric site is 6.0 (±2.2) × 1012 M-1 with a functional "division of labor" among the four metal ligands. N-terminal domain ligands H89 and C100 contribute far more to KZn than H107 and E122, while C100S AbZur uniquely fails to bind to DNA tightly as measured by an in vitro transcription assay. The heterotropic allosteric coupling free energy, ΔGc, is negative, consistent with a higher KZn for the AbZur-DNA complex and defining a bioavailable ZnII set-point of ≈6 × 10-14 M. Small-angle X-ray scattering (SAXS) experiments reveal that only the wild-type Zn homodimer undergoes allosteric switching, while the C100S AbZur fails to switch. These data collectively suggest that switching to a high affinity DNA-binding conformation involves a rotation/translation of one protomer relative to the other in a way that is dependent on the integrity of C100. We place these findings in the context of other Zur proteins and Fur family repressors more broadly.
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Affiliation(s)
- Minyong Kim
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405-7102, United States
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, Indiana 47405, United States
| | - My Tra Le
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, Indiana 47405, United States
| | - Lixin Fan
- Basic Science Program, Frederick National Laboratory for Cancer Research, SAXS Core Facility of the National Cancer Institute, Frederick, Maryland 21702, United States
| | - Courtney Campbell
- Department of Pharmaceutical Sciences, Wayne State University, Detroit, Michigan 48201-2417, United States
| | - Sambuddha Sen
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405-7102, United States
| | - Daiana A Capdevila
- Fundación Instituto Leloir, Instituto de Investigaciones Bioquímicas de Buenos Aires (IIBBA-CONICET), C1405 BWE Buenos Aires, Argentina
| | - Timothy L Stemmler
- Department of Pharmaceutical Sciences, Wayne State University, Detroit, Michigan 48201-2417, United States
| | - David P Giedroc
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405-7102, United States
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, Indiana 47405, United States
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11
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McEwan AG. Metalloproteome plasticity - a factor in bacterial pathogen adaptive responses? Emerg Top Life Sci 2024; 8:57-60. [PMID: 38323345 PMCID: PMC10903460 DOI: 10.1042/etls20230116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2023] [Revised: 01/16/2024] [Accepted: 01/17/2024] [Indexed: 02/08/2024]
Abstract
Through homeostatic processes, bacterial cells maintain intracytoplasmic metal ions at concentrations which enable the 'correct' metal to be inserted into an enzyme, thereby ensuring function. However, fluctuations in intracytoplasmic metal ion concentrations mean that under different conditions certain enzymes may contain different metals at their active site. This perspective describes examples of such cases and suggests that metalloproteome plasticity may contribute to the dynamic adaptation of pathogens to stresses in the host environment.
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Affiliation(s)
- Alastair G. McEwan
- Australian Infectious Diseases Research Centre, School of Chemistry and Biosciences, The University of Queensland, St Lucia 4072, Australia
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12
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Shisler KA, Kincannon WM, Mattice JR, Larson J, Valaydon-Pillay A, Mus F, Flusche T, Kumar Nath A, Stoian SA, Raugei S, Bothner B, DuBois JL, Peters JW. Homologous acetone carboxylases select Fe(II) or Mn(II) as the catalytic cofactor. mBio 2024; 15:e0298723. [PMID: 38126751 PMCID: PMC10865871 DOI: 10.1128/mbio.02987-23] [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: 11/13/2023] [Accepted: 11/16/2023] [Indexed: 12/23/2023] Open
Abstract
Acetone carboxylases (ACs) catalyze the metal- and ATP-dependent conversion of acetone and bicarbonate to form acetoacetate. Interestingly, two homologous ACs that have been biochemically characterized have been reported to have different metal complements, implicating different metal dependencies in catalysis. ACs from proteobacteria Xanthobacter autotrophicus and Aromatoleum aromaticum share 68% sequence identity but have been proposed to have different catalytic metals. In this work, the two ACs were expressed under the same conditions in Escherichia coli and were subjected to parallel chelation and reconstitution experiments with Mn(II) or Fe(II). Electron paramagnetic and Mössbauer spectroscopies identified signatures, respectively, of Mn(II) or Fe(II) bound at the active site. These experiments showed that the respective ACs, without the assistance of chaperones, second metal sites, or post-translational modifications facilitate correct metal incorporation, and despite the expected thermodynamic preference for Fe(II), each preferred a distinct metal. Catalysis was likewise associated uniquely with the cognate metal, though either could potentially serve the proposed Lewis acidic role. Subtle differences in the protein structure are implicated in serving as a selectivity filter for Mn(II) or Fe(II).IMPORTANCEThe Irving-Williams series refers to the predicted stabilities of transition metal complexes where the observed general stability for divalent first-row transition metal complexes increase across the row. Acetone carboxylases (ACs) use a coordinated divalent metal at their active site in the catalytic conversion of bicarbonate and acetone to form acetoacetate. Highly homologous ACs discriminate among different divalent metals at their active sites such that variations of the enzyme prefer Mn(II) over Fe(II), defying Irving-Williams-predicted behavior. Defining the determinants that promote metal discrimination within the first-row transition metals is of broad fundamental importance in understanding metal-mediated catalysis and metal catalyst design.
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Affiliation(s)
- Krista A. Shisler
- Institute of Biological Chemistry, Washington State University, Pullman, Washington, USA
| | - William M. Kincannon
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana, USA
| | - Jenna R. Mattice
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana, USA
| | - James Larson
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana, USA
| | | | - Florence Mus
- Institute of Biological Chemistry, Washington State University, Pullman, Washington, USA
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, Oklahoma, USA
| | - Tamara Flusche
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, Oklahoma, USA
| | - Arnab Kumar Nath
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana, USA
| | | | - Simone Raugei
- Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington, USA
| | - Brian Bothner
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana, USA
| | - Jennifer L. DuBois
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana, USA
| | - John W. Peters
- Institute of Biological Chemistry, Washington State University, Pullman, Washington, USA
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, Oklahoma, USA
- Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington, USA
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13
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Bakhtiar D, Vondraskova K, Pengelly RJ, Chivers M, Kralovicova J, Vorechovsky I. Exonic splicing code and coordination of divalent metals in proteins. Nucleic Acids Res 2024; 52:1090-1106. [PMID: 38055834 PMCID: PMC10853796 DOI: 10.1093/nar/gkad1161] [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] [Received: 06/16/2023] [Revised: 11/15/2023] [Accepted: 11/17/2023] [Indexed: 12/08/2023] Open
Abstract
Exonic sequences contain both protein-coding and RNA splicing information but the interplay of the protein and splicing code is complex and poorly understood. Here, we have studied traditional and auxiliary splicing codes of human exons that encode residues coordinating two essential divalent metals at the opposite ends of the Irving-Williams series, a universal order of relative stabilities of metal-organic complexes. We show that exons encoding Zn2+-coordinating amino acids are supported much less by the auxiliary splicing motifs than exons coordinating Ca2+. The handicap of the former is compensated by stronger splice sites and uridine-richer polypyrimidine tracts, except for position -3 relative to 3' splice junctions. However, both Ca2+ and Zn2+ exons exhibit close-to-constitutive splicing in multiple tissues, consistent with their critical importance for metalloprotein function and a relatively small fraction of expendable, alternatively spliced exons. These results indicate that constraints imposed by metal coordination spheres on RNA splicing have been efficiently overcome by the plasticity of exon-intron architecture to ensure adequate metalloprotein expression.
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Affiliation(s)
- Dara Bakhtiar
- University of Southampton, Faculty of Medicine, Southampton SO16 6YD, UK
| | - Katarina Vondraskova
- Slovak Academy of Sciences, Centre of Biosciences, 840 05 Bratislava, Slovak Republic
| | - Reuben J Pengelly
- University of Southampton, Faculty of Medicine, Southampton SO16 6YD, UK
| | - Martin Chivers
- University of Southampton, Faculty of Medicine, Southampton SO16 6YD, UK
| | - Jana Kralovicova
- University of Southampton, Faculty of Medicine, Southampton SO16 6YD, UK
- Slovak Academy of Sciences, Centre of Biosciences, 840 05 Bratislava, Slovak Republic
| | - Igor Vorechovsky
- University of Southampton, Faculty of Medicine, Southampton SO16 6YD, UK
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14
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Chakraborty UK, Park Y, Sengupta K, Jung W, Joshi CP, Francis DH, Chen P. A 'through-DNA' mechanism for metal uptake-vs.-efflux regulation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.05.570191. [PMID: 38105935 PMCID: PMC10723295 DOI: 10.1101/2023.12.05.570191] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2023]
Abstract
Transition metals like Zn are essential for all organisms including bacteria, but fluctuations of their concentrations in the cell can be lethal. Organisms have thus evolved complex mechanisms for cellular metal homeostasis. One mechanistic paradigm involves pairs of transcription regulators sensing intracellular metal concentrations to regulate metal uptake and efflux. Here we report that Zur and ZntR, a prototypical pair of regulators for Zn uptake and efflux in E. coli , respectively, can coordinate their regulation through DNA, besides sensing cellular Zn 2+ concentrations. Using a combination of live-cell single-molecule tracking and in vitro single-molecule FRET measurements, we show that unmetallated ZntR can enhance the unbinding kinetics of Zur from DNA by directly acting on Zur-DNA complexes, possibly through forming heteromeric ternary and quaternary complexes that involve both protein-DNA and protein-protein interactions. This 'through-DNA' mechanism may functionally facilitate the switching in Zn uptake regulation when bacteria encounter changing Zn environments; it could also be relevant for regulating the uptake-vs.-efflux of various metals across different bacterial species and yeast.
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15
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Hati D, Brault A, Gupta M, Fletcher K, Jacques JF, Labbé S, Outten CE. Iron homeostasis proteins Grx4 and Fra2 control activity of the Schizosaccharomyces pombe iron repressor Fep1 by facilitating [2Fe-2S] cluster removal. J Biol Chem 2023; 299:105419. [PMID: 37923140 PMCID: PMC10704371 DOI: 10.1016/j.jbc.2023.105419] [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: 06/15/2023] [Revised: 10/12/2023] [Accepted: 10/26/2023] [Indexed: 11/07/2023] Open
Abstract
The Bol2 homolog Fra2 and monothiol glutaredoxin Grx4 together play essential roles in regulating iron homeostasis in Schizosaccharomyces pombe. In vivo studies indicate that Grx4 and Fra2 act as coinhibitory partners that inactivate the transcriptional repressor Fep1 in response to iron deficiency. In Saccharomyces cerevisiae, Bol2 is known to form a [2Fe-2S]-bridged heterodimer with the monothiol Grxs Grx3 and Grx4, with the cluster ligands provided by conserved residues in Grx3/4 and Bol2 as well as GSH. In this study, we characterized this analogous [2Fe-2S]-bridged Grx4-Fra2 complex in S. pombe by identifying the specific residues in Fra2 that act as ligands for the Fe-S cluster and are required to regulate Fep1 activity. We present spectroscopic and biochemical evidence confirming the formation of a [2Fe-2S]-bridged Grx4-Fra2 heterodimer with His66 and Cys29 from Fra2 serving as Fe-S cluster ligands in S. pombe. In vivo transcription and growth assays confirm that both His66 and Cys29 are required to fully mediate the response of Fep1 to low iron conditions. Furthermore, we analyzed the interaction between Fep1 and Grx4-Fra2 using CD spectroscopy to monitor changes in Fe-S cluster coordination chemistry. These experiments demonstrate unidirectional [2Fe-2S] cluster transfer from Fep1 to Grx4-Fra2 in the presence of GSH, revealing the Fe-S cluster dependent mechanism of Fep1 inactivation mediated by Grx4 and Fra2 in response to iron deficiency.
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Affiliation(s)
- Debolina Hati
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina, USA
| | - Ariane Brault
- Département de Biochimie et de Génomique Fonctionnelle, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Malini Gupta
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina, USA
| | - Kylie Fletcher
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina, USA
| | - Jean-François Jacques
- Département de Biochimie et de Génomique Fonctionnelle, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Simon Labbé
- Département de Biochimie et de Génomique Fonctionnelle, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Caryn E Outten
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina, USA.
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16
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Basak P, Cabelli DE, Chivers PT, Farquhar ER, Maroney MJ. In vitro maturation of NiSOD reveals a role for cytoplasmic histidine in processing and metalation. Metallomics 2023; 15:mfad054. [PMID: 37723610 PMCID: PMC10628968 DOI: 10.1093/mtomcs/mfad054] [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: 06/13/2023] [Accepted: 09/16/2023] [Indexed: 09/20/2023]
Abstract
The importance of cellular low molecular weight ligands in metalloenzyme maturation is largely unexplored. Maturation of NiSOD requires post-translational N-terminal processing of the proenzyme, SodN, by its cognate protease, SodX. Here we provide evidence for the participation of L-histidine in the protease-dependent maturation of nickel-dependent superoxide dismutase (NiSOD) from Streptomyces coelicolor. In vitro studies using purified proteins cloned from S. coelicolor and overexpressed in E. coli support a model where a ternary complex formed between the substrate (SodN), the protease (SodX) and L-Histidine creates a novel Ni-binding site that is capable of the N-terminal processing of SodN and specifically incorporates Ni into the apo-NiSOD product. Thus, L-Histidine serves many of the functions associated with a metallochaperone or, conversely, eliminates the need for a metallochaperone in NiSOD maturation.
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Affiliation(s)
- Priyanka Basak
- Department of Chemistry, University of Massachusetts, Amherst, MA 01003, USA
| | - Diane E Cabelli
- Department of Chemistry, Brookhaven National Laboratory, Upton, NY 11973, USA
| | - Peter T Chivers
- Departments of Biosciences and Chemistry, Durham University, Durham, DH1 3LE, UK
| | - Erik R Farquhar
- National Synchrotron Light Source-II, Brookhaven National Laboratory, Upton, NY 11973, USA
| | - Michael J Maroney
- Department of Chemistry, University of Massachusetts, Amherst, MA 01003, USA
- Program in Molecular and Cellular Biology, University of Massachusetts, Amherst, MA 01003, USA
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17
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Igbaria-Jaber Y, Hofmann L, Gevorkyan-Airapetov L, Shenberger Y, Ruthstein S. Revealing the DNA Binding Modes of CsoR by EPR Spectroscopy. ACS OMEGA 2023; 8:39886-39895. [PMID: 37901548 PMCID: PMC10601412 DOI: 10.1021/acsomega.3c06336] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Accepted: 09/28/2023] [Indexed: 10/31/2023]
Abstract
In pathogens, a unique class of metalloregulator proteins, called gene regulatory proteins, sense specific metal ions that initiate gene transcription of proteins that export metal ions from the cell, thereby preventing toxicity and cell death. CsoR is a metalloregulator protein found in various bacterial systems that "sense" Cu(I) ions with high affinity. Upon copper binding, CsoR dissociates from the DNA promoter region, resulting in initiation of gene transcription. Crystal structures of CsoR in the presence and absence of Cu(I) from various bacterial systems have been reported, suggesting either a dimeric or tetrameric structure of these helical proteins. However, structural information about the CsoR-DNA complex is missing. Here, we applied electron paramagnetic resonance (EPR) spectroscopy to follow the conformational and dynamical changes that Mycobacterium tuberculosis CsoR undergoes upon DNA binding in solution. We showed that the quaternary structure is predominantly dimeric in solution, and only minor conformational and dynamical changes occur in the DNA bound state. Also, labeling of the unresolved C- terminus revealed no significant change in dynamics upon DNA binding. These observations are unique, since for other bacterial copper metalloregulators, such as the MerR and CopY families, major conformational changes were observed upon DNA binding, indicating a different mode of action for this protein family.
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Affiliation(s)
- Yasmin Igbaria-Jaber
- Department of Chemistry and the Institute
of Nanotechnology and Advanced Materials (BINA), Bar-Ilan University, Ramat-Gan 52900, Israel
| | - Lukas Hofmann
- Department of Chemistry and the Institute
of Nanotechnology and Advanced Materials (BINA), Bar-Ilan University, Ramat-Gan 52900, Israel
| | - Lada Gevorkyan-Airapetov
- Department of Chemistry and the Institute
of Nanotechnology and Advanced Materials (BINA), Bar-Ilan University, Ramat-Gan 52900, Israel
| | - Yulia Shenberger
- Department of Chemistry and the Institute
of Nanotechnology and Advanced Materials (BINA), Bar-Ilan University, Ramat-Gan 52900, Israel
| | - Sharon Ruthstein
- Department of Chemistry and the Institute
of Nanotechnology and Advanced Materials (BINA), Bar-Ilan University, Ramat-Gan 52900, Israel
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18
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He B, Sachla AJ, Helmann JD. TerC proteins function during protein secretion to metalate exoenzymes. Nat Commun 2023; 14:6186. [PMID: 37794032 PMCID: PMC10550928 DOI: 10.1038/s41467-023-41896-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Accepted: 09/14/2023] [Indexed: 10/06/2023] Open
Abstract
Cytosolic metalloenzymes acquire metals from buffered intracellular pools. How exported metalloenzymes are appropriately metalated is less clear. We provide evidence that TerC family proteins function in metalation of enzymes during export through the general secretion (Sec-dependent) pathway. Bacillus subtilis strains lacking MeeF(YceF) and MeeY(YkoY) have a reduced capacity for protein export and a greatly reduced level of manganese (Mn) in the secreted proteome. MeeF and MeeY copurify with proteins of the general secretory pathway, and in their absence the FtsH membrane protease is essential for viability. MeeF and MeeY are also required for efficient function of the Mn2+-dependent lipoteichoic acid synthase (LtaS), a membrane-localized enzyme with an extracytoplasmic active site. Thus, MeeF and MeeY, representative of the widely conserved TerC family of membrane transporters, function in the co-translocational metalation of Mn2+-dependent membrane and extracellular enzymes.
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Affiliation(s)
- Bixi He
- Department of Microbiology, Cornell University, 370 Wing Hall, 123 Wing Drive, Ithaca, NY, 14853-8101, USA
| | - Ankita J Sachla
- Department of Microbiology, Cornell University, 370 Wing Hall, 123 Wing Drive, Ithaca, NY, 14853-8101, USA
| | - John D Helmann
- Department of Microbiology, Cornell University, 370 Wing Hall, 123 Wing Drive, Ithaca, NY, 14853-8101, USA.
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19
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Kunkle DE, Skaar EP. Moving metals: How microbes deliver metal cofactors to metalloproteins. Mol Microbiol 2023; 120:547-554. [PMID: 37408317 PMCID: PMC10592388 DOI: 10.1111/mmi.15117] [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: 02/13/2023] [Revised: 06/08/2023] [Accepted: 06/13/2023] [Indexed: 07/07/2023]
Abstract
First row d-block metal ions serve as vital cofactors for numerous essential enzymes and are therefore required nutrients for all forms of life. Despite this requirement, excess free transition metals are toxic. Free metal ions participate in the production of noxious reactive oxygen species and mis-metalate metalloproteins, rendering enzymes catalytically inactive. Thus, bacteria require systems to ensure metalloproteins are properly loaded with cognate metal ions to maintain protein function, while avoiding metal-mediated cellular toxicity. In this perspective we summarize the current mechanistic understanding of bacterial metallocenter maturation with specific emphasis on metallochaperones; a group of specialized proteins that both shield metal ions from inadvertent reactions and distribute them to cognate target metalloproteins. We highlight several recent advances in the field that have implicated new classes of proteins in the distribution of metal ions within bacterial proteins, while speculating on the future of the field of bacterial metallobiology.
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Affiliation(s)
- Dillon E. Kunkle
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA
- Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Eric P. Skaar
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA
- Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University Medical Center, Nashville, TN, USA
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20
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Rivera M. Mobilization of iron stored in bacterioferritin, a new target for perturbing iron homeostasis and developing antibacterial and antibiofilm molecules. J Inorg Biochem 2023; 247:112306. [PMID: 37451083 DOI: 10.1016/j.jinorgbio.2023.112306] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Revised: 06/08/2023] [Accepted: 06/24/2023] [Indexed: 07/18/2023]
Abstract
Antibiotic resistance is a global public health threat. The care of chronic infections is complicated by bacterial biofilms. Biofilm embedded cells can be up to 1000-fold more tolerant to antibiotic treatment than planktonic cells. Antibiotic tolerance is a condition which does not involve mutation and enables bacteria to survive in the presence of antibiotics. The antibiotic tolerance of biofilm-cells often renders antibiotics ineffective, even against strains that do not carry resistance-impairing mutations. This review discusses bacterial iron homeostasis and the strategies being developed to target this bacterial vulnerability, with emphasis on a recently proposed approach which aims at targeting the iron storage protein bacterioferritin (Bfr) and its physiological partner, the ferredoxin Bfd. Bfr regulates cytosolic iron concentrations by oxidizing Fe2+ and storing Fe3+ in its internal cavity, and by forming a complex with Bfd to reduce Fe3+ in the internal cavity and release Fe2+ to the cytosol. Blocking the Bfr-Bfd complex in P. aeruginosa cells causes an irreversible accumulation of Fe3+ in BfrB and simultaneous cytosolic iron depletion, which leads to impaired biofilm maintenance and biofilm cell death. Recently discovered small molecule inhibitors of the Bfr-Bfd complex, which bind Bfr at the Bfd binding site, inhibit iron mobilization, and elicit biofilm cell death.
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Affiliation(s)
- Mario Rivera
- Department of Chemistry, Louisiana State University, 232 Choppin Hall, Baton Rouge, LA 70803, USA.
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21
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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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22
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Hay Mele B, Monticelli M, Leone S, Bastoni D, Barosa B, Cascone M, Migliaccio F, Montemagno F, Ricciardelli A, Tonietti L, Rotundi A, Cordone A, Giovannelli D. Oxidoreductases and metal cofactors in the functioning of the earth. Essays Biochem 2023; 67:653-670. [PMID: 37503682 PMCID: PMC10423856 DOI: 10.1042/ebc20230012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2023] [Revised: 07/03/2023] [Accepted: 07/10/2023] [Indexed: 07/29/2023]
Abstract
Life sustains itself using energy generated by thermodynamic disequilibria, commonly existing as redox disequilibria. Metals are significant players in controlling redox reactions, as they are essential components of the engine that life uses to tap into the thermodynamic disequilibria necessary for metabolism. The number of proteins that evolved to catalyze redox reactions is extraordinary, as is the diversification level of metal cofactors and catalytic domain structures involved. Notwithstanding the importance of the topic, the relationship between metals and the redox reactions they are involved in has been poorly explored. This work reviews the structure and function of different prokaryotic organometallic-protein complexes, highlighting their pivotal role in controlling biogeochemistry. We focus on a specific subset of metal-containing oxidoreductases (EC1 or EC7.1), which are directly involved in biogeochemical cycles, i.e., at least one substrate or product is a small inorganic molecule that is or can be exchanged with the environment. Based on these inclusion criteria, we select and report 59 metalloenzymes, describing the organometallic structure of their active sites, the redox reactions in which they are involved, and their biogeochemical roles.
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Affiliation(s)
- Bruno Hay Mele
- Department of Biology, University of Naples Federico II, Naples, Italy
| | - Maria Monticelli
- Department of Biology, University of Naples Federico II, Naples, Italy
- National Research Council - Institute of Biomolecular Chemistry - CNR-ICB, Pozzuoli, Italy
| | - Serena Leone
- Dipartimento di Biologia ed Evoluzione degli Organismi Marini, Stazione Zoologica Anton. Dohrn, Napoli, Italy
| | - Deborah Bastoni
- Department of Biology, University of Naples Federico II, Naples, Italy
| | - Bernardo Barosa
- Department of Biology, University of Naples Federico II, Naples, Italy
| | - Martina Cascone
- Department of Biology, University of Naples Federico II, Naples, Italy
| | - Flavia Migliaccio
- Department of Biology, University of Naples Federico II, Naples, Italy
| | | | | | - Luca Tonietti
- Department of Biology, University of Naples Federico II, Naples, Italy
- Department of Science and Technology, University of Naples Parthenope, Naples, Italy
| | - Alessandra Rotundi
- Department of Science and Technology, University of Naples Parthenope, Naples, Italy
| | - Angelina Cordone
- Department of Biology, University of Naples Federico II, Naples, Italy
| | - Donato Giovannelli
- Department of Biology, University of Naples Federico II, Naples, Italy
- Department of Science and Technology, University of Naples Parthenope, Naples, Italy
- National Research Council - Institute of Marine Biological Resources and Biotechnologies - CNR-IRBIM, Ancona, Italy
- Department of Marine and Coastal Science, Rutgers University, New Brunswick, NJ, U.S.A
- Marine Chemistry and Geochemistry Department - Woods Hole Oceanographic Institution, MA, U.S.A
- Earth-Life Science Institute, Tokyo Institute of Technology, Tokyo, Japan
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23
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Young TR, Deery E, Foster AW, Martini MA, Osman D, Warren MJ, Robinson NJ. Two Distinct Thermodynamic Gradients for Cellular Metalation of Vitamin B 12. JACS AU 2023; 3:1472-1483. [PMID: 37234125 PMCID: PMC10206600 DOI: 10.1021/jacsau.3c00119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Revised: 04/13/2023] [Accepted: 04/25/2023] [Indexed: 05/27/2023]
Abstract
The acquisition of CoII by the corrin component of vitamin B12 follows one of two distinct pathways, referred to as early or late CoII insertion. The late insertion pathway exploits a CoII metallochaperone (CobW) from the COG0523 family of G3E GTPases, while the early insertion pathway does not. This provides an opportunity to contrast the thermodynamics of metalation in a metallochaperone-requiring and a metallochaperone-independent pathway. In the metallochaperone-independent route, sirohydrochlorin (SHC) associates with the CbiK chelatase to form CoII-SHC. CoII-buffered enzymatic assays indicate that SHC binding enhances the thermodynamic gradient for CoII transfer from the cytosol to CbiK. In the metallochaperone-dependent pathway, hydrogenobyrinic acid a,c-diamide (HBAD) associates with the CobNST chelatase to form CoII-HBAD. Here, CoII-buffered enzymatic assays indicate that CoII transfer from the cytosol to HBAD-CobNST must somehow traverse a highly unfavorable thermodynamic gradient for CoII binding. Notably, there is a favorable gradient for CoII transfer from the cytosol to the MgIIGTP-CobW metallochaperone, but further transfer of CoII from the GTP-bound metallochaperone to the HBAD-CobNST chelatase complex is thermodynamically unfavorable. However, after nucleotide hydrolysis, CoII transfer from the chaperone to the chelatase complex is calculated to become favorable. These data reveal that the CobW metallochaperone can overcome an unfavorable thermodynamic gradient for CoII transfer from the cytosol to the chelatase by coupling this process to GTP hydrolysis.
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Affiliation(s)
- Tessa R. Young
- Department
of Biosciences, Durham University, Durham DH1 3LE, U.K.
- Department
of Chemistry, Durham University, Durham DH1 3LE, U.K.
| | - Evelyne Deery
- School
of Biosciences, University of Kent, Canterbury CT2 7NJ, U.K.
| | - Andrew W. Foster
- Department
of Biosciences, Durham University, Durham DH1 3LE, U.K.
- Department
of Chemistry, Durham University, Durham DH1 3LE, U.K.
| | - Maria Alessandra Martini
- Department
of Biosciences, Durham University, Durham DH1 3LE, U.K.
- Department
of Inorganic Spectroscopy, Max Planck Institute
for Chemical Energy Conversion, 45470 Mülheim an der Ruhr, Germany
| | - Deenah Osman
- Department
of Biosciences, Durham University, Durham DH1 3LE, U.K.
- Department
of Chemistry, Durham University, Durham DH1 3LE, U.K.
| | - Martin J. Warren
- School
of Biosciences, University of Kent, Canterbury CT2 7NJ, U.K.
- Quadram
Institute Bioscience, Norwich Research Park, Norwich NR4 7UQ, U.K.
| | - Nigel J. Robinson
- Department
of Biosciences, Durham University, Durham DH1 3LE, U.K.
- Department
of Chemistry, Durham University, Durham DH1 3LE, U.K.
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24
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He B, Sachla AJ, Helmann JD. TerC Proteins Function During Protein Secretion to Metalate Exoenzymes. RESEARCH SQUARE 2023:rs.3.rs-2860473. [PMID: 37292672 PMCID: PMC10246235 DOI: 10.21203/rs.3.rs-2860473/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Cytosolic metalloenzymes acquire metals from buffered intracellular pools. How exported metalloenzymes are appropriately metalated is less clear. We provide evidence that TerC family proteins function in metalation of enzymes during export through the general secretion (Sec-dependent) pathway. Bacillus subtilis strains lacking MeeF(YceF) and MeeY(YkoY) have a reduced capacity for protein export and a greatly reduced level of manganese (Mn) in the secreted proteome. MeeF and MeeY copurify with proteins of the general secretory pathway, and in their absence the FtsH membrane protease is essential for viability. MeeF and MeeY are also required for efficient function of the Mn2+-dependent lipoteichoic acid synthase (LtaS), a membrane-localized enzyme with an extracytoplasmic active site. Thus, MeeF and MeeY, representative of the widely conserved TerC family of membrane transporters, function in the co-translocational metalation of Mn2+-dependent membrane and extracellular enzymes.
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Affiliation(s)
- Bixi He
- Department of Microbiology, Cornell University, 370 Wing Hall, 123 Wing Drive, Ithaca, New York 14853-8101, USA
| | - Ankita J. Sachla
- Department of Microbiology, Cornell University, 370 Wing Hall, 123 Wing Drive, Ithaca, New York 14853-8101, USA
| | - John D. Helmann
- Department of Microbiology, Cornell University, 370 Wing Hall, 123 Wing Drive, Ithaca, New York 14853-8101, USA
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25
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Marcos-Torres FJ, Juniar L, Griese JJ. The molecular mechanisms of the bacterial iron sensor IdeR. Biochem Soc Trans 2023:233013. [PMID: 37140254 DOI: 10.1042/bst20221539] [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: 03/09/2023] [Revised: 04/12/2023] [Accepted: 04/18/2023] [Indexed: 05/05/2023]
Abstract
Life came to depend on iron as a cofactor for many essential enzymatic reactions. However, once the atmosphere was oxygenated, iron became both scarce and toxic. Therefore, complex mechanisms have evolved to scavenge iron from an environment in which it is poorly bioavailable, and to tightly regulate intracellular iron contents. In bacteria, this is typically accomplished with the help of one key regulator, an iron-sensing transcription factor. While Gram-negative bacteria and Gram-positive species with low guanine-cytosine (GC) content generally use Fur (ferric uptake regulator) proteins to regulate iron homeostasis, Gram-positive species with high GC content use the functional homolog IdeR (iron-dependent regulator). IdeR controls the expression of iron acquisition and storage genes, repressing the former, and activating the latter in an iron-dependent manner. In bacterial pathogens such as Corynebacterium diphtheriae and Mycobacterium tuberculosis, IdeR is also involved in virulence, whereas in non-pathogenic species such as Streptomyces, it regulates secondary metabolism as well. Although in recent years the focus of research on IdeR has shifted towards drug development, there is much left to learn about the molecular mechanisms of IdeR. Here, we summarize our current understanding of how this important bacterial transcriptional regulator represses and activates transcription, how it is allosterically activated by iron binding, and how it recognizes its DNA target sites, highlighting the open questions that remain to be addressed.
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Affiliation(s)
- Francisco Javier Marcos-Torres
- Department of Cell and Molecular Biology, Uppsala University, 751 24 Uppsala, Sweden
- Department of Biotechnology and Environmental Protection, Estación Experimental del Zaidín-CSIC, 18011 Granada, Spain
| | - Linda Juniar
- Department of Cell and Molecular Biology, Uppsala University, 751 24 Uppsala, Sweden
| | - Julia J Griese
- Department of Cell and Molecular Biology, Uppsala University, 751 24 Uppsala, Sweden
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26
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Abstract
The ferric uptake regulator (Fur) protein is the founding member of the FUR superfamily of metalloregulatory proteins that control metal homeostasis in bacteria. FUR proteins regulate metal homeostasis in response to the binding of iron (Fur), zinc (Zur), manganese (Mur), or nickel (Nur). FUR family proteins are generally dimers in solution, but the DNA-bound complex can involve a single dimer, a dimer-of-dimers, or an extended array of bound protein. Elevated FUR levels due to changes in cell physiology increase DNA occupancy and may also kinetically facilitate protein dissociation. Interactions between FUR proteins and other regulators are commonplace, often including cooperative and competitive DNA-binding interactions within the regulatory region. Further, there are many emerging examples of allosteric regulators that interact directly with FUR family proteins. Here, we focus on newly uncovered examples of allosteric regulation by diverse Fur antagonists (Escherichia coli YdiV/SlyD, Salmonella enterica EIIANtr, Vibrio parahaemolyticus FcrX, Acinetobacter baumannii BlsA, Bacillus subtilis YlaN, and Pseudomonas aeruginosa PacT) as well as one Zur antagonist (Mycobacterium bovis CmtR). Small molecules and metal complexes may also serve as regulatory ligands, with examples including heme binding to Bradyrhizobium japonicum Irr and 2-oxoglutarate binding to Anabaena FurA. How these protein-protein and protein-ligand interactions act in conjunction with regulatory metal ions to facilitate signal integration is an active area of investigation.
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Affiliation(s)
| | - John D. Helmann
- Department of Microbiology, Cornell University, Ithaca, New York, USA
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27
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He B, Sachla AJ, Helmann JD. TerC Proteins Function During Protein Secretion to Metalate Exoenzymes. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.10.536223. [PMID: 37090602 PMCID: PMC10120614 DOI: 10.1101/2023.04.10.536223] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/25/2023]
Abstract
Cytosolic metalloenzymes acquire metals from buffered intracellular pools. How exported metalloenzymes are appropriately metalated is less clear. We provide evidence that TerC family proteins function in metalation of enzymes during export through the general secretion (Sec-dependent) pathway. Bacillus subtilis strains lacking MeeF(YceF) and MeeY(YkoY) have a reduced capacity for protein export and a greatly reduced level of manganese (Mn) in the secreted proteome. MeeF and MeeY copurify with proteins of the general secretory pathway, and in their absence the FtsH membrane protease is essential for viability. MeeF and MeeY are also required for efficient function of the Mn 2+ -dependent lipoteichoic acid synthase (LtaS), a membrane-localized enzyme with an extracytoplasmic active site. Thus, MeeF and MeeY, representative of the widely conserved TerC family of membrane transporters, function in the co-translocational metalation of Mn 2+ -dependent membrane and extracellular enzymes.
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Affiliation(s)
- Bixi He
- Department of Microbiology, Cornell University, 370 Wing Hall, 123 Wing Drive, Ithaca, New York 14853-8101, USA
| | - Ankita J. Sachla
- Department of Microbiology, Cornell University, 370 Wing Hall, 123 Wing Drive, Ithaca, New York 14853-8101, USA
| | - John D. Helmann
- Department of Microbiology, Cornell University, 370 Wing Hall, 123 Wing Drive, Ithaca, New York 14853-8101, USA
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28
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Sendra KM, Barwinska-Sendra A, Mackenzie ES, Baslé A, Kehl-Fie TE, Waldron KJ. An ancient metalloenzyme evolves through metal preference modulation. Nat Ecol Evol 2023; 7:732-744. [PMID: 37037909 PMCID: PMC10172142 DOI: 10.1038/s41559-023-02012-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Accepted: 02/15/2023] [Indexed: 04/12/2023]
Abstract
Evolution creates functional diversity of proteins, the essential building blocks of all biological systems. However, studies of natural proteins sampled across the tree of life and evaluated in a single experimental system are lacking. Almost half of enzymes require metals, and metalloproteins tend to optimally utilize the physicochemical properties of a specific metal co-factor. Life must adapt to changes in metal bioavailability, including those during the transition from anoxic to oxic Earth or pathogens' exposure to nutritional immunity. These changes can challenge the ability of metalloenzymes to maintain activity, presumptively driving their evolution. Here we studied metal-preference evolution within the natural diversity of the iron/manganese superoxide dismutase (SodFM) family of reactive oxygen species scavengers. We identified and experimentally verified residues with conserved roles in determining metal preference that, when combined with an understanding of the protein's evolutionary history, improved prediction of metal utilization across the five SodFM subfamilies defined herein. By combining phylogenetics, biochemistry and structural biology, we demonstrate that SodFM metal utilization can be evolutionarily fine tuned by sliding along a scale between perfect manganese and iron specificities. Over the history of life, SodFM metal preference has been modulated multiple independent times within different evolutionary and ecological contexts, and can be changed within short evolutionary timeframes.
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Affiliation(s)
- K M Sendra
- Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK.
| | - A Barwinska-Sendra
- Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - E S Mackenzie
- Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - A Baslé
- Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - T E Kehl-Fie
- Department of Microbiology, University of Illinois Urbana-Champaign, Urbana, IL, USA.
- Carl R. Woese Institute for Genomic Biology, University of Illinois Urbana-Champaign, Urbana, IL, USA.
| | - K J Waldron
- Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK.
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland.
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29
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Robison ATR, Sturrock GR, Zaengle-Barone JM, Wiebelhaus N, Dharani A, Williams IG, Fitzgerald MC, Franz KJ. Analysis of copper-induced protein precipitation across the E. coli proteome. Metallomics 2023; 15:mfac098. [PMID: 36549662 PMCID: PMC9830969 DOI: 10.1093/mtomcs/mfac098] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Accepted: 12/14/2022] [Indexed: 12/24/2022]
Abstract
Metal cations have been exploited for their precipitation properties in a wide variety of studies, ranging from differentiating proteins from serum and blood to identifying the protein targets of drugs. Despite widespread recognition of this phenomenon, the mechanisms of metal-induced protein aggregation have not been fully elucidated. Recent studies have suggested that copper's (Cu) ability to induce protein aggregation may be a main contributor to Cu-induced cell death. Here, we provide the first proteome-wide analysis of the relative sensitivities of proteins across the Escherichia coli proteome to Cu-induced aggregation. We utilize a metal-induced protein precipitation (MiPP) methodology that relies on quantitative bottom-up proteomics to define the metal concentration-dependent precipitation properties of proteins on a proteomic scale. Our results establish that Cu far surpasses other metals in promoting protein aggregation and that the protein aggregation is reversible upon metal chelation. The bulk of the Cu bound in the protein aggregates is Cu1+, regardless of the Cu2+ source. Analysis of our MiPP data allows us to investigate underlying biophysical characteristics that determine a protein's sensitivity to Cu-induced aggregation, which is independent of the relative concentration of protein in the lysate. Overall, this analysis provides new insights into the mechanism behind Cu cytotoxicity, as well as metal cation-induced protein aggregation.
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Affiliation(s)
- Amy T R Robison
- Department of Chemistry, Duke University, Durham, NC 27708, USA
| | | | | | | | - Azim Dharani
- Department of Chemistry, Duke University, Durham, NC 27708, USA
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30
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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: 16] [Impact Index Per Article: 16.0] [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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31
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Steingard CH, Pinochet-Barros A, Wendel BM, Helmann JD. Iron homeostasis in Bacillus subtilis relies on three differentially expressed efflux systems. MICROBIOLOGY (READING, ENGLAND) 2023; 169:001289. [PMID: 36748638 PMCID: PMC9993123 DOI: 10.1099/mic.0.001289] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
In Bacillus subtilis, iron homeostasis is maintained by the ferric uptake regulator (Fur) and manganese homeostasis relies on the manganese transport regulator (MntR). Both Fur and MntR function as bi-functional metalloregulators that repress import and activate metal ion efflux systems. The ferrous iron efflux ATPase, PfeT, is derepressed by hydrogen peroxide (H2O2) as sensed by PerR and induced by iron as sensed by Fur. Mutants lacking PfeT are sensitive to iron intoxication. Here, we show that mntR mutants are also iron-sensitive, largely due to decreased expression of the MntR-activated MneP and MneS cation diffusion facilitator (CDF) proteins previously defined for their role in Mn2+ export. The ability of MneP and MneS to export iron is apparent even when their expression is not induced by Mn2+. Our results demonstrate that PfeT, MneP and MneS each contribute to iron homeostasis, and a triple mutant lacking all three is more iron-sensitive than any single mutant. We further show that sensitivity to H2O2 does not correlate with iron sensitivity. For example, an mntR mutant is H2O2-sensitive due to elevated Mn(II) that increases PerR-mediated repression of peroxide resistance genes, and this repression is antagonized by elevated Fe2+ in an mntR pfeT mutant. Thus, H2O2-sensitivity reflects the relative levels of Mn2+ and Fe2+ as sensed by the PerR regulatory protein. These results underscore the complex interplay between manganese, iron and oxidative stress in B. subtilis.
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Affiliation(s)
- Caroline H Steingard
- Department of Microbiology, Cornell University, Ithaca, New York 14853-8101, USA
| | - Azul Pinochet-Barros
- Department of Microbiology, Cornell University, Ithaca, New York 14853-8101, USA
| | - Brian M Wendel
- Department of Microbiology, Cornell University, Ithaca, New York 14853-8101, USA
| | - John D Helmann
- Department of Microbiology, Cornell University, Ithaca, New York 14853-8101, USA
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32
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Park J, Cleary MB, Li D, Mattocks JA, Xu J, Wang H, Mukhopadhyay S, Gale EM, Cotruvo JA. A genetically encoded fluorescent sensor for manganese(II), engineered from lanmodulin. Proc Natl Acad Sci U S A 2022; 119:e2212723119. [PMID: 36508659 PMCID: PMC9907080 DOI: 10.1073/pnas.2212723119] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Accepted: 11/10/2022] [Indexed: 12/15/2022] Open
Abstract
The design of selective metal-binding sites is a challenge in both small-molecule and macromolecular chemistry. Selective recognition of manganese (II)-the first-row transition metal ion that tends to bind with the lowest affinity to ligands, as described by the Irving-Williams series-is particularly difficult. As a result, there is a dearth of chemical biology tools with which to study manganese physiology in live cells, which would advance understanding of photosynthesis, host-pathogen interactions, and neurobiology. Here we report the rational re-engineering of the lanthanide-binding protein, lanmodulin, into genetically encoded fluorescent sensors for MnII, MnLaMP1 and MnLaMP2. These sensors with effective Kd(MnII) of 29 and 7 µM, respectively, defy the Irving-Williams series to selectively detect MnII in vitro and in vivo. We apply both sensors to visualize kinetics of bacterial labile manganese pools. Biophysical studies indicate the importance of coordinated solvent and hydrophobic interactions in the sensors' selectivity. Our results establish lanmodulin as a versatile scaffold for design of selective protein-based biosensors and chelators for metals beyond the f-block.
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Affiliation(s)
- Jennifer Park
- Department of Chemistry, The Pennsylvania State University, University Park, PA16802
| | - Michael B. Cleary
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital / Harvard Medical School, Charlestown, MA02129
| | - Danyang Li
- Division of Pharmacology and Toxicology, College of Pharmacy, Institute for Cellular and Molecular Biology, and Institute for Neuroscience, The University of Texas at Austin, Austin, TX78712
| | - Joseph A. Mattocks
- Department of Chemistry, The Pennsylvania State University, University Park, PA16802
| | - Jiansong Xu
- Department of Chemistry, The Pennsylvania State University, University Park, PA16802
| | - Huan Wang
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital / Harvard Medical School, Charlestown, MA02129
| | - Somshuvra Mukhopadhyay
- Division of Pharmacology and Toxicology, College of Pharmacy, Institute for Cellular and Molecular Biology, and Institute for Neuroscience, The University of Texas at Austin, Austin, TX78712
| | - Eric M. Gale
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital / Harvard Medical School, Charlestown, MA02129
| | - Joseph A. Cotruvo
- Department of Chemistry, The Pennsylvania State University, University Park, PA16802
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33
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Jordan MR, Gonzalez-Gutierrez G, Trinidad JC, Giedroc DP. Metal retention and replacement in QueD2 protect queuosine-tRNA biosynthesis in metal-starved Acinetobacter baumannii. Proc Natl Acad Sci U S A 2022; 119:e2213630119. [PMID: 36442121 PMCID: PMC9894224 DOI: 10.1073/pnas.2213630119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Accepted: 10/28/2022] [Indexed: 11/29/2022] Open
Abstract
In response to bacterial infection, the vertebrate host employs the metal-sequestering protein calprotectin (CP) to withhold essential transition metals, notably Zn(II), to inhibit bacterial growth. Previous studies of the impact of CP-imposed transition-metal starvation in A. baumannii identified two enzymes in the de novo biosynthesis pathway of queuosine-transfer ribonucleic acid (Q-tRNA) that become cellularly abundant, one of which is QueD2, a 6-carboxy-5,6,7,8-tetrahydropterin (6-CPH4) synthase that catalyzes the initial, committed step of the pathway. Here, we show that CP strongly disrupts Q incorporation into tRNA. As such, we compare the AbQueD2 "low-zinc" paralog with a housekeeping, obligatory Zn(II)-dependent enzyme QueD. The crystallographic structure of Zn(II)-bound AbQueD2 reveals a distinct catalytic site coordination sphere and assembly state relative to QueD and possesses a dynamic loop, immediately adjacent to the catalytic site that coordinates a second Zn(II) in the structure. One of these loop-coordinating residues is an invariant Cys18, that protects QueD2 from dissociation of the catalytic Zn(II) while maintaining flux through the Q-tRNA biosynthesis pathway in cells. We propose a "metal retention" model where Cys18 introduces coordinative plasticity into the catalytic site which slows metal release, while also enhancing the metal promiscuity such that Fe(II) becomes an active cofactor. These studies reveal a complex, multipronged evolutionary adaptation to cellular Zn(II) limitation in a key Zn(II) metalloenzyme in an important human pathogen.
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Affiliation(s)
- Matthew R. Jordan
- Department of Chemistry, Indiana University, Bloomington, IN47405
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN47405
| | | | - Jonathan C. Trinidad
- Department of Chemistry, Indiana University, Bloomington, IN47405
- Laboratory for Biological Mass Spectrometry, Department of Chemistry, Indiana University, Bloomington, IN47405
| | - David P. Giedroc
- Department of Chemistry, Indiana University, Bloomington, IN47405
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34
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Choi TS, Tezcan FA. Design of a Flexible, Zn-Selective Protein Scaffold that Displays Anti-Irving-Williams Behavior. J Am Chem Soc 2022; 144:18090-18100. [PMID: 36154053 PMCID: PMC9949983 DOI: 10.1021/jacs.2c08050] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Selective metal binding is a key requirement not only for the functions of natural metalloproteins but also for the potential applications of artificial metalloproteins in heterogeneous environments such as cells and environmental samples. The selection of transition-metal ions through protein design can, in principle, be achieved through the appropriate choice and the precise positioning of amino acids that comprise the primary metal coordination sphere. However, this task is made difficult by the intrinsic flexibility of proteins and the fact that protein design approaches generally lack the sub-Å precision required for the steric selection of metal ions. We recently introduced a flexible/probabilistic protein design strategy (MASCoT) that allows metal ions to search for optimal coordination geometry within a flexible, yet covalently constrained dimer interface. In an earlier proof-of-principle study, we used MASCoT to generate an artificial metalloprotein dimer, (AB)2, which selectively bound CoII and NiII over CuII (as well as other first-row transition-metal ions) through the imposition of a rigid octahedral coordination geometry, thus countering the Irving-Williams trend. In this study, we set out to redesign (AB)2 to examine the applicability of MASCoT to the selective binding of other metal ions. We report here the design and characterization of a new flexible protein dimer, B2, which displays ZnII selectivity over all other tested metal ions including CuII both in vitro and in cellulo. Selective, anti-Irving-Williams ZnII binding by B2 is achieved through the formation of a unique trinuclear Zn coordination motif in which His and Glu residues are rigidly placed in a tetrahedral geometry. These results highlight the utility of protein flexibility in the design and discovery of selective binding motifs.
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35
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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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36
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Foster AW, Clough SE, Aki Z, Young TR, Clarke AR, Robinson NJ. Metalation calculators for E. coli strain JM109 (DE3): Aerobic, anaerobic and hydrogen peroxide exposed cells cultured in LB media. Metallomics 2022; 14:6657815. [PMID: 35933161 PMCID: PMC9434800 DOI: 10.1093/mtomcs/mfac058] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Accepted: 07/24/2022] [Indexed: 11/14/2022]
Abstract
Three web-based calculators, and three analogous spreadsheets, have been generated that predict in vivo metal occupancies of proteins based on known metal affinities. The calculations exploit estimates of the availabilities of the labile buffered pools of different metals inside a cell. Here, metal availabilities have been estimated for a strain of E. coli that is commonly used in molecular biology and biochemistry research, for example in the production of recombinant proteins. Metal availabilities have been examined for cells grown in LB medium aerobically, anaerobically and in response to H2O2 by monitoring the abundance of a selected set of metal-responsive transcripts by qPCR. The selected genes are regulated by DNA-binding metal sensors that have been thermodynamically characterised in related bacterial cells enabling gene expression to be read-out as a function of intracellular metal availabilities expressed as free energies for forming metal complexes. The calculators compare these values with the free energies for forming complexes with the protein of interest, derived from metal affinities, to estimate how effectively the protein can compete with exchangeable binding sites in the intracellular milieu. The calculators then inter-compete the different metals, limiting total occupancy of the site to a maximum stoichiometry of 1, to output percentage occupancies with each metal. In addition to making these new and conditional calculators available, an original purpose of this article was to provide a tutorial which discusses constraints of this approach and presents ways in which such calculators might be exploited in basic and applied research, and in next-generation manufacturing.
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Affiliation(s)
- Andrew W Foster
- Department of Biosciences, Durham University, Durham, UK.,Department of Chemistry, Durham University, Durham, UK
| | - Sophie E Clough
- Department of Biosciences, Durham University, Durham, UK.,Department of Chemistry, Durham University, Durham, UK
| | - Zeynep Aki
- Advanced Research Computing, Durham University, Durham, UK
| | - Tessa R Young
- Department of Biosciences, Durham University, Durham, UK.,Department of Chemistry, Durham University, Durham, UK
| | | | - Nigel J Robinson
- Department of Biosciences, Durham University, Durham, UK.,Department of Chemistry, Durham University, Durham, UK
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37
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Li P, Nayeri N, Górecki K, Becares ER, Wang K, Mahato DR, Andersson M, Abeyrathna SS, Lindkvist‐Petersson K, Meloni G, Missel JW, Gourdon P. PcoB is a defense outer membrane protein that facilitates cellular uptake of copper. Protein Sci 2022; 31:e4364. [PMID: 35762724 PMCID: PMC9210255 DOI: 10.1002/pro.4364] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Revised: 05/03/2022] [Accepted: 05/27/2022] [Indexed: 01/17/2023]
Abstract
Copper (Cu) is one of the most abundant trace metals in all organisms, involved in a plethora of cellular processes. Yet elevated concentrations of the element are harmful, and interestingly prokaryotes are more sensitive for environmental Cu stress than humans. Various transport systems are present to maintain intracellular Cu homeostasis, including the prokaryotic plasmid-encoded multiprotein pco operon, which is generally assigned as a defense mechanism against elevated Cu concentrations. Here we structurally and functionally characterize the outer membrane component of the Pco system, PcoB, recovering a 2.0 Å structure, revealing a classical β-barrel architecture. Unexpectedly, we identify a large opening on the extracellular side, linked to a considerably electronegative funnel that becomes narrower towards the periplasm, defining an ion-conducting pathway as also supported by metal binding quantification via inductively coupled plasma mass spectrometry and molecular dynamics (MD) simulations. However, the structure is partially obstructed towards the periplasmic side, and yet flux is permitted in the presence of a Cu gradient as shown by functional characterization in vitro. Complementary in vivo experiments demonstrate that isolated PcoB confers increased sensitivity towards Cu. Aggregated, our findings indicate that PcoB serves to permit Cu import. Thus, it is possible the Pco system physiologically accumulates Cu in the periplasm as a part of an unorthodox defense mechanism against metal stress. These results point to a previously unrecognized principle of maintaining Cu homeostasis and may as such also assist in the understanding and in efforts towards combatting bacterial infections of Pco-harboring pathogens.
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Affiliation(s)
- Ping Li
- Department of Experimental Medical ScienceLund UniversityLundSweden
| | - Niloofar Nayeri
- Department of Experimental Medical ScienceLund UniversityLundSweden
| | - Kamil Górecki
- Department of Experimental Medical ScienceLund UniversityLundSweden
| | - Eva Ramos Becares
- Department of Biomedical SciencesUniversity of CopenhagenCopenhagenDenmark
| | - Kaituo Wang
- Department of Biomedical SciencesUniversity of CopenhagenCopenhagenDenmark
| | | | | | - Sameera S. Abeyrathna
- Department of Chemistry and BiochemistryThe University of Texas at DallasRichardsonTexasUSA
| | | | - Gabriele Meloni
- Department of Chemistry and BiochemistryThe University of Texas at DallasRichardsonTexasUSA
| | | | - Pontus Gourdon
- Department of Experimental Medical ScienceLund UniversityLundSweden
- Department of Biomedical SciencesUniversity of CopenhagenCopenhagenDenmark
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38
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Xia Y, Cheng Z, Hou C, Peplowski L, Zhou Z, Chen X. Discovery of the ATPase Activity of a Cobalt-Type Nitrile Hydratase Activator and Its Promoting Effect on Enzyme Maturation. Biochemistry 2022; 61:2940-2947. [PMID: 35673797 DOI: 10.1021/acs.biochem.2c00167] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
An activator protein and a metal ion are two factors known to be indispensable for the maturation of nitrile hydratase (NHase). Here, the third key factor, adenosine triphosphate (ATP), was identified to play an important role in the activation of Co-type NHase. Free phosphate measurements revealed that the Co-type activator protein can hydrolyze ATP/GTP with appreciable performance and that such catalytic performance is related to NHase activity. Computational analysis and site-directed mutagenesis identified several potential hot spot residues involved in the binding of ATP to Co-type activator protein, and an E60A/W61A/D62A/I139A/T141A combinatorial variant reduced the ATPase activity to 18% of its original level. Further NHase activation studies using the combinatorial variant demonstrated that although the ATPase activity of the Co-type activator protein correlated with NHase activity, a low ATP concentration of 0.5 mmol/L was optimal for NHase activation, with higher ATP concentrations potentially inhibiting NHase activity.
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Affiliation(s)
- Yuanyuan Xia
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 1800 Lihu Avenue, Wuxi 214122, China
| | - Zhongyi Cheng
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 1800 Lihu Avenue, Wuxi 214122, China
| | - Chen Hou
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 1800 Lihu Avenue, Wuxi 214122, China
| | - Lukasz Peplowski
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University in Torun, Grudziadzka 5, 87-100 Torun, Poland
| | - Zhemin Zhou
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 1800 Lihu Avenue, Wuxi 214122, China
| | - Xianzhong Chen
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 1800 Lihu Avenue, Wuxi 214122, China
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39
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Senges CHR, Warmuth HL, Vázquez-Hernández M, Uzun HD, Sagurna L, Dietze P, Schmidt C, Mücher B, Herlitze S, Krämer U, Ott I, Pomorski TG, Bandow JE. Effects of 4-Br-A23187 on Bacillus subtilis cells and unilamellar vesicles reveal it to be a potent copper ionophore. Proteomics 2022; 22:e2200061. [PMID: 35666003 PMCID: PMC10140759 DOI: 10.1002/pmic.202200061] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Revised: 05/19/2022] [Accepted: 06/03/2022] [Indexed: 11/12/2022]
Abstract
Ionophores are small molecules or peptides that transport metal ions across biological membranes. Their transport capabilities are typically characterized in vitro using vesicles and single ion species. It is difficult to infer from these data which effects ionophores have on living cells in a complex environment (e.g. culture medium), since net ion movement is influenced by many factors including ion composition of the medium, concentration gradients, pH gradient, and protein-mediated transport processes across the membrane. To gain insights into the antibacterial mechanism of action of the semisynthetic polyether ionophore 4-Br-A23187, known to efficiently transport zinc and manganese in vitro, we investigated its effects on the gram-positive model organism Bacillus subtilis. In addition to monitoring cellular ion concentrations, the physiological impact of treatment was assessed on the proteome level. 4-Br-A23187 treatment resulted in an increase in intracellular copper levels, the extent of which depended on the copper concentration of the medium. Effects of copper accumulation mirrored by the proteomic response included oxidative stress, disturbance of proteostasis, metal and sulfur homeostasis. The antibiotic effect of 4-Br-A23187 is further aggravated by a decrease in intracellular manganese and magnesium. A liposome model confirmed that 4-Br-A23187 acts as copper ionophore in vitro. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Christoph H R Senges
- Applied Microbiology, Faculty of Biology and Biotechnology, Ruhr University Bochum, 44801, Bochum, Germany
| | - Helen L Warmuth
- Applied Microbiology, Faculty of Biology and Biotechnology, Ruhr University Bochum, 44801, Bochum, Germany
| | - Melissa Vázquez-Hernández
- Applied Microbiology, Faculty of Biology and Biotechnology, Ruhr University Bochum, 44801, Bochum, Germany
| | - Huriye Deniz Uzun
- Department of Molecular Biochemistry, Faculty of Chemistry and Biochemistry, Ruhr University Bochum, 44801, Bochum, Germany
| | - Leonie Sagurna
- Applied Microbiology, Faculty of Biology and Biotechnology, Ruhr University Bochum, 44801, Bochum, Germany
| | - Pascal Dietze
- Applied Microbiology, Faculty of Biology and Biotechnology, Ruhr University Bochum, 44801, Bochum, Germany
| | - Claudia Schmidt
- Inorganic and Organometallic Medicinal Chemistry, Faculty of Life Sciences, Technical University Braunschweig, 38106, Braunschweig, Germany.,Institute for Drug Research, Hebrew University of Jerusalem, Jerusalem, 9112001, Israel
| | - Brix Mücher
- Department of Zoology and Neurobiology, Ruhr University Bochum, 44801, Bochum, Germany
| | - Stefan Herlitze
- Department of Zoology and Neurobiology, Ruhr University Bochum, 44801, Bochum, Germany
| | - Ute Krämer
- Molecular Genetics and Physiology of Plants, Faculty of Biology and Biotechnology, Ruhr University Bochum, 44801, Bochum, Germany
| | - Ingo Ott
- Inorganic and Organometallic Medicinal Chemistry, Faculty of Life Sciences, Technical University Braunschweig, 38106, Braunschweig, Germany
| | - Thomas Günther Pomorski
- Department of Molecular Biochemistry, Faculty of Chemistry and Biochemistry, Ruhr University Bochum, 44801, Bochum, Germany
| | - Julia E Bandow
- Applied Microbiology, Faculty of Biology and Biotechnology, Ruhr University Bochum, 44801, Bochum, Germany
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40
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Xu J, Cotruvo JA. Iron-responsive riboswitches. Curr Opin Chem Biol 2022; 68:102135. [PMID: 35427920 PMCID: PMC9133107 DOI: 10.1016/j.cbpa.2022.102135] [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: 12/24/2021] [Revised: 02/27/2022] [Accepted: 03/02/2022] [Indexed: 11/23/2022]
Abstract
All cells must manage deficiency, sufficiency, and excess of essential metal ions. Although iron has been one of most important metals in biology for billions of years, the mechanisms by which bacteria cope with high intracellular iron concentrations are only recently coming into focus. Recent work has suggested that an RNA riboswitch (czcD or "NiCo"), originally thought to respond specifically to CoII and NiII excess, is more likely a selective regulator of FeII levels in important human gut bacteria and pathogens. We discuss the challenges and controversies encountered in the characterization of iron-responsive riboswitches, and we suggest a physiological role in responding to iron overload, perhaps during anaerobiosis. Finally, we place these riboswitches in the context of the better understood mechanisms of protein-based metal ion regulation, proposing that riboswitch-mediated mechanisms may be particularly important in regulating transport of the weakest-binding biological divalent metal ions, MgII, MnII, and FeII.
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Affiliation(s)
- Jiansong Xu
- Department of Chemistry and Center for RNA Molecular Biology, The Pennsylvania State University, University Park, PA 16802, USA
| | - Joseph A Cotruvo
- Department of Chemistry and Center for RNA Molecular Biology, The Pennsylvania State University, University Park, PA 16802, USA.
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41
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Mehlenbacher MR, Elsiesy R, Lakha R, Villones RLE, Orman M, Vizcarra CL, Meloni G, Wilcox DE, Austin RN. Metal binding and interdomain thermodynamics of mammalian metallothionein-3: enthalpically favoured Cu + supplants entropically favoured Zn 2+ to form Cu 4 + clusters under physiological conditions. Chem Sci 2022; 13:5289-5304. [PMID: 35655557 PMCID: PMC9093145 DOI: 10.1039/d2sc00676f] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Accepted: 04/01/2022] [Indexed: 01/02/2023] Open
Abstract
Metallothioneins (MTs) are a ubiquitous class of small metal-binding proteins involved in metal homeostasis and detoxification. While known for their high affinity for d10 metal ions, there is a surprising dearth of thermodynamic data on metals binding to MTs. In this study, Zn2+ and Cu+ binding to mammalian metallothionein-3 (MT-3) were quantified at pH 7.4 by isothermal titration calorimetry (ITC). Zn2+ binding was measured by chelation titrations of Zn7MT-3, while Cu+ binding was measured by Zn2+ displacement from Zn7MT-3 with competition from glutathione (GSH). Titrations in multiple buffers enabled a detailed analysis that yielded condition-independent values for the association constant (K) and the change in enthalpy (ΔH) and entropy (ΔS) for these metal ions binding to MT-3. Zn2+ was also chelated from the individual α and β domains of MT-3 to quantify the thermodynamics of inter-domain interactions in metal binding. Comparative titrations of Zn7MT-2 with Cu+ revealed that both MT isoforms have similar Cu+ affinities and binding thermodynamics, indicating that ΔH and ΔS are determined primarily by the conserved Cys residues. Inductively coupled plasma mass spectrometry (ICP-MS) analysis and low temperature luminescence measurements of Cu-replete samples showed that both proteins form two Cu4 +-thiolate clusters when Cu+ displaces Zn2+ under physiological conditions. Comparison of the Zn2+ and Cu+ binding thermodynamics reveal that enthalpically-favoured Cu+, which forms Cu4 +-thiolate clusters, displaces the entropically-favoured Zn2+. These results provide a detailed thermodynamic analysis of d10 metal binding to these thiolate-rich proteins and quantitative support for, as well as molecular insight into, the role that MT-3 plays in the neuronal chemistry of copper.
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Affiliation(s)
| | - Rahma Elsiesy
- Department of Chemistry, Barnard College of Columbia University New York NY 10027 USA
| | - Rabina Lakha
- Department of Chemistry, Barnard College of Columbia University New York NY 10027 USA
| | - Rhiza Lyne E Villones
- Department of Chemistry and Biochemistry, University of Texas at Dallas Richardson TX 75080 USA
| | - Marina Orman
- Department of Chemistry, Barnard College of Columbia University New York NY 10027 USA
| | - Christina L Vizcarra
- Department of Chemistry, Barnard College of Columbia University New York NY 10027 USA
| | - Gabriele Meloni
- Department of Chemistry and Biochemistry, University of Texas at Dallas Richardson TX 75080 USA
| | - Dean E Wilcox
- Department of Chemistry, Dartmouth College Hanover NH 03755 USA
| | - Rachel N Austin
- Department of Chemistry, Barnard College of Columbia University New York NY 10027 USA
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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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43
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Choi TS, Tezcan FA. Overcoming universal restrictions on metal selectivity by protein design. Nature 2022; 603:522-527. [PMID: 35236987 PMCID: PMC9157509 DOI: 10.1038/s41586-022-04469-8] [Citation(s) in RCA: 27] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Accepted: 01/21/2022] [Indexed: 11/09/2022]
Abstract
Selective metal coordination is central to the functions of metalloproteins:1,2 each metalloprotein must pair with its cognate metallocofactor to fulfil its biological role3. However, achieving metal selectivity solely through a three-dimensional protein structure is a great challenge, because there is a limited set of metal-coordinating amino acid functionalities and proteins are inherently flexible, which impedes steric selection of metals3,4. Metal-binding affinities of natural proteins are primarily dictated by the electronic properties of metal ions and follow the Irving-Williams series5 (Mn2+ < Fe2+ < Co2+ < Ni2+ < Cu2+ > Zn2+) with few exceptions6,7. Accordingly, metalloproteins overwhelmingly bind Cu2+ and Zn2+ in isolation, regardless of the nature of their active sites and their cognate metal ions1,3,8. This led organisms to evolve complex homeostatic machinery and non-equilibrium strategies to achieve correct metal speciation1,3,8-10. Here we report an artificial dimeric protein, (AB)2, that thermodynamically overcomes the Irving-Williams restrictions in vitro and in cells, favouring the binding of lower-Irving-Williams transition metals over Cu2+, the most dominant ion in the Irving-Williams series. Counter to the convention in molecular design of achieving specificity through structural preorganization, (AB)2 was deliberately designed to be flexible. This flexibility enabled (AB)2 to adopt mutually exclusive, metal-dependent conformational states, which led to the discovery of structurally coupled coordination sites that disfavour Cu2+ ions by enforcing an unfavourable coordination geometry. Aside from highlighting flexibility as a valuable element in protein design, our results illustrate design principles for constructing selective metal sequestration agents.
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Affiliation(s)
- Tae Su Choi
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA, USA
| | - F Akif Tezcan
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA, USA.
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44
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Morris JA, Lickey BS, Liptak MD. Insertion of cobalt into tetrapyrroles. VITAMINS AND HORMONES 2022; 119:1-22. [PMID: 35337616 DOI: 10.1016/bs.vh.2022.01.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Vitamin B12 is one of the most complex cofactors known, and this chapter will discuss current understanding with regards to the cobalt insertion step of its syntheses. Two total syntheses of vitamin B12 were reported in the 1970s, which remain two of the most exceptional achievements of natural product synthesis. In subsequent years, two distinct biosynthetic pathways were identified in aerobic and anaerobic organisms. For these biosynthetic pathways, selectivity for Co(II) over other divalent metal ions with similar ionic radii and coordination chemistry remains an open question with three competing hypotheses proposed: metal affinity, tetrapyrrole distortion, and product inhibition. A 20 step biosynthetic route to convert 5-aminolevulinic acid (ALA) to vitamin B12 was elucidated in aerobic organisms in the 1990s, where cobalt is inserted relatively late in the pathway by the CobNST multi-protein complex. This chapter includes a mechanistic proposal for this reaction, but the majority of the proposal is based upon analogy to the ChlDHI magnesium chelatase complex as critical data for the cobalt chelatase is lacking. Later, in the 2010s, a distinct 21 step pathway from ALA to vitamin B12 was reported in anaerobic organisms, where cobalt is inserted early in the pathway by the enzyme CbiK. A recent study strongly suggests that the cobalt affinity of CbiK is the origin of cobalt selectivity for CbiK, but several important mechanistic questions remain unanswered. In general, it is expected that significant insight into the cobalt insertion mechanisms of CobNST and CbiK could be derived from additional structural, spectroscopic, and computational data.
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Affiliation(s)
- J A Morris
- Department of Chemistry, University of Vermont, Burlington, VT, United States
| | - B S Lickey
- Department of Chemistry, University of Vermont, Burlington, VT, United States
| | - M D Liptak
- Department of Chemistry, University of Vermont, Burlington, VT, United States.
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45
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Wendel BM, Pi H, Krüger L, Herzberg C, Stülke J, Helmann JD. A Central Role for Magnesium Homeostasis during Adaptation to Osmotic Stress. mBio 2022; 13:e0009222. [PMID: 35164567 PMCID: PMC8844918 DOI: 10.1128/mbio.00092-22] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Accepted: 01/18/2022] [Indexed: 02/06/2023] Open
Abstract
Osmotic stress is a significant physical challenge for free-living cells. Cells from all three domains of life maintain viability during osmotic stress by tightly regulating the major cellular osmolyte potassium (K+) and by import or synthesis of compatible solutes. It has been widely established that in response to high salt stress, many bacteria transiently accumulate high levels of K+, leading to bacteriostasis, with growth resuming only when compatible solutes accumulate and K+ levels are restored to biocompatible levels. Using Bacillus subtilis as a model system, we provide evidence that K+ fluxes perturb Mg2+ homeostasis: import of K+ upon osmotic upshift is correlated with Mg2+ efflux, and Mg2+ reimport is critical for adaptation. The transient growth inhibition resulting from hyperosmotic stress is coincident with loss of Mg2+ and a decrease in protein translation. Conversely, the reimport of Mg2+ is a limiting factor during resumption of growth. Furthermore, we show the essential signaling dinucleotide cyclic di-AMP fluctuates dynamically in coordination with Mg2+ and K+ levels, consistent with the proposal that cyclic di-AMP orchestrates the cellular response to osmotic stress. IMPORTANCE Environments with high concentrations of salt or other solutes impose an osmotic stress on cells, ultimately limiting viability by dehydration of the cytosol. A very common cellular response to high osmolarity is to immediately import high levels of potassium ion (K+), which helps prevent dehydration and allows time for the import or synthesis of biocompatible solutes that allow a resumption of growth. Here, using Bacillus subtilis as a model, we demonstrate that concomitant with K+ import there is a large reduction in intracellular magnesium (Mg2+) mediated by specific efflux pumps. Further, it is the reimport of Mg2+ that is rate-limiting for the resumption of growth. These coordinated fluxes of K+ and Mg2+ are orchestrated by cyclic-di-AMP, an essential second messenger in Firmicutes. These findings amend the conventional model for osmoadaptation and reveal that Mg2+ limitation is the proximal cause of the bacteriostasis that precedes resumption of growth.
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Affiliation(s)
- Brian M. Wendel
- Department of Microbiology, Cornell University, Ithaca, New York, USA
| | - Hualiang Pi
- Department of Microbiology, Cornell University, Ithaca, New York, USA
| | - Larissa Krüger
- Department of General Microbiology, GZMB, Georg August University, Göttingen, Germany
| | - Christina Herzberg
- Department of General Microbiology, GZMB, Georg August University, Göttingen, Germany
| | - Jörg Stülke
- Department of General Microbiology, GZMB, Georg August University, Göttingen, Germany
| | - John D. Helmann
- Department of Microbiology, Cornell University, Ithaca, New York, USA
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Bacterial Transcriptional Regulators: A Road Map for Functional, Structural, and Biophysical Characterization. Int J Mol Sci 2022; 23:ijms23042179. [PMID: 35216300 PMCID: PMC8879271 DOI: 10.3390/ijms23042179] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Revised: 02/11/2022] [Accepted: 02/11/2022] [Indexed: 12/12/2022] Open
Abstract
The different niches through which bacteria move during their life cycle require a fast response to the many environmental queues they encounter. The sensing of these stimuli and their correct response is driven primarily by transcriptional regulators. This kind of protein is involved in sensing a wide array of chemical species, a process that ultimately leads to the regulation of gene transcription. The allosteric-coupling mechanism of sensing and regulation is a central aspect of biological systems and has become an important field of research during the last decades. In this review, we summarize the state-of-the-art techniques applied to unravel these complex mechanisms. We introduce a roadmap that may serve for experimental design, depending on the answers we seek and the initial information we have about the system of study. We also provide information on databases containing available structural information on each family of transcriptional regulators. Finally, we discuss the recent results of research about the allosteric mechanisms of sensing and regulation involving many transcriptional regulators of interest, highlighting multipronged strategies and novel experimental techniques. The aim of the experiments discussed here was to provide a better understanding at a molecular level of how bacteria adapt to the different environmental threats they face.
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Mikhaylina A, Scott L, Scanlan DJ, Blindauer CA. A metallothionein from an open ocean cyanobacterium removes zinc from the sensor protein controlling its transcription. J Inorg Biochem 2022; 230:111755. [DOI: 10.1016/j.jinorgbio.2022.111755] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Revised: 02/05/2022] [Accepted: 02/06/2022] [Indexed: 10/19/2022]
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Bahr G, González LJ, Vila AJ. Metallo-β-lactamases and a tug-of-war for the available zinc at the host-pathogen interface. Curr Opin Chem Biol 2022; 66:102103. [PMID: 34864439 PMCID: PMC8860843 DOI: 10.1016/j.cbpa.2021.102103] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2021] [Revised: 10/16/2021] [Accepted: 10/28/2021] [Indexed: 02/03/2023]
Abstract
Metallo-β-lactamases (MBLs) are zinc-dependent hydrolases that inactivate virtually all β-lactam antibiotics. The expression of MBLs by Gram-negative bacteria severely limits the therapeutic options to treat infections. MBLs bind the essential metal ions in the bacterial periplasm, and their activity is challenged upon the zinc starvation conditions elicited by the native immune response. Metal depletion compromises both the enzyme activity and stability in the periplasm, impacting on the resistance profile in vivo. Thus, novel inhibitory approaches involve the use of chelating agents or metal-based drugs that displace the native metal ion. However, newer MBL variants incorporate mutations that improve their metal binding abilities or stabilize the metal-depleted form, revealing that metal starvation is a driving force acting on MBL evolution. Future challenges require addressing the gap between in cell and in vitro studies, dissecting the mechanism for MBL metalation and determining the metal content in situ.
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Affiliation(s)
- Guillermo Bahr
- Instituto de Biología Molecular y Celular de Rosario (IBR, CONICET-UNR), S2000EXF Rosario, Argentina; Área Biofísica, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, S2002LRK Rosario, Argentina
| | - Lisandro J González
- Instituto de Biología Molecular y Celular de Rosario (IBR, CONICET-UNR), S2000EXF Rosario, Argentina; Área Biofísica, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, S2002LRK Rosario, Argentina
| | - Alejandro J Vila
- Instituto de Biología Molecular y Celular de Rosario (IBR, CONICET-UNR), S2000EXF Rosario, Argentina; Área Biofísica, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, S2002LRK Rosario, Argentina.
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MntP and YiiP Contribute to Manganese Efflux in Salmonella enterica Serovar Typhimurium under Conditions of Manganese Overload and Nitrosative Stress. Microbiol Spectr 2022; 10:e0131621. [PMID: 35019706 PMCID: PMC8754126 DOI: 10.1128/spectrum.01316-21] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
The divalent transition metal cation manganese is important for protein function, particularly under conditions of iron limitation, nitrosative stress, and oxidative stress, but can mediate substantial toxicity in excess. Salmonella enterica serovar Typhimurium possesses multiple manganese importers, but the pathways for manganese efflux remain poorly defined. The S. Typhimurium ATCC 14028s genome was analyzed for putative manganese export pathways, which identified a previously uncharacterized homologue of the Escherichia coli manganese exporter mntP, stm1834, and two cation diffusion facilitator family transporters, zitB (stm0758) and yiiP (stm4061). Manganese acquisition by S. Typhimurium has been shown to occur in response to nitric oxide, an important chemical mediator of the mammalian innate immune response. However, cellular manganese can rapidly return to prechallenge levels, strongly suggesting that one or more S. Typhimurium exporters may contribute to this process. Here, we report that mntP and yiiP contribute to manganese resistance and export in S. Typhimurium. YiiP, also known as FieF, has previously been associated with zinc and iron transport, although its physiological role remains ambiguous due to a lack of zinc-sensitive phenotypes in yiiP mutant strains of S. Typhimurium and E. coli. We report that S. Typhimurium ΔmntP ΔyiiP mutants are exquisitely sensitive to manganese and show that both YiiP and MntP contribute to manganese efflux following nitric oxide exposure. IMPORTANCE Transition metal cations are required for the function of many proteins but can mediate toxicity when present in excess. Identifying transporters that facilitate metal ion export, the conditions under which they are expressed, and the role they play in bacterial physiology is an evolving area of interest for environmental and pathogenic organisms. Determining the native targets of metal transporters has proved challenging since bioinformatic predictions, in vitro transport data, and mutant phenotypes do not always agree. This work identifies two transporters that mediate manganese efflux from the Gram-negative pathogen Salmonella enterica serovar Typhimurium in response to manganese overload and nitric oxide stress. While homologues of MntP have been characterized previously, this is the first observation of YiiP contributing to manganese export.
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50
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Metal sequestration by S100 proteins in chemically diverse environments. Trends Microbiol 2022; 30:654-664. [DOI: 10.1016/j.tim.2021.12.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Revised: 12/07/2021] [Accepted: 12/08/2021] [Indexed: 12/22/2022]
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