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Raz Zarivach - One of the best experts on this subject based on the ideXlab platform.
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metal transport mechanism of the Cation Diffusion Facilitator cdf protein family a structural perspective on human cdf znt related diseases
RSC Chemical Biology, 2021Co-Authors: Shiran Barberzucker, Arie Moran, Raz ZarivachAbstract:Divalent d-block metal Cations (DDMCs) participate in many cellular functions; however, their accumulation in cells can be cytotoxic. The Cation Diffusion Facilitator (CDF) family is a ubiquitous family of transmembrane DDMC exporters that ensures their homeostasis. Severe diseases, such as type II diabetes, Parkinson's and Alzheimer's disease, were linked to dysfunctional human CDF proteins, ZnT-1-10 (SLC30A1-10). Each member of the CDF family reduces the cytosolic concentration of a specific DDMC by transporting it from the cytoplasm to the extracellular environment or into intracellular compartments. This process is usually achieved by utilizing the proton motive force. In addition to their activity as DDMC transporters, CDFs also have other cellular functions such as the regulation of ion channels and enzymatic activity. The combination of structural and biophysical studies of different bacterial and eukaryotic CDF proteins led to significant progress in the understanding of the mutual interaction among CDFs and DDMCs, their involvement in ion binding and selectivity, conformational changes and the consequent transporting mechanisms. Here, we review these studies, provide our mechanistic interpretation of CDF proteins based on the current literature and relate the above to known human CDF-related diseases. Our analysis provides a common structure–function relationship to this important protein family and closes the gap between eukaryote and prokaryote CDFs.
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The metal binding site composition of the Cation Diffusion Facilitator protein MamM cytoplasmic domain impacts its metal responsivity
Springer Science and Business Media LLC, 2020Co-Authors: Shiran Barber-zucker, Anat Shahar, Sofiya Kolusheva, Raz ZarivachAbstract:AbstractThe Cation Diffusion Facilitator (CDF) is a conserved family of divalent d-block metal Cation transporters that extrude these Cations selectively from the cytoplasm. CDF proteins are composed of two domains: the transmembrane domain, through which the Cations are transported, and a regulatory cytoplasmic C-terminal domain (CTD). It was recently shown that the CTD of the CDF protein MamM from magnetotactic bacteria has a role in metal selectivity, as binding of different metal Cations exhibits distinctive affinities and conformations. It is yet unclear whether the composition of the CTD binding sites can impact metal selectivity and if we can manipulate the CTD to response to other non-native metals in CDF proteins. Here we performed a mutational study of the model protein MamM CTD, where we exchanged the native metal binding residues with different metal-binding amino acids. Using X-ray crystallography and Trp-fluorescence spectrometry, we studied the impact of these mutations on the CTD conformation in the presence of non-native metals. Our results reveal that the incorporation of such mutations alters the domain response to metals in vitro, as mutant forms of the CTD bind metals differently in terms of the composition of the binding sites and the CTD conformation. Therefore, the results demonstrate the direct influence of the CTD binding site composition on CDF proteins structure and hence, function, and constitute a first step for rational design of MamM for transporting different metals in vivo.
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the Cation Diffusion Facilitator protein mamm s cytoplasmic domain exhibits metal type dependent binding modes and discriminates against mn2
Journal of Biological Chemistry, 2020Co-Authors: Shiran Barberzucker, Jenny Hall, Sofiya Kolusheva, Fraser Macmillan, Afonso Froes, Raz ZarivachAbstract:Cation Diffusion Facilitator (CDF) proteins are a conserved family of divalent transition metal Cation transporters. CDF proteins are usually composed of two domains: the transmembrane domain, in which the metal Cations are transported through, and a regulatory cytoplasmic C-terminal domain (CTD). Each CDF protein transports either one specific metal or multiple metals from the cytoplasm, and it is not known whether the CTD takes an active regulatory role in metal recognition and discrimination during Cation transport. Here, the model CDF protein MamM, an iron transporter from magnetotactic bacteria, was used to probe the role of the CTD in metal recognition and selectivity. Using a combination of biophysical and structural approaches, the binding of different metals to MamM CTD was characterized. Results reveal that different metals bind distinctively to MamM CTD in terms of their binding sites, thermodynamics, and binding-dependent conformations, both in crystal form and in solution, which suggests a varying level of functional discrimination between CDF domains. Furthermore, these results provide the first direct evidence that CDF CTDs play a role in metal selectivity. We demonstrate that MamM's CTD can discriminate against Mn2+, supporting its postulated role in preventing magnetite formation poisoning in magnetotactic bacteria via Mn2+ incorporation.
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the metal binding site composition of the Cation Diffusion Facilitator protein mamm cytoplasmic domain impacts its metal responsivity
bioRxiv, 2020Co-Authors: Shiran Barberzucker, Sofiya Kolusheva, Anat Shahar, Raz ZarivachAbstract:The Cation Diffusion Facilitator (CDF) is a conserved family of divalent d-block metal Cation transporters that extrude these Cations selectively from the cytoplasm. CDF proteins are composed of two domains: the transmembrane domain, through which the Cations are transported, and a regulatory cytoplasmic C-terminal domain (CTD). Metal binding to the CTD leads to its tighter conformation, and this sequentially promotes conformational change of the transmembrane domain which allows the actual transport of specific metal Cations. It was recently shown that the magnetotactic bacterial CDF protein MamM CTD has a role in metal selectivity, as binding of different metal Cations exhibits distinctive affinities and conformations. It is yet unclear whether the composition of the CTD binding sites can impact metal selectivity. Here we performed a mutational study of MamM CTD, where we exchanged the metal binding residues with different metal-binding amino acids. Using X-ray crystallography and Trp-fluorescence spectrometry, we studied the impact of the mutations on the CTD conformation in the presence of different metals. Our results reveal that the incorporation of such mutations alters the domain response to metals in vitro, as mutant forms of the CTD bind metals differently in terms of the composition of the binding sites and the CTD conformation.
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the Cation Diffusion Facilitator protein mamm s cytoplasmic domain exhibits metal type dependent binding modes and discriminates against mn2
bioRxiv, 2020Co-Authors: Shiran Barberzucker, Jenny Hall, Sofiya Kolusheva, Fraser Macmillan, Afonso Froes, Raz ZarivachAbstract:Cation Diffusion Facilitator (CDF) proteins are a conserved family of divalent transition metal Cation transporters. CDF proteins are usually composed of two domains: the transmembrane domain (TMD), in which the metal Cations are transported through, and a regulatory cytoplasmic C-terminal domain (CTD). Each CDF protein transports either one specific metal, or multiple metals, from the cytoplasm. Here, the model CDF protein MamM, from magnetotactic bacteria, was used to probe the role of the CTD in metal selectivity. Using a combination of biophysical and structural approaches, the binding of different metals to MamM CTD was characterized. Results reveal that different metals bind distinctively to MamM CTD in terms of; their binding sites, thermodynamics and binding-dependent conformation, both in crystal form and in solution. Furthermore, the results indicate that the CTD discriminates against Mn2+ and provides the first direct evidence that CDF CTD9s play a role in metal selectivity.
Shiran Barberzucker - One of the best experts on this subject based on the ideXlab platform.
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metal transport mechanism of the Cation Diffusion Facilitator cdf protein family a structural perspective on human cdf znt related diseases
RSC Chemical Biology, 2021Co-Authors: Shiran Barberzucker, Arie Moran, Raz ZarivachAbstract:Divalent d-block metal Cations (DDMCs) participate in many cellular functions; however, their accumulation in cells can be cytotoxic. The Cation Diffusion Facilitator (CDF) family is a ubiquitous family of transmembrane DDMC exporters that ensures their homeostasis. Severe diseases, such as type II diabetes, Parkinson's and Alzheimer's disease, were linked to dysfunctional human CDF proteins, ZnT-1-10 (SLC30A1-10). Each member of the CDF family reduces the cytosolic concentration of a specific DDMC by transporting it from the cytoplasm to the extracellular environment or into intracellular compartments. This process is usually achieved by utilizing the proton motive force. In addition to their activity as DDMC transporters, CDFs also have other cellular functions such as the regulation of ion channels and enzymatic activity. The combination of structural and biophysical studies of different bacterial and eukaryotic CDF proteins led to significant progress in the understanding of the mutual interaction among CDFs and DDMCs, their involvement in ion binding and selectivity, conformational changes and the consequent transporting mechanisms. Here, we review these studies, provide our mechanistic interpretation of CDF proteins based on the current literature and relate the above to known human CDF-related diseases. Our analysis provides a common structure–function relationship to this important protein family and closes the gap between eukaryote and prokaryote CDFs.
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the Cation Diffusion Facilitator protein mamm s cytoplasmic domain exhibits metal type dependent binding modes and discriminates against mn2
Journal of Biological Chemistry, 2020Co-Authors: Shiran Barberzucker, Jenny Hall, Sofiya Kolusheva, Fraser Macmillan, Afonso Froes, Raz ZarivachAbstract:Cation Diffusion Facilitator (CDF) proteins are a conserved family of divalent transition metal Cation transporters. CDF proteins are usually composed of two domains: the transmembrane domain, in which the metal Cations are transported through, and a regulatory cytoplasmic C-terminal domain (CTD). Each CDF protein transports either one specific metal or multiple metals from the cytoplasm, and it is not known whether the CTD takes an active regulatory role in metal recognition and discrimination during Cation transport. Here, the model CDF protein MamM, an iron transporter from magnetotactic bacteria, was used to probe the role of the CTD in metal recognition and selectivity. Using a combination of biophysical and structural approaches, the binding of different metals to MamM CTD was characterized. Results reveal that different metals bind distinctively to MamM CTD in terms of their binding sites, thermodynamics, and binding-dependent conformations, both in crystal form and in solution, which suggests a varying level of functional discrimination between CDF domains. Furthermore, these results provide the first direct evidence that CDF CTDs play a role in metal selectivity. We demonstrate that MamM's CTD can discriminate against Mn2+, supporting its postulated role in preventing magnetite formation poisoning in magnetotactic bacteria via Mn2+ incorporation.
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the metal binding site composition of the Cation Diffusion Facilitator protein mamm cytoplasmic domain impacts its metal responsivity
bioRxiv, 2020Co-Authors: Shiran Barberzucker, Sofiya Kolusheva, Anat Shahar, Raz ZarivachAbstract:The Cation Diffusion Facilitator (CDF) is a conserved family of divalent d-block metal Cation transporters that extrude these Cations selectively from the cytoplasm. CDF proteins are composed of two domains: the transmembrane domain, through which the Cations are transported, and a regulatory cytoplasmic C-terminal domain (CTD). Metal binding to the CTD leads to its tighter conformation, and this sequentially promotes conformational change of the transmembrane domain which allows the actual transport of specific metal Cations. It was recently shown that the magnetotactic bacterial CDF protein MamM CTD has a role in metal selectivity, as binding of different metal Cations exhibits distinctive affinities and conformations. It is yet unclear whether the composition of the CTD binding sites can impact metal selectivity. Here we performed a mutational study of MamM CTD, where we exchanged the metal binding residues with different metal-binding amino acids. Using X-ray crystallography and Trp-fluorescence spectrometry, we studied the impact of the mutations on the CTD conformation in the presence of different metals. Our results reveal that the incorporation of such mutations alters the domain response to metals in vitro, as mutant forms of the CTD bind metals differently in terms of the composition of the binding sites and the CTD conformation.
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the Cation Diffusion Facilitator protein mamm s cytoplasmic domain exhibits metal type dependent binding modes and discriminates against mn2
bioRxiv, 2020Co-Authors: Shiran Barberzucker, Jenny Hall, Sofiya Kolusheva, Fraser Macmillan, Afonso Froes, Raz ZarivachAbstract:Cation Diffusion Facilitator (CDF) proteins are a conserved family of divalent transition metal Cation transporters. CDF proteins are usually composed of two domains: the transmembrane domain (TMD), in which the metal Cations are transported through, and a regulatory cytoplasmic C-terminal domain (CTD). Each CDF protein transports either one specific metal, or multiple metals, from the cytoplasm. Here, the model CDF protein MamM, from magnetotactic bacteria, was used to probe the role of the CTD in metal selectivity. Using a combination of biophysical and structural approaches, the binding of different metals to MamM CTD was characterized. Results reveal that different metals bind distinctively to MamM CTD in terms of; their binding sites, thermodynamics and binding-dependent conformation, both in crystal form and in solution. Furthermore, the results indicate that the CTD discriminates against Mn2+ and provides the first direct evidence that CDF CTD9s play a role in metal selectivity.
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metal binding to the dynamic cytoplasmic domain of the Cation Diffusion Facilitator cdf protein mamm induces a locked in configuration
FEBS Journal, 2019Co-Authors: Shiran Barberzucker, Raz Zarivach, Jenny Hall, Sivasubramanyan Venkata Mangapuram, Itamar Kass, Sofiya Kolusheva, Fraser Macmillan, Arnon HennAbstract:Cation Diffusion Facilitator (CDF) proteins are a conserved family of transmembrane transporters that ensure cellular homeostasis of divalent transition metal Cations. Metal Cations bind to CDF protein's cytoplasmic C-terminal domain (CTD), leading to closure from its apo open V-shaped dimer to a tighter packed structure, followed by a conformational change of the transmembrane domain thus enabling transport of the metal Cation. By implementing a comprehensive range of biochemical and biophysical methods, we studied the molecular mechanism of metal binding to the magnetotactic bacterial CDF protein MamM CTD. Our results reveal that the CTD is rather dynamic in its apo form, and that two dependent metal binding sites, a single central binding site and two symmetrical, peripheral sites, are available for metal binding. However, only Cation binding to the peripheral sites leads to conformational changes that lock the protein in a compact state. Thus, this work reveals how metal binding is regulating the sequential uptakes of metal Cations by MamM, and extends our understanding of the complex regulation mechanism of CDF proteins. This article is protected by copyright. All rights reserved.
Michel Chalot - One of the best experts on this subject based on the ideXlab platform.
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Phylogenetic and functional analysis of the Cation Diffusion Facilitator (CDF) family: improved signature and prediction of substrate specificity-0
2011Co-Authors: Barbara Montanini, Damien Blaudez, Sylvain Jeandroz, Dale Sanders, Michel ChalotAbstract:Copyright information:Taken from "Phylogenetic and functional analysis of the Cation Diffusion Facilitator (CDF) family: improved signature and prediction of substrate specificity"http://www.biomedcentral.com/1471-2164/8/107BMC Genomics 2007;8():107-107.Published online 23 Apr 2007PMCID:PMC1868760.t. Amino acid position refers to PtdMTP1. The hypothetical secondary structure (TMDs II and III) is shown below
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Phylogenetic and functional analysis of the Cation Diffusion Facilitator (CDF) family: improved signature and prediction of substrate specificity-2
2011Co-Authors: Barbara Montanini, Damien Blaudez, Sylvain Jeandroz, Dale Sanders, Michel ChalotAbstract:Copyright information:Taken from "Phylogenetic and functional analysis of the Cation Diffusion Facilitator (CDF) family: improved signature and prediction of substrate specificity"http://www.biomedcentral.com/1471-2164/8/107BMC Genomics 2007;8():107-107.Published online 23 Apr 2007PMCID:PMC1868760.ith respect to metal specificity: blue is for zinc, green for iron/zinc, violet for manganese and brown for unknown specificity. The three CDF groups are surrounded with coloured boxes with the same colour-code. Bootstrap values are indicated for each cluster. The scale bar indicates an evolutionary distance of 0.1 amino acid substitution per site
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Phylogenetic and functional analysis of the Cation Diffusion Facilitator (CDF) family: improved signature and prediction of substrate specificity-1
2011Co-Authors: Barbara Montanini, Damien Blaudez, Sylvain Jeandroz, Dale Sanders, Michel ChalotAbstract:Copyright information:Taken from "Phylogenetic and functional analysis of the Cation Diffusion Facilitator (CDF) family: improved signature and prediction of substrate specificity"http://www.biomedcentral.com/1471-2164/8/107BMC Genomics 2007;8():107-107.Published online 23 Apr 2007PMCID:PMC1868760.SD) until O.D. = 1. Serial dilutions were spotted on SD or on SD + 15 mM ZnCl(15 mM Zn). Photographs were taken after 6 days of growth at 30°C. For each mutation different yeast transformants were used and gave the same results. The amino acid substitutions along with their topological positions are shown on the left. EV: empty vector; PtdMTP1: wild type protein
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Phylogenetic and functional analysis of the Cation Diffusion Facilitator (CDF) family: improved signature and prediction of substrate specificity-3
2011Co-Authors: Barbara Montanini, Damien Blaudez, Sylvain Jeandroz, Dale Sanders, Michel ChalotAbstract:Copyright information:Taken from "Phylogenetic and functional analysis of the Cation Diffusion Facilitator (CDF) family: improved signature and prediction of substrate specificity"http://www.biomedcentral.com/1471-2164/8/107BMC Genomics 2007;8():107-107.Published online 23 Apr 2007PMCID:PMC1868760.) regions are indicated for each cluster. When more than one metal is transported, the metal preference is reflected by the written order within these metals. For each group and for Zrg17-like and ZnT9-like clusters logos showing the conserved residues in TMDs II and V are shown on the right. A simplified phylogenetic tree representation, expressed as a dendogram using Zrg17-like cluster as outgroup, is shown on the left. B. Montanini, D. Blaudez, M. Chalot, unpublished data; D. Blaudez, M. Chalot, unpublished data; assessed by heterologous complementation; deduced by mutant phenotype or over-expression in homologous system; measured in reconstituted proteoliposomes or in everted membrane vesicles; indirect evidence; measured in oocytes; by referring to the CDF domain
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phylogenetic and functional analysis of the Cation Diffusion Facilitator cdf family improved signature and prediction of substrate specificity
BMC Genomics, 2007Co-Authors: Barbara Montanini, Damien Blaudez, Sylvain Jeandroz, Dale Sanders, Michel ChalotAbstract:The Cation Diffusion Facilitator (CDF) family is a ubiquitous family of heavy metal transporters. Much interest in this family has focused on impliCations for human health and bioremediation. In this work a broad phylogenetic study has been undertaken which, considered in the context of the functional characteristics of some fully characterised CDF transporters, has aimed at identifying molecular determinants of substrate selectivity and at suggesting metal specificity for newly identified CDF transporters. Representative CDF members from all three kingdoms of life (Archaea, Eubacteria, Eukaryotes) were retrieved from genomic databases. Protein sequence alignment has allowed detection of a modified signature that can be used to identify new hypothetical CDF members. Phylogenetic reconstruction has classified the majority of CDF family members into three groups, each containing characterised members that share the same specificity towards the principally-transported metal, i.e. Zn, Fe/Zn or Mn. The metal selectivity of newly identified CDF transporters can be inferred by their position in one of these groups. The function of some conserved amino acids was assessed by site-directed mutagenesis in the poplar Zn2+ transporter PtdMTP1 and compared with similar experiments performed in prokaryotic members. An essential structural role can be assigned to a widely conserved glycine residue, while aspartate and histidine residues, highly conserved in putative transmembrane domains, might be involved in metal transport. The potential role of group-conserved amino acid residues in metal specificity is discussed. In the present study phylogenetic and functional analyses have allowed the identifiCation of three major substrate-specific CDF groups. The metal selectivity of newly identified CDF transporters can be inferred by their position in one of these groups. The modified signature sequence proposed in this work can be used to identify new hypothetical CDF members.
Barbara Montanini - One of the best experts on this subject based on the ideXlab platform.
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Phylogenetic and functional analysis of the Cation Diffusion Facilitator (CDF) family: improved signature and prediction of substrate specificity-0
2011Co-Authors: Barbara Montanini, Damien Blaudez, Sylvain Jeandroz, Dale Sanders, Michel ChalotAbstract:Copyright information:Taken from "Phylogenetic and functional analysis of the Cation Diffusion Facilitator (CDF) family: improved signature and prediction of substrate specificity"http://www.biomedcentral.com/1471-2164/8/107BMC Genomics 2007;8():107-107.Published online 23 Apr 2007PMCID:PMC1868760.t. Amino acid position refers to PtdMTP1. The hypothetical secondary structure (TMDs II and III) is shown below
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Phylogenetic and functional analysis of the Cation Diffusion Facilitator (CDF) family: improved signature and prediction of substrate specificity-2
2011Co-Authors: Barbara Montanini, Damien Blaudez, Sylvain Jeandroz, Dale Sanders, Michel ChalotAbstract:Copyright information:Taken from "Phylogenetic and functional analysis of the Cation Diffusion Facilitator (CDF) family: improved signature and prediction of substrate specificity"http://www.biomedcentral.com/1471-2164/8/107BMC Genomics 2007;8():107-107.Published online 23 Apr 2007PMCID:PMC1868760.ith respect to metal specificity: blue is for zinc, green for iron/zinc, violet for manganese and brown for unknown specificity. The three CDF groups are surrounded with coloured boxes with the same colour-code. Bootstrap values are indicated for each cluster. The scale bar indicates an evolutionary distance of 0.1 amino acid substitution per site
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Phylogenetic and functional analysis of the Cation Diffusion Facilitator (CDF) family: improved signature and prediction of substrate specificity-1
2011Co-Authors: Barbara Montanini, Damien Blaudez, Sylvain Jeandroz, Dale Sanders, Michel ChalotAbstract:Copyright information:Taken from "Phylogenetic and functional analysis of the Cation Diffusion Facilitator (CDF) family: improved signature and prediction of substrate specificity"http://www.biomedcentral.com/1471-2164/8/107BMC Genomics 2007;8():107-107.Published online 23 Apr 2007PMCID:PMC1868760.SD) until O.D. = 1. Serial dilutions were spotted on SD or on SD + 15 mM ZnCl(15 mM Zn). Photographs were taken after 6 days of growth at 30°C. For each mutation different yeast transformants were used and gave the same results. The amino acid substitutions along with their topological positions are shown on the left. EV: empty vector; PtdMTP1: wild type protein
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Phylogenetic and functional analysis of the Cation Diffusion Facilitator (CDF) family: improved signature and prediction of substrate specificity-3
2011Co-Authors: Barbara Montanini, Damien Blaudez, Sylvain Jeandroz, Dale Sanders, Michel ChalotAbstract:Copyright information:Taken from "Phylogenetic and functional analysis of the Cation Diffusion Facilitator (CDF) family: improved signature and prediction of substrate specificity"http://www.biomedcentral.com/1471-2164/8/107BMC Genomics 2007;8():107-107.Published online 23 Apr 2007PMCID:PMC1868760.) regions are indicated for each cluster. When more than one metal is transported, the metal preference is reflected by the written order within these metals. For each group and for Zrg17-like and ZnT9-like clusters logos showing the conserved residues in TMDs II and V are shown on the right. A simplified phylogenetic tree representation, expressed as a dendogram using Zrg17-like cluster as outgroup, is shown on the left. B. Montanini, D. Blaudez, M. Chalot, unpublished data; D. Blaudez, M. Chalot, unpublished data; assessed by heterologous complementation; deduced by mutant phenotype or over-expression in homologous system; measured in reconstituted proteoliposomes or in everted membrane vesicles; indirect evidence; measured in oocytes; by referring to the CDF domain
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phylogenetic and functional analysis of the Cation Diffusion Facilitator cdf family improved signature and prediction of substrate specificity
BMC Genomics, 2007Co-Authors: Barbara Montanini, Damien Blaudez, Sylvain Jeandroz, Dale Sanders, Michel ChalotAbstract:The Cation Diffusion Facilitator (CDF) family is a ubiquitous family of heavy metal transporters. Much interest in this family has focused on impliCations for human health and bioremediation. In this work a broad phylogenetic study has been undertaken which, considered in the context of the functional characteristics of some fully characterised CDF transporters, has aimed at identifying molecular determinants of substrate selectivity and at suggesting metal specificity for newly identified CDF transporters. Representative CDF members from all three kingdoms of life (Archaea, Eubacteria, Eukaryotes) were retrieved from genomic databases. Protein sequence alignment has allowed detection of a modified signature that can be used to identify new hypothetical CDF members. Phylogenetic reconstruction has classified the majority of CDF family members into three groups, each containing characterised members that share the same specificity towards the principally-transported metal, i.e. Zn, Fe/Zn or Mn. The metal selectivity of newly identified CDF transporters can be inferred by their position in one of these groups. The function of some conserved amino acids was assessed by site-directed mutagenesis in the poplar Zn2+ transporter PtdMTP1 and compared with similar experiments performed in prokaryotic members. An essential structural role can be assigned to a widely conserved glycine residue, while aspartate and histidine residues, highly conserved in putative transmembrane domains, might be involved in metal transport. The potential role of group-conserved amino acid residues in metal specificity is discussed. In the present study phylogenetic and functional analyses have allowed the identifiCation of three major substrate-specific CDF groups. The metal selectivity of newly identified CDF transporters can be inferred by their position in one of these groups. The modified signature sequence proposed in this work can be used to identify new hypothetical CDF members.
Dietrich H. Nies - One of the best experts on this subject based on the ideXlab platform.
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the chromosomally encoded Cation Diffusion Facilitator proteins dmef and fief from wautersia metallidurans ch34 are transporters of broad metal specificity
Journal of Bacteriology, 2004Co-Authors: Doreen Munkelt, Gregor Grass, Dietrich H. NiesAbstract:Genomic sequencing of the β-proteobacterium Wautersia (previously Ralstonia) metallidurans CH34 revealed the presence of three genes encoding proteins of the Cation Diffusion Facilitator (CDF) family. One, CzcD, was previously found to be part of the high-level metal resistance system Czc that mediates the efflux of Co(II), Zn(II), and Cd(II) ions catalyzed by the CzcCBA Cation-proton antiporter. The second CDF protein, FieF, is probably mainly a ferrous iron detoxifying protein but also mediated some resistance against other divalent metal Cations such as Zn(II), Co(II), Cd(II), and Ni(II) in W. metallidurans or Escherichia coli. The third CDF protein, DmeF, showed the same substrate spectrum as FieF, but with different preferences. DmeF plays the central role in cobalt homeostasis in W. metallidurans, and a disruption of dmeF rendered the high-level metal Cation resistance systems Czc and Cnr ineffective against Co(II). This is evidence for the periplasmic detoxifiCation of substrates by RND transporters of the heavy metal efflux family subgroup.
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efflux mediated heavy metal resistance in prokaryotes
Fems Microbiology Reviews, 2003Co-Authors: Dietrich H. NiesAbstract:What makes a heavy metal resistant bacterium heavy metal resistant? The mechanisms of action, physiological functions, and distribution of metal-exporting proteins are outlined, namely: CBA efflux pumps driven by proteins of the resistance–nodulation–cell division superfamily, P-type ATPases, Cation Diffusion Facilitator and chromate proteins, NreB- and CnrT-like resistance factors. The complement of efflux systems of 63 sequenced prokaryotes was compared with that of the heavy metal resistant bacterium Ralstonia metallidurans. This comparison shows that heavy metal resistance is the result of multiple layers of resistance systems with overlapping substrate specificities, but unique functions. Some of these systems are widespread and serve in the basic defense of the cell against superfluous heavy metals, but some are highly specialized and occur only in a few bacteria. Possession of the latter systems makes a bacterium heavy metal resistant.
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a transporter in the endoplasmic reticulum of schizosaccharomyces pombe cells mediates zinc storage and differentially affects transition metal tolerance
Journal of Biological Chemistry, 2002Co-Authors: Stephan Clemens, Dietrich H. Nies, Tanja Bloss, Christoph Vess, Dieter Neumann, Uta Zur NiedenAbstract:Abstract The Cation Diffusion Facilitator (CDF) family represents a class of ubiquitous metal transporters. Inactivation of a CDF in Schizosaccharomyces pombe, Zhf, causes drastically different effects on the tolerance toward various metals. A deletion mutant is Zn2+/Co2+-hypersensitive yet displays significantly enhanced Cd2+ and Ni2+ tolerance. Accumulation of zinc, cobalt, and cadmium is reduced in mutant cells. Non-vacuolar zinc content, as measured by analytical electron microscopy, is lower in zhf− cells compared with wild-type cells in the presence of elevated Zn2+concentrations. The protective effect against cadmium toxicity is independent of the phytochelatin detoxifiCation pathway. Phytochelatin synthase-deficient cells show extremely enhanced (about 200-fold) cadmium tolerance when zhf is disrupted. Immunogold labeling indicates endoplasmic reticulum (ER) localization of Zhf. Electron spectroscopic imaging shows that accumulation of zinc coincides with Zhf localization, demonstrating a major role of the ER for metal storage and the involvement of Zhf in cellular zinc homeostasis. Also, these observations indicate that Cd2+ions exert their toxic effects on cellular metabolism in the ER rather than in the cytosol.
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zitb ybgr a member of the Cation Diffusion Facilitator family is an additional zinc transporter in escherichia coli
Journal of Bacteriology, 2001Co-Authors: Gregor Grass, Dietrich H. Nies, Bin Fan, Barry P Rosen, Sylvia Franke, Christopher RensingAbstract:The Escherichia coli zitB gene encodes a Zn(II) transporter belonging to the Cation Diffusion Facilitator family. ZitB is specifically induced by zinc. ZitB expression on a plasmid rendered zntA-disrupted E. coli cells more resistant to zinc, and the cells exhibited reduced accumulation of 65Zn, suggesting ZitB-mediated efflux of zinc.
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czcd is a heavy metal ion transporter involved in regulation of heavy metal resistance in ralstonia sp strain ch34
Journal of Bacteriology, 1999Co-Authors: Andreas Anton, Cornelia Grose, Jana Reismann, Thomas Pribyl, Dietrich H. NiesAbstract:The Czc system of Ralstonia sp. strain CH34 mediates resistance to cobalt, zinc, and cadmium through ion efflux catalyzed by the CzcCB2A Cation-proton antiporter. The CzcD protein is involved in the regulation of the Czc system. It is a membrane-bound protein with at least four transmembrane α-helices and is a member of a subfamily of the Cation Diffusion Facilitator (CDF) protein family, which occurs in all three domains of life. The deletion of czcD in a Ralstonia sp. led to partially constitutive expression of the Czc system due to an increased transcription of the structural czcCBA genes, both in the absence and presence of inducers. The czcD deletion could be fully complemented in trans by CzcD and two other CDF proteins from Saccharomyces cerevisiae, ZRC1p and COT1p. All three proteins mediated a small but significant resistance to cobalt, zinc, and cadmium in Ralstonia, and this resistance was based on a reduced accumulation of the Cations. Thus, CzcD appeared to repress the Czc system by an export of the inducing Cations.