The Experts below are selected from a list of 2064 Experts worldwide ranked by ideXlab platform
Luciano A Abriata - One of the best experts on this subject based on the ideXlab platform.
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homology and coevolution consistent structural models of bacterial copper tolerance protein copm support a Metal Sponge function and suggest regions for Metal dependent protein protein interactions
bioRxiv, 2015Co-Authors: Luciano A AbriataAbstract:Copper is essential for life but toxic, therefore all organisms control tightly its intracellular abundance. Bacteria have indeed whole operons devoted to copper resistance, with genes that code for efflux pumps, oxidases, etc. Recently, the CopM protein of the CopMRS operon was described as a novel important element for copper tolerance in Synechocystis. This protein consists of a domain of unknown function, and was proposed to act as a periplasmic/extracellular copper binder. This work describes a bioinformatic study of CopM including structural models based on homology modeling and on residue coevolution, to help expand on its recent biochemical characterization. The protein is predicted to be periplasmic but membrane-anchored, not secreted. Two disordered regions are predicted, both possibly involved in protein-protein interactions. The 3D models disclose a 4-helix bundle with several potential copper-binding sites, most of them largely buried inside the bundle lumen. Some of the predicted copper-binding sites involve residues from the disordered regions, suggesting they could gain structure upon copper binding and thus possibly modulate the interactions they mediate. All the models are provided as PDB files in the Supporting Information, and can be viewed in 3D online at http://lucianoabriata.altervista.org/modelshome.html
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an homology and coevolution consistent structural model of bacterial copper tolerance protein copm supports function as a Metal Sponge and suggests regions for Metal dependent interactions with other proteins
bioRxiv, 2015Co-Authors: Luciano A AbriataAbstract:Copper is essential for life but toxic, therefore all organisms control tightly its intracellular abundance. Bacteria have indeed whole operons devoted to copper resistance, with genes that code for efflux pumps, oxidases, etc. Recently, the CopM protein of the CopMRS operon was described as an important element for copper tolerance in Synechocystis. This protein consists of a domain of unknown function, and was suggested to act as a periplasmic/extracellular copper binder. This work describes a bioinformatic characterization of CopM including structural models based on homology modeling and on residue coevolution, to help expand on the recently reported experiments. The protein is predicted to be membrane-anchored, not secreted. Two disordered regions are predicted, both possibly involved in protein-protein interactions. The 3D models disclose a 4-helix bundle fold with several potential copper-binding sites, most of them largely buried inside the lumen of the bundle. Some of the predicted copper-binding sites involve residues from the disordered regions, suggesting that copper binding could induce structuring of these disordered regions and thus modulate the interactions they mediate.
Anthony G Wedd - One of the best experts on this subject based on the ideXlab platform.
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pcoe a Metal Sponge expressed to the periplasm of copper resistance escherichia coli implication of its function role in copper resistance
Journal of Inorganic Biochemistry, 2012Co-Authors: Matthias Zimmermann, Saumya R Udagedara, Chak Ming Sze, Timothy M Ryan, Geoffrey J Howlett, Zhiguang Xiao, Anthony G WeddAbstract:Expression of the periplasmic protein PcoE of Escherichia coli is induced strongly by cupric salts under the control of the chromosomal copper tolerance system cusRS. Its isolation and study were complicated by de-amidation of Asn 54 and 103 at alkaline pH. Its apo form is essentially unstructured in solution and can be likened to a large unstructured multidentate ligand carrying multiple Metal binding sites (15 Met; 10 His; 13 Asp, Glu; 10 Asn; 6 Lys). As expected, it binds multiple soft Metal ions Cu(+) and Ag(+) non-cooperatively with the highest affinity for Cu(I) in the picomolar range (K(D)~10(-12) M). Binding of multiple soft ions induced dimerization and formation of some α-helical structure. PcoE also binds the harder Metal ions Cu(2+) or Zn(2+) but with lower affinities and in smaller numbers. Cu(II) bound in PcoE is reduced readily to more tightly bound Cu(I). Overall, these properties mean that it is difficult to characterize individual species of defined Metal content. Similar properties and difficulties have been reported for the homologous silver-binding protein SilE from Salmonella. However, the properties are consistent with a role for PcoE as a 'Metal Sponge' acting as a first line of defence against Metal toxicity (under the control of the copper tolerance system cusRS) until the copper resistance operon pcoABCD is expressed.
Matthias Zimmermann - One of the best experts on this subject based on the ideXlab platform.
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pcoe a Metal Sponge expressed to the periplasm of copper resistance escherichia coli implication of its function role in copper resistance
Journal of Inorganic Biochemistry, 2012Co-Authors: Matthias Zimmermann, Saumya R Udagedara, Chak Ming Sze, Timothy M Ryan, Geoffrey J Howlett, Zhiguang Xiao, Anthony G WeddAbstract:Expression of the periplasmic protein PcoE of Escherichia coli is induced strongly by cupric salts under the control of the chromosomal copper tolerance system cusRS. Its isolation and study were complicated by de-amidation of Asn 54 and 103 at alkaline pH. Its apo form is essentially unstructured in solution and can be likened to a large unstructured multidentate ligand carrying multiple Metal binding sites (15 Met; 10 His; 13 Asp, Glu; 10 Asn; 6 Lys). As expected, it binds multiple soft Metal ions Cu(+) and Ag(+) non-cooperatively with the highest affinity for Cu(I) in the picomolar range (K(D)~10(-12) M). Binding of multiple soft ions induced dimerization and formation of some α-helical structure. PcoE also binds the harder Metal ions Cu(2+) or Zn(2+) but with lower affinities and in smaller numbers. Cu(II) bound in PcoE is reduced readily to more tightly bound Cu(I). Overall, these properties mean that it is difficult to characterize individual species of defined Metal content. Similar properties and difficulties have been reported for the homologous silver-binding protein SilE from Salmonella. However, the properties are consistent with a role for PcoE as a 'Metal Sponge' acting as a first line of defence against Metal toxicity (under the control of the copper tolerance system cusRS) until the copper resistance operon pcoABCD is expressed.
Roger Acey - One of the best experts on this subject based on the ideXlab platform.
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a heavy Metal Sponge for selective removal and recovery of toxic or precious Metals from water 844 8
The FASEB Journal, 2014Co-Authors: Phuc Nguyen, Paul Madera, Aaron Ong, Herbert Mao, Nancy Trujillo, Adrian Rendon, Roger AceyAbstract:Metallothionein (MT) is a low molecular weight Metal binding protein. It has the unique ability to selective bind trace amounts of toxic heavy Metals such as lead and cadmium. It does not bind essential Metals such as sodium or calcium. We are developing a novel patented “heavy Metal Sponge” technology for the removal and recovery of toxic, e.g., lead and mercury, and precious Metal, e.g., gold and platinum, from water. MT also has the ability to bind the lanthanides lanthanum and europium. Recombinant MT was cloned into pET vectors with and without a Pel secretory sequence, pPMpel, and pCODAmt, respectively. The protein is expressed in bacteria and purified to near homogeneity from cell lysates by a simple and cost effective method using FPLC anion exchange chromatography. The purity of the preparation was confirmed by SDS-PAGE. Expression of MT and secretion of the protein using the pPMpel construct is pH dependent. The level of expression from both constructs was the same for IPTG ranging from 0.5 to 2...
Geoffrey J Howlett - One of the best experts on this subject based on the ideXlab platform.
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pcoe a Metal Sponge expressed to the periplasm of copper resistance escherichia coli implication of its function role in copper resistance
Journal of Inorganic Biochemistry, 2012Co-Authors: Matthias Zimmermann, Saumya R Udagedara, Chak Ming Sze, Timothy M Ryan, Geoffrey J Howlett, Zhiguang Xiao, Anthony G WeddAbstract:Expression of the periplasmic protein PcoE of Escherichia coli is induced strongly by cupric salts under the control of the chromosomal copper tolerance system cusRS. Its isolation and study were complicated by de-amidation of Asn 54 and 103 at alkaline pH. Its apo form is essentially unstructured in solution and can be likened to a large unstructured multidentate ligand carrying multiple Metal binding sites (15 Met; 10 His; 13 Asp, Glu; 10 Asn; 6 Lys). As expected, it binds multiple soft Metal ions Cu(+) and Ag(+) non-cooperatively with the highest affinity for Cu(I) in the picomolar range (K(D)~10(-12) M). Binding of multiple soft ions induced dimerization and formation of some α-helical structure. PcoE also binds the harder Metal ions Cu(2+) or Zn(2+) but with lower affinities and in smaller numbers. Cu(II) bound in PcoE is reduced readily to more tightly bound Cu(I). Overall, these properties mean that it is difficult to characterize individual species of defined Metal content. Similar properties and difficulties have been reported for the homologous silver-binding protein SilE from Salmonella. However, the properties are consistent with a role for PcoE as a 'Metal Sponge' acting as a first line of defence against Metal toxicity (under the control of the copper tolerance system cusRS) until the copper resistance operon pcoABCD is expressed.