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Barry P. Rosen - One of the best experts on this subject based on the ideXlab platform.
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Biochemical characterization of a novel ArsA ATPase complex from Alkaliphilus metalliredigens QYMF
FEBS Letters, 2010Co-Authors: Barry P. Rosen, Hiranmoy BhattacharjeeAbstract:The two putative ars operons in Alkaliphilus metalliredigens QYMF are distinctive in that the arsA gene is split in halves, amarsA1 and amarsA2, and, acr3 but not an arsB gene coexists with arsA. Heterologous expression of one of the A. metalliredigens ars operons (ars1) conferred arsenite but not Antimonite resistance to Δars Escherichia coli. Only the co-expressed AmArsA1 and AmArsA2 displayed arsenite or Antimonite stimulated ATPase activity. The results show that AmArsA1–AmArsA2 interaction is needed to form the functional ArsA ATPase. This novel AmArsA1–AmArsA2 complex may provide insight in how it participates with Acr3 in arsenite detoxification.
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Original Research Report: Structure-Function Analysis of the ArsA ATPase: Contribution of Histidine Residues
Journal of Bioenergetics and Biomembranes, 2001Co-Authors: Hiranmoy Bhattacharjee, Barry P. RosenAbstract:The ArsA ATPase is the catalytic subunit of the ArsAB oxyanion pump in Escherichia coli that is responsible for extruding arsenite or Antimonite from inside the cell, thereby conferring resistance. Either Antimonite or arsenite stimulates ArsA ATPase activity. In this study, the role of histidine residues in ArsA activity was investigated. Treatment of ArsA with diethyl pyrocarbonate (DEPC) resulted in complete loss of catalytic activity. The inactivation could be reversed upon subsequent incubation with hydroxylamine, suggesting specific modification of histidine residues. ATP and oxyanions afforded significant protection against DEPC inactivation, indicating that the histidines are located at the active site. ArsA has 13 histidine residues located at position 138, 148, 219, 327, 359, 368, 388, 397, 453, 465, 477, 520, and 558. Each histidine was individually altered to alanine by site-directed mutagenesis. Cells expressing the altered ArsA proteins were resistant to both arsenite and Antimonite. The results indicate that no single histidine residue plays a direct role in catalysis, and the inhibition by DEPC may be caused by steric hindrance from the carbethoxy group.
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Structure-function analysis of the ArsA ATPase: contribution of histidine residues.
Journal of Bioenergetics and Biomembranes, 2001Co-Authors: Hiranmoy Bhattacharjee, Barry P. RosenAbstract:The ArsA ATPase is the catalytic subunit of the ArsAB oxyanion pump in Escherichia coli that is responsible for extruding arsenite or Antimonite from inside the cell, thereby conferring resistance. Either Antimonite or arsenite stimulates ArsA ATPase activity. In this study, the role of histidine residues in ArsA activity was investigated. Treatment of ArsA with diethyl pyrocarbonate (DEPC) resulted in complete loss of catalytic activity. The inactivation could be reversed upon subsequent incubation with hydroxylamine, suggesting specific modification of histidine residues. ATP and oxyanions afforded significant protection against DEPC inactivation, indicating that the histidines are located at the active site. ArsA has 13 histidine residues located at position 138, 148, 219, 327, 359, 368, 388, 397, 453, 465, 477, 520, and 558. Each histidine was individually altered to alanine by site-directed mutagenesis. Cells expressing the altered ArsA proteins were resistant to both arsenite and Antimonite. The results indicate that no single histidine residue plays a direct role in catalysis, and the inhibition by DEPC may be caused by steric hindrance from the carbethoxy group.
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Bacteria-based chemiluminescence sensing system using β-galactosidase under the control of the ArsR regulatory protein of the ars operon
Analytica Chimica Acta, 1998Co-Authors: Sridhar Ramanathan, Barry P. Rosen, Weiping Shi, Sylvia DaunertAbstract:Abstract A highly sensitive and selective sensing system for Antimonite and arsenite was developed based on genetically engineered bacteria harboring the plasmid pBGD23. In this plasmid, arsR , the gene encoding for the ArsR regulatory protein of the ars operon, is fused to lacZ , the gene encoding for the reporter enzyme β-galactosidase. The expression of β-galactosidase in E. coli strains bearing pBGD23 is controlled by ArsR, and this can be related to the concentration of Antimonite/arsenite employed to induce the production of β-galactosidase in the bacteria. ArsR has a high specificity for Antimonite/arsenite, thus conferring the developed sensing system with high selectivity. This was demonstrated by evaluating several oxoanions and soft metals as potential interferents. The concentration of β-galactosidase expressed in the bacteria was monitored by chemiluminescence. Using this sensing system, Antimonite can be detected at concentrations as low as 10 −15 M. The importance of the E. coli chromosomal ars operon on the observed response was evaluated by employing a strain of E. coli where the chromosomal ars operon has been deleted.
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sensing Antimonite and arsenite at the subattomole level with genetically engineered bioluminescent bacteria
Analytical Chemistry, 1997Co-Authors: Sridhar Ramanathan, Barry P. Rosen, Sylvia DaunertAbstract:A highly sensitive and selective optical sensing system for Antimonite has been developed using genetically engineered bacteria. The basis of this system is the ability of certain bacteria to survive in environments that are contaminated with Antimonite, arsenite, and arsenate. The survival is conferred to the bacteria by the ars operon, which consists of five genes that code for three structural proteins, ArsA, ArsB, and ArsC, and two regulatory proteins, ArsD and ArsR. ArsA, ArsB, and ArsC form a protein pump system that extrudes Antimonite, arsenite, and arsenate once these anions reach the cytoplasm of the bacterium. A method was developed for monitoring Antimonite and arsenite by using a single plasmid that incorporates the regulatory gene of the extrusion system, arsR, and the genes of bacterial luciferase, luxA and luxB. In the designed plasmid, ArsR regulates the expression of bacterial luciferase in a manner that is dependent on the concentration of Antimonite and arsenite in the sample. Thus, th...
Changlun Chen - One of the best experts on this subject based on the ideXlab platform.
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Screening of Zirconium-Based Metal–Organic Frameworks for Efficient Simultaneous Removal of Antimonite (Sb(III)) and Antimonate (Sb(V)) from Aqueous Solution
ACS Sustainable Chemistry & Engineering, 2017Co-Authors: Tasawar Hayat, Ahmed Alsaedi, Changlun ChenAbstract:Seven kinds of zirconium-based metal–organic frameworks (Zr-MOFs) with different aperture size and organic linkers functionalized with different functional groups (−NH2, −OH, and −SO3H) were screened for their ability to remove Antimonite (Sb(III)) and antimonate (Sb(V)) anions from water. Zr-bound hydroxides in Zr-MOFs can simultaneously remove both Sb(III) and Sb(V) via a mechanism of anion exchange. For antimony removal by UiO-66-NH2, the anion exchange seemed to be strengthened due to the Lewis acid–base interactions between the −NH2 groups on the BDC ligand and the antimony oxyanions. Among seven kinds of Zr-MOFs selected here, NU-1000 exhibited fast adsorption kinetics and high removal capacity for both Sb(III) (136.97 mg/g) and Sb(V) (287.88 mg/g), which was much higher than many antimony adsorbents described to date. Uptake of antimony at low concentrations of 100 μg/L (with a remaining antimony concentration of only ∼2 μg/L in 10 min) disclosed that current U.S. Environmental Protection Agency st...
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screening of zirconium based metal organic frameworks for efficient simultaneous removal of Antimonite sb iii and antimonate sb v from aqueous solution
ACS Sustainable Chemistry & Engineering, 2017Co-Authors: Tasawar Hayat, Ahmed Alsaedi, Changlun ChenAbstract:Seven kinds of zirconium-based metal–organic frameworks (Zr-MOFs) with different aperture size and organic linkers functionalized with different functional groups (−NH2, −OH, and −SO3H) were screened for their ability to remove Antimonite (Sb(III)) and antimonate (Sb(V)) anions from water. Zr-bound hydroxides in Zr-MOFs can simultaneously remove both Sb(III) and Sb(V) via a mechanism of anion exchange. For antimony removal by UiO-66-NH2, the anion exchange seemed to be strengthened due to the Lewis acid–base interactions between the −NH2 groups on the BDC ligand and the antimony oxyanions. Among seven kinds of Zr-MOFs selected here, NU-1000 exhibited fast adsorption kinetics and high removal capacity for both Sb(III) (136.97 mg/g) and Sb(V) (287.88 mg/g), which was much higher than many antimony adsorbents described to date. Uptake of antimony at low concentrations of 100 μg/L (with a remaining antimony concentration of only ∼2 μg/L in 10 min) disclosed that current U.S. Environmental Protection Agency st...
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Screening of Zirconium-Based Metal–Organic Frameworks for Efficient Simultaneous Removal of Antimonite (Sb(III)) and Antimonate (Sb(V)) from Aqueous Solution
2017Co-Authors: Tasawar Hayat, Ahmed Alsaedi, Changlun ChenAbstract:Seven kinds of zirconium-based metal–organic frameworks (Zr-MOFs) with different aperture size and organic linkers functionalized with different functional groups (−NH2, −OH, and −SO3H) were screened for their ability to remove Antimonite (Sb(III)) and antimonate (Sb(V)) anions from water. Zr-bound hydroxides in Zr-MOFs can simultaneously remove both Sb(III) and Sb(V) via a mechanism of anion exchange. For antimony removal by UiO-66-NH2, the anion exchange seemed to be strengthened due to the Lewis acid–base interactions between the −NH2 groups on the BDC ligand and the antimony oxyanions. Among seven kinds of Zr-MOFs selected here, NU-1000 exhibited fast adsorption kinetics and high removal capacity for both Sb(III) (136.97 mg/g) and Sb(V) (287.88 mg/g), which was much higher than many antimony adsorbents described to date. Uptake of antimony at low concentrations of 100 μg/L (with a remaining antimony concentration of only ∼2 μg/L in 10 min) disclosed that current U.S. Environmental Protection Agency standards for antimony can be reached by using NU-1000 as an adsorbent. Additionally, the effects of coexisting anions such as As(III), As(V), PO43–, SO42–, NO3–, and F– on the antimony adsorption onto NU-1000 were also studied. Finally, the Sb adsorption mechanism of NU-1000 was studied via X-ray photon spectroscopy and attenuated total reflection infrared spectroscopy techniques to explore the important characteristics that make NU-1000 a compelling candidate for wastewater management
Tasawar Hayat - One of the best experts on this subject based on the ideXlab platform.
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Screening of Zirconium-Based Metal–Organic Frameworks for Efficient Simultaneous Removal of Antimonite (Sb(III)) and Antimonate (Sb(V)) from Aqueous Solution
ACS Sustainable Chemistry & Engineering, 2017Co-Authors: Tasawar Hayat, Ahmed Alsaedi, Changlun ChenAbstract:Seven kinds of zirconium-based metal–organic frameworks (Zr-MOFs) with different aperture size and organic linkers functionalized with different functional groups (−NH2, −OH, and −SO3H) were screened for their ability to remove Antimonite (Sb(III)) and antimonate (Sb(V)) anions from water. Zr-bound hydroxides in Zr-MOFs can simultaneously remove both Sb(III) and Sb(V) via a mechanism of anion exchange. For antimony removal by UiO-66-NH2, the anion exchange seemed to be strengthened due to the Lewis acid–base interactions between the −NH2 groups on the BDC ligand and the antimony oxyanions. Among seven kinds of Zr-MOFs selected here, NU-1000 exhibited fast adsorption kinetics and high removal capacity for both Sb(III) (136.97 mg/g) and Sb(V) (287.88 mg/g), which was much higher than many antimony adsorbents described to date. Uptake of antimony at low concentrations of 100 μg/L (with a remaining antimony concentration of only ∼2 μg/L in 10 min) disclosed that current U.S. Environmental Protection Agency st...
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screening of zirconium based metal organic frameworks for efficient simultaneous removal of Antimonite sb iii and antimonate sb v from aqueous solution
ACS Sustainable Chemistry & Engineering, 2017Co-Authors: Tasawar Hayat, Ahmed Alsaedi, Changlun ChenAbstract:Seven kinds of zirconium-based metal–organic frameworks (Zr-MOFs) with different aperture size and organic linkers functionalized with different functional groups (−NH2, −OH, and −SO3H) were screened for their ability to remove Antimonite (Sb(III)) and antimonate (Sb(V)) anions from water. Zr-bound hydroxides in Zr-MOFs can simultaneously remove both Sb(III) and Sb(V) via a mechanism of anion exchange. For antimony removal by UiO-66-NH2, the anion exchange seemed to be strengthened due to the Lewis acid–base interactions between the −NH2 groups on the BDC ligand and the antimony oxyanions. Among seven kinds of Zr-MOFs selected here, NU-1000 exhibited fast adsorption kinetics and high removal capacity for both Sb(III) (136.97 mg/g) and Sb(V) (287.88 mg/g), which was much higher than many antimony adsorbents described to date. Uptake of antimony at low concentrations of 100 μg/L (with a remaining antimony concentration of only ∼2 μg/L in 10 min) disclosed that current U.S. Environmental Protection Agency st...
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Screening of Zirconium-Based Metal–Organic Frameworks for Efficient Simultaneous Removal of Antimonite (Sb(III)) and Antimonate (Sb(V)) from Aqueous Solution
2017Co-Authors: Tasawar Hayat, Ahmed Alsaedi, Changlun ChenAbstract:Seven kinds of zirconium-based metal–organic frameworks (Zr-MOFs) with different aperture size and organic linkers functionalized with different functional groups (−NH2, −OH, and −SO3H) were screened for their ability to remove Antimonite (Sb(III)) and antimonate (Sb(V)) anions from water. Zr-bound hydroxides in Zr-MOFs can simultaneously remove both Sb(III) and Sb(V) via a mechanism of anion exchange. For antimony removal by UiO-66-NH2, the anion exchange seemed to be strengthened due to the Lewis acid–base interactions between the −NH2 groups on the BDC ligand and the antimony oxyanions. Among seven kinds of Zr-MOFs selected here, NU-1000 exhibited fast adsorption kinetics and high removal capacity for both Sb(III) (136.97 mg/g) and Sb(V) (287.88 mg/g), which was much higher than many antimony adsorbents described to date. Uptake of antimony at low concentrations of 100 μg/L (with a remaining antimony concentration of only ∼2 μg/L in 10 min) disclosed that current U.S. Environmental Protection Agency standards for antimony can be reached by using NU-1000 as an adsorbent. Additionally, the effects of coexisting anions such as As(III), As(V), PO43–, SO42–, NO3–, and F– on the antimony adsorption onto NU-1000 were also studied. Finally, the Sb adsorption mechanism of NU-1000 was studied via X-ray photon spectroscopy and attenuated total reflection infrared spectroscopy techniques to explore the important characteristics that make NU-1000 a compelling candidate for wastewater management
Lena Q. - One of the best experts on this subject based on the ideXlab platform.
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uptake of Antimonite and antimonate by arsenic hyperaccumulator pteris vittata effects of chemical analogs and transporter inhibitor
Environmental Pollution, 2015Co-Authors: Lena Q., Rujira Tisarum, Yanshan Chen, Xiaoling Dong, Jason T LesslAbstract:Abstract Antimonite (SbIII) is transported into plants via aquaglyceroporin channels but it is unknown in As-hyperaccumulator Ptreis vittata (PV). We tested the effects of SbIII analogs (arsenite-AsIII, glycerol, silicic acid-Si, and, glucose), antimonate (SbV) analog (phosphate-P), and aquaglyceroporin transporter inhibitor (silver, Ag) on the uptake of SbIII or SbV by PV gametophytes. PV gametophytes were grown in 20% Hoagland solution containing 65 μM SbIII or SbV and increasing concentrations of analogs at 65–6500 μM for 2 h or 4 h under sterile condition. After exposing to 65 μM Sb for 2 h, PV accumulated 767 mg/kg Sb in SbIII treatment and 419 mg/kg in SbV treatment. SbIII uptake by PV gametophytes was not impacted by glycerol or AsIII nor aquaglyceroporin inhibitor Ag during 2 h exposure. While Si increased SbIII uptake and glucose decreased SbIII uptake by PV gametophytes, the impact disappeared during 4 h exposure. Under P-sufficient condition, P increased SbIII uptake and decreased SbV uptake during 2 h exposure, but the effect again disappeared after 4 h. After being P-starved for 2 weeks, P decreased SbIII with no effect on SbV uptake during 2 h exposure. Our results indicated that: 1) PV gametophytes could serve as an efficient model to study Sb uptake, and 2) unique SbIII uptake by PV may be related to its trait of As hyperaccumulation.
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antimony uptake efflux and speciation in arsenic hyperaccumulator pteris vittata
Environmental Pollution, 2014Co-Authors: Rujira Tisarum, Xiaoling Dong, Jason T Lessl, Letuzia M De Oliveira, Bala Rathinasabapathi, Lena Q.Abstract:Even though antimony (Sb) and arsenic (As) are chemical analogs, differences exist on how they are taken up and translocated in plants. We investigated 1) Sb uptake, efflux and speciation in arsenic hyperaccumulator Pteris vittata after 1 d exposure to 1.6 or 8 mg/L Antimonite (SbIII) or antimonate (SbV), 2) Sb uptake by PV accessions from Florida, China, and Brazil after 7 d exposure to 8 mg/L SbIII, and 3) Sb uptake and oxidation by excised PV fronds after 1 d exposure to 8 mg/L SbIII or SbV. After 1 d exposure, P. vittata took 23e32 times more SbIII than SbV, with all Sb being accumulated in the roots with the highest at 4,192 mg/kg. When exposed to 8 mg/L SbV, 98% of Sb existed as SbV in the roots. In comparison, when exposed to 8 mg/L SbIII, 81% of the total Sb remained as SbIII and 26% of the total Sb was effluxed out into the media. The three PV accessions had a similar ability to accumulate Sb at 12,000 mg/kg in the roots, with >99% of total Sb in the roots. Excised PV fronds translocated SbV more efficiently from the petioles to pinnae than SbIII and were unable to oxidize SbIII. Overall, P. vittata displayed efficient root uptake and efflux of SbIII with limited ability to translocate and transform in the roots.
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Antimony uptake, translocation and speciation in rice plants exposed to Antimonite and antimonate
Science of The Total Environment, 2014Co-Authors: Jing–hua Ren, Lena Q., Hong-jie Sun, Fei Cai, Jun LuoAbstract:Abstract Antimony (Sb) accumulation in rice is a potential threat to human health, but its uptake mechanisms are unclear. A hydroponic experiment was conducted to investigate uptake, translocation, speciation and subcellular distribution of Sb in rice plants exposed to Antimonite (SbIII) and antimonate (SbV) at 0.2, 1.0 or 5.0 mg/L for 4 h. More Sb was accumulated in iron plaque than in the plant, with both the roots (~ 10–12 times) and Fe plaque (~ 28–54 times) sequestering more SbIII than SbV. The presence of iron plaque decreased uptake of both SbV and SbIII. SbIII uptake kinetics fitted better to the Michaelis–Menten function than SbV. Antimonate (56 to 98%) was the predominant form in rice plant with little methylated species being detected using HPLC–ICP-MS. Cell walls accumulated more Sb than organelles and cytosol, which were considered as the first barrier against Sb entering into cells. Sb transformation and subcellular distribution can help to understand the metabolic mechanisms of Sb in rice.
Sylvia Daunert - One of the best experts on this subject based on the ideXlab platform.
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Bacteria-based chemiluminescence sensing system using β-galactosidase under the control of the ArsR regulatory protein of the ars operon
Analytica Chimica Acta, 1998Co-Authors: Sridhar Ramanathan, Barry P. Rosen, Weiping Shi, Sylvia DaunertAbstract:Abstract A highly sensitive and selective sensing system for Antimonite and arsenite was developed based on genetically engineered bacteria harboring the plasmid pBGD23. In this plasmid, arsR , the gene encoding for the ArsR regulatory protein of the ars operon, is fused to lacZ , the gene encoding for the reporter enzyme β-galactosidase. The expression of β-galactosidase in E. coli strains bearing pBGD23 is controlled by ArsR, and this can be related to the concentration of Antimonite/arsenite employed to induce the production of β-galactosidase in the bacteria. ArsR has a high specificity for Antimonite/arsenite, thus conferring the developed sensing system with high selectivity. This was demonstrated by evaluating several oxoanions and soft metals as potential interferents. The concentration of β-galactosidase expressed in the bacteria was monitored by chemiluminescence. Using this sensing system, Antimonite can be detected at concentrations as low as 10 −15 M. The importance of the E. coli chromosomal ars operon on the observed response was evaluated by employing a strain of E. coli where the chromosomal ars operon has been deleted.
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sensing Antimonite and arsenite at the subattomole level with genetically engineered bioluminescent bacteria
Analytical Chemistry, 1997Co-Authors: Sridhar Ramanathan, Barry P. Rosen, Sylvia DaunertAbstract:A highly sensitive and selective optical sensing system for Antimonite has been developed using genetically engineered bacteria. The basis of this system is the ability of certain bacteria to survive in environments that are contaminated with Antimonite, arsenite, and arsenate. The survival is conferred to the bacteria by the ars operon, which consists of five genes that code for three structural proteins, ArsA, ArsB, and ArsC, and two regulatory proteins, ArsD and ArsR. ArsA, ArsB, and ArsC form a protein pump system that extrudes Antimonite, arsenite, and arsenate once these anions reach the cytoplasm of the bacterium. A method was developed for monitoring Antimonite and arsenite by using a single plasmid that incorporates the regulatory gene of the extrusion system, arsR, and the genes of bacterial luciferase, luxA and luxB. In the designed plasmid, ArsR regulates the expression of bacterial luciferase in a manner that is dependent on the concentration of Antimonite and arsenite in the sample. Thus, th...
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Genetically engineered bacteria: electrochemical sensing systems for Antimonite and arsenite.
Analytical Chemistry, 1997Co-Authors: Donna L. Scott, Barry P. Rosen, Sridhar Ramanathan, Weiping Shi, Sylvia DaunertAbstract:A bacterial sensing system that responds selectively to Antimonite and arsenite has been investigated. The bacteria used in these studies have been genetically engineered to produce the enzyme β-galactosidase in response to these ions. This is accomplished by using a plasmid that incorporates the gene for β-galactosidase (reporter gene) under the control of the promoter of the ars operon. This plasmid also encodes for the ArsR protein, a regulatory protein of the ars operon, which, in the absence of Antimonite or arsenite, restricts the expression of β-galactosidase. In the presence of Antimonite or arsenite the ArsR protein is released from the operator/promoter region of the ars operon and β-galactosidase is expressed. The activity of this enzyme was monitored electrochemically using p-aminophenyl β-d-galactopyranoside as the substrate. The bacterial sensing system responds selectively to arsenite and Antimonite (and to a lesser extent arsenate) and shows no significant response to phosphate, sulfate, n...
