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Carole Dauberschmidt - One of the best experts on this subject based on the ideXlab platform.
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Toxicity of Organophosphorus Insecticides in the Zebra Mussel, Dreissena polymorpha P.
Archives of Environmental Contamination and Toxicology, 1996Co-Authors: Carole Dauberschmidt, Daniel R. Dietrich, Christian SchlatterAbstract:The 96-h toxicity of four Organophosphates (thiometon, disulfoton, malathion, and demeton-S-methyl, the oxygen analogue of thiometon) in the freshwater bivalve mollusc Dreissena polymorpha was tested using different nominal concentrations ranging between 6 and 50 mg/L. No mortalities were observed in mussels exposed to malathion and demeton-S-methyl (26 mg/L and 6 mg/L, respectively), and at the lowest concentrations of thiometon and disulfoton (6 and 10 mg/L, respectively). At higher thiometon and disulfoton concentrations, mortalities occurred. At the highest concentrations of 50 mg thiometon/L and 30 mg disulfoton/L, mussel mortalities of 88 and 93%, respectively, were determined. Organophosphate concentrations of up to a factor 10 times higher than in the ambient water were found in exposed mussels, irrespective of whether they were alive or dead. The search for organophosphate metabolites via GC/MS analysis of mussel tissue extracts was negative, suggesting lacking or low oxidative activation of the insecticides used. The mollusc is highly resistant to toxic effects of organophosphate insecticides and their biological active oxygen analogues.
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Organophosphates in the Zebra Mussel Dreissena polymorpha: Subacute Exposure, Body Burdens, and Organ Concentrations
1996Co-Authors: Carole Dauberschmidt, D. R. Dietrich, C. SchlatterAbstract:Abstract. Subacute exposures (10 d) of the freshwater mollusc Dreissena polymorpha to disulfoton (10 mg/L), thiometon (6 mg/L), and its activated oxygen analogue demeton-S-methyl (6 mg/L) corroborate earlier findings of organophosphate resis-tance and accumulation in the organism. Mortality occurred not before the ninth day of exposure. Mortality was induced at high ambient water concentrations and must be due to unknown specific organophosphate effects. Body burdens reached satura-tion levels within one week being around 40 mg/kg wet weight for thiometon and 60 mg/kg for disulfoton. Mussels dying during the tests showed lower tissue concentrations. Elimina-tion of accumulated Organophosphates was so low in the mussel, that an efficient metabolism of these compounds in the mussel was unlikely. Different organs of Dreissena previously acutely exposed (96 h) to the organophosphate thiometon (6
Christian Schlatter - One of the best experts on this subject based on the ideXlab platform.
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Toxicity of Organophosphorus Insecticides in the Zebra Mussel, Dreissena polymorpha P.
Archives of Environmental Contamination and Toxicology, 1996Co-Authors: Carole Dauberschmidt, Daniel R. Dietrich, Christian SchlatterAbstract:The 96-h toxicity of four Organophosphates (thiometon, disulfoton, malathion, and demeton-S-methyl, the oxygen analogue of thiometon) in the freshwater bivalve mollusc Dreissena polymorpha was tested using different nominal concentrations ranging between 6 and 50 mg/L. No mortalities were observed in mussels exposed to malathion and demeton-S-methyl (26 mg/L and 6 mg/L, respectively), and at the lowest concentrations of thiometon and disulfoton (6 and 10 mg/L, respectively). At higher thiometon and disulfoton concentrations, mortalities occurred. At the highest concentrations of 50 mg thiometon/L and 30 mg disulfoton/L, mussel mortalities of 88 and 93%, respectively, were determined. Organophosphate concentrations of up to a factor 10 times higher than in the ambient water were found in exposed mussels, irrespective of whether they were alive or dead. The search for organophosphate metabolites via GC/MS analysis of mussel tissue extracts was negative, suggesting lacking or low oxidative activation of the insecticides used. The mollusc is highly resistant to toxic effects of organophosphate insecticides and their biological active oxygen analogues.
Dayananda Siddavattam - One of the best experts on this subject based on the ideXlab platform.
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organophosphate hydrolase is a lipoprotein and interacts with pi specific transport system to facilitate growth of brevundimonas diminuta using op insecticide as source of phosphate
Journal of Biological Chemistry, 2016Co-Authors: Sunil Parthasarathy, Hari Parapatla, Aparna Nandavaram, Tracy Palmer, Dayananda SiddavattamAbstract:Organophosphate hydrolase (OPH), encoded by the organophosphate degradation (opd) island, hydrolyzes the triester bond found in a variety of organophosphate insecticides and nerve agents. OPH is targeted to the inner membrane of Brevundimonas diminuta in a pre-folded conformation by the twin arginine transport (Tat) pathway. The OPH signal peptide contains an invariant cysteine residue at the junction of the signal peptidase (Spase) cleavage site along with a well conserved lipobox motif. Treatment of cells producing native OPH with the signal peptidase II inhibitor globomycin resulted in accumulation of most of the pre-OPH in the cytoplasm with negligible processed OPH detected in the membrane. Substitution of the conserved lipobox cysteine to serine resulted in release of OPH into the periplasm, confirming that OPH is a lipoprotein. Analysis of purified OPH revealed that it was modified with the fatty acids palmitate and stearate. Membrane-bound OPH was shown to interact with the outer membrane efflux protein TolC and with PstS, the periplasmic component of the ABC transporter complex (PstSACB) involved in phosphate transport. Interaction of OPH with PstS appears to facilitate transport of Pi generated from Organophosphates due to the combined action of OPH and periplasmically located phosphatases. Consistent with this model, opd null mutants of B. diminuta failed to grow using the organophosphate insecticide methyl parathion as sole source of phosphate.
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Organophosphate Hydrolase Is a Lipoprotein and Interacts with Pi-specific Transport System to Facilitate Growth of Brevundimonas diminuta Using OP Insecticide as Source of Phosphate.
Journal of Biological Chemistry, 2016Co-Authors: Sunil Parthasarathy, Hari Parapatla, Aparna Nandavaram, Tracy Palmer, Dayananda SiddavattamAbstract:Abstract Organophosphate hydrolase (OPH), encoded by the organophosphate degradation (opd) island, hydrolyses the triester bond found in a variety of organophosphate insecticides and nerve agents. OPH is targeted to the inner membrane of Brevundimonas diminuta in a pre-folded conformation by the Twin Arginine Transport (Tat) pathway. The OPH signal peptide contains an invariant cysteine residue at the junction of the signal peptidase (Spase) cleavage site along with a well conserved lipobox motif. Treatment of cells producing native OPH with the signal peptidase II inhibitor globomycin resulted in accumulation of most of the preOPH in cytoplasm with negligible processed OPH detected in the membrane. Substitution of the conserved lipobox cysteine to serine resulted in release of OPH into the periplasm, confirming that OPH is a lipoprotein. Analysis of purified OPH revealed that it was modified with the fatty acids palmitate and stearate. Membrane-bound OPH was shown to interact with the outer membrane efflux protein TolC and with PstS, the periplasmic component of ABC transporter complex (PstSACB) involved in phosphate transport. Interaction of OPH with PstS appears to facilitate transport of Pi generated from Organophosphates due to the combined action of OPH and periplasmically located phosphatases. Consisent with this model, opd null mutants of B. diminuta failed to grow using the organophosphate insecticide methyl parathion as sole source of phosphate.
Sunil Parthasarathy - One of the best experts on this subject based on the ideXlab platform.
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organophosphate hydrolase is a lipoprotein and interacts with pi specific transport system to facilitate growth of brevundimonas diminuta using op insecticide as source of phosphate
Journal of Biological Chemistry, 2016Co-Authors: Sunil Parthasarathy, Hari Parapatla, Aparna Nandavaram, Tracy Palmer, Dayananda SiddavattamAbstract:Organophosphate hydrolase (OPH), encoded by the organophosphate degradation (opd) island, hydrolyzes the triester bond found in a variety of organophosphate insecticides and nerve agents. OPH is targeted to the inner membrane of Brevundimonas diminuta in a pre-folded conformation by the twin arginine transport (Tat) pathway. The OPH signal peptide contains an invariant cysteine residue at the junction of the signal peptidase (Spase) cleavage site along with a well conserved lipobox motif. Treatment of cells producing native OPH with the signal peptidase II inhibitor globomycin resulted in accumulation of most of the pre-OPH in the cytoplasm with negligible processed OPH detected in the membrane. Substitution of the conserved lipobox cysteine to serine resulted in release of OPH into the periplasm, confirming that OPH is a lipoprotein. Analysis of purified OPH revealed that it was modified with the fatty acids palmitate and stearate. Membrane-bound OPH was shown to interact with the outer membrane efflux protein TolC and with PstS, the periplasmic component of the ABC transporter complex (PstSACB) involved in phosphate transport. Interaction of OPH with PstS appears to facilitate transport of Pi generated from Organophosphates due to the combined action of OPH and periplasmically located phosphatases. Consistent with this model, opd null mutants of B. diminuta failed to grow using the organophosphate insecticide methyl parathion as sole source of phosphate.
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Organophosphate Hydrolase Is a Lipoprotein and Interacts with Pi-specific Transport System to Facilitate Growth of Brevundimonas diminuta Using OP Insecticide as Source of Phosphate.
Journal of Biological Chemistry, 2016Co-Authors: Sunil Parthasarathy, Hari Parapatla, Aparna Nandavaram, Tracy Palmer, Dayananda SiddavattamAbstract:Abstract Organophosphate hydrolase (OPH), encoded by the organophosphate degradation (opd) island, hydrolyses the triester bond found in a variety of organophosphate insecticides and nerve agents. OPH is targeted to the inner membrane of Brevundimonas diminuta in a pre-folded conformation by the Twin Arginine Transport (Tat) pathway. The OPH signal peptide contains an invariant cysteine residue at the junction of the signal peptidase (Spase) cleavage site along with a well conserved lipobox motif. Treatment of cells producing native OPH with the signal peptidase II inhibitor globomycin resulted in accumulation of most of the preOPH in cytoplasm with negligible processed OPH detected in the membrane. Substitution of the conserved lipobox cysteine to serine resulted in release of OPH into the periplasm, confirming that OPH is a lipoprotein. Analysis of purified OPH revealed that it was modified with the fatty acids palmitate and stearate. Membrane-bound OPH was shown to interact with the outer membrane efflux protein TolC and with PstS, the periplasmic component of ABC transporter complex (PstSACB) involved in phosphate transport. Interaction of OPH with PstS appears to facilitate transport of Pi generated from Organophosphates due to the combined action of OPH and periplasmically located phosphatases. Consisent with this model, opd null mutants of B. diminuta failed to grow using the organophosphate insecticide methyl parathion as sole source of phosphate.
Reinhard Sterner - One of the best experts on this subject based on the ideXlab platform.
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molecular engineering of organophosphate hydrolysis activity from a weak promiscuous lactonase template
Journal of the American Chemical Society, 2013Co-Authors: Monika M Meier, Chitra Rajendran, Christoph Malisi, Nicholas G Fox, Sandra Schlee, David P Barondeau, Birte Hocker, Reinhard SternerAbstract:Rapid evolution of enzymes provides unique molecular insights into the remarkable adaptability of proteins and helps to elucidate the relationship between amino acid sequence, structure, and function. We interrogated the evolution of the phosphotriesterase from Pseudomonas diminuta (PdPTE), which hydrolyzes synthetic Organophosphates with remarkable catalytic efficiency. PTE is thought to be an evolutionarily “young” enzyme, and it has been postulated that it has evolved from members of the phosphotriesterase-like lactonase (PLL) family that show promiscuous organophosphate-degrading activity. Starting from a weakly promiscuous PLL scaffold (Dr0930 from Deinococcus radiodurans), we designed an extremely efficient organophosphate hydrolase (OPH) with broad substrate specificity using rational and random mutagenesis in combination with in vitro activity screening. The OPH activity for seven organophosphate substrates was simultaneously enhanced by up to 5 orders of magnitude, achieving absolute values of ca...
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Molecular Engineering of Organophosphate Hydrolysis Activity from a Weak Promiscuous Lactonase Template
2013Co-Authors: Monika M Meier, Chitra Rajendran, Christoph Malisi, Nicholas G Fox, Sandra Schlee, David P Barondeau, Birte Höcker, Reinhard SternerAbstract:Rapid evolution of enzymes provides unique molecular insights into the remarkable adaptability of proteins and helps to elucidate the relationship between amino acid sequence, structure, and function. We interrogated the evolution of the phosphotriesterase from Pseudomonas diminuta (PdPTE), which hydrolyzes synthetic Organophosphates with remarkable catalytic efficiency. PTE is thought to be an evolutionarily “young” enzyme, and it has been postulated that it has evolved from members of the phosphotriesterase-like lactonase (PLL) family that show promiscuous organophosphate-degrading activity. Starting from a weakly promiscuous PLL scaffold (Dr0930 from Deinococcus radiodurans), we designed an extremely efficient organophosphate hydrolase (OPH) with broad substrate specificity using rational and random mutagenesis in combination with in vitro activity screening. The OPH activity for seven organophosphate substrates was simultaneously enhanced by up to 5 orders of magnitude, achieving absolute values of catalytic efficiencies up to 106 M–1 s–1. Structural and computational analyses identified the molecular basis for the enhanced OPH activity of the engineered PLL variants and demonstrated that OPH catalysis in PdPTE and the engineered PLL differ significantly in the mode of substrate binding