The Experts below are selected from a list of 176928 Experts worldwide ranked by ideXlab platform

Himadri B Pakrasi - One of the best experts on this subject based on the ideXlab platform.

  • the irt1 protein from arabidopsis thaliana is a metal transporter with a broad Substrate Range
    Plant Molecular Biology, 1999
    Co-Authors: Y O Korshunova, David J Eide, Mary Lou Guerinot, W G Clark, Himadri B Pakrasi
    Abstract:

    The molecular basis for the transport of manganese across membranes in plant cells is poorly understood. We have found that IRT1, an Arabidopsis thaliana metal ion transporter, can complement a mutant Saccharomyces cerevisiae strain defective in high-affinity manganese uptake (smf1Δ). The IRT1 protein has previously been identified as an iron transporter. The current studies demonstrated that IRT1, when expressed in yeast, can transport manganese as well. This manganese uptake activity was inhibited by cadmium, iron(II) and zinc, suggesting that IRT1 can transport these metals. The IRT1 cDNA also complements a zinc uptake-deficient yeast mutant strain (zrt1zrt2), and IRT1-dependent zinc transport in yeast cells is inhibited by cadmium, copper, cobalt and iron(III). However, IRT1 did not complement a copper uptake-deficient yeast mutant (ctr1), implying that this transporter is not involved in the uptake of copper in plant cells. The expression of IRT1 is enhanced in A. thaliana plants grown under iron deficiency. Under these conditions, there were increased levels of root-associated manganese, zinc and cobalt, suggesting that, in addition to iron, IRT1 mediates uptake of these metals into plant cells. Taken together, these data indicate that the IRT1 protein is a broad-Range metal ion transporter in plants.

  • the irt1 protein from arabidopsis thaliana is a metal transporter with a broad Substrate Range
    Plant Molecular Biology, 1999
    Co-Authors: Y O Korshunova, David J Eide, Mary Lou Guerinot, W G Clark, Himadri B Pakrasi
    Abstract:

    The molecular basis for the transport of manganese across membranes in plant cells is poorly understood. We have found that IRT1, an Arabidopsis thaliana metal ion transporter, can complement a mutant Saccharomyces cerevisiae strain defective in high-affinity manganese uptake (smf1 delta). The IRT1 protein has previously been identified as an iron transporter. The current studies demonstrated that IRT1, when expressed in yeast, can transport manganese as well. This manganese uptake activity was inhibited by cadmium, iron(II) and zinc, suggesting that IRT1 can transport these metals. The IRT1 cDNA also complements a zinc uptake-deficient yeast mutant strain (zrt1zrt2), and IRT1-dependent zinc transport in yeast cells is inhibited by cadmium, copper, cobalt and iron(III). However, IRT1 did not complement a copper uptake-deficient yeast mutant (ctr1), implying that this transporter is not involved in the uptake of copper in plant cells. The expression of IRT1 is enhanced in A. thaliana plants grown under iron deficiency. Under these conditions, there were increased levels of root-associated manganese, zinc and cobalt, suggesting that, in addition to iron, IRT1 mediates uptake of these metals into plant cells. Taken together, these data indicate that the IRT1 protein is a broad-Range metal ion transporter in plants.

Nir Shapir - One of the best experts on this subject based on the ideXlab platform.

  • purification Substrate Range and metal center of atzc the n isopropylammelide aminohydrolase involved in bacterial atrazine metabolism
    Journal of Bacteriology, 2002
    Co-Authors: Nir Shapir, Jeffrey P Osborne, Gilbert Johnson, Michael J Sadowsky, Lawrence P Wackett
    Abstract:

    N-Isopropylammelide isopropylaminohydrolase, AtzC, the third enzyme in the atrazine degradation pathway in Pseudomonas sp. strain ADP, catalyzes the stoichiometric hydrolysis of N-isopropylammelide to cyanuric acid and isopropylamine. The atzC gene was cloned downstream of the tac promoter and expressed in Escherichia coli, where the expressed enzyme comprised 36% of the soluble protein. AtzC was purified to homogeneity by ammonium sulfate precipitation and phenyl column chromatography. It has a subunit size of 44,938 kDa and a holoenzyme molecular weight of 174,000. The Km and kcat values for AtzC with N-isopropylammelide were 406 μM and 13.3 s−1, respectively. AtzC hydrolyzed other N-substituted amino dihydroxy-s-triazines, and those with linear N-alkyl groups had higher kcat values than those with branched alkyl groups. Native AtzC contained 0.50 eq of Zn per subunit. The activity of metal-depleted AtzC was restored with Zn(II), Fe(II), Mn(II), Co(II), and Ni(II) salts. Cobalt-substituted AtzC had a visible absorbance band at 540 nm (Δe = 84 M−1 cm−1) and exhibited an axial electron paramagnetic resonance (EPR) signal with the following effective values: g(x) = 5.18, g(y) = 3.93, and g(z) = 2.24. Incubating cobalt-AtzC with the competitive inhibitor 5-azacytosine altered the effective EPR signal values to g(x) = 5.11, g(y) = 4.02, and g(z) = 2.25 and increased the microwave power at half saturation at 10 K from 31 to 103 mW. Under the growth conditions examined, our data suggest that AtzC has a catalytically essential, five-coordinate Zn(II) metal center in the active site and specifically catalyzes the hydrolysis of intermediates generated during the metabolism of s-triazine herbicides.

  • purification Substrate Range and metal center of atzc the n isopropylammelide aminohydrolase involved in bacterial atrazine metabolism
    Journal of Bacteriology, 2002
    Co-Authors: Nir Shapir, Jeffrey P Osborne, Gilbert Johnson, Michael J Sadowsky, Lawrence P Wackett
    Abstract:

    N-Isopropylammelide isopropylaminohydrolase, AtzC, the third enzyme in the atrazine degradation pathway in Pseudomonas sp. strain ADP, catalyzes the stoichiometric hydrolysis of N-isopropylammelide to cyanuric acid and isopropylamine. The atzC gene was cloned downstream of the tac promoter and expressed in Escherichia coli, where the expressed enzyme comprised 36% of the soluble protein. AtzC was purified to homogeneity by ammonium sulfate precipitation and phenyl column chromatography. It has a subunit size of 44,938 kDa and a holoenzyme molecular weight of 174,000. The Km and kcat values for AtzC with N-isopropylammelide were 406 M and 13.3 s 1 , respectively. AtzC hydrolyzed other N-substituted amino dihydroxys-triazines, and those with linear N-alkyl groups had higher kcat values than those with branched alkyl groups. Native AtzC contained 0.50 eq of Zn per subunit. The activity of metal-depleted AtzC was restored with Zn(II), Fe(II), Mn(II), Co(II), and Ni(II) salts. Cobalt-substituted AtzC had a visible absorbance band at 540 nm ( 84 M 1 cm 1 ) and exhibited an axial electron paramagnetic resonance (EPR) signal with the following effective values: g(x) 5.18, g(y) 3.93, and g(z) 2.24. Incubating cobalt-AtzC with the competitive inhibitor 5-azacytosine altered the effective EPR signal values to g(x) 5.11, g(y) 4.02, and g(z) 2.25 and increased the microwave power at half saturation at 10 K from 31 to 103 mW. Under the growth conditions examined, our data suggest that AtzC has a catalytically essential, five-coordinate Zn(II) metal center in the active site and specifically catalyzes the hydrolysis of intermediates generated during the metabolism of s-triazine herbicides.

Lawrence P Wackett - One of the best experts on this subject based on the ideXlab platform.

  • purification Substrate Range and metal center of atzc the n isopropylammelide aminohydrolase involved in bacterial atrazine metabolism
    Journal of Bacteriology, 2002
    Co-Authors: Nir Shapir, Jeffrey P Osborne, Gilbert Johnson, Michael J Sadowsky, Lawrence P Wackett
    Abstract:

    N-Isopropylammelide isopropylaminohydrolase, AtzC, the third enzyme in the atrazine degradation pathway in Pseudomonas sp. strain ADP, catalyzes the stoichiometric hydrolysis of N-isopropylammelide to cyanuric acid and isopropylamine. The atzC gene was cloned downstream of the tac promoter and expressed in Escherichia coli, where the expressed enzyme comprised 36% of the soluble protein. AtzC was purified to homogeneity by ammonium sulfate precipitation and phenyl column chromatography. It has a subunit size of 44,938 kDa and a holoenzyme molecular weight of 174,000. The Km and kcat values for AtzC with N-isopropylammelide were 406 μM and 13.3 s−1, respectively. AtzC hydrolyzed other N-substituted amino dihydroxy-s-triazines, and those with linear N-alkyl groups had higher kcat values than those with branched alkyl groups. Native AtzC contained 0.50 eq of Zn per subunit. The activity of metal-depleted AtzC was restored with Zn(II), Fe(II), Mn(II), Co(II), and Ni(II) salts. Cobalt-substituted AtzC had a visible absorbance band at 540 nm (Δe = 84 M−1 cm−1) and exhibited an axial electron paramagnetic resonance (EPR) signal with the following effective values: g(x) = 5.18, g(y) = 3.93, and g(z) = 2.24. Incubating cobalt-AtzC with the competitive inhibitor 5-azacytosine altered the effective EPR signal values to g(x) = 5.11, g(y) = 4.02, and g(z) = 2.25 and increased the microwave power at half saturation at 10 K from 31 to 103 mW. Under the growth conditions examined, our data suggest that AtzC has a catalytically essential, five-coordinate Zn(II) metal center in the active site and specifically catalyzes the hydrolysis of intermediates generated during the metabolism of s-triazine herbicides.

  • purification Substrate Range and metal center of atzc the n isopropylammelide aminohydrolase involved in bacterial atrazine metabolism
    Journal of Bacteriology, 2002
    Co-Authors: Nir Shapir, Jeffrey P Osborne, Gilbert Johnson, Michael J Sadowsky, Lawrence P Wackett
    Abstract:

    N-Isopropylammelide isopropylaminohydrolase, AtzC, the third enzyme in the atrazine degradation pathway in Pseudomonas sp. strain ADP, catalyzes the stoichiometric hydrolysis of N-isopropylammelide to cyanuric acid and isopropylamine. The atzC gene was cloned downstream of the tac promoter and expressed in Escherichia coli, where the expressed enzyme comprised 36% of the soluble protein. AtzC was purified to homogeneity by ammonium sulfate precipitation and phenyl column chromatography. It has a subunit size of 44,938 kDa and a holoenzyme molecular weight of 174,000. The Km and kcat values for AtzC with N-isopropylammelide were 406 M and 13.3 s 1 , respectively. AtzC hydrolyzed other N-substituted amino dihydroxys-triazines, and those with linear N-alkyl groups had higher kcat values than those with branched alkyl groups. Native AtzC contained 0.50 eq of Zn per subunit. The activity of metal-depleted AtzC was restored with Zn(II), Fe(II), Mn(II), Co(II), and Ni(II) salts. Cobalt-substituted AtzC had a visible absorbance band at 540 nm ( 84 M 1 cm 1 ) and exhibited an axial electron paramagnetic resonance (EPR) signal with the following effective values: g(x) 5.18, g(y) 3.93, and g(z) 2.24. Incubating cobalt-AtzC with the competitive inhibitor 5-azacytosine altered the effective EPR signal values to g(x) 5.11, g(y) 4.02, and g(z) 2.25 and increased the microwave power at half saturation at 10 K from 31 to 103 mW. Under the growth conditions examined, our data suggest that AtzC has a catalytically essential, five-coordinate Zn(II) metal center in the active site and specifically catalyzes the hydrolysis of intermediates generated during the metabolism of s-triazine herbicides.

Michael J Sadowsky - One of the best experts on this subject based on the ideXlab platform.

  • purification Substrate Range and metal center of atzc the n isopropylammelide aminohydrolase involved in bacterial atrazine metabolism
    Journal of Bacteriology, 2002
    Co-Authors: Nir Shapir, Jeffrey P Osborne, Gilbert Johnson, Michael J Sadowsky, Lawrence P Wackett
    Abstract:

    N-Isopropylammelide isopropylaminohydrolase, AtzC, the third enzyme in the atrazine degradation pathway in Pseudomonas sp. strain ADP, catalyzes the stoichiometric hydrolysis of N-isopropylammelide to cyanuric acid and isopropylamine. The atzC gene was cloned downstream of the tac promoter and expressed in Escherichia coli, where the expressed enzyme comprised 36% of the soluble protein. AtzC was purified to homogeneity by ammonium sulfate precipitation and phenyl column chromatography. It has a subunit size of 44,938 kDa and a holoenzyme molecular weight of 174,000. The Km and kcat values for AtzC with N-isopropylammelide were 406 μM and 13.3 s−1, respectively. AtzC hydrolyzed other N-substituted amino dihydroxy-s-triazines, and those with linear N-alkyl groups had higher kcat values than those with branched alkyl groups. Native AtzC contained 0.50 eq of Zn per subunit. The activity of metal-depleted AtzC was restored with Zn(II), Fe(II), Mn(II), Co(II), and Ni(II) salts. Cobalt-substituted AtzC had a visible absorbance band at 540 nm (Δe = 84 M−1 cm−1) and exhibited an axial electron paramagnetic resonance (EPR) signal with the following effective values: g(x) = 5.18, g(y) = 3.93, and g(z) = 2.24. Incubating cobalt-AtzC with the competitive inhibitor 5-azacytosine altered the effective EPR signal values to g(x) = 5.11, g(y) = 4.02, and g(z) = 2.25 and increased the microwave power at half saturation at 10 K from 31 to 103 mW. Under the growth conditions examined, our data suggest that AtzC has a catalytically essential, five-coordinate Zn(II) metal center in the active site and specifically catalyzes the hydrolysis of intermediates generated during the metabolism of s-triazine herbicides.

  • purification Substrate Range and metal center of atzc the n isopropylammelide aminohydrolase involved in bacterial atrazine metabolism
    Journal of Bacteriology, 2002
    Co-Authors: Nir Shapir, Jeffrey P Osborne, Gilbert Johnson, Michael J Sadowsky, Lawrence P Wackett
    Abstract:

    N-Isopropylammelide isopropylaminohydrolase, AtzC, the third enzyme in the atrazine degradation pathway in Pseudomonas sp. strain ADP, catalyzes the stoichiometric hydrolysis of N-isopropylammelide to cyanuric acid and isopropylamine. The atzC gene was cloned downstream of the tac promoter and expressed in Escherichia coli, where the expressed enzyme comprised 36% of the soluble protein. AtzC was purified to homogeneity by ammonium sulfate precipitation and phenyl column chromatography. It has a subunit size of 44,938 kDa and a holoenzyme molecular weight of 174,000. The Km and kcat values for AtzC with N-isopropylammelide were 406 M and 13.3 s 1 , respectively. AtzC hydrolyzed other N-substituted amino dihydroxys-triazines, and those with linear N-alkyl groups had higher kcat values than those with branched alkyl groups. Native AtzC contained 0.50 eq of Zn per subunit. The activity of metal-depleted AtzC was restored with Zn(II), Fe(II), Mn(II), Co(II), and Ni(II) salts. Cobalt-substituted AtzC had a visible absorbance band at 540 nm ( 84 M 1 cm 1 ) and exhibited an axial electron paramagnetic resonance (EPR) signal with the following effective values: g(x) 5.18, g(y) 3.93, and g(z) 2.24. Incubating cobalt-AtzC with the competitive inhibitor 5-azacytosine altered the effective EPR signal values to g(x) 5.11, g(y) 4.02, and g(z) 2.25 and increased the microwave power at half saturation at 10 K from 31 to 103 mW. Under the growth conditions examined, our data suggest that AtzC has a catalytically essential, five-coordinate Zn(II) metal center in the active site and specifically catalyzes the hydrolysis of intermediates generated during the metabolism of s-triazine herbicides.

Y O Korshunova - One of the best experts on this subject based on the ideXlab platform.

  • the irt1 protein from arabidopsis thaliana is a metal transporter with a broad Substrate Range
    Plant Molecular Biology, 1999
    Co-Authors: Y O Korshunova, David J Eide, Mary Lou Guerinot, W G Clark, Himadri B Pakrasi
    Abstract:

    The molecular basis for the transport of manganese across membranes in plant cells is poorly understood. We have found that IRT1, an Arabidopsis thaliana metal ion transporter, can complement a mutant Saccharomyces cerevisiae strain defective in high-affinity manganese uptake (smf1Δ). The IRT1 protein has previously been identified as an iron transporter. The current studies demonstrated that IRT1, when expressed in yeast, can transport manganese as well. This manganese uptake activity was inhibited by cadmium, iron(II) and zinc, suggesting that IRT1 can transport these metals. The IRT1 cDNA also complements a zinc uptake-deficient yeast mutant strain (zrt1zrt2), and IRT1-dependent zinc transport in yeast cells is inhibited by cadmium, copper, cobalt and iron(III). However, IRT1 did not complement a copper uptake-deficient yeast mutant (ctr1), implying that this transporter is not involved in the uptake of copper in plant cells. The expression of IRT1 is enhanced in A. thaliana plants grown under iron deficiency. Under these conditions, there were increased levels of root-associated manganese, zinc and cobalt, suggesting that, in addition to iron, IRT1 mediates uptake of these metals into plant cells. Taken together, these data indicate that the IRT1 protein is a broad-Range metal ion transporter in plants.

  • the irt1 protein from arabidopsis thaliana is a metal transporter with a broad Substrate Range
    Plant Molecular Biology, 1999
    Co-Authors: Y O Korshunova, David J Eide, Mary Lou Guerinot, W G Clark, Himadri B Pakrasi
    Abstract:

    The molecular basis for the transport of manganese across membranes in plant cells is poorly understood. We have found that IRT1, an Arabidopsis thaliana metal ion transporter, can complement a mutant Saccharomyces cerevisiae strain defective in high-affinity manganese uptake (smf1 delta). The IRT1 protein has previously been identified as an iron transporter. The current studies demonstrated that IRT1, when expressed in yeast, can transport manganese as well. This manganese uptake activity was inhibited by cadmium, iron(II) and zinc, suggesting that IRT1 can transport these metals. The IRT1 cDNA also complements a zinc uptake-deficient yeast mutant strain (zrt1zrt2), and IRT1-dependent zinc transport in yeast cells is inhibited by cadmium, copper, cobalt and iron(III). However, IRT1 did not complement a copper uptake-deficient yeast mutant (ctr1), implying that this transporter is not involved in the uptake of copper in plant cells. The expression of IRT1 is enhanced in A. thaliana plants grown under iron deficiency. Under these conditions, there were increased levels of root-associated manganese, zinc and cobalt, suggesting that, in addition to iron, IRT1 mediates uptake of these metals into plant cells. Taken together, these data indicate that the IRT1 protein is a broad-Range metal ion transporter in plants.