The Experts below are selected from a list of 1833 Experts worldwide ranked by ideXlab platform

Charles O. Rock - One of the best experts on this subject based on the ideXlab platform.

  • response of bacillus subtilis to Cerulenin and acquisition of resistance
    Journal of Bacteriology, 2001
    Co-Authors: Gustavo E Schujman, Charles O. Rock, Keum-hwa Choi, Silvia Altabe, Diego De Mendoza
    Abstract:

    Cerulenin is a fungal mycotoxin that potently inhibits fatty acid synthesis by covalent modification of the active site thiol of the chain-elongation subtypes of beta-ketoacyl-acyl carrier protein (ACP) synthases. The Bacillus subtilis fabF (yjaY) gene (fabF(b)) encodes an enzyme that catalyzes the condensation of malonyl-ACP with acyl-ACP to extend the growing acyl chain by two carbons. There were two mechanisms by which B. subtilis adapted to exposure to this antibiotic. First, reporter gene analysis demonstrated that transcription of the operon containing the fabF gene increased eightfold in response to a Cerulenin challenge. This response was selective for the inhibition of fatty acid synthesis, since triclosan, an inhibitor of enoyl-ACP reductase, triggered an increase in fabF reporter gene expression while nalidixic acid did not. Second, spontaneous mutants arose that exhibited a 10-fold increase in the MIC of Cerulenin. The mutation mapped at the B. subtilis fabF locus, and sequence analysis of the mutant fabF allele showed that a single base change resulted in the synthesis of FabF(b)[I108F]. The purified FabF(b) and FabF(b)[I108F] proteins had similar specific activities with myristoyl-ACP as the substrate. FabF(b) exhibited a 50% inhibitory concentration (IC(50)) of Cerulenin of 0.1 microM, whereas the IC(50) for FabF(b)[I108] was 50-fold higher (5 microM). These biochemical data explain the absence of an overt growth defect coupled with the Cerulenin resistance phenotype of the mutant strain.

  • inhibition of beta ketoacyl acyl carrier protein synthases by thiolactomycin and Cerulenin structure and mechanism
    Journal of Biological Chemistry, 2001
    Co-Authors: Allen C. Price, Richard J. Heath, Stephen W White, Keum-hwa Choi, Charles O. Rock
    Abstract:

    The beta-ketoacyl-acyl carrier protein (ACP) synthases are key regulators of type II fatty acid synthesis and are the targets for two natural products, thiolactomycin (TLM) and Cerulenin. The high resolution structures of the FabB-TLM and FabB-Cerulenin binary complexes were determined. TLM mimics malonyl-ACP in the FabB active site. It forms strong hydrogen bond interactions with the two catalytic histidines, and the unsaturated alkyl side chain interaction with a small hydrophobic pocket is stabilized by pi stacking interactions. Cerulenin binding mimics the condensation transition state. The subtle differences between the FabB-Cerulenin and FabF-Cerulenin (Moche, M., Schneider, G., Edwards, P., Dehesh, K., and Lindqvist, Y. (1999) J. Biol. Chem. 244, 6031-6034) structures explain the differences in the sensitivity of the two enzymes to the antibiotic and may reflect the distinct substrate specificities that differentiate the two enzymes. The FabB[H333N] protein was prepared to convert the FabB His-His-Cys active site triad into the FabH His-Asn-Cys configuration to test the importance of the two His residues in TLM and Cerulenin binding. FabB[H333N] was significantly more resistant to both antibiotics than FabB and had an affinity for TLM an order of magnitude less than the wild-type enzyme, illustrating that the two-histidine active site architecture is critical to protein-antibiotic interaction. These data provide a structural framework for understanding antibiotic sensitivity within this group of enzymes.

  • inhibition of beta ketoacyl acyl carrier protein synthases by thiolactomycin and Cerulenin structure and mechanism
    Journal of Biological Chemistry, 2001
    Co-Authors: Allen C. Price, Richard J. Heath, Charles O. Rock, Stephen W White, Keum-hwa Choi
    Abstract:

    The β-ketoacyl-acyl carrier protein (ACP) synthases are key regulators of type II fatty acid synthesis and are the targets for two natural products, thiolactomycin (TLM) and Cerulenin. The high resolution structures of the FabB-TLM and FabB-Cerulenin binary complexes were determined. TLM mimics malonyl-ACP in the FabB active site. It forms strong hydrogen bond interactions with the two catalytic histidines, and the unsaturated alkyl side chain interaction with a small hydrophobic pocket is stabilized by π stacking interactions. Cerulenin binding mimics the condensation transition state. The subtle differences between the FabB-Cerulenin and FabF-Cerulenin (Moche, M., Schneider, G., Edwards, P., Dehesh, K., and Lindqvist, Y. (1999) J. Biol. Chem. 244, 6031–6034) structures explain the differences in the sensitivity of the two enzymes to the antibiotic and may reflect the distinct substrate specificities that differentiate the two enzymes. The FabB[H333N] protein was prepared to convert the FabB His-His-Cys active site triad into the FabH His-Asn-Cys configuration to test the importance of the two His residues in TLM and Cerulenin binding. FabB[H333N] was significantly more resistant to both antibiotics than FabB and had an affinity for TLM an order of magnitude less than the wild-type enzyme, illustrating that the two-histidine active site architecture is critical to protein-antibiotic interaction. These data provide a structural framework for understanding antibiotic sensitivity within this group of enzymes.

Keum-hwa Choi - One of the best experts on this subject based on the ideXlab platform.

  • response of bacillus subtilis to Cerulenin and acquisition of resistance
    Journal of Bacteriology, 2001
    Co-Authors: Gustavo E Schujman, Charles O. Rock, Keum-hwa Choi, Silvia Altabe, Diego De Mendoza
    Abstract:

    Cerulenin is a fungal mycotoxin that potently inhibits fatty acid synthesis by covalent modification of the active site thiol of the chain-elongation subtypes of beta-ketoacyl-acyl carrier protein (ACP) synthases. The Bacillus subtilis fabF (yjaY) gene (fabF(b)) encodes an enzyme that catalyzes the condensation of malonyl-ACP with acyl-ACP to extend the growing acyl chain by two carbons. There were two mechanisms by which B. subtilis adapted to exposure to this antibiotic. First, reporter gene analysis demonstrated that transcription of the operon containing the fabF gene increased eightfold in response to a Cerulenin challenge. This response was selective for the inhibition of fatty acid synthesis, since triclosan, an inhibitor of enoyl-ACP reductase, triggered an increase in fabF reporter gene expression while nalidixic acid did not. Second, spontaneous mutants arose that exhibited a 10-fold increase in the MIC of Cerulenin. The mutation mapped at the B. subtilis fabF locus, and sequence analysis of the mutant fabF allele showed that a single base change resulted in the synthesis of FabF(b)[I108F]. The purified FabF(b) and FabF(b)[I108F] proteins had similar specific activities with myristoyl-ACP as the substrate. FabF(b) exhibited a 50% inhibitory concentration (IC(50)) of Cerulenin of 0.1 microM, whereas the IC(50) for FabF(b)[I108] was 50-fold higher (5 microM). These biochemical data explain the absence of an overt growth defect coupled with the Cerulenin resistance phenotype of the mutant strain.

  • inhibition of beta ketoacyl acyl carrier protein synthases by thiolactomycin and Cerulenin structure and mechanism
    Journal of Biological Chemistry, 2001
    Co-Authors: Allen C. Price, Richard J. Heath, Stephen W White, Keum-hwa Choi, Charles O. Rock
    Abstract:

    The beta-ketoacyl-acyl carrier protein (ACP) synthases are key regulators of type II fatty acid synthesis and are the targets for two natural products, thiolactomycin (TLM) and Cerulenin. The high resolution structures of the FabB-TLM and FabB-Cerulenin binary complexes were determined. TLM mimics malonyl-ACP in the FabB active site. It forms strong hydrogen bond interactions with the two catalytic histidines, and the unsaturated alkyl side chain interaction with a small hydrophobic pocket is stabilized by pi stacking interactions. Cerulenin binding mimics the condensation transition state. The subtle differences between the FabB-Cerulenin and FabF-Cerulenin (Moche, M., Schneider, G., Edwards, P., Dehesh, K., and Lindqvist, Y. (1999) J. Biol. Chem. 244, 6031-6034) structures explain the differences in the sensitivity of the two enzymes to the antibiotic and may reflect the distinct substrate specificities that differentiate the two enzymes. The FabB[H333N] protein was prepared to convert the FabB His-His-Cys active site triad into the FabH His-Asn-Cys configuration to test the importance of the two His residues in TLM and Cerulenin binding. FabB[H333N] was significantly more resistant to both antibiotics than FabB and had an affinity for TLM an order of magnitude less than the wild-type enzyme, illustrating that the two-histidine active site architecture is critical to protein-antibiotic interaction. These data provide a structural framework for understanding antibiotic sensitivity within this group of enzymes.

  • inhibition of beta ketoacyl acyl carrier protein synthases by thiolactomycin and Cerulenin structure and mechanism
    Journal of Biological Chemistry, 2001
    Co-Authors: Allen C. Price, Richard J. Heath, Charles O. Rock, Stephen W White, Keum-hwa Choi
    Abstract:

    The β-ketoacyl-acyl carrier protein (ACP) synthases are key regulators of type II fatty acid synthesis and are the targets for two natural products, thiolactomycin (TLM) and Cerulenin. The high resolution structures of the FabB-TLM and FabB-Cerulenin binary complexes were determined. TLM mimics malonyl-ACP in the FabB active site. It forms strong hydrogen bond interactions with the two catalytic histidines, and the unsaturated alkyl side chain interaction with a small hydrophobic pocket is stabilized by π stacking interactions. Cerulenin binding mimics the condensation transition state. The subtle differences between the FabB-Cerulenin and FabF-Cerulenin (Moche, M., Schneider, G., Edwards, P., Dehesh, K., and Lindqvist, Y. (1999) J. Biol. Chem. 244, 6031–6034) structures explain the differences in the sensitivity of the two enzymes to the antibiotic and may reflect the distinct substrate specificities that differentiate the two enzymes. The FabB[H333N] protein was prepared to convert the FabB His-His-Cys active site triad into the FabH His-Asn-Cys configuration to test the importance of the two His residues in TLM and Cerulenin binding. FabB[H333N] was significantly more resistant to both antibiotics than FabB and had an affinity for TLM an order of magnitude less than the wild-type enzyme, illustrating that the two-histidine active site architecture is critical to protein-antibiotic interaction. These data provide a structural framework for understanding antibiotic sensitivity within this group of enzymes.

Allen C. Price - One of the best experts on this subject based on the ideXlab platform.

  • inhibition of beta ketoacyl acyl carrier protein synthases by thiolactomycin and Cerulenin structure and mechanism
    Journal of Biological Chemistry, 2001
    Co-Authors: Allen C. Price, Richard J. Heath, Stephen W White, Keum-hwa Choi, Charles O. Rock
    Abstract:

    The beta-ketoacyl-acyl carrier protein (ACP) synthases are key regulators of type II fatty acid synthesis and are the targets for two natural products, thiolactomycin (TLM) and Cerulenin. The high resolution structures of the FabB-TLM and FabB-Cerulenin binary complexes were determined. TLM mimics malonyl-ACP in the FabB active site. It forms strong hydrogen bond interactions with the two catalytic histidines, and the unsaturated alkyl side chain interaction with a small hydrophobic pocket is stabilized by pi stacking interactions. Cerulenin binding mimics the condensation transition state. The subtle differences between the FabB-Cerulenin and FabF-Cerulenin (Moche, M., Schneider, G., Edwards, P., Dehesh, K., and Lindqvist, Y. (1999) J. Biol. Chem. 244, 6031-6034) structures explain the differences in the sensitivity of the two enzymes to the antibiotic and may reflect the distinct substrate specificities that differentiate the two enzymes. The FabB[H333N] protein was prepared to convert the FabB His-His-Cys active site triad into the FabH His-Asn-Cys configuration to test the importance of the two His residues in TLM and Cerulenin binding. FabB[H333N] was significantly more resistant to both antibiotics than FabB and had an affinity for TLM an order of magnitude less than the wild-type enzyme, illustrating that the two-histidine active site architecture is critical to protein-antibiotic interaction. These data provide a structural framework for understanding antibiotic sensitivity within this group of enzymes.

  • inhibition of beta ketoacyl acyl carrier protein synthases by thiolactomycin and Cerulenin structure and mechanism
    Journal of Biological Chemistry, 2001
    Co-Authors: Allen C. Price, Richard J. Heath, Charles O. Rock, Stephen W White, Keum-hwa Choi
    Abstract:

    The β-ketoacyl-acyl carrier protein (ACP) synthases are key regulators of type II fatty acid synthesis and are the targets for two natural products, thiolactomycin (TLM) and Cerulenin. The high resolution structures of the FabB-TLM and FabB-Cerulenin binary complexes were determined. TLM mimics malonyl-ACP in the FabB active site. It forms strong hydrogen bond interactions with the two catalytic histidines, and the unsaturated alkyl side chain interaction with a small hydrophobic pocket is stabilized by π stacking interactions. Cerulenin binding mimics the condensation transition state. The subtle differences between the FabB-Cerulenin and FabF-Cerulenin (Moche, M., Schneider, G., Edwards, P., Dehesh, K., and Lindqvist, Y. (1999) J. Biol. Chem. 244, 6031–6034) structures explain the differences in the sensitivity of the two enzymes to the antibiotic and may reflect the distinct substrate specificities that differentiate the two enzymes. The FabB[H333N] protein was prepared to convert the FabB His-His-Cys active site triad into the FabH His-Asn-Cys configuration to test the importance of the two His residues in TLM and Cerulenin binding. FabB[H333N] was significantly more resistant to both antibiotics than FabB and had an affinity for TLM an order of magnitude less than the wild-type enzyme, illustrating that the two-histidine active site architecture is critical to protein-antibiotic interaction. These data provide a structural framework for understanding antibiotic sensitivity within this group of enzymes.

Stephen W White - One of the best experts on this subject based on the ideXlab platform.

  • inhibition of beta ketoacyl acyl carrier protein synthases by thiolactomycin and Cerulenin structure and mechanism
    Journal of Biological Chemistry, 2001
    Co-Authors: Allen C. Price, Richard J. Heath, Stephen W White, Keum-hwa Choi, Charles O. Rock
    Abstract:

    The beta-ketoacyl-acyl carrier protein (ACP) synthases are key regulators of type II fatty acid synthesis and are the targets for two natural products, thiolactomycin (TLM) and Cerulenin. The high resolution structures of the FabB-TLM and FabB-Cerulenin binary complexes were determined. TLM mimics malonyl-ACP in the FabB active site. It forms strong hydrogen bond interactions with the two catalytic histidines, and the unsaturated alkyl side chain interaction with a small hydrophobic pocket is stabilized by pi stacking interactions. Cerulenin binding mimics the condensation transition state. The subtle differences between the FabB-Cerulenin and FabF-Cerulenin (Moche, M., Schneider, G., Edwards, P., Dehesh, K., and Lindqvist, Y. (1999) J. Biol. Chem. 244, 6031-6034) structures explain the differences in the sensitivity of the two enzymes to the antibiotic and may reflect the distinct substrate specificities that differentiate the two enzymes. The FabB[H333N] protein was prepared to convert the FabB His-His-Cys active site triad into the FabH His-Asn-Cys configuration to test the importance of the two His residues in TLM and Cerulenin binding. FabB[H333N] was significantly more resistant to both antibiotics than FabB and had an affinity for TLM an order of magnitude less than the wild-type enzyme, illustrating that the two-histidine active site architecture is critical to protein-antibiotic interaction. These data provide a structural framework for understanding antibiotic sensitivity within this group of enzymes.

  • inhibition of beta ketoacyl acyl carrier protein synthases by thiolactomycin and Cerulenin structure and mechanism
    Journal of Biological Chemistry, 2001
    Co-Authors: Allen C. Price, Richard J. Heath, Charles O. Rock, Stephen W White, Keum-hwa Choi
    Abstract:

    The β-ketoacyl-acyl carrier protein (ACP) synthases are key regulators of type II fatty acid synthesis and are the targets for two natural products, thiolactomycin (TLM) and Cerulenin. The high resolution structures of the FabB-TLM and FabB-Cerulenin binary complexes were determined. TLM mimics malonyl-ACP in the FabB active site. It forms strong hydrogen bond interactions with the two catalytic histidines, and the unsaturated alkyl side chain interaction with a small hydrophobic pocket is stabilized by π stacking interactions. Cerulenin binding mimics the condensation transition state. The subtle differences between the FabB-Cerulenin and FabF-Cerulenin (Moche, M., Schneider, G., Edwards, P., Dehesh, K., and Lindqvist, Y. (1999) J. Biol. Chem. 244, 6031–6034) structures explain the differences in the sensitivity of the two enzymes to the antibiotic and may reflect the distinct substrate specificities that differentiate the two enzymes. The FabB[H333N] protein was prepared to convert the FabB His-His-Cys active site triad into the FabH His-Asn-Cys configuration to test the importance of the two His residues in TLM and Cerulenin binding. FabB[H333N] was significantly more resistant to both antibiotics than FabB and had an affinity for TLM an order of magnitude less than the wild-type enzyme, illustrating that the two-histidine active site architecture is critical to protein-antibiotic interaction. These data provide a structural framework for understanding antibiotic sensitivity within this group of enzymes.

Richard J. Heath - One of the best experts on this subject based on the ideXlab platform.

  • inhibition of beta ketoacyl acyl carrier protein synthases by thiolactomycin and Cerulenin structure and mechanism
    Journal of Biological Chemistry, 2001
    Co-Authors: Allen C. Price, Richard J. Heath, Stephen W White, Keum-hwa Choi, Charles O. Rock
    Abstract:

    The beta-ketoacyl-acyl carrier protein (ACP) synthases are key regulators of type II fatty acid synthesis and are the targets for two natural products, thiolactomycin (TLM) and Cerulenin. The high resolution structures of the FabB-TLM and FabB-Cerulenin binary complexes were determined. TLM mimics malonyl-ACP in the FabB active site. It forms strong hydrogen bond interactions with the two catalytic histidines, and the unsaturated alkyl side chain interaction with a small hydrophobic pocket is stabilized by pi stacking interactions. Cerulenin binding mimics the condensation transition state. The subtle differences between the FabB-Cerulenin and FabF-Cerulenin (Moche, M., Schneider, G., Edwards, P., Dehesh, K., and Lindqvist, Y. (1999) J. Biol. Chem. 244, 6031-6034) structures explain the differences in the sensitivity of the two enzymes to the antibiotic and may reflect the distinct substrate specificities that differentiate the two enzymes. The FabB[H333N] protein was prepared to convert the FabB His-His-Cys active site triad into the FabH His-Asn-Cys configuration to test the importance of the two His residues in TLM and Cerulenin binding. FabB[H333N] was significantly more resistant to both antibiotics than FabB and had an affinity for TLM an order of magnitude less than the wild-type enzyme, illustrating that the two-histidine active site architecture is critical to protein-antibiotic interaction. These data provide a structural framework for understanding antibiotic sensitivity within this group of enzymes.

  • inhibition of beta ketoacyl acyl carrier protein synthases by thiolactomycin and Cerulenin structure and mechanism
    Journal of Biological Chemistry, 2001
    Co-Authors: Allen C. Price, Richard J. Heath, Charles O. Rock, Stephen W White, Keum-hwa Choi
    Abstract:

    The β-ketoacyl-acyl carrier protein (ACP) synthases are key regulators of type II fatty acid synthesis and are the targets for two natural products, thiolactomycin (TLM) and Cerulenin. The high resolution structures of the FabB-TLM and FabB-Cerulenin binary complexes were determined. TLM mimics malonyl-ACP in the FabB active site. It forms strong hydrogen bond interactions with the two catalytic histidines, and the unsaturated alkyl side chain interaction with a small hydrophobic pocket is stabilized by π stacking interactions. Cerulenin binding mimics the condensation transition state. The subtle differences between the FabB-Cerulenin and FabF-Cerulenin (Moche, M., Schneider, G., Edwards, P., Dehesh, K., and Lindqvist, Y. (1999) J. Biol. Chem. 244, 6031–6034) structures explain the differences in the sensitivity of the two enzymes to the antibiotic and may reflect the distinct substrate specificities that differentiate the two enzymes. The FabB[H333N] protein was prepared to convert the FabB His-His-Cys active site triad into the FabH His-Asn-Cys configuration to test the importance of the two His residues in TLM and Cerulenin binding. FabB[H333N] was significantly more resistant to both antibiotics than FabB and had an affinity for TLM an order of magnitude less than the wild-type enzyme, illustrating that the two-histidine active site architecture is critical to protein-antibiotic interaction. These data provide a structural framework for understanding antibiotic sensitivity within this group of enzymes.