Inhibition of β-Ketoacyl-Acyl Carrier Protein Synthases by Thiolactomycin and Cerulenin
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 mal...
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Published in: | The Journal of biological chemistry 2001-03, Vol.276 (9), p.6551 |
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Main Authors: | , , , , , |
Format: | Article |
Language: | eng |
Online Access: | Get full text |
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Summary: | 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 Ï 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, 6031â6034) 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. |
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ISSN: | 0021-9258 1083-351X |