Structure-based Inhibitor Design of Accd5, an Essential Acyl-coa Carboxylase Carboxyltransferase Domain of Mycobacterium Tuberculosis.
From: Department of Molecular Biology and Biochemistry, University of California, Irvine, 92697, USA.
Proceedings of the National Academy of Sciences of the United States of America
- Publish Date: Feb 2006
- ISSN: 0027-8424
- Volume: 103
- Issue: 9
- Pages: 3072-7
- Medium: Print
- Language: English
- Citation (JAMA): Lin Ting-Wan, Melgar Melrose M, Kurth Daniel, et al. Structure-based Inhibitor Design of Accd5, an Essential Acyl-coa Carboxylase Carboxyltransferase Domain of Mycobacterium Tuberculosis.. Proc. Natl. Acad. Sci. U.S.A. Feb 2006;103:3072-7
Abstract
Mycolic acids and multimethyl-branched fatty acids are found uniquely in the cell envelope of pathogenic mycobacteria. These unusually long fatty acids are essential for the survival, virulence, and antibiotic resistance of Mycobacterium tuberculosis. Acyl-CoA carboxylases (ACCases) commit acyl-CoAs to the biosynthesis of these unique fatty acids. Unlike other organisms such as Escherichia coli or humans that have only one or two ACCases, M. tuberculosis contains six ACCase carboxyltransferase domains, AccD1-6, whose specific roles in the pathogen are not well defined. Previous studies indicate that AccD4, AccD5, and AccD6 are important for cell envelope lipid biosynthesis and that its disruption leads to pathogen death. We have determined the 2.9-Angstroms crystal structure of AccD5, whose sequence, structure, and active site are highly conserved with respect to the carboxyltransferase domain of the Streptomyces coelicolor propionyl-CoA carboxylase. Contrary to the previous proposal that AccD4-5 accept long-chain acyl-CoAs as their substrates, both crystal structure and kinetic assay indicate that AccD5 prefers propionyl-CoA as its substrate and produces methylmalonyl-CoA, the substrate for the biosyntheses of multimethyl-branched fatty acids such as mycocerosic, phthioceranic, hydroxyphthioceranic, mycosanoic, and mycolipenic acids. Extensive in silico screening of National Cancer Institute compounds and the University of California, Irvine, ChemDB database resulted in the identification of one inhibitor with a K(i) of 13.1 microM. Our results pave the way toward understanding the biological roles of key ACCases that commit acyl-CoAs to the biosynthesis of cell envelope fatty acids, in addition to providing a target for structure-based development of antituberculosis therapeutics.
Mesh Headings (Keywords): Antitubercular Agents, Binding Sites, Carbon-Carbon Ligases, Computational Biology, Drug Design, Enzyme Inhibitors, Ligands, Models, Molecular, Mycobacterium tuberculosis, Protein Structure, Quaternary, Substrate Specificity
Check for Full Text / PubMed Unique Identifier (PMID): 16492739
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