Beta-Ketoacyl ACP synthase III (KASIII) catalyzes the decarboxylative condensation of acetyl CoA and malonyl ACP to generate beta-ketobutyryl ACP. This reaction represents first step in initiation of fatty acid biosynthesis in the dissociated type II fatty acid synthases (FASs) of plants and bacteria. Thiolactomycin (TLM) is a potent antibiotic that has been shown to efficiently inhibit this enzyme in a broad range of organisms, including pathogenic bacteria. This application seeks to discover novel inhibitors of KASIII as potential agents to treat emerging and reemerging human pathogens. An approach that draws both on the proven track record of natural products as sources of bioactive molecules and the powerful techniques of structure-based drug discovery will be taken. In the first specific aim of the project an enzyme-coupled spectrophotometric assay for KASIII will be established. This assay will then be used to screen a library of 2000 purified diverse natural products that have previously been structurally characterized. Two additional libraries, consisting 3000 crude natural product extracts, and 3000 pure compounds prepared by multiple parallel synthetic approaches using natural products as templates, will be screened for KASIII inhibitors. The second specific aim of the project is to determine conditions in which KASIII can be crystallized, preferably with either TLM, or malonyl ACP in the active site. X-ray diffraction will then be used to obtain the 3-dimensional structure of KASIII. In the long term this information will be used as a basis to rationally design KASIII inhibitors.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Small Research Grants (R03)
Project #
5R03AI044772-03
Application #
6374074
Study Section
Bio-Organic and Natural Products Chemistry Study Section (BNP)
Program Officer
Korpela, Jukka K
Project Start
1999-09-01
Project End
2003-02-28
Budget Start
2001-09-01
Budget End
2003-02-28
Support Year
3
Fiscal Year
2001
Total Cost
$72,500
Indirect Cost
Name
Virginia Commonwealth University
Department
Pharmacology
Type
Schools of Pharmacy
DUNS #
City
Richmond
State
VA
Country
United States
Zip Code
23298
He, Xin; Reeve, Anne McElwee; Desai, Umesh R et al. (2004) 1,2-dithiole-3-ones as potent inhibitors of the bacterial 3-ketoacyl acyl carrier protein synthase III (FabH). Antimicrob Agents Chemother 48:3093-102
Prigge, Sean T; He, Xin; Gerena, Lucia et al. (2003) The initiating steps of a type II fatty acid synthase in Plasmodium falciparum are catalyzed by pfACP, pfMCAT, and pfKASIII. Biochemistry 42:1160-9
Smirnova, N; Reynolds, K A (2001) Branched-chain fatty acid biosynthesis in Escherichia coli. J Ind Microbiol Biotechnol 27:246-51
Scarsdale, J N; Kazanina, G; He, X et al. (2001) Crystal structure of the Mycobacterium tuberculosis beta-ketoacyl-acyl carrier protein synthase III. J Biol Chem 276:20516-22
Smirnova, N; Reynolds, K A (2001) Engineered fatty acid biosynthesis in Streptomyces by altered catalytic function of beta-ketoacyl-acyl carrier protein synthase III. J Bacteriol 183:2335-42
He, X; Mueller, J P; Reynolds, K A (2000) Development of a scintillation proximity assay for beta-ketoacyl-acyl carrier protein synthase III. Anal Biochem 282:107-14