Identification, Characterization, and Inhibition of Plasmodium falciparum \beta -Hydroxyacyl-Acyl Carrier Protein Dehydratase (FabZ)

Sharma, Shailendra Kumar and Kapoor, Mili and Ramya, TNC and Kumar, Sanjay and Kumar, Gyanendra and Modak, Rahul and Sharma, Shilpi and Surolia, Namita and Surolia, Avadhesha (2003) Identification, Characterization, and Inhibition of Plasmodium falciparum \beta -Hydroxyacyl-Acyl Carrier Protein Dehydratase (FabZ). In: The Journal Of Biological Chemistry, 278 (46). pp. 45661-45671.

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Abstract

The emergence of drug-resistant forms of Plasmodium falciparum emphasizes the need to develop new antimalarials. In this context, the fatty acid biosynthesis (FAS) pathway of the malarial parasite has recently received a lot of attention. Due to differences in the fatty acid biosynthesis systems of Plasmodium and man, this pathway is a good target for the development of new and selective therapeutic drugs directed against malaria. In continuation of these efforts we report cloning and overexpression of P. falciparum beta-hydroxyacyl-acyl carrier protein (ACP) dehydratase (PffabZ) gene that codes for a 17-kDa protein. The enzyme catalyzes the dehydration of beta-hydroxyacyl-ACP to trans-2-acyl-ACP, the third step in the elongation phase of the FAS cycle. It has a K-m of 199 muM and k(cat)/K-m of 80.4 M-1 s(-1) for the substrate analog beta-hydroxybutyryl-CoA but utilizes crotonoyl-CoA, the product of the reaction, more efficiently (K-m=86 muM, k(cat)/K-m=220 M-1 s(-1)). More importantly, we also identify inhibitors (NAS-91 and NAS-21) for the enzyme. Both the inhibitors prevented the binding of crotonoyl-CoA to PfFabZ in a competitive fashion. Indeed these inhibitors compromised the growth of P. falciparum in cultures and inhibited the parasite fatty acid synthesis pathway both in cell-free extracts as well as in situ. We modeled them structure of PfFabZ using Escherichia coli beta-hydroxydecanoyl thioester dehydratase (EcFabA) as a template. We also modeled the inhibitor complexes of PfFabZ to elucidate the mode of binding of these compounds to FabZ. The discovery of the inhibitors of FabZ, reported for the first time against any member of this family of enzymes, essential to the type II FAS pathway opens up new avenues for treating a number of infectious diseases including malaria.

Item Type:	Journal Article
Publication:	The Journal Of Biological Chemistry
Publisher:	The American Society for Biochemistry and Molecular Biology, Inc.
Additional Information:	Copyright of this article belongs to The American Society for Biochemistry and Molecular Biology.
Department/Centre:	Division of Biological Sciences > Molecular Biophysics Unit
Date Deposited:	14 Aug 2009 06:58
Last Modified:	19 Sep 2010 04:55
URI:	http://eprints.iisc.ac.in/id/eprint/17055

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