title: Mass spectrometry-based systems approach for identification of inhibitors of Plasmodium falciparum fatty acid synthase.
abstract: The emergence of strains of Plasmodium falciparum resistant to the commonly used antimalarials warrants the development of new antimalarial agents. The discovery of type II fatty acid synthase (FAS) in Plasmodium distinct from the FAS in its human host (type I FAS) opened up new avenues for the development of novel antimalarials. The process of fatty acid synthesis takes place by iterative elongation of butyryl-acyl carrier protein (butyryl-ACP) by two carbon units, with the successive action of four enzymes constituting the elongation module of FAS until the desired acyl length is obtained. The study of the fatty acid synthesis machinery of the parasite inside the red blood cell culture has always been a challenging task. Here, we report the in vitro reconstitution of the elongation module of the FAS of malaria parasite involving all four enzymes, FabB/F (beta-ketoacyl-ACP synthase), FabG (beta-ketoacyl-ACP reductase), FabZ (beta-ketoacyl-ACP dehydratase), and FabI (enoyl-ACP reductase), and its analysis by matrix-assisted laser desorption-time of flight mass spectrometry (MALDI-TOF MS). That this in vitro systems approach completely mimics the in vivo machinery is confirmed by the distribution of acyl products. Using known inhibitors of the enzymes of the elongation module, cerulenin, triclosan, NAS-21/91, and (-)-catechin gallate, we demonstrate that accumulation of intermediates resulting from the inhibition of any of the enzymes can be unambiguously followed by MALDI-TOF MS. Thus, this work not only offers a powerful tool for easier and faster throughput screening of inhibitors but also allows for the study of the biochemical properties of the FAS pathway of the malaria parasite.
authors.affiliation: Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560012, India.
authors.forename: Shilpi
authors.initials: S
authors.lastname: Sharma
authors.forename: Shailendra Kumar
authors.initials: SK
authors.lastname: Sharma
authors.forename: Rahul
authors.initials: R
authors.lastname: Modak
authors.forename: Krishanpal
authors.initials: K
authors.lastname: Karmodiya
authors.forename: Namita
authors.initials: N
authors.lastname: Surolia
authors.forename: Avadhesha
authors.initials: A
authors.lastname: Surolia
mesh_terms: D000818:Animals; D002392:Catechin / Q000031:analogs & derivatives / Q000494:pharmacology; D002569:Cerulenin / Q000494:pharmacology; D064429:Fatty Acid Synthases / Q000032:analysis* / Q000037:antagonists & inhibitors* / Q000302:isolation & purification; D013058:Mass Spectrometry / Q000379:methods*; D008954:Models, Biological; D010963:Plasmodium falciparum / Q000201:enzymology*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D014260:Triclosan / Q000494:pharmacology
chemical_list: D002569:Cerulenin; D014260:Triclosan; C417939:catechin gallate; D002392:Catechin; D064429:Fatty Acid Synthases