Functional characterizations of malonyl-CoA:acyl carrier protein transacylase (MCAT) in Eimeria tenella

Eimeria tenella, an apicomplexan parasite in chickens, possesses an apicoplast and its associated metabolic pathways including the Type II fatty acid synthesis (FAS II). Malonyl-CoA:acyl-carry protein transacylase (MCAT) encoded by the fabD gene is one of the essential enzymes in the FAS II system. In the present study, the entire E. tenella MCAT gene (EtfabD) was cloned and sequenced. Immunolabeling located this protein in the apicoplast organelle in coccidial sporozoites. Functional replacement of the fabD gene with amber mutation of E. coli temperature-sensitive LA2-89 strain by E. tenella EtMCAT demonstrated that EcFabD and EtMCAT perform the same biochemical function. The recombinant EtMCAT protein was expressed and its general biochemical features were also determined. An alkaloid natural product corytuberine (CAS: 517-56-6) could specifically inhibit the EtMCAT activity (IC50 = 16.47 μM), but the inhibition of parasite growth in vitro by corytuberine was very weak (the predicted MIC50 = 0.65 mM).

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► E. coli FabD and E. tenella MCAT perform the same biochemical function.
► Recombinantly expressed EtMCAT could catalyze the transfer of a malonyl moiety.
► Corytuberine displayed a moderate inhibitory effect on the EtMCAT activity.
► EtMCAT was located in the apicoplast organelle in coccidial sporozoites.