Biochemical characterization of enoyl reductase involved in Type II fatty acid synthesis in the intestinal coccidium Eimeria tenella (Phylum Apicomplexa).

An enoyl reductase (EtENR) closely related to those of green algae and involved in Type II fatty acid synthesis was characterized and localized to the apicoplast in the coccidium Eimeria tenella. Biochemical analysis using native EtENR protein extracted from parasites confirmed its function as an enoyl reductase using NADH as a cofactor. However, the recombinant form (rEtENR) expressed in bacteria was only able to oxidize NADH, but unable to transfer the electron to enoyl-CoA, possibly due to the inappropriate folding of rEtENR expressed in bacteria. The functions of both native and recombinant EtENR could be inhibited by triclosan (IC(50)=1.45 microM), suggesting that this enzyme may be explored as a drug target against coccidiosis.