Crystal structure of CfFPPS2, a lepidopteran type-II farnesyl diphosphate synthase, complexed with IPP and [2-(1-methylpyridin-2-yl)-1-phosphono-ethyl]phosphonic acid (inhibitor 1b)
Structural characterization of a lepidopteran type-II farnesyl diphosphate synthase from the spruce budworm, Choristoneura fumiferana: Implications for inhibitor design.
Farnesyl diphosphate synthase (FPPS) is an enzyme from the class of short chain (E)-prenyltransferases that catalyzes the condensation of two molecules of isopentenyl diphosphate (IPP, C 5 ) with dimethylallyl diphosphate (DMAPP, C 5 ) to generate the C 15 product FPP ...
Farnesyl diphosphate synthase (FPPS) is an enzyme from the class of short chain (E)-prenyltransferases that catalyzes the condensation of two molecules of isopentenyl diphosphate (IPP, C 5 ) with dimethylallyl diphosphate (DMAPP, C 5 ) to generate the C 15 product FPP. In insects, FPPS plays a key role in the biosynthesis of the morphogenetic and gonadotropic "juvenile hormone" (JH). Lepidopteran genomes encode two very distinct FPPS paralogs, one of which ("type-II") is expressed almost exclusively in the JH-producing glands, the corpora allata. This paralog has been hypothesized to display structural features that enable the binding of the bulkier precursors required for the biosynthesis of lepidopteran ethyl-branched JHs. Here, we report on the first crystal structures of an insect FPPS solved to date. Apo, ligand-bound, and inhibitor-bound structures of type-II FPPS (FPPS2) from the spruce budworm, Choristoneura fumiferana (Order: Lepidoptera), were obtained. Comparison of apo and inhibitor-bound enzymes revealed differences in both inhibitor binding and structural plasticity of CfFPPS2 compared to other FPPSs. Our data showed that IPP is not essential to the closure of the C-terminal tail. Ortho-substituted pyridinium bisphosphonates, previously shown to inhibit CfFPPS2, bound to the allylic site, as predicted; however, their alkyl groups were oriented towards the homoallylic binding site, with the bulkier propyl-substituted inhibitor penetrating deeply into the IPP binding pocket. The current study sheds light on the structural basis of substrate specificity of type-II FPPS of the spruce budworm. Through a comparison with other inhibitor-bound FPPSs, we propose several approaches to improve inhibitor selectivity and potency.
Organizational Affiliation:
Département de biochimie, de microbiologie et de bio-informatique, Institut de Biologie Intégrative et des Systèmes, PROTEO, Université Laval, Quebec City, QC, G1V 0A6, Canada; Natural Resources Canada, Canadian Forest Service, Laurentian Forestry Centre, 1055 du P.E.P.S., C.P. 10380, Station Sainte-Foy, Quebec City, QC, G1V 4C7, Canada. Electronic address: michel.cusson@canada.ca.
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