Molecular basis for MPD binding to the JH-binding pocket of JHBP.

<p>(A) Interactions between JHBP and MPD1 bound in the JH-binding pocket observed for MPD-complex C. Residues involved in the recognition are shown as stick models and MPD1 as a ball-and-stick model. Hydrogen bond and CH-π stacking interactions used for recognition of MPD1 are indicated by light blue and orange dotted lines, respectively. (B) For comparison with (A), interactions of JHBP with the epoxy moiety of JH II observed for JH-complex A are displayed where JH II is shown as a ball-and-stick model. (C) Overlay of the JHBP-bound MPD1 (orange) and JH II (light blue) molecules. The red ball represents the oxygen atom which forms an intermolecular hydrogen bond with Tyr128 O^ηH of JHBP. (D) Chemical structures of JH II, MPD, methoprene, and methyl farnesoate (MF), the unepoxidated form of JH III, are shown from the top. The asterisk denotes a chiral carbon atom. (E) Competitive binding assay for MPD, methoprene and MF. The inhibition of JH binding to JHBP by the tested ligand was followed by monitoring the reduction of the radioactivity of the JHBP-bound ³H-labeled JH III. The relative radioactivity is plotted as a function of the ligand concentration: MPD (filled circles in red), methoprene (filled diamonds in green), and MF (filled squares in light-blue). The values represent the average for two to six experiments.