Homology model of juvenile hormone esterase from the crop pest, Heliothis virescens.

Juvenile Hormone Esterase (JHE) plays an essential role in the development of insects since it is partially responsible for clearing juvenile hormone (JH), one of the hormones that is responsible for insect metamorphosis. JHE is a 60 kDa enzyme that selectively hydrolyzes the alpha/beta unsaturated ester of JH. Because of its pivotal role in insect development, we have targeted JHE for use as a biopesticide. In this study, we have constructed a homology-based molecular model of JHE from the agricultural crop pest, Heliothis virescens. JHE is a member of the alpha/beta hydrolase fold family of enzymes and was built according to two structures in the same family: acetylcholinesterase from Torpedo californica and lipase from Geotrichum candidum. Analysis of the active site region reveals extensive conservation between JHE and its templates. A surprise was the presence of a conserved Ser near the catalytic triad. Docking of JH III into the active site has provided insight into protein-substrate interactions that are corroborated by experimental observation. The model is being used as a predictive basis to design biopesticides. In this regard, we have identified a site on the protein surface that is suggestive of a recognition site for the putative JHE receptor.