The long term objective of this project is to gain an understanding of the biochemical regulation of juvenile hormone (JH) synthesis in insects. This basic research will provide the information necessary for future rational design of compounds or molecular strategies that would disrupt JH synthesis and thus insect development and reproduction. Over the last several years, research has focused on the biochemistry and neuroendocrine control of JH synthesis in the viviparous cockroach, Diploptera punctata. Work on the biochemistry of JH synthesis in adult female D. punctata will continue by focusing on the structure, function and regulation of two cytochrome P450 monooxygenases (P450) that are selectively expressed in the corpora allata (CA), the endocrine glands that synthesize and release insect juvenile hormone. One of these P450s is methyl farnesoate epoxidase, the enzyme that introduces the epoxide moiety characteristic of the sesquiterpenoid juvenile hormones. The other P450 is CYP4C7, which has been cloned, sequenced, and shown in preliminary studies to be related to the process of suppression of biosynthetic activity in the corpora allata.
The specific aims of this proposal are: 1. To clone and sequence the cDNA and reconstitute activity of methyl farnesoate epoxidase from the corpora allata. 2. To characterize the substrate binding site of methyl farnesoate epoxidase by an integrated approach of computer modeling and biochemical analysis. 3. To study the regulation and function of a cytochrome P450 (CYP4C7) selectively expressed in corpora allata with suppressed biosynthetic activity. The study of methyl farnesoate epoxidase should establish this enzyme as a viable target for biorational control agents, and should facilitate the eventual cloning of the homologous enzyme(s) from insect vectors of disease. The study of CYP4C7 is a first and unique opportunity to study the processes by which the corpora allata are turned off. These processes have until now been addressed mostly at the morphological level.
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