Molecular characterization and enzymatic analysis of juvenile hormone epoxide hydrolase genes in the red flour beetle Tribolium castaneum

Juvenile hormone epoxide hydrolases (JHEHs) degrade juvenile hormones (JHs) and are important for JH titre regulation. Here, we report the cloning and analysis of five jheh-related (jheh-r1-r5) genes in the red flour beetle, Tribolium castaneum, a model species for the coleopteran insects. T. castaneum JHEH-r (TcJHEH-r) proteins show high homology to lepidopteran JHEHs and also to human microsomal epoxide hydrolase. In the phylogenetic tree, Tcjheh-rs were clustered, and interestingly, they were also clustered in the genome. Examination of enzymatic activities using recombinant TcJHEH-r proteins showed that TcJHEH-r3 had strong degradation activity for JH III, whereas TcJHEH-r4 had weak activity. The study has yielded significant information that will facilitate further analysis of JHEHs and epoxide hydrolases.