AN INSECT JUVENILE HORMONE-SPECIFIC EPOXIDE HYDROLASE IS RELATED TO VERTEBRATE MICROSOMAL EPOXIDE HYDROLASES

We describe the first cDNA sequence encoding a juvenile hormone-specif ic epoxide hydrolase from an insect. A full-length cDNA clone revealed a 462-amino-acid open reading frame encoding an amino acid sequence w ith 44% identity and 64% similarity to human microsomal epoxide hydrol ase. All residues in the catalytic triad (residues Asp(227)-His(428)-A sp(350) in the M. sexta protein) were present, as was the conserved Tr p(154) corresponding to the oxyanion hole. The surprising similarity o f insect juvenile hormone epoxide hydrolase to vertebrate microsomal e poxide hydrolases, coupled with the ancient lineage of the epoxide hyd rolases and haloalkane dehalogenases, suggests that this catabolic enz yme evolved from an original ubiquitous detoxication function to a mor e recent role in hormonal regulation. (C) 1996 Academic Press, Inc.