Isolation and characterization of the epoxide hydrolase-encoding gene fromXanthophyllomyces dendrorhous

The epoxide hydrolase (EH)-encoding gene (EPH1) from the basidiomycetous ye ast Xanthophyllomyces dendrorhous was isolated. The genomic sequence has a 1,236-bp open reading frame which is interrupted by eight introns that enco de a 411-amino-acid polypeptide with a calculated molecular mass of 46.2 kD a, The amino acid sequence is similar to that of microsomal EH and belongs to the alpha/beta hydrolase fold family. The EPH1 gene was not essential fo r growth of X. dendrorhous in rich medium under laboratory conditions. The Eph1-encoding cDNA was functionally expressed in Escherichia coli. A sixfol d increase in specific activity was observed when we used resting cells rat her than X. dendrorhous. The epoxides 1,2-epoxyhexane and 1-methylcyclohexe ne oxide were substrates for both native and recombinant Eph1, Isolation an d characterization of the X, dendrorhous EH-encoding gene are essential ste ps in developing a yeast EH-based epoxide biotransformation system.