Expression of rat 5α-reductase in Saccharomyces cerevisiae

Dihydrotestosterone (DHT) is the principle androgen in certain tissues such as the prostate. DHT is formed from testosterone by the NADPH-dependent enzyme 5α-reductase (5AR). In this paper we report the expression of catalytically active steroid 5AR from the rat in Saccharomyces cerevisiae. A full length cDNA coding for 5AR was isolated from a rat liver cDNA library and fixed in frame to the signal sequence of yeast acid phosphatase. A constitutive short promoter fragment of the acid phosphatase gene (PHO5) and the PHO5 transcriptional terminator were added and the expression cassette ligated into the yeast 2μ vector pDP34. S. cerevisiae transformed with the 5AR expression plasmid pDP34/PHO5AR exhibited about 100-fold more activity per gram wet weight than rat prostate.