Expression of 17 beta-hydroxysteroid dehydrogenases in mesophilic and extremophilic yeast

17 beta -hydroxysteroid dehydrogenases (17 beta -HSDs) are enzymes responsi ble for reversible interconversions of biologically active 17-hydroxy and i nactive 17-keto steroids. We have performed a survey of 17 beta -HSD activi ty in yeast. Constitutive 17 beta -HSD activity was found in three mesophil ic yeast species: Candida tropicalis, Cryptococcus tsukubaensis, and Saccha romyces cerevisiae as well as in three extremophilic black yeast species: H ortaea werneckii, Trimmatostroma salinum, and Phaeotheca triangularis, indi cating that 17 beta -HSD activity is widely distributed among yeast. In ext remophilic black yeast, NaCl modulated enzyme activity. Enzymes resembling 17 beta -HSD from the filamentous fungus Cochliobolus lunatus were detected in Trimmatostroma salinum and Phaeotheca triangularis. Sequences with iden tity to the Saccharomyces cerevisiae YBR159w gene were not observed in othe r yeast species possessing a similar enzyme activity. The results suggest t he existence of at least three different types of 17 beta -HSD in yeast. (C ) 2001 Elsevier Science Inc. All rights reserved.