The occurrence of progesterone 5β-reductase is not limited to the Angiosperms, a functional enzyme was characterized from Picea sitchensis

Abstract

Early steps in cardenolide biosynthesis are catalyzed by 3β-hydroxysteroid dehydrogenase (3βHSD), ketosteroidisomerase (KSI) and progesterone 5β-reductase (P5βR, [1]). Inspecting public data bases, a homologous cDNA sequence was detected with respect to Picea sitchensis. Following its transfer into E. coli, a recombinant enzyme was overexpressed owing the reduction of progesterone to 5β-pregnane-3,20-dione in a stereo-specific manner [2]. The small substrate 2-cyclohexene-1-on was also found to be reduced. This enzymatic data provide first-time evidence concerning the occurrence of P5βR within the Coniferales.