Planta Med 2015; 81 - PM_225
DOI: 10.1055/s-0035-1565602

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

K Rudolph 1, T Wiegert 2, F Mueller-Uri 1, R Schubert 2
  • 1University Erlangen-Nuremberg, Department of Biology, Chair of Pharmaceutical Biology Staudtstr.5 D-91058, Erlangen, Germany
  • 2University of Applied Sciences, Biotechnology Group, Theodor-Körner-Allee 16, D-02763, Zittau, Germany

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.

It is presently unclear what a role the newly detected enzyme, belonging to the broadly documented SDR family [3], could play in planta since P. sitchensis does not produce cardenolides. However, P5βRs are also involved in the iridoid biosynthesis [4, 5]. This hypothesis has to be proven for P. sitchensis in future.

References:

[1] Herl V et al., 2006

[2] Bauer P et al., 2010

[3] Thorn A et al. 2008

[4] Geu-Flores et al. 2014

[5] Munkert J et al. 2015