Biosynthetic approach to combine the first steps of cardenolide formation in Saccharomyces cerevisiae
Related Experiment Video
Updated: Jan 20, 2026

Efficient Sporulation of Saccharomyces cerevisiae in a 96 Multiwell Format
Published on: September 17, 2016
Christoph Rieck1, Daniel Geiger1, Jennifer Munkert1
1Department Biology, Friedrich-Alexander-University Erlangen-Nuremberg, Erlangen, Germany.
Abstract:
A yeast expression plasmid was constructed containing a cardenolide biosynthetic module, referred to as CARD II, using the AssemblX toolkit, which enables the assembly of large DNA constructs. The genes cloned into the vector were (a) a Δ5 -3β-hydroxysteroid dehydrogenase gene from Digitalis lanata, (b) a steroid Δ5 -isomerase gene from Comamonas testosteronii, (c) a mutated steroid-5β-reductase gene from Arabidopsis thaliana, and (d) a steroid 21-hydroxylase gene from Mus musculus. A second plasmid bearing an ADR/ADX fusion gene from Bos taurus was also constructed. A Saccharomyces cerevisiae strain bearing these two plasmids was generated. This strain, termed "CARD II yeast", was capable of producing 5β-pregnane-3β,21-diol-20-one, a central intermediate in 5β-cardenolide biosynthesis, starting from pregnenolone which was added to the culture medium. Using this approach, five consecutive steps in cardenolide biosynthesis were realized in baker's yeast.
Related Concept Videos
Amino Acid Biosynthetic Pathways
Rate-Determining Steps
In a multistep reaction mechanism, one of the elementary steps progresses significantly slower than the others. This slowest step is called the rate-limiting step (or rate-determining step). A reaction cannot proceed faster than its slowest step, and hence, the rate-determining step limits the overall reaction rate.
The concept of rate-determining step can be understood from the analogy of a 4-lane freeway with a short-stretch of traffic-bottleneck caused due to...
Standard Enthalpy of Formation
Formation of Complex Ions
Formation of Species
Solution Formation
This selective...

