Production of salidroside in metabolically engineered Escherichia coli

Abstract

Salidroside (1) is the most important bioactive component of Rhodiola (also called as “Tibetan Ginseng”), which is a valuable medicinal herb exhibiting several adaptogenic properties. Due to the inefficiency of plant extraction and chemical synthesis, the supply of salidroside (1) is currently limited. Herein, we achieved unprecedented biosynthesis of salidroside (1) from glucose in a microorganism. First, the pyruvate decarboxylase ARO10 and endogenous alcohol dehydrogenases were recruited to convert 4-hydroxyphenylpyruvate (2), an intermediate of L-tyrosine pathway, to tyrosol (3) in Escherichia coli. Subsequently, tyrosol production was improved by overexpressing the pathway genes, and by eliminating competing pathways and feedback inhibition. Finally, by introducing Rhodiola-derived glycosyltransferase UGT73B6 into the above-mentioned recombinant strain, salidroside (1) was produced with a titer of 56.9 mg/L. Interestingly, the Rhodiola-derived glycosyltransferase, UGT73B6, also catalyzed the attachment of glucose to the phenol position of tyrosol (3) to form icariside D2 (4), which was not reported in any previous literatures.

Family-wide Structural Characterization and Genomic Comparisons Decode the Diversity-oriented Biosynthesis of Thalassospiramides by Marine Proteobacteria

“…Although there is no evidence that glutamate is directly involved in thalassospiramide biosynthesis, glutamate metabolism is at the center of several amino acid metabolic pathways, and it affects the biosynthesis of a variety of bacterium-sourced natural products (16,17). Enhancement of the tyrosine biosynthetic pathway can increase the production of salidrosides in engineered Escherichia coli (18). The biosynthetic steps to form the thalassospiramides directly involve tyrosine, suggesting potential linkages between tyrosine metabolic pathways and thalassospiramide biosynthesis.…”

Rhodiola rosea L.: from golden root to green cell factories

“…rosea L. is a dioecious, perennial plant native to East Asia, Russia, Japan, Korea and Southern China (Martin et al 2010). In the mountains it grows at altitudes between 2 000 and 2 600 m (Platikanov and Evstatieva 2008) The natural habitats of R. rosea are at the edge of exhaustion due to indiscriminate harvesting of R. rosea plants for their valuable pharmacological substances (Ling-ling et al 2007;Bai et al 2014). That is why this species is with high conservation value throughout its area of distribution.…”

“…It is formed as a product of dehydration between the hemiacetal hydroxyl of glucose and the ethanol hydroxyl of tyrosol (4-hydroxyphenylethanol) (Ling-ling et al 2007). The biosynthetic pathway of salidroside (figure 2, arrow types B-G) is still elusive and its regulation is not very well understood (Ma et al 2008;Bai et al 2014). …”

“…More supporting facts show that the addition of 1 mM Tyr or 1 mM tyrosol increased 9-fold the salidroside content in cell cultures of R. sachalinensis, resulting in the highest ever reported salidroside content by Rhodiola cell suspension culture (154.95 mg/g), while the Phe did not exhibit the same effect (Xu et al 1998b). expressed, but when the competitive pathways and negative regulation were eliminated as well (Bai et al 2014).…”

“…The pronounced physiological and pharmacological activities of R. rosea lead to indiscriminate harvesting and depletion of its natural habitats (Bai et al 2014). Therefore, it is a priority plant with vulnerable to critically endangered status, strictly forbidden for harvesting (Platikanov and Evstatieva 2008;Cuerrier et al 2015) and included in the Red List of protected plant species in many countries throughout the world (Mossberg and Stenberg 2003;Sidjimova et al 2014).…”