Efficient biosynthesis of resveratrol via combining phenylalanine and tyrosine pathways in Saccharomyces cerevisiae.

BACKGROUND: Resveratrol is a commercially available stilbenoid widely used as dietary supplements, functional food ingredients, and cosmetic ingredients due to its diverse physiological activities. The production of resveratrol in microorganisms provides an ideal source that reduces the cost of resveratrol, but the titer in Saccharomyces cerevisiae was still much lower than that in other hosts. RESULTS: To achieve enhanced production of resveratrol in S. cerevisiae, we constructed a biosynthetic pathway via combining phenylalanine and tyrosine pathways by introducing a bi-functional phenylalanine/tyrosine ammonia lyase from Rhodotorula toruloides. The combination of phenylalanine pathway with tyrosine pathway led to a 462% improvement of resveratrol production in yeast extract peptone dextrose (YPD) medium with 4% glucose, suggesting an alternative strategy for producing p-coumaric acid-derived compounds. Then the strains were further modified by integrating multi-copy biosynthetic pathway genes, improving metabolic flux to aromatic amino acids and malonyl-CoA, and deleting by-pathway genes, which resulted in 1155.0 mg/L resveratrol in shake flasks when cultured in YPD medium. Finally, a non-auxotrophic strain was tailored for resveratrol production in minimal medium without exogenous amino acid addition, and the highest resveratrol titer (4.1 g/L) ever reported was achieved in S. cerevisiae to our knowledge. CONCLUSIONS: This study demonstrates the advantage of employing a bi-functional phenylalanine/tyrosine ammonia lyase in the biosynthetic pathway of resveratrol, suggesting an effective alternative in the production of p-coumaric acid-derived compounds. Moreover, the enhanced production of resveratrol in S. cerevisiae lays a foundation for constructing cell factories for various stilbenoids.

Characterization of a Group of UDP-Glycosyltransferases Involved in the Biosynthesis of Triterpenoid Saponins of Panax notoginseng.

UDP-glycosyltransferase (UGT)-mediated glycosylation is a common modification in triterpene saponins, which exhibit a wide range of bioactivities and important pharmacological effects. However, few UGTs involved in saponin biosynthesis have been identified, limiting the biosynthesis of saponins. In this study, an efficient heterologous expression system was established for evaluating the UGT-mediated glycosylation process of triterpene saponins. Six UGTs (UGTPn17, UGTPn42, UGTPn35, UGTPn87, UGTPn19, and UGTPn12) from Panax notoginseng were predicted and found to be responsible for efficient and direct enzymatic biotransformation of 21 triterpenoid saponins via 26 various glycosylation reactions. Among them, UGTPn87 exhibited promiscuous sugar-donor specificity of UDP-glucose (UDP-Glc) and UDP-xylose (UDP-Xyl) by catalyzing the elongation of the second sugar chain at the C3 or/and C20 sites of protopanaxadiol-type saponins with a UDP-Glc or UDP-Xyl donor, as well as at the C20 site of protopanaxadiol-type saponins with a UDP-Glc donor. Two new saponins, Fd-Xyl and Fe-Xyl, were generated by catalyzing the C3-O-Glc xylosylations of notoginsenoside Fd and notoginsenoside Fe when incubated with UGTPn87. Moreover, the complete biosynthetic pathways of 17 saponins were elucidated, among which notoginsenoside L, vinaginsenoside R16, gypenoside LXXV, and gypenoside XVII were revealed in Panax for the first time. A yeast cell factory was constructed with a yield of Rh2 at 354.69 mg/L and a glycosylation ratio of 60.40% in flasks. Our results reveal the biosynthetic pathway of a group of saponins in P. notoginseng and provide a theoretical basis for producing rare and valuable saponins, promoting their industrial application in medicine and functional foods.

H2S inhibits angiotensin II-induced atrial Kv1.5 upregulation by attenuating Nox4-mediated ROS generation during atrial fibrillation.

Our previous study demonstrated that angiotensin II (Ang II) upregulates the expression of Kv1.5, a promising target for atrial fibrillation (AF) therapy, by activating ROS-dependent P-Smad2/3 and P-ERK 1/2. A recent study showed that hydrogen sulfide (H2S) may modulate the effects of angiotensin II (Ang II) by inhibiting the NADPH oxidase 4 (Nox4)-ROS signaling in the heart. The present study aimed to determine whether H2S is involved in the regulation of atrial Kv1.5 via ROS-related mechanisms in AF. Cultured neonatal rat atrial myocytes and a beagle model of AF were used for this study. In the neonatal rat atrial myocytes, quantitative PCR and enzyme immunoassays revealed that the mRNA expression levels of angiotensinogen, angiotensin-converting enzyme, and Ang II type I receptor (AT1R) and the Ang II supernatant concentration were significantly increased by hydrogen peroxide (H2O2) incubation, and these H2O2-induced alterations were reversed by diphenyleneiodonium, apocynin and H2S supplementation. Flow cytometry and Western blotting revealed that blockade of H2S biosynthesis using dl-propargylglycine increased ROS production and the expression of Ang II and Kv1.5. Sodium hydrosulfide (an exogenous H2S donor) and Nox4 siRNA inhibited Ang II-induced ROS production and Ang II-induced expression of Kv1.5, P-Smad2/3, P-ERK 1/2. Sodium hydrosulfide suppressed the Ang II-induced upregulation of Nox4. In our beagle AF model, 24 h of rapid atrial pacing (RAP) increased the atrial Ang II concentration, ROS production and the protein expression of Nox4, Kv1.5, P-Smad2/3 and P-ERK 1/2. These RAP-induced changes were inhibited by H2S supplementation and losartan (an AT1R blocker) pretreatment. In conclusion, our study indicates that H2S downregulates Ang II-induced atrial Kv1.5 expression by attenuating Nox4-related ROS-triggered P-Smad2/3 and P-ERK 1/2 activation during AF. H2S supplementation would be beneficial for AF treatment via the suppression of atrial Kv1.5 expression.

[Therapeutic Effects of Berberine Capsule on Patients with Mild Hyperlipidemia].

OBJECTIVE: To observe the therapeutic effects of Berberine Capsule (BC) on patients with mild hyperlipidemia. METHODS: Totally 102 mild hyperlipemia patients were recruited. All patients were suggested to have proper diet and physical activity as basic therapy for 1 month of run-in period. Totally 97 patients completed it. Then they were randomly assigned to the berberine group (the treatment group, 49 cases) and the placebo group (the control group, 48 cases). Patients in the treatment group took BC 300 mg, while those in the control group took placebo 300 mg, thrice per day for 3 successive months. Then placebos and BC were interrupted for 2 months (as washout period). All subjects received only diet control and physical activity during washout period. After washout period, placebos and BC were re-administered to all patients in the same way for 3 months. Body mass index (BMI), fasting plasma glucose (FPG), TG, TC, LDL-C, and HDL-C were assessed after run-in period, washout period, at month 1, 2, 3 after the first therapy, at month 1, 2, 3 after second treatment, respectively. RESULTS: Compared with the end of run-in period, TG, TC, and LDL-C decreased, and HDL-C increased in the treatment group (P < 0.05) after first 3 months of treatment. Compared with 3 months after the first therapy, TG, TC, and LDL-C increased and HDL-C decreased in the treatment group after washout period (P < 0.05). Compared with the end of wash- out period, TC and LDL-C decreased in the treatment group at month 2 after second treatment (P < 0.05); TG, TC, and LDL-C decreased (P < 0.01, P < 0.05), and HDL-C increased (P < 0.05) at month 3 after second treatment. Compared with the control group at month 3 after second treatment, TG, TC, and LDL-C all decreased, and HDL-C increased in the treatment group (all P < 0.05). CONCLUSION: BC was effective in improving blood lipid level in mild hyperlipidemia patients.