Endophytic fungus Pseudodidymocyrtis lobariellae KL27 promotes taxol biosynthesis and accumulation in Taxus chinensis

Background Taxol from Taxus species is a precious drug used for the treatment of cancer and can effectively inhibit the proliferation of cancer cells. However, the growth of Taxus plants is very slow and the content of taxol is quite low. Therefore, it is of great significance to improve the yield of taxol by modern biotechnology without destroying the wild forest resources. Endophytic fungus which symbiosis with their host plants can promote the growth and secondary metabolism of medicinal plants. Results Here, an endophytic fungus KL27 was isolated from T. chinensis, and identified as Pseudodidymocyrtis lobariellae. The fermentation broth of KL27 (KL27-FB) could significantly promote the accumulation of taxol in needles of T. chinensis, reaching 0.361 ± 0.082 mg/g·DW (dry weight) at 7 days after KL27-FB treatment, which is 3.26-fold increase as compared to the control. The RNA-seq and qRT-PCR showed that KL27-FB could significantly increase the expression of key genes involved in the upstream pathway of terpene synthesis (such as DXS and DXR) and those in the taxol biosynthesis pathway (such as GGPPS, TS, T5OH, TAT, T10OH, T14OH, T2OH, TBT, DBAT and PAM), especially at the early stage of the stimulation. Moreover, the activation of jasmonic acid (JA) biosynthesis and JA signal transduction, and its crosstalk with other hormones, such as gibberellin acid (GA), ethylene (ET) and salicylic acid (SA), explained the elevation of most of the differential expressed genes related to taxol biosynthesis pathway. Moreover, TF (transcriptional factor)-encoding genes, including MYBs, ethylene-responsive transcription factors (ERFs) and basic/helix-loop-helix (bHLH), were detected as differential expressed genes after KL27-FB treatment, further suggested that the regulation of hormone signaling on genes of taxol biosynthesis was mediated by TFs. Conclusions Our results indicated that fermentation broth of endophytic fungus KL27-FB could effectively enhance the accumulation of taxol in T. chinensis needles by regulating the phytohormone metabolism and signal transduction and further up-regulating the expression of multiple key genes involved in taxol biosynthesis. This study provides new insight into the regulatory mechanism of how endophytic fungus promotes the production and accumulation of taxol in Taxus sp.

Compound Taxus chinensis Capsule Combined with Chemotherapy for Non-Small-Cell Lung Cancer: A PRISMA-Compliant Systematic Review and Meta-Analysis of Randomized Controlled Trials

Background. Compound Taxus chinensis capsule (CTCC), an antitumor Chinese patent medicine, has been commonly prescribed as an adjunctive agent to chemotherapy for the management of non-small-cell lung cancer (NSCLC); however, the effects of CTCC added to chemotherapy for NSCLC patients have never been comprehensively evaluated or summarized. Purpose. To assess the synergistic effects of CTCC and chemotherapy on NSCLC. Study Design. Evidence-based study, systematic review, and quantitative meta-analysis. Methods. This systematic review and meta-analysis was implemented in accordance with the PRISMA (Preferred Reported Items for Systematic Review and Meta-Analysis) guidelines. Eight databases including China National Knowledge Infrastructure, SINOMED, China Biomedical Literature Database, Wanfang Database, VIP, PubMed, Cochrane Library, and EMBASE were searched for relevant RCTs from their inception until May 24, 2021, and hand-searching was also carried out to identify additional studies. All randomized controlled trials (RCTs) that compared CTCC combined with chemotherapy versus chemotherapy alone were included in our study. The Cochrane Risk-of-Bias tool was used to determine the risk of bias and methodological quality of the included RCTs. Review Manager 5.3 software was used for comprehensive analysis. The primary outcome measure for this study was the disease control rate (DCR), and the secondary outcomes included the objective response rate (ORR), adverse reactions, and quality of life (QOL). Results. Six RCTs with a total sample size of 410 were finally included. The pooled data showed that, compared with chemotherapy alone, CTCC combined with chemotherapy significantly improved DCR (RR = 1.15, 95% CI: 1.06–1.25, P = 0.006), ORR (RR = 1.38, 95% CI: 1.18–1.63, P < 0.00001), and QOL (MD = 8.69, 95% CI: 7.26–10.13, P < 0.006) and reduced the incidence of total adverse reactions (RR = 0.48, 95% CI: 0.38–0.60, P < 0.00001). The subgroup analyses indicated that CTCC plus chemotherapy significantly improved gastrointestinal reactions ( P = 0.004), leukopenia ( P = 0.0009), thrombocytopenia ( P = 0.01), rash ( P = 0.002), and fever ( P = 0.007). Conclusion. Based on the available evidence, compared with chemotherapy alone, CTCC used as an adjunctive agent to chemotherapy for NSCLC can improve the clinical efficacy and quality of life and decrease the likelihood of adverse reactions, suggesting that CTCC might be an effective and safe adjunctive medicine to chemotherapy for NSCLC. However, considering the relatively small sample size and the inherent imperfections of the included randomized controlled trials, more high-quality clinical trials with longer follow-up time are needed to further assess the efficacy and safety of this combined treatment regimen.

Computational-Designed Enzyme for β-Tyrosine Production in Lignin Valorization

Lignin is an underutilized sustainable source of aromatic compounds. To valorize the low-value lignin monomers, we proposed an efficient strategy, involving enzymatic conversion from trans-p-hydroxycinnamic acids to generate valued-added canonical and non-canonical aromatic amino acids. Among them, β-amino acids are recognized as building blocks for bioactive natural products and pharmaceutical ingredients due to their attractive antitumor properties. Using computational enzyme design, the (R)-β-selective phenylalanine aminomutase from Taxus chinensis (TchPAM) was successfully mutated to accept β-tyrosine as the substrate, as well as to generate the (R)-β-tyrosine with excellent enantiopurity (ee > 99%) as the unique product from trans-p-hydroxycinnamic acid. Moreover, the kinetic parameters were determined for the reaction of four Y424 enzyme variants with the synthesis of different phenylalanine and tyrosine enantiomers. In the ammonia elimination reaction of (R)-β-tyrosine, the variants Y424N and Y424C displayed a two-fold increased catalytic efficiency of the wild type. In this work, a binding pocket in the active site, including Y424, K427, I431, and E455, was examined for its influence on the β-enantioselectivity of this enzyme family. Combining the upstream lignin depolymerization and downstream production, a sustainable value chain based on lignin is enabled. In summary, we report a β-tyrosine synthesis process from a monolignol component, offering a new way for lignin valorization by biocatalyst modification.

Salicylic Acid-Responsive Factor TcWRKY33 Positively Regulates Taxol Biosynthesis in Taxus chinensis in Direct and Indirect Ways

Taxol is a rare secondary metabolite that accumulates considerably in Taxus species under salicylic acid (SA) and methyl jasmonate treatment. However, the molecular mechanism of its accumulation remains unclear. We investigated TcWRKY33, a nuclear-localized group I WRKY transcription factor, as an SA-responsive regulator of taxol biosynthesis. Overexpression and RNA interference of TcWRKY33 confirmed that TcWRKY33 regulates the expression of most taxol biosynthesis genes, especially 10-deacetylbaccatin III-10-O-acetyltransferase (DBAT) and taxadiene synthase (TASY), which were considered as key enzymes in taxol biosynthesis. Transient overexpression of TcWRKY33 in Taxus chinensis leaves resulted in increased taxol and 10-deacetylbaccatin accumulation by 1.20 and 2.16 times compared with the control, respectively. Furthermore, TcWRKY33, DBAT, and TASY were confirmed to respond positively to SA signals. These results suggested that TcWRKY33 was the missing component of taxol biosynthesis that responds to SA. The sequence analysis identified two W-box motifs in the promoter of DBAT but not in the TASY. Yeast one-hybrid and dual-luciferase activity assays confirmed that TcWRKY33 can bind to the two W-boxes in the promoter of DBAT, upregulating its expression level. Hence, DBAT is a direct target of TcWRKY33. Furthermore, TcERF15, encoding a TASY activator, also contains two W-boxes in its promoter. Yeast one-hybrid and dual-luciferase activity assays further confirmed that TcWRKY33 can upregulate TASY expression through the activation of TcERF15. In summary, TcWRKY33 transmits SA signals and positively regulates taxol biosynthesis genes in two ways: directly and through the activation of other activators. Therefore, TcWRKY33 is an excellent candidate for genetically engineering regulation of taxol biosynthesis in Taxus plants.

The Taxus genome provides insights into paclitaxel biosynthesis

The ancient gymnosperm genus Taxus is the exclusive source of the anticancer drug paclitaxel, yet no reference genome sequences are available for comprehensively elucidating the paclitaxel biosynthesis pathway. We have completed a chromosome-level genome of Taxus chinensis var. mairei with a total length of 10.23 gigabases. Taxus shared an ancestral whole-genome duplication with the coniferophyte lineage and underwent distinct transposon evolution. We discovered a unique physical and functional grouping of CYP725As (cytochrome P450) in the Taxus genome for paclitaxel biosynthesis. We also identified a gene cluster for taxadiene biosynthesis, which was formed mainly by gene duplications. This study will facilitate the elucidation of paclitaxel biosynthesis and unleash the biotechnological potential of Taxus.