A homomeric geranyl diphosphate synthase-encoding gene from Camptotheca acuminata and its combinatorial optimization for production of geraniol in Escherichia coli

CaERF1- mediated ABA signal positively regulates camptothecin biosynthesis by activating the iridoid pathway in Camptotheca acuminata

Camptotheca acuminata is one of the primary sources of camptothecin (CPT), which is widely used in the treatment of human malignancies because of its inhibitory activity against DNA topoisomerase I. Although several transcription factors have been identified for regulating CPT biosynthesis in other species, such as Ophiorrhiza pumila, the specific regulatory components controlling CPT biosynthesis in C. acuminata have yet to be definitively determined. In this study, CaERF1, an DREB subfamily of the APETALA2/ethylene response factors (AP2ERFs), was identified in C. acuminata. The transient overexpression and silencing of CaERF1 in C. acuminata leaves confirmed that it positively regulates the accumulation of CPT by inducing the expression of CaCYC1 and CaG8O in the iridoid pathway. Results of transient transcriptional activity assay and yeast one-hybrid assays have showed that CaERF1 transcriptionally activates the expression of CaCYC1 and CaG8O by binding to RAA and CEI elements in the promoter regions of these two genes. Furthermore, the expression of CaCYC1 and CaG8O in CaERF1-silenced leaves was less sensitive to ABA treatment, indicating that CaERF1 is a crucial component involved in ABA-regulated CPT biosynthesis in C. acuminata.

Cloning and Expression Analysis of Key Enzyme Gene CoGPPS Involved in Iridoid Glycoside Synthesis in Cornus officinalis

Cornus iridoid glycosides (CIGs), including loganin and morroniside, are the main active components of Cornus officinalis. As one of the key enzymes in the biosynthesis of CIGs, geranyl pyrophosphate synthase (GPPS) catalyzes the formation of geranyl pyrophosphate, which is the direct precursor of CIGs. In this study, the C. officinalis geranyl pyrophosphate synthase (CoGPPS) sequence was cloned from C. officinalis and analyzed. The cDNA sequence of the CoGPPS gene was 915 bp (GenBank No. OR725699). Phylogenetic analysis showed that CoGPPS was closely related to the GPPS sequence of Actinidia chinensis and Camellia sinensis, but relatively distantly related to Paeonia lactiflora and Tripterygium wilfordii. Results from the quantitative real-time PCR showed the spatiotemporal expression pattern of CoGPPS; that is, CoGPPS was specifically expressed in the fruits. Subcellular localization assay proved that CoGPPS was specifically found in chloroplasts. Loganin and morroniside contents in the tissues were detected by high-performance liquid chromatography, and both compounds were found to be at higher levels in the fruits than in leaves. Thus, this study laid the foundation for further studies on the synthetic pathway of CIGs.

Proteomics-Guided Mining and Characterization of Epoxidase Involved in Camptothecin Biosynthesis from Camptotheca acuminata

The detailed metabolic map for camptothecin (CPT) biosynthesis in Camptotheca acuminata has been proposed according to our combined omics results. However, the CYP450-mediated epoxidation step in CPT biosynthesis remains unexplored. A proteomics-guided approach was used to identify and annotate the proteins enriched during the vigorous CPT metabolism period in mature C. acuminata and seedlings. Comparative analyses revealed that the CPT and flavonoid biosyntheses were vigorous in stems and all of the samples except the leaves, respectively. The CYP71BE genes were screened based on their enrichment patterns at the transcriptomic-proteomic level and biochemically characterized in Saccharomyces cerevisiae WAT11. Four CYP71BE proteins exhibited in vitro isoliquiritigenin epoxidase activity. Additionally, CYP71BE206 showed epoxidase activity toward strictosamide, the critical precursor for CPT biosynthesis, both in vitro and in Nicotiana benthamiana. In planta functional verification suggested that CYP71BE206 is involved in CPT biosynthesis. Their catalytic conditions were optimized, and the enzymatic parameters were determined. This study provides valuable insight into the CYP71BE-mediated epoxidation step for CPT biosynthesis and offers evidence to verify that the newly characterized epoxidase (CYP71BE206) is simultaneously responsible for the biosynthesis of CPT and the flavonoid in this plant. An evolution event probably happened on ancestral CYP71BE, resulting in the neofunctionalization of CYP71BE206.

Integrative Analysis of Elicitor-Induced Camptothecin Biosynthesis in Camptotheca acuminata Plantlets Through a Combined Omics Approach

Treatments with abiotic elicitors can efficiently induce the accumulation of specialized metabolites in plants. We used a combined omics approach to analyze the elicitation effects of MeJa, AgNO₃, and PEG on camptothecin (CPT) biosynthesis in Camptotheca acuminata plantlets. Untargeted analyses revealed that treatments with MeJa, AgNO₃, and PEG significantly inhibited the photosynthetic pathway and promoted carbon metabolism and secondary metabolic pathways. The CPT levels increased by 78.6, 73.3, and 50.0% in the MeJa, AgNO₃, and PEG treatment groups, respectively. Using C. acuminata plantlets after elicitation treatment, we mined and characterized 15 new alkaloids, 25 known CPT analogs and precursors, 9 iridoid biosynthetic precursors, and 15 tryptamine biosynthetic precursors based on their MS/MS fragmentation spectra. Using 32 characterized genes involved in CPT biosynthesis as bait, we mined 12 prioritized CYP450 genes from the 416 CYP450 candidates that had been identified based on co-expression analysis, conserved domain analysis, and their elicitation-associated upregulation patterns. This study provides a comprehensive perspective on CPT biosynthesis in C. acuminata plantlets after abiotic elicitation. The findings enable us to elucidate the previously unexplored CYP450-mediated oxidation steps for CPT biosynthesis.

The beauty of biocatalysis: sustainable synthesis of ingredients in cosmetics

Covering: 2015 up to July 2021The market for cosmetics is consumer driven and the desire for green, sustainable and natural ingredients is increasing. The use of isolated enzymes and whole-cell organisms to synthesise these products is congruent with these values, especially when combined with the use of renewable, recyclable or waste feedstocks. The literature of biocatalysis for the synthesis of ingredients in cosmetics in the past five years is herein reviewed.

Metabolic engineering and synthetic biology for isoprenoid production in Escherichia coli and Saccharomyces cerevisiae

Isoprenoids, often called terpenoids, are the most abundant and highly diverse family of natural organic compounds. In plants, they play a distinct role in the form of photosynthetic pigments, hormones, electron carrier, structural components of membrane, and defence. Many isoprenoids have useful applications in the pharmaceutical, nutraceutical, and chemical industries. They are synthesized by various isoprenoid synthase enzymes by several consecutive steps. Recent advancement in metabolic engineering and synthetic biology has enabled the production of these isoprenoids in the heterologous host systems like Escherichia coli and Saccharomyces cerevisiae. Both heterologous systems have been engineered for large-scale production of value-added isoprenoids. This review article will provide the detailed description of various approaches used for engineering of methyl-D-erythritol-4-phosphate (MEP) and mevalonate (MVA) pathway for synthesizing isoprene units (C₅) and ultimate production of diverse isoprenoids. The review particularly highlighted the efforts taken for the production of C₅-C₂₀ isoprenoids by metabolic engineering techniques in E. coli and S. cerevisiae over a decade. The challenges and strategies are also discussed in detail for scale-up and engineering of isoprenoids in the heterologous host systems.Key points• Isoprenoids are beneficial and valuable natural products.• E. coli and S. cerevisiae are the promising host for isoprenoid biosynthesis.• Emerging techniques in synthetic biology enabled the improved production.• Need to expand the catalogue and scale-up of un-engineered isoprenoids. Metabolic engineering and synthetic biology for isoprenoid production in Escherichia coli and Saccharomyces cerevisiae.

Possible clues for camptothecin biosynthesis from the metabolites in camptothecin-producing plants

The plant derived camptothecin (CPT) is a pentacyclic pyrroloquinoline alkaloid with unique antitumor activity. Successive discoveries of new CPT-producing plants occurred in recent years due to market demands. The scattered distribution among angiosperms drew researchers' attention. The aim of this review is to appraise the literature available to date for CPT distribution and the phytochemistry of these CPT-producing plants. Metabolite comparative analyses between the plants were also conducted for tracking of possible clues for CPT biosynthesis. Forty-three plant species in total were reported to possess CPT-producing capability, and one hundred twenty-five alkaloids classified into three major categories are summarized herein. Metabolite comparative analysis between these plants suggests the probability that the formation of the central intermediate for CPT biosynthesis has multiple origins. A more complete biogenetic reasoning for CPT and its structural homolog was delineated based on this fragmentary phytochemical evidence from a chemical point of view. Furthermore, an in-house compound database was constructed for further metabolomic analysis.