Genome Mining of Fungal Unique Trichodiene Synthase-like Sesquiterpene Synthases.

Sesquiterpenoids served as an important source for natural product drug discovery. Although genome mining approaches have revealed numerous novel sesquiterpenoids and biosynthetic enzymes, the comprehensive landscape of fungal sesquiterpene synthases (STSs) remains elusive. In this study, 123 previously reported fungal STSs were subjected to phylogenetic analysis, resulting in the identification of a fungi-specific STS family known as trichodiene synthase-like sesquiterpene synthases (TDTSs). Subsequently, the application of hidden Markov models allowed the discovery of 517 TDTSs from our in-house fungi genome library of over 400 sequenced genomes, and these TDTSs were defined into 79 families based on a sequence similarity network. Based on the novelty of protein sequences and the completeness of their biosynthetic gene clusters, 23 TDTS genes were selected for heterologous expression in Aspergillus oryzae. In total, 10 TDTSs were active and collectively produced 12 mono- and sesquiterpenes, resulting in the identification of the first chamipinene synthase, as well as the first fungi-derived cedrene, sabinene, and camphene synthases. Additionally, with the guidance of functionally characterized TDTSs, we found that TDTSs in Family 1 could produce bridged-cyclic sesquiterpenes, while those in Family 2 could synthesize spiro- and bridged-cyclic sesquiterpenes. Our research presents a new avenue for the genome mining of fungal sesquiterpenoids.

Characterization and Engineering of Two Highly Paralogous Sesquiterpene Synthases Reveal a Regioselective Reprotonation Switch.

Sesquiterpene synthases (STPSs) catalyze carbocation-driven cyclization reactions that can generate structurally diverse hydrocarbons. The deprotonation-reprotonation process is widely used in STPSs to promote structural diversity, largely attributable to the distinct regio/stereoselective reprotonations. However, the molecular basis for reprotonation regioselectivity remains largely understudied. Herein, we analyzed two highly paralogous STPSs, Artabotrys hexapetalus (-)-cyperene synthase (AhCS) and ishwarane synthase (AhIS), which catalyze reactions that are distinct from the regioselective protonation of germacrene A (GA), resulting in distinct skeletons of 5/5/6 tricyclic (-)-cyperene and 6/6/5/3 tetracyclic ishwarane, respectively. Isotopic labeling experiments demonstrated that these protonations occur at C3 and C6 of GA in AhCS and AhIS, respectively. The cryo-electron microscopy-derived AhCS complex structure provided the structural basis for identifying different key active site residues that may govern their functional disparity. The structure-guided mutagenesis of these residues resulted in successful functional interconversion between AhCS and AhIS, thus targeting the three active site residues [L311-S419-C458]/[M311-V419-A458] that may act as a C3/C6 reprotonation switch for GA. These findings facilitate the rational design or directed evolution of STPSs with structurally diverse skeletons.

The Integration of the Metabolome and Transcriptome for Dendrobium nobile Lindl. in Response to Methyl Jasmonate.

Dendrobium nobile Lindl., as an endangered medicinal plant within the genus Dendrobium, is widely distributed in southwestern China and has important ecological and economic value. There are a variety of metabolites with pharmacological activity in D. nobile. The alkaloids and polysaccharides contained within D. nobile are very important active components, which mainly have antiviral, anti-tumor, and immunity improvement effects. However, the changes in the compounds and functional genes of D. nobile induced by methyl jasmonate (MeJA) are not clearly understood. In this study, the metabolome and transcriptome of D. nobile were analyzed after exposure to MeJA. A total of 377 differential metabolites were obtained through data analysis, of which 15 were related to polysaccharide pathways and 35 were related to terpenoids and alkaloids pathways. Additionally, the transcriptome sequencing results identified 3256 differentially expressed genes that were discovered in 11 groups. Compared with the control group, 1346 unigenes were differentially expressed in the samples treated with MeJA for 14 days (TF14). Moreover, the expression levels of differentially expressed genes were also significant at different growth and development stages. According to GO and KEGG annotations, 189 and 99 candidate genes were identified as being involved in terpenoid biosynthesis and polysaccharide biosynthesis, respectively. In addition, the co-expression analysis indicated that 238 and 313 transcription factors (TFs) may contribute to the regulation of terpenoid and polysaccharide biosynthesis, respectively. Through a heat map analysis, fourteen terpenoid synthetase genes, twenty-three cytochrome P450 oxidase genes, eight methyltransferase genes, and six aminotransferase genes were identified that may be related to dendrobine biosynthesis. Among them, one sesquiterpene synthase gene was found to be highly expressed after the treatment with MeJA and was positively correlated with the content of dendrobine. This study provides important and valuable metabolomics and transcriptomic information for the further understanding of D. nobile at the metabolic and molecular levels and provides candidate genes and possible intermediate compounds for the dendrobine biosynthesis pathway, which lays a certain foundation for further research on and application of Dendrobium.

Identification and characterization of novel sesquiterpene synthases TPS9 and TPS12 from Aquilaria sinensis.

Sesquiterpenes are characteristic components and important quality criterions for agarwood. Although sesquiterpenes are well-known to be biosynthesized by sesquiterpene synthases (TPSs), to date, only a few TPS genes involved in agarwood formation have been reported. Here, two new TPS genes, namely, TPS9 and TPS12, were isolated from Aquilaria sinensis (Lour.) Gilg, and their functions were examined in Escherichia coli BL21(DE3), with farnesyl pyrophosphate (FPP) and geranyl pyrophosphate (GPP) as the substrate of the corresponding enzyme activities. They were both identified as a multiproduct enzymes. After incubation with FPP, TPS9 liberated ß-farnesene and cis-sesquisabinene hydrate as main products, with cedrol and another unidentified sesquiterpene as minor products. TPS12 catalyzes the formation of ß-farnesene, nerolidol, γ-eudesmol, and hinesol. After incubation with GPP, TPS9 generated citronellol and geraniol as main products, with seven minor products. TPS12 converted GPP into four monoterpenes, with citral as the main product, and three minor products. Both TPS9 and TPS12 showed much higher expression in the two major tissues emitting floral volatiles: flowers and agarwood. Further, RT-PCR analysis showed TPS9 and TPS12 are typical genes mainly expressed during later stages of stress response, which is better known than that of chromone derivatives. This study will advance our understanding of agarwood formation and provide a solid theoretical foundation for clarifying its mechanism in A. sinensis.

Identification of a (+)-cubenene synthase from filamentous fungi Acremonium chrysogenum.

Sesquiterpene synthases convert farnesyl diphosphate into various sesquiterpenes, which find wide applications in the food, cosmetics and pharmaceutical industries. Although numerous putative sesquiterpene synthases have been identified in fungal genomes, many lack biochemical characterization. In this study, we identified a putative terpene synthase AcTPS3 from Acremonium chrysogenum. Through sequence analysis and in vitro enzyme assay, AcTPS3 was identified as a sesquiterpene synthase. To obtain sufficient product for NMR testing, a metabolic engineered Saccharomyces cerevisiae was constructed to overproduce the product of AcTPS3. The major product of AcTPS3 was identified as (+)-cubenene (55.46%) by GC-MS and NMR. Thus, AcTPS3 was confirmed as (+)-cubenene synthase, which is the first report of (+)-cubenene synthase. The optimized S. cerevisiae strain achieved a biosynthesis titer of 597.3 mg/L, the highest reported for (+)-cubenene synthesis.

Predicting functions of putative fungal sesquiterpene synthase genes based on multiomics data analysis.

Sesquiterpenes (STs) are secondary metabolites, which mediate biotic interactions between different organisms. Predicting the species-specific ST repertoires can contribute to deciphering the language of communication between organisms of the same or different species. High biochemical plasticity and catalytic promiscuity of sesquiterpene synthases (STSs), however, challenge the homology-based prediction of the STS functions. Using integrated analyses of genomic, transcriptomic, volatilomic, and metabolomic data, we predict product profiles for 116 out of 146 putative STS genes identified in the genomes of 30 fungal species from different trophic groups. Our prediction method is based on the observation that STSs encoded by genes closely related phylogenetically are likely to share the initial enzymatic reactions of the ST biosynthesis pathways and, therefore, produce STs via the same reaction route. The classification by reaction routes allows to assign STs known to be emitted by a particular species to the putative STS genes from this species. Gene expression information helps to further specify these ST-to-STS assignments. Validation of the computational predictions of the STS functions using both in silico and experimental approaches shows that integrated multiomic analyses are able to correctly link cyclic STs of non-cadalane type to genes. In the process of the experimental validation, we characterized catalytic properties of several putative STS genes from the mycorrhizal fungus Laccaria bicolor. We show that the STSs encoded by the L.bicolor mycorrhiza-induced genes emit either nerolidol or α-cuprenene and α-cuparene, and discuss the possible roles of these STs in the mycorrhiza formation.

Tandem expression of Ganoderma sinense sesquiterpene synthase and IDI promotes the production of gleenol in E. coli.

Ganoderma sinense, with more than 2000 years of medicinal history, is a fungus of the basidiomycetes that is rich in polysaccharides and terpenoids. However, the biosynthesis of terpenes, especially sesquiterpenes, has been little studied. The functional identification of sesquiterpene synthases from G. sinense is of great significance to the study of fungal terpenoid biosynthesis and regulation. Our research group has completed the functional characterization of 21 sesquiterpene synthase genes from G. sinense. It was found that gleenol, biosynthesis of which is catalyzed by the sesquiterpene synthase GsSTS26 and GsSTS27, has the functions of killing termites, antihelminth, and plant growth regulation. In the unmodified E. coli Rosetta (DE3) strain, the content of gleenol produced by sesquiterpene synthase from G. sinense is low, which makes it difficult to meet the demand of industrial production and the market. Therefore, it is of great significance to obtain high-yielding strains by means of synthetic biology. In this study, we constructed eight recombinant strains by using tandem gene expression and promoter engineering, and the content of gleenol was increased by up to 23-fold. In this study, we realized the de novo synthesis of gleenol in E. coli and provided a basis for the biosynthesis of terpenoids in basidiomycetes. KEY POINTS: • Eight recombinant expression systems were constructed by using tandem genes and promoter engineering. • The recombinant strain promoted the efficient production of gleenol in E. coli Rosetta (DE3). • The recombinant strain achieved de novo production of gleenol in E. coli.

Biosynthesis of Sesquiterpenes in Basidiomycetes: A Review.

Sesquiterpenes are common small-molecule natural products with a wide range of promising applications and are biosynthesized by sesquiterpene synthase (STS). Basidiomycetes are valuable and important biological resources. To date, hundreds of related sesquiterpenoids have been discovered in basidiomycetes, and the biosynthetic pathways of some of these compounds have been elucidated. This review summarizes 122 STSs and 2 fusion enzymes STSs identified from 26 species of basidiomycetes over the past 20 years. The biological functions of enzymes and compound structures are described, and related research is discussed.

Cloning and functional characterization of three sesquiterpene synthase genes from Chamaecyparis formosensis Matsumura.

Terpene synthase (TPS) analysis may contribute to a better understanding of terpenoids biosynthesis and the evolution of phylogenetic taxonomy. Chamaecyparis formosensis Matsumura is an endemic and valuable conifer of Taiwan. Its excellent wood quality, fragrance, and durability make it become the five precious conifers in Taiwan. In this study, three sesquiterpene synthase genes that belong to the TPS-d2 clade were isolated and characterized through in vitro reaction of recombinant protein and in vivo reaction of Escherichia coli heterologous expression system. The main product of Cf-GerA was germacrene A using GC/MS analysis, while the product of Cf-Aco and Cf-Gor were identified as acora-4(14),8-diene and (5R,6R,10S)-α-gorgonene by using NMR analysis. These are the first reported enzymes that biosynthesize acora-4(14),8-diene and (5 R,6 R,10 S)-α-gorgonene. Both sesquiterpene synthases may isomerize the farnesyl pyrophosphate substrate to nerolidyl pyrophosphate for further cyclization. Cf-Aco may catalyze 1,6-cyclization of nerolidyl cation while Cf-Gor may catalyze through an uncharged intermediate, isogermacrene A.

Latent potentials of the white-rot basidiomycete Phanerochaete chrysosporium responsible for sesquiterpene metabolism: CYP5158A1 and CYP5144C8 decorate (E)-α-bisabolene.

Basidiomycetes produce various sesquiterpenoids and their relevance for pharmaceutical and agricultural applications and understanding their biosynthetic machinery to produce these secondary metabolites have attracted significant interest. Because sesquiterpene synthases (STSs) and cytochrome P450 monooxygenases (P450s) play pivotal roles in the production of sesquiterpenoids, functional characterization of these enzymes is fundamentally essential. In this study, we found 11 possible STSs from the white-rot basidiomycete Phanerochaete chrysosporium (PcSTSs) and isolated nine of these as full-length cDNAs encoding a mature open reading frame. Using the isolated cDNAs, we performed heterologous expression of PcSTSs in Saccharomyces cerevisiae. Metabolic studies revealed that seven of the PcSTSs produce a series of sesquiterpene scaffolds, including (E)-α-bisabolene. Furthermore, we constructed a co-expression system of (E)-α-bisabolene synthase and P450 from P. chrysosporium (PcCYP). Semi-comprehensive screening using 120 isoforms of PcCYPs resulted in the identification of CYP5158A1 and CYP5144C8, two P450s capable of decorating (E)-α-bisabolene.

Elucidation of the essential oil biosynthetic pathways in Cinnamomum burmannii through identification of six terpene synthases.

Cinnamomum burmannii is a traditional plant that has long been used as a spice, food preservative, and food flavoring. Essential oils in C. burmannii, which mainly consist of mono- and sesquiterpenes such borneol, linalool, and caryophyllene, have impressive pharmaceutical properties. Although the transcriptome-based discovery of (+)-bornyl diphosphate synthase (CbTPS1) from C. burmannii was reported in our previous study, the remaining terpene synthases (TPSs) corresponding to various terpene biosynthesis pathways remain unidentified. In this study, we report the results of RNA-sequencing of a borneol type plant and functional characterization of six additional full-length candidate TPS genes (named CbTPS2-7). Phylogenetic analysis revealed that CbTPS2 and CbTPS3 together with the previously identified CbTPS1 protein belong to the TPS-b subfamily, and enzyme assays using geranyl diphosphate (GPP) and farnesyl diphosphate (FPP) as substrates revealed that CbTPS1, CbTPS2 and CbTPS3 catalyze the formation of monoterpenes. CbTPS4, CbTPS5, and CbTPS6, which belong to the TPS-a clade, generated monoterpenes and sesquiterpenes. CbTPS7, which belongs to the TPS-g clade, showed linalool/nerolidol synthase activity. These CbTPSs identified in C. burmannii produced a total of 10 monoterpenes and 14 sesquiterpenes in an in vitro assay. These findings clarify the biosynthesis pathways of 13 monoterpenoids and 12 sesquiterpenoids in the leaf essential oil of C. burmannii and shed light on terpene biosynthesis in Cinnamomum.

[Research advances in methods of cyclezation mechanism of sesquiterpenes].

Terpenes are the largest group of natural products and contain the widest assortment of structural types. Terpene cyclization is also the most complex reaction found in nature. For a long time, terpenoids with diverse structures have attracted natural product chemists to explore their biosynthesis mechanism. Such a large number of terpene skeletons are catalyzed by enzymes called terpene synthase. Sesquiterpene synthase is a kind of terpene synthase, which can catalyze the cyclization of linear precursor farnesyl pyrophosphate(FPP) to sesquiterpene skeletons. Sesquiterpene synthase cyclize a single precursor FPP into many sesquiterpene skeletons. With the continuous discovery of sesquiterpene synthase, the cyclization mechanism of sesquiterpene synthase has been studied deeply. In recent years, with the development and improvement of isotope labeling of substrate FPP and structural analysis of sesquiterpene synthase, the structure and cyclization mechanism of sesquiterpene synthase have been studied more systematically and accurately. In this review, we reviewed the progress of the research methods on the mechanism of sesquiterpene cyclization by substrate isotope labeling and protein structure, as well as the summary and prospect of sesquiterpene synthase research.

[Advances in biosynthesis of cadinane sesquiterpenes].

Cadinanes are a class of bicyclic sesquiterpenes with complex stereochemistry and broad pharmacological activities, such as antibacterial, anti-inflammatory, and hypoglycemic activities. To date, structurally diverse and bioactive cadinane sesquiterpenes have been isolated and identified from a variety of plants and microorganisms. Moreover, deeper understandings on cadinane sesquiterpene synthases have been made. This article categorized the 124 new cadinanes which were published in the literatures in the past four years (2017-2020) into five structural types, and presented their pharmacological activities. We also illustrated the elucidation of the biosynthetic pathways for typical cadinanes, summarized the research progress on cadinane sesquiterpene synthases. Finally, current challenges and future prospects were proposed and discussed.

Functional characterization and substrate promiscuity of sesquiterpene synthases from Tripterygium wilfordii.

Acyclic terpenes, commonly found in plants, are of high physiological importance and commercial value, and their diversity was controlled by different terpene synthases. During the screen of sesquiterpene synthases from Tripterygium wilfordii, we observed that Ses-TwTPS1-1 and Ses-TwTPS2 promiscuously accepted GPP, FPP, and GGPP to produce corresponding terpene alcohols (linalool/nerolidol/geranyllinalool). The Ses-TwTPS1-2, Ses-TwTPS3, and Ses-TwTPS4 also showed unusual substrate promiscuity by catalyzing GGPP or GPP in addition to FPP as substrate. Furthermore, key residues for the generation of diterpene product, (E, E)-geranyllinalool, were screened depending on mutagenesis studies. The functional analysis of Ses-TwTPS1-1:V199I and Ses-TwTPS1-2:I199V showed that Val in 199 site assisted the produce of diterpene product geranyllinalool by enzyme mutation studies, which indicated that subtle differences away from the active site could alter the product outcome. Moreover, an engineered sesquiterpene high-yielding yeast that produced 162 mg/L nerolidol in shake flask conditions was constructed to quickly identify the function of sesquiterpene synthases in vivo and develop potential applications in microbial fermentation. Our functional characterization of acyclic sesquiterpene synthases will give some insights into the substrate promiscuity of diverse acyclic terpene synthases and provide key residues for expanding the product portfolio.

The Sesquiterpene Synthase PtTPS5 Produces (1S,5S,7R,10R)-Guaia-4(15)-en-11-ol and (1S,7R,10R)-Guaia-4-en-11-ol in Oomycete-Infected Poplar Roots.

Pathogen infection often leads to the enhanced formation of specialized plant metabolites that act as defensive barriers against microbial attackers. In this study, we investigated the formation of potential defense compounds in roots of the Western balsam poplar (Populus trichocarpa) upon infection with the generalist root pathogen Phytophthora cactorum (Oomycetes). P. cactorum infection led to an induced accumulation of terpenes, aromatic compounds, and fatty acids in poplar roots. Transcriptome analysis of uninfected and P. cactorum-infected roots revealed a terpene synthase gene PtTPS5 that was significantly induced upon pathogen infection. PtTPS5 had been previously reported as a sesquiterpene synthase producing two unidentified sesquiterpene alcohols as major products and hedycaryol as a minor product. Using heterologous expression in Escherichia coli, enzyme assays with deuterium-labeled substrates, and NMR analysis of reaction products, we could identify the major PtTPS5 products as (1S,5S,7R,10R)-guaia-4(15)-en-11-ol and (1S,7R,10R)-guaia-4-en-11-ol, with the former being a novel compound. The transcript accumulation of PtTPS5 in uninfected and P. cactorum-infected poplar roots matched the accumulation of (1S,5S,7R,10R)-guaia-4(15)-en-11-ol, (1S,7R,10R)-guaia-4-en-11-ol, and hedycaryol in this tissue, suggesting that PtTPS5 likely contributes to the pathogen-induced formation of these compounds in planta.

Integrated transcriptomic and metabolomic analyses reveal regulation of terpene biosynthesis in the stems of Sindora glabra.

Sesquiterpenes are important defensive secondary metabolites that are synthesized in various plant organs. Methyl jasmonate (MeJA) plays a key role in plant defense responses and secondary metabolism. Sindora glabra Merr. ex de Wit produces abundant sesquiterpenes in its trunks, and was subjected to investigation after MeJA treatment in order to characterize the molecular mechanisms underlying the regulation of sesquiterpene biosynthesis in plant stems and further our understanding of oleoresin production in trees. A total of 14 types of sesquiterpenes in the stems of mature S. glabra trees were identified. The levels of two sesquiterpenes, α-copaene and ß-caryophyllene, significantly increased after MeJA treatment. Differentially expressed genes involved in terpenoid backbone biosynthesis were significantly enriched over time, while the expression of JAZ genes involved in the jasmonic acid signaling pathway and TGA genes involved in the salicylic acid signaling pathway was significantly enriched at later time points after treatment. Two new terpene synthase genes, SgSTPS4 and SgSTPS5, were also identified. Following MeJA treatment, the expression levels of SgSTPS1, SgSTPS2 and SgSTPS4 decreased, while SgSTPS5 expression increased. The major enzymatic products of SgSTPS4 were identified as ß-elemene and cyperene, while SgSTPS5 was identified as a bifunctional mono/sesquiterpene synthase that could catalyze farnesyl pyrophosphate to produce nine types of sesquiterpenes, including α-copaene and ß-caryophyllene, while SgSTPS5 could also use geranyl pyrophosphate to produce geraniol. Dramatic changes in the amounts of α-copaene and ß-caryophyllene in response to MeJA were correlated with transcriptional expression changes of SgSTPS5 in the wood tissues. In addition, the transcription factors MYB, NAC, ARF, WRKY, MYC, ERF and GRAS were co-expressed with terpene biosynthesis genes and might potentially regulate terpene biosynthesis. Metabolite changes were further investigated with UPLC-TOF/MS following MeJA treatment. These results contribute to the elucidation of the molecular mechanisms of terpene biosynthesis and regulation as well as to the identification of candidate genes involved in these processes.

De novo assembly of the Mylia taylorii transcriptome and identification of sesquiterpene synthases.

Mylia taylorii is an ancient nonseed land plant that accumulates various sesquiterpenes with insecticidal and antibacterial activities. Recently, microbial-type sesquiterpene synthases (STSs) with atypical aspartate-rich metal ion binding motifs have been identified in some liverworts. Here, transcriptome analysis of M. taylorii was performed to identify M. taylorii sesquiterpene synthases (MtSTSs) that are potentially involved in sesquiterpene biosynthesis and diversity. A total of 255,669 unigenes were obtained with an average length of 963 bp in the transcriptome data of M. taylorii, among which 148,093 (57.92%) unigenes had BLAST results. Forty-eight unigenes were related to the sesquiterpene backbone biosynthesis according to KEGG annotation. In addition, MtSTS1, MtSTS2 and MtSTS3 identified from putative MtSTSs display sesquiterpene catalytic activities on the basis of functional characterizations in yeast. Interestingly, MtSTSs exhibit a noncanonical metal ion binding motif and the structural composition of a single α-domain, which are features of microbial STSs instead of archetypical plant STSs. This study revealed new microbial-type STS members of nonseed plants, and functionally identified that MtSTSs may contribute to the investigation of the biosynthesis and biological role of sesquiterpenes in M. taylorii.

Characterization of defensive cadinenes and a novel sesquiterpene synthase responsible for their biosynthesis from the invasive Eupatorium adenophorum.

Eupatorium adenophorum is a malignant invasive plant possessing extraordinary defense potency, but its chemical weaponry and formation mechanism have not yet been extensively investigated. We identified six cadinene sesquiterpenes, including two volatiles (amorpha-4,7(11)-diene and (-)-amorph-4-en-7-ol) and four nonvolatiles (9-oxo-10,11-dehydroageraphorone, muurol-4-en-3,8-dione, 9-oxo-ageraphorone and 9ß-hydroxy-ageraphorone), as the major constitutive and inducible chemicals of E. adenophorum. All cadinenes showed potent antifeedant activity against a generalist insect Spodoptera exigua, indicating that they have significant defensive roles. We cloned and functionally characterized a sesquiterpene synthase from E. adenophorum (EaTPS1), catalyzing the conversion of farnesyl diphosphate to amorpha-4,7(11)-diene and (-)-amorph-4-en-7-ol, which were purified from engineered Escherichia coli and identified by extensive nuclear magnetic resonance (NMR) spectroscopy. EaTPS1 was highly expressed in the aboveground organs, which was congruent with the dominant distribution of cadinenes, suggesting that EaTPS1 is likely involved in cadinene biosynthesis. Mechanical wounding and methyl jasmonate negatively regulated EaTPS1 expression but caused the release of amorpha-4,7(11)-diene and (-)-amorph-4-en-7-ol. Nicotiana benthamiana transiently expressing EaTPS1 also produced amorpha-4,7(11)-diene and (-)-amorph-4-en-7-ol, and showed enhanced defense function. The findings presented here uncover the role and formation of the chemical defense mechanism of E. adenophorum - which probably contributes to the invasive success of this plant - and provide a tool for manipulating the biosynthesis of biologically active cadinene natural products.

Research advances in methods of cyclezation mechanism of sesquiterpenes / 中国中药杂志

Terpenes are the largest group of natural products and contain the widest assortment of structural types. Terpene cyclization is also the most complex reaction found in nature. For a long time, terpenoids with diverse structures have attracted natural product chemists to explore their biosynthesis mechanism. Such a large number of terpene skeletons are catalyzed by enzymes called terpene synthase. Sesquiterpene synthase is a kind of terpene synthase, which can catalyze the cyclization of linear precursor farnesyl pyrophosphate(FPP) to sesquiterpene skeletons. Sesquiterpene synthase cyclize a single precursor FPP into many sesquiterpene skeletons. With the continuous discovery of sesquiterpene synthase, the cyclization mechanism of sesquiterpene synthase has been studied deeply. In recent years, with the development and improvement of isotope labeling of substrate FPP and structural analysis of sesquiterpene synthase, the structure and cyclization mechanism of sesquiterpene synthase have been studied more systematically and accurately. In this review, we reviewed the progress of the research methods on the mechanism of sesquiterpene cyclization by substrate isotope labeling and protein structure, as well as the summary and prospect of sesquiterpene synthase research.

Advances in biosynthesis of cadinane sesquiterpenes / 生物工程学报

Cadinanes are a class of bicyclic sesquiterpenes with complex stereochemistry and broad pharmacological activities, such as antibacterial, anti-inflammatory, and hypoglycemic activities. To date, structurally diverse and bioactive cadinane sesquiterpenes have been isolated and identified from a variety of plants and microorganisms. Moreover, deeper understandings on cadinane sesquiterpene synthases have been made. This article categorized the 124 new cadinanes which were published in the literatures in the past four years (2017-2020) into five structural types, and presented their pharmacological activities. We also illustrated the elucidation of the biosynthetic pathways for typical cadinanes, summarized the research progress on cadinane sesquiterpene synthases. Finally, current challenges and future prospects were proposed and discussed.