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Zingerone (vanillylacetone; 4-hydroxy-3-methoxyphenylethyl methyl ketone) is a key component responsible for the pungency of ginger (Zingiber officinale). In this study, it was confirmed that a type III polyketide synthase (PKS) gene (pmpks) from Piper methysticum exhibits feruloyl-CoA-preferred benzalacetone synthase (BAS) activity. Based on these results, we constructed an artificial biosynthetic pathway for zingerone production from supplemented ferulic acid with 4-coumarate CoA ligase (4CL), PmPKS, and benzalacetone reductase (BAR). Furthermore, a de novo pathway for the production of zingerone was assembled using six heterologous genes, encoding tyrosine ammonia-lyase (optal), cinnamate-4-hydroxlase (sam5), caffeic acid O-methyltransferase (com), 4CL (4cl2nt), BAS (pmpks), and BAR (rzs1), in Escherichia coli. Using the engineered l-tyrosine-overproducing E. coli ΔCOS4 strain as a host, a maximum yield of 24.03 ± 2.53 mg/L zingerone was achieved by complete de novo synthesis.

Six ansamycin derivatives were isolated from the culture broth of

A bioassay-guided investigation led to the isolation of three new carbazole glycosides, jejucarbazoles A–C (1–3), from Streptomyces sp. KCB15JA151. Their planar structures were elucidated by detailed NMR and MS spectroscopic analysis with a literature study. Their relative and absolute configurations were established by ROESY correlations, coupling constants, LC-MS analysis of thiocarbamoyl-thiazolidine carboxylate derivatives, and ECD calculation. Compounds 1–3 showed indoleamine 2,3-dioxygenase 1 (IDO1) inhibitory activity with IC50 values of 18.38, 9.17, and 8.81 μM. The molecular docking analysis suggested that all compounds act as heme-displacing inhibitors against IDO1 enzyme.

A LC-MS-guided screening led to the isolation of two new streptimidone derivatives (2 and 3) containing a glutarimide ring and two glutarimide ring-opened compounds (4 and 5) along with a known glutarimide-containing polyketide, streptimidone (1) from Streptomyces sp. W3002 strain. Their structures were elucidated by MS and NMR spectroscopic analyses and by comparison with data from the literature. Compound 2 is a non-hydroxylated analog at the C-5 position of streptimidone. The structure of 3 was determined as a streptimidone derivative possessing the α, β-unsaturated ketone moiety at positions C-5 and C-6. Compound 4 had similar chemical shifts and splitting patterns with 3, but the glutarimide ring is opened. Compound 5 closely resembles that of 4 with the only difference being the existence of an additional methoxy group instead of an amide group. Streptimidone (1) and 3 showed weak cytotoxic activity against three human cancer cell lines, respectively.

Zingerone (vanillylacetone; 4-hydroxy-3-methoxyphenylethyl methyl ketone) is a key component responsible for the pungency of ginger (

A bioassay-guided investigation led to the isolation of three new carbazole glycosides, jejucarbazoles A-C (1-3), from

New glycosylated 26-membered triene macrolides catenulisporolides, the first polyketide metabolites from Catenulispora species, were obtained by targeting slow-forming colonies on selection agar plates and applying long-term cultivation. Their structures, including the full stereochemistry, were defined by comprehensive spectroscopic and chemical methods and confirmed by bioinformatics analysis. Analysis of the genome sequence revealed the responsible biosynthetic gene cluster spanning ∼160 kbp, and feeding experiments with isotope-labeled precursors showed that isovaleric acid acts as a rare starter unit. Catenulisporolides exhibited antimalarial activities against resistant strains of Plasmodium falciparum, and enhanced activity was observed in semisynthetic derivatives.

One of the optimization strategies of an artificial biosynthetic metabolic flux with a multienzyme pathway is when the enzyme concentrations are present at the appropriate ratios rather than at their maximum expression. Thus, many recent research efforts have focused on the development of tools that fine-tune the enzyme expression, and these research efforts have facilitated the search for the optimum balance between pathway expression and cell viability. However, the rational approach has some limitations in finding the most optimized expression ratio in in vivo systems. In our study, we focused on fine-tuning the expression level of a six-enzyme reaction for the artificial biosynthesis of curcumin by screening a library of 5'-untranslational region (UTR) sequence mutants made by a multiplex automatic genome engineering (MAGE) tool. From the screening results, a variant (6M08rv) showed about a 38.2-fold improvement in the production of curcumin compared to the parent strain, in which the calculated expression levels of 4-coumarate:CoA ligase (4CL) and phenyldiketide-CoA synthase (DCS), two of the six enzymes, were much lower than those of the parent strain.

A new series comprising phenylacetyl-homoserine lactones (HSLs), caffeoyl-HSL and feruloyl-HSL, was biologically synthesized using an artificial de novo biosynthetic pathway. We developed an Escherichia coli system containing artificial biosynthetic pathways that yield phenylacetyl-HSLs from simple carbon sources. These artificial biosynthetic pathways contained the LuxI-type synthase gene (rpaI) in addition to caffeoyl-CoA and feruloyl-CoA biosynthetic genes, respectively. Finally, the yields for caffeoyl-HSL and feruloyl-HSL were 97.1 ± 10.3 and 65.2 ± 5.7 mg/l, respectively, by tyrosine-overproducing E. coli with a L-methionine feeding strategy. In a quorum sensing (QS) competition assay, feruloyl-HSL and p-coumaroyl-HSL antagonized the QS receptor TraR in Agrobacterium tumefaciens NT1, whereas caffeoyl-HSL did not.

Analysis of the genome sequence of Streptomyces sp. KCB13F003 showed the presence of a cryptic gene cluster encoding flavin-dependent halogenase and nonribosomal peptide synthetase. Pleiotropic approaches using multiple culture media followed by LC-MS-guided isolation and spectroscopic analysis enabled the identification of two new chlorinated cyclic hexapeptides, ulleungmycins A and B (1 and 2). Their structures, including absolute configurations, were determined by 1D and 2D NMR techniques, advanced Marfey's analysis, and GITC derivatization. The new peptides, featuring unusual amino acids 5-chloro-l-tryptophan and d-homoleucine, exhibited moderate antibacterial activities against Gram-positive pathogenic bacteria including methicillin-resistant and quinolone-resistant Staphylococcus aureus.

Piceatannol is an important natural stilbene, which show a broad range of biological activities of medicinal interest. In recent studies, the Sam5 enzyme from Saccharothrix espanaensis was found to catalyze the conversion of p-coumaric acid to caffeic acid as a coumarate 3-hydroxylase (C3H). In this report, we show that purified recombinant Sam5 enzyme exhibited 5.7-fold higher resveratrol ortho-hydroxylation (resveratrol 3’-hydroxylase; R3’H) activity to produce piceatannol compared to the C3H activity. The substrate saturation curve of the Sam5 enzyme for resveratrol is far superior to that for p-coumaric acid. In addition, we constructed a biological platform to produce piceatannol by adding a sam5 gene in a resveratrol artificial biosynthetic pathway that was already made. According to the results, piceatannol production as high as 31.5 ± 6.3 mg/L was achieved.

The flavin-dependent monooxygenase Sam5 was previously reported to be a bifunctional hydroxylase with a coumarte 3-hydroxylase and a resveratrol 3'-hydroxylase activity. In this article, we showed the Sam5 enzyme has 3'-hydroxylation activities for methylated resveratrol (pinostilbene and pterostilbene), hydroxylated resveratrol (oxyresveratrol) and glycosylated resveratrol (piceid) as substrates. However, the use of piceid, a glycone type stilbene, as a substrate for bioconversion experiments with the Sam5 enzyme expressed in, Escherichia coli does not convert to the hydroxylated compound astringin, but it has converted in vitro enzyme reactions. Finally, we report a novel catalytic activity of Sam5 monooxygenase for the synthesis of piceatannol derivatives, 3'-hydroxylated stilbene compounds. Development of this bioproduction method for the hydroxylation of stilbenes is challenging because of the difficulty in expressing P450-type hydroxylase in E. coli and regionspecific chemical synthesis.

Background Pterostilbene, a structural analog of resveratrol, has higher oral bioavailability and bioactivity than that of the parent compound; but is far less abundant in natural sources. Thus, to efficiently obtain this bioactive resveratrol analog, it is necessary to develop new bioproduction systems. Results We identified a resveratrol O-methyltransferase (ROMT) function from a multifunctional caffeic acid O-methyltransferase (COMT) originating from Arabidopsis, which catalyzes the transfer of a methyl group to resveratrol resulting in pterostilbene production. In addition, we constructed a biological platform to produce pterostilbene with this ROMT gene. Pterostilbene can be synthesized from intracellular l-tyrosine, which requires the activities of four enzymes: tyrosine ammonia lyase (TAL), p-coumarate:CoA ligase (CCL), stilbene synthase (STS) and resveratrol O-methyltransferase (ROMT). For the efficient production of pterostilbene in E. coli, we used an engineered E. coli strain to increase the intracellular pool of l-tyrosine, which is the initial precursor of pterostilbene. Next, we tried to produce pterostilbene in the engineered E. coli strain using l-methionine containing media, which is used to increase the intracellular pool of S-adenosyl-l-methionine (SAM). According to this result, pterostilbene production as high as 33.6 ± 4.1 mg/L was achieved, which was about 3.6-fold higher compared with that in the parental E. coli strain harboring a plasmid for pterostilbene biosynthesis. Conclusion As a potential phytonutrient, pterostilbene was successfully produced in E. coli from a glucose medium using a single vector system, and its production titer was also significantly increased using a l-methionine containing medium in combination with a strain that had an engineered metabolic pathway for l-tyrosine. Additionally, we provide insights into the dual functions of COMT from A. thaliana which was characterized as a ROMT enzyme. Electronic supplementary material The online version of this article (doi:10.1186/s12934-017-0644-6) contains supplementary material, which is available to authorized users.