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1.
J Nat Med ; 2020 Jun 22.
Artigo em Inglês | MEDLINE | ID: mdl-32572667

RESUMO

The article Biosynthesis of medicinally important plant metabolites by unusual.

2.
J Nat Med ; 2020 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-32500363

RESUMO

Recent research progress on the "second generation" type III polyketide synthases is summarized. This class of enzymes catalyzes unusual condensation chemistries of CoA thioesters to generate various core structures of medicinally important plant secondary metabolites, including the R1-C-R2 scaffold of alkyl quinolones, curcuminoids, as well as the 8-azabicyclo[3.2.1]octane ring of tropane alkaloids. The discovery of this fascinating enzyme superfamily provides excellent opportunities for the manipulation of the enzyme reactions to expand the supply of natural and unnatural molecules for future drug development.

3.
Org Lett ; 22(11): 4311-4315, 2020 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-32402203

RESUMO

The biosynthetic gene cluster of the fungal meroterpenoid emeridone F (8) was discovered in the genome of Aspergillus sp. TJ23, and its late-stage biosynthesis was elucidated by characterizing two α-ketoglutarate (αKG)-dependent dioxygenases, SptF and SptN. SptF catalyzes oxidative rearrangement followed by epoxidation, whereas SptN serves as the C-9 hydroxylase. Our study provides insight into the biosynthetic mechanisms of other andiconin (1)-derived natural products, exemplifying the important roles of αKG-dependent enzymes in the structural complexifications.

4.
Artigo em Inglês | MEDLINE | ID: mdl-32364293

RESUMO

The alkyne is a biologically significant moiety found in many natural products and a versatile functional group widely used in modern chemistry. Recent studies have revealed the biosynthesis of acetylenic bonds in fatty acids and amino acids. However, the molecular basis for the alkynyl moiety in acetylenic prenyl chains occurring in a number of meroterpenoids remains obscure. Here, we identify the biosynthetic gene cluster and characterize the biosynthetic pathway of an acetylenic meroterpenoid biscognienyne B based on heterologous expression, feeding experiments, and in vitro assay. This work shows that the alkyne moiety is constructed by an unprecedented cytochrome P450 enzyme BisI, which shows promiscuous activity towards C5 and C15 prenyl chains. This finding provides an opportunity for discovery of new compounds, featuring acetylenic prenyl chains, through genome mining, and it also expands the enzyme inventory for de novo biosynthesis of alkynes.

5.
J Nat Med ; 74(3): 571-578, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32328863

RESUMO

Three new quassinoids, javanicinols A and B (1 and 2) and 4-keto-(16S)-methoxyjavanicin B (3), together with three known quassinoids (4-6) were isolated from the chloroform-soluble fraction of the methanol extract of the Picrasma javanica wood. The structures of 1-3 were determined by spectroscopic analyses, including 1D and 2D NMR, HRESIMS, and CD. The anti-HIV-1 viral protein R (Vpr) assay revealed that 1 and 2 exhibited potent anti-Vpr activities at 1.25 µM. Furthermore, the assay also revealed the potent anti-Vpr activities of (16R)-methoxyjavanicin B (7) and (16S)-methoxyjavanicin B (8), which were previously isolated from the Picrasma javanica wood.

6.
Nat Commun ; 11(1): 1473, 2020 03 19.
Artigo em Inglês | MEDLINE | ID: mdl-32193380

RESUMO

Caffeine is a major component of xanthine alkaloids and commonly consumed in many popular beverages. Due to its occasional side effects, reduction of caffeine in a natural way is of great importance and economic significance. Recent studies reveal that caffeine can be converted into non-stimulatory theacrine in the rare tea plant Camellia assamica var. kucha (Kucha), which involves oxidation at the C8 and methylation at the N9 positions of caffeine. However, the underlying molecular mechanism remains unclear. Here, we identify the theacrine synthase CkTcS from Kucha, which possesses novel N9-methyltransferase activity using 1,3,7-trimethyluric acid but not caffeine as a substrate, confirming that C8 oxidation takes place prior to N9-methylation. The crystal structure of the CkTcS complex reveals the key residues that are required for the N9-methylation, providing insights into how caffeine N-methyltransferases in tea plants have evolved to catalyze regioselective N-methylation through fine tuning of their active sites. These results may guide the future development of decaffeinated drinks.

7.
Prog Chem Org Nat Prod ; 111: 1-79, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32114662

RESUMO

Sesterterpenoids are known as a relatively small group of natural products. However, they represent a variety of simple to more complex structural types. This contribution focuses on the chemical structures of sesterterpenoids and how their structures are constructed in Nature.


Assuntos
Produtos Biológicos/química , Sesterterpenos/química
8.
Chem Commun (Camb) ; 56(33): 4607-4610, 2020 Apr 28.
Artigo em Inglês | MEDLINE | ID: mdl-32211655

RESUMO

Sporormielones A-E (1-5), novel C-C coupled orsellinic acid derivative dimers containing tricyclic cores with a dimethylcyclopentenone unit, were obtained, of which 1-3 and 5 showed obvious short-term memory improvement activity in AD flies. Based on transcriptome analysis, 13C labelling, and gene deletion, their plausible biosynthetic mechanism was proposed.

9.
Angew Chem Int Ed Engl ; 59(10): 3988-3993, 2020 Mar 02.
Artigo em Inglês | MEDLINE | ID: mdl-31886618

RESUMO

C-S bond formation reactions are widely distributed in the biosynthesis of biologically active molecules, and thus have received much attention over the past decades. Herein, we report intramolecular C-S bond formation by a P450 monooxygenase, TleB, which normally catalyzes a C-N bond formation in teleocidin biosynthesis. Based on the proposed reaction mechanism of TleB, a thiol-substituted substrate analogue was synthesized and tested in the enzyme reaction, which afforded the unprecedented sulfur-containing thio-indolactam V, in addition to an unusual indole-fused 6/5/8-tricyclic product whose structure was determined by the crystalline sponge method. Interestingly, conformational analysis revealed that the SOFA conformation is stable in thio-indolactam V, in sharp contrast to the major TWIST form in indolactam V, resulting in differences in their biological activities.

10.
Nat Chem Biol ; 15(12): 1206-1213, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31636430

RESUMO

The catalytic versatility of cytochrome P450 monooxygenases is remarkable. Here, we present mechanistic and structural characterizations of TleB from Streptomyces blastmyceticus and its homolog HinD from Streptoalloteichus hindustanus, which catalyze unusual intramolecular C-N bond formation to generate indolactam V from the dipeptide N-methylvalyl-tryptophanol. In vitro analyses demonstrated that both P450s exhibit promiscuous substrate specificity, and modification of the N13-methyl group resulted in the formation of indole-fused 6/5/6 tricyclic products. Furthermore, X-ray crystal structures in complex with substrates and structure-based mutagenesis revealed the intimate structural details of the enzyme reactions. We propose that the generation of a diradical species is critical for the indolactam formation, and that the intramolecular C(sp2)-H amination is initiated by the abstraction of the N1 indole hydrogen. After indole radical repositioning and subsequent removal of the N13 hydrogen, the coupling of the properly-folded diradical leads to the formation of the C4-N13 bond of indolactam.


Assuntos
Sistema Enzimático do Citocromo P-450/metabolismo , Lactamas/metabolismo , Catálise , Streptomyces/metabolismo , Especificidade por Substrato
11.
Angew Chem Int Ed Engl ; 58(45): 16141-16146, 2019 11 04.
Artigo em Inglês | MEDLINE | ID: mdl-31515901

RESUMO

A biomimetic route to farnesyl pyrophosphate and dimethyl orsellinic acid (DMOA)-derived meroterpenoid scaffolds has yet to be reported despite great interest from the chemistry and biomedical research communities. A concise synthetic route with the potential to access DMOA-derived meroterpenoids is highly desirable to create a library of related compounds. Herein, we report novel dearomatization methodology followed by polyene cyclization to access DMOA-derived meroterpenoid frameworks in six steps from commercially available starting materials. Furthermore, several farnesyl alkene substrates were used to generate structurally novel, DMOA-derived meroterpenoid derivatives. DFT calculations combined with experimentation provided a rationale for the observed thermodynamic distribution of polycyclization products.

12.
J Biol Chem ; 294(41): 15121-15136, 2019 Oct 11.
Artigo em Inglês | MEDLINE | ID: mdl-31471316

RESUMO

Type III polyketide synthases (PKSs) produce an incredibly diverse group of plant specialized metabolites with medical importance despite their structural simplicity compared with the modular type I and II PKS systems. The type III PKSs use homodimeric proteins to construct the molecular scaffolds of plant polyketides by iterative condensations of starter and extender CoA thioesters. Ever since the structure of chalcone synthase (CHS) was disclosed in 1999, crystallographic and mutational studies of the type III PKSs have explored the intimate structural features of these enzyme reactions, revealing that seemingly minor alterations in the active site can drastically change the catalytic functions and product profiles. New structures described in this review further build on this knowledge, elucidating the detailed catalytic mechanism of enzymes that make curcuminoids, use extender substrates without the canonical CoA activator, and use noncanonical starter substrates, among others. These insights have been critical in identifying structural features that can serve as a platform for enzyme engineering via structure-guided and precursor-directed engineered biosynthesis of plant polyketides. In addition, we describe the unique properties of the recently discovered "second-generation" type III PKSs that catalyzes the one-pot formation of complex molecular scaffolds from three distinct CoA thioesters or from "CoA-free" substrates, which are also providing exciting new opportunities for synthetic biology approaches. Finally, we consider post-type III PKS tailoring enzymes, which can also serve as useful tools for combinatorial biosynthesis of further unnatural novel molecules. Recent progress in the field has led to an exciting time of understanding and manipulating these fascinating enzymes.

13.
Chem Pharm Bull (Tokyo) ; 67(8): 775-777, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31366826

RESUMO

Nocardia is a potent bacterial producer of bioactive compounds. From a culture of Nocardia beijingensis NBRC 16342, we isolated four aromatic compounds, named beijinchromes A-D (1-4). We purified them by silica gel chromatography and reverse phase HPLC, and identified their structures by NMR and high resolution (HR)-MS analyses. 1, 2, and 4 are novel 1,2,3,8-tetrasubstituted naphthalenes, and 3 is a novel 3,8-disubstituted ortho-naphthoquinone. 1 and 2 exert antioxidant activities, and 3 exhibits antibiotic activity. Remarkably, the putative biosynthetic gene clusters for 1-4 are widely distributed in 37 Nocardia species, implying their potential to produce this family of compounds and important biological functions of beijinchromes.


Assuntos
Naftalenos/química , Naftoquinonas/química , Nocardia/química , Estrutura Molecular , Naftalenos/isolamento & purificação , Naftalenos/farmacologia , Naftoquinonas/isolamento & purificação , Naftoquinonas/farmacologia , Estereoisomerismo
14.
Org Lett ; 21(16): 6519-6522, 2019 08 16.
Artigo em Inglês | MEDLINE | ID: mdl-31386371

RESUMO

Tenebrathin (1), a new C-5-substituted γ-pyrone with a nitroaryl side chain, was isolated from the rare actinomycete Streptoalloteichus tenebrarius NBRC 16177. The chemical structure of 1 was elucidated by a spectroscopic analysis using the crystalline sponge method of crystallization-free X-ray crystallography. The biosynthetic origin of the unusual C-5-substituted γ-pyrone in 1 was revealed by a 13C-labeling experiment. Compound 1 exhibited moderate cytotoxicity against several cancer cell lines and likely targets some protein kinases.

15.
Beilstein J Org Chem ; 15: 1890-1897, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31467610

RESUMO

We previously showed that the regio- and stereoselectivity in terpene-forming reactions are determined by the conformations of the carbocation intermediates, which reflect the initial conformation of the substrate, geranylfarnesyl diphosphate (GFPP). However, it remains unclear how the initial conformation of GFPP is controlled, and which part(s) of the GFPP molecule are important for its fixation inside the substrate-binding pocket. Here, we present the first detailed analysis of the inherent atomic mobility in carbocation intermediates during sesterterpene biosynthesis. We identified two methyl groups as the least mobile of all the carbons of the carbocation intermediates in the first half of the cyclization cascade. Our analysis suggests that these two methyl groups are critical for the preorganization of GFPP in the biosynthetic pathways leading to sesterfisherol and quiannulatene.

16.
Beilstein J Org Chem ; 15: 1545-1551, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31354873

RESUMO

Aromatic prenyltransferases (PTases) are enzymes that catalyze Friedel-Crafts reactions between aromatic compounds and isoprenoid diphosphates. In hapalindole biosynthesis, the aromatic PTases AmbP1 and AmbP3 exhibit surprisingly plastic selectivities. AmbP1 not only transfers the geranyl group on the C-3 of cis-indolylvinyl isonitrile, but also on the C-2, which is supressed in the presence of Mg2+ ions. AmbP3 transfers the dimethylallyl group on C-2 of hapalindole U in the reverse manner, but on C-2 of its C-10 stereoisomer in the normal manner. This review highlights the molecular bases of the AmbP1 and AmbP3 functions, elucidated through their X-ray crystal structures. The knowledge presented here will contribute to the understanding of aromatic PTase reactions and will enhance their uses as biocatalysts.

17.
J Biosci Bioeng ; 128(4): 445-449, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31076338

RESUMO

Viral protein R (Vpr) is a small, basic accessory protein (14 kDa) that is well conserved in Human immunodeficiency virus-1 (HIV-1), HIV-2, and simian immunodeficiency virus (SIV). Numerous investigations over the past 2 decades have suggested that Vpr would be an attractive target for HIV disease treatment. Small molecules, including fumagillin, damnacanthal, quercetin, vipirinin, isopimarane diterpenoids, picrasane quassinoids, iridoids, and bis-iridoid glycosides, have been reported as potent Vpr inhibitors. These compounds may not only represent HIV drug seeds, but also could be new target compounds for biochemical synthesis such as current synthetic biology and enzyme bioengineering approaches, due to their anti-Vpr activities. In our investigations of different types of compounds with Vpr inhibitory activity, we found that the CHCl3 soluble, crude extract of the whole Swertia chirata plant inhibited the expression of Vpr in Hela cells harboring the TREx plasmid encoding full-length Vpr (TREx-HeLa-Vpr cells). The purification and isolation of the active CHCl3 soluble portion afforded six secondary metabolites, including four xanthone derivatives, decussatine (1), methylswertianin (2), 1-hydroxy-3,5-dimethoxyxanthone (3), and bellidifolin (4), and two triterpenoids, oleanolic acid (5) and 12-hydroxyoleanolic lactone (6). The evaluation of the anti-Vpr activities of 1, 2, and 4-6 against TREx-HeLa-Vpr cells revealed that 4 and 5 are potent Vpr inhibitors with an effective dose of 10 µM, and are chemically and structurally distinct from previously reported inhibitors.


Assuntos
Produtos do Gene vpr/antagonistas & inibidores , Swertia/química , Antivirais/farmacologia , Células HeLa , Humanos , Xantonas/farmacologia
18.
Acta Pharm Sin B ; 9(2): 433-442, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30972287

RESUMO

Fusidic acid is the only fusidane-type antibiotic that has been clinically used. However, biosynthesis of this important molecule in fungi is poorly understood. We have recently elucidated the biosynthesis of fusidane-type antibiotic helvolic acid, which provides us with clues to identify a possible gene cluster for fusidic acid (fus cluster). This gene cluster consists of eight genes, among which six are conserved in the helvolic acid gene cluster except fusC1 and fusB1. Introduction of the two genes into the Aspergillus oryzae NSAR1 expressing the conserved six genes led to the production of fusidic acid. A stepwise introduction of fusC1 and fusB1 revealed that the two genes worked independently without a strict reaction order. Notably, we identified two short-chain dehydrogenase/reductase genes fusC1 and fusC2 in the fus cluster, which showed converse stereoselectivity in 3-ketoreduction. This is the first report on the biosynthesis and heterologous expression of fusidic acid.

19.
Proc Natl Acad Sci U S A ; 116(17): 8269-8274, 2019 04 23.
Artigo em Inglês | MEDLINE | ID: mdl-30952781

RESUMO

Ascofuranone (AF) and ascochlorin (AC) are meroterpenoids produced by various filamentous fungi, including Acremonium egyptiacum (synonym: Acremonium sclerotigenum), and exhibit diverse physiological activities. In particular, AF is a promising drug candidate against African trypanosomiasis and a potential anticancer lead compound. These compounds are supposedly biosynthesized through farnesylation of orsellinic acid, but the details have not been established. In this study, we present all of the reactions and responsible genes for AF and AC biosyntheses in A. egyptiacum, identified by heterologous expression, in vitro reconstruction, and gene deletion experiments with the aid of a genome-wide differential expression analysis. Both pathways share the common precursor, ilicicolin A epoxide, which is processed by the membrane-bound terpene cyclase (TPC) AscF in AC biosynthesis. AF biosynthesis branches from the precursor by hydroxylation at C-16 by the P450 monooxygenase AscH, followed by cyclization by a membrane-bound TPC AscI. All genes required for AC biosynthesis (ascABCDEFG) and a transcriptional factor (ascR) form a functional gene cluster, whereas those involved in the late steps of AF biosynthesis (ascHIJ) are present in another distantly located cluster. AF is therefore a rare example of fungal secondary metabolites requiring multilocus biosynthetic clusters, which are likely to be controlled by the single regulator, AscR. Finally, we achieved the selective production of AF in A. egyptiacum by genetically blocking the AC biosynthetic pathway; further manipulation of the strain will lead to the cost-effective mass production required for the clinical use of AF.


Assuntos
Acremonium , Alcenos , Fenóis , Sesquiterpenos , Acremonium/enzimologia , Acremonium/genética , Acremonium/metabolismo , Alcenos/química , Alcenos/metabolismo , Vias Biossintéticas/fisiologia , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Genes Fúngicos/genética , Modelos Moleculares , Família Multigênica/genética , Fenóis/química , Fenóis/metabolismo , Sesquiterpenos/química , Sesquiterpenos/metabolismo
20.
Org Lett ; 21(7): 2330-2334, 2019 04 05.
Artigo em Inglês | MEDLINE | ID: mdl-30900461

RESUMO

Ascochlorin is a medicinally important fungal meroterpenoid. Its biosynthetic pathway in Fusarium sp. was identified, and the stereoselective epoxidation of the farnesyl group by the multidomain, soluble P450 monooxygenase AscE and the subsequent formation of the unique timethylcyclohexanone ring by the membrane-bound cyclase AscF were investigated. Precursor-directed biosynthesis generated novel bromo-substituted derivatives, which exhibited potent cytotoxic activities. This study paves the way for the future metabolic engineering of medicinally important meroterpenoids for drug discovery.


Assuntos
Alcenos/química , Fungos/metabolismo , Fusarium/química , Oxigenases de Função Mista/metabolismo , Oxirredutases/metabolismo , Fenóis/química , Terpenos/química , Vias Biossintéticas , Oxigenases de Função Mista/química , Estrutura Molecular , Oxirredutases/química , Oxirredutases/isolamento & purificação , Terpenos/isolamento & purificação
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