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Mushroom terpenoids are biologically and chemically diverse fungal metabolites. Among them, melleolides are representative sesquiterpenoids with a characteristic protoilludane skeleton. In this study, we applied a recently established hot spot knock‐in method to elucidate the biosynthetic pathway leading to 1α‐hydroxymelleolide. The biosynthesis of the sesquiterpene core involves the cytochrome P450 catalyzing stepwise hydroxylation of the Δ6‐protoilludene framework and a stereochemical inversion process at the C5 position catalyzed by short‐chain dehydrogenase/reductase family proteins. The highlight of the biosynthesis is that the flavoprotein Mld7 catalyzes an oxidation‐triggered double‐bond shift accompanying dehydration and acyl‐group‐assisted substitution with two different nucleophiles at the C6 position to afford the Δ7‐protoilludene derivatives, such as melleolide and armillarivin. The complex reaction mechanism was proposed by DFT calculations. Of particular importance is that product distribution is regulated by interaction with the cell membrane. [ABSTRACT FROM AUTHOR]

Plant-associated fungi show diverse lifestyles from pathogenic to mutualistic to the host; however, the principles and mechanisms through which they shift the lifestyles require elucidation. The root fungus Colletotrichum tofieldiae (Ct) promotes Arabidopsis thaliana growth under phosphate limiting conditions. Here we describe a Ct strain, designated Ct3, that severely inhibits plant growth. Ct3 pathogenesis occurs through activation of host abscisic acid pathways via a fungal secondary metabolism gene cluster related to the biosynthesis of sesquiterpene metabolites, including botrydial. Cluster activation during root infection suppresses host nutrient uptake-related genes and changes mineral contents, suggesting a role in manipulating host nutrition state. Conversely, disruption or environmental suppression of the cluster renders Ct3 beneficial for plant growth, in a manner dependent on host phosphate starvation response regulators. Our findings indicate that a fungal metabolism cluster provides a means by which infectious fungi modulate lifestyles along the parasitic–mutualistic continuum in fluctuating environments. Plant-associated fungi range from pathogens to mutualists. Here the authors identify a gene cluster in a Colletotrichum tofieldiae strain that is required to allow the fungus to transition from a mutualist to a pathogen depending on the nutritional status of the host. [ABSTRACT FROM AUTHOR]

Covering: 2013 to 2022 In this review, we provide an overview elucidating the biosynthetic pathway and heterologous production of fungal indole diterpenes (IDTs). Based on the studies of six IDT biosynthesis, we extracted nature's strategy: (1) two-stage synthesis for the core scaffold and platform intermediates, and (2) late-stage modifications for installing an additional cyclic system on the indole ring. Herein, we describe reconstitution studies applying this strategy to the synthesis of highly elaborated IDTs. We also discuss its potential for future biosynthetic engineering. [ABSTRACT FROM AUTHOR]

UstYa family proteins (DUF3328) are widely and specifically distributed in fungi. They are known to be involved in the biosynthesis of ribosomally synthesized and posttranslationally modified peptides (RiPPs) and nonribosomal peptides, and possibly catalyze various reactions, including oxidative cyclization and chlorination. In this study, we focused on phomopsin A, a fungal RiPP consisting of unique nonproteinogenic amino acids. Gene knockout experiments demonstrated that three UstYa homologues, phomYc, phomYd, and phomYe, are essential for the desaturation of amino acid moieties, showing unprecedented function among UstYa family proteins. Sequence similarity network analysis indicated that their amino acid sequences are highly diverged and that most remain uncharacterized, paving the way for genome mining of fungal metabolites with unique modifications. [ABSTRACT FROM AUTHOR]

Lolitrems are tremorgenic indole diterpenes that exhibit a unique 5/6 bicyclic system of the indole moiety. Although genetic analysis has indicated that the prenyltransferase LtmE and the cytochrome P450 LtmJ are involved in the construction of this unique structure, the detailed mechanism remains to be elucidated. Herein, we report the reconstitution of the biosynthetic pathway for lolitrems employing a recently established genome‐editing technique for the expression host Aspergillus oryzae. Heterologous expression and bioconversion of the various intermediates revealed that LtmJ catalyzes multistep oxidation to furnish the lolitrem core. We also isolated the key reaction intermediate with an epoxyalcohol moiety. This observation allowed us to establish the mechanism of radical‐induced cyclization, which was firmly supported by density functional theory calculations and a model experiment with a synthetic analogue. [ABSTRACT FROM AUTHOR]

Fungal polyketide synthase (PKS)–nonribosomal peptide synthetase (NRPS) hybrids are key enzymes for synthesizing structurally diverse hybrid natural products (NPs) with characteristic biological activities. Predicting their chemical space is of particular importance in the field of natural product chemistry. However, the unexplored programming rule of the PKS module has prevented prediction of its chemical structure based on amino acid sequences. Here, we conducted a phylogenetic analysis of 884 PKS–NRPS hybrids and a modification enzyme analysis of the corresponding biosynthetic gene cluster, revealing a hidden relationship between its genealogy and core structures. This unexpected result allowed us to predict 18 biosynthetic gene cluster (BGC) groups producing known carbon skeletons (number of BGCs; 489) and 11 uncharacterized BGC groups (171). The limited number of carbon skeletons suggests that fungi tend to select PK skeletons for survival during their evolution. The possible involvement of a horizontal gene transfer event leading to the diverse distribution of PKS–NRPS genes among fungal species is also proposed. This study provides insight into the chemical space of fungal PKs and the distribution of their biosynthetic gene clusters. [ABSTRACT FROM AUTHOR]

Covering: 2000 to 2019 Rapid access to genomic data has facilitated the identification of the biosynthetic enzyme genes of alkaloid natural products and elucidation of their biosynthetic pathways. Enzymes for the rapid construction of molecular scaffolds and versatile modifications during the late-stage biosynthesis of complex molecular skeletons constitute unique features of biosynthetic machineries. For example, enzymes involved in an alkaloid biosynthesis. In this review, we discuss three types of useful enzymes and enzymatic reactions that have been found in the biosynthetic studies of several alkaloids, and discuss their applications for the total synthesis of natural alkaloids and their derivatives. The selected examples include a single non-ribosomal peptide synthetase SfmC that catalyzes key Pictet–Spengler reactions, which construct a characteristic tetrahydroisoquinoline skeleton in antitumor antibiotics such as saframycin, prenylation–oxidative modification enzymes involved in the biosynthesis of fungal tremorgenic mycotoxins such as penitrem as well as versatile Diels-Alderases recently discovered in the biosynthesis of plant monoterpene indole alkaloids of iboga and aspidosperma type. [ABSTRACT FROM AUTHOR]

The first enzymatic conversions of bisepoxides into lasalocid skeletons are described. The studies have shown that lasalocid biosynthetic genes Lsd19 is regarded as a model enzyme for studying multiple catalysis and regioselectivity in intramolecular cyclic ether formation.

Conidiogenone, a diterpene with a unique structure, is known to induce the conidiation of Penicillium cyclopium. The biosynthetic pathway of (−)-conidiogenone has been fully elucidated by the heterologous expression of biosynthetic genes in Aspergillus oryzae and by in vitro enzyme assay with 13C-labeled substrates. After construction of deoxyconidiogenol by the action of bifunctional terpene synthase, one cytochrome P450 catalyzes two rounds of oxidation to furnish conidiogenone. Notably, similar biosynthetic genes are conserved among more than 10 Penicillium sp., suggesting that conidiogenone is a common conidiation inducer in this genus. The cyclization mechanism catalyzed by terpene synthase, which involves successive 1,2-alkyl shifts, was fully elucidated using 13C-labeled geranylgeranyl pyrophosphate (GGPP) as substrate. During the structural analysis of deoxyconidiogenol, we observed broadening of some of the 13C signals measured at room temperature, which has not been observed with other structurally related compounds. Careful examination using techniques including 13C NMR studies at −80 °C, conformational analysis and prediction of the 13C chemical shifts using density functional theory gave insights into this intriguing phenomenon. [ABSTRACT FROM AUTHOR]

Abstract: Longestin (KS‐505a), a specific inhibitor of phosphodiesterase, is a meroterpenoid that consists of a unique octacyclic terpene skeleton with branched methyl groups at unusual positions (C1 and C12). Biochemical analysis of Lon23, a methyltransferase involved in the biosynthesis of longestin, demonstrated that it methylates homoisopentenyl diphosphate (homo‐IPP) to afford (3Z)‐3‐methyl IPP. This compound, along with IPP, is selectively accepted as extender units by Lon22, a geranylgeranyl diphosphate (GGPP) synthase homologue, to yield dimethylated GGPP (dmGGPP). The absolute configuration of dmGGPP was determined to be (4R,12R) by degradation and chiral GC analysis. These findings allowed us to propose an enzymatic sequence for key steps of the biosynthetic pathway of the unusual homoterpenoid longestin. [ABSTRACT FROM AUTHOR]

The biosynthetic machinery of the first fungal ribosomally synthesized and post-translationally modified peptide (RiPP) ustiloxinB was elucidated through a series of gene inactivation and heterologous expression studies. The results confirmed an essential requirement for novel oxidases possessing the DUF3328 motif for macrocyclization, and highly unique side-chain modifications by three oxidases (UstCF1F2) and a pyridoxal 5'-phosphate (PLP)-dependent enzyme (UstD). These findings provide new insight into the expression of the RiPP gene clusters found in various fungi. [ABSTRACT FROM AUTHOR]

A unique highly reducing polyketide synthase (HR-PKS) with a reductase domain was identified in a betaenone biosynthetic gene cluster. Successful heterologous expression and characterization of the HR-PKS and trans-acting enoyl reductase (ER) provide insights into the core structure formation with a decalin scaffold and allow reconstitution of the betaenone biosynthetic machinery. [ABSTRACT FROM AUTHOR]

The biosynthetic gene cluster of antifungal agent jawsamycin (FR-900848) has been identified by heterologous expression. A series of gene inactivations and in vitro and in vivo analysis of key enzymes in the biosynthetic pathway established their functions. A novel mechanism involving a radical S-adenosyl methionine (SAM) cyclopropanase collaborating with an iterative polyketide synthase is proposed for the construction of the unique polycyclopropanated backbone. Our reconstitution system sets the stage for studying the catalytic mechanism of this intriguing contiguous cyclopropanation. [ABSTRACT FROM AUTHOR]

Paxilline is an indole-diterpene produced by Penicillium paxilli. Six genes ( paxB, C, G, M, P, and Q) in paxilline biosynthetic gene cluster were previously shown to be responsible for paxilline biosynthesis. In this study, we have characterized paxD, which is located next to paxQ and has weak similarities to fungal dimethylallyl tryptophan synthase genes. PaxD was overexpressed in Escherichia coli and the purified enzyme was used for in vitro analysis. When paxilline and dimethylallyl diphosphate were used as substrates, one major and one minor product, which were identified as di-prenyl paxilline and mono-prenyl paxilline by liquid chromatography-mass spectrometry analysis, were formed. The structure of the major product was determined to be 21,22-diprenylated paxilline, showing that PaxD catalyzed the successive di-prenylation. Traces of both products were detected in culture broth of P. paxilli by liquid chromatography-mass spectrometry analysis. The enzyme is likely to be a dimer and required no divalent cations. The optimum pH and temperature were 8.0 and 37 °C, respectively. The Km values were calculated as 106.4 ± 5.4 μM for paxilline and 0.57 ± 0.02 μM for DMAPP with a kcat of 0.97 ± 0.01/s. [ABSTRACT FROM AUTHOR]

Polycyclic polyether natural products have fascinated chemists and biologists alike owing to their useful biological activity, highly complex structure and intriguing biosynthetic mechanisms. Following the original proposal for the polyepoxide origin of lasalocid and isolasalocid and the experimental determination of the origins of the oxygen and carbon atoms of both lasalocid and monensin, a unified stereochemical model for the biosynthesis of polyether ionophore antibiotics was proposed. The model was based on a cascade of nucleophilic ring closures of postulated polyepoxide substrates generated by stereospecific oxidation of all-trans polyene polyketide intermediates. Shortly thereafter, a related model was proposed for the biogenesis of marine ladder toxins, involving a series of nominally disfavoured anti-Baldwin, endo-tet epoxide-ring-opening reactions. Recently, we identified Lsd19 from the Streptomyces lasaliensis gene cluster as the epoxide hydrolase responsible for the epoxide-opening cyclization of bisepoxyprelasalocid A to form lasalocid A. Here we report the X-ray crystal structure of Lsd19 in complex with its substrate and product analogue to provide the first atomic structure-to our knowledge-of a natural enzyme capable of catalysing the disfavoured epoxide-opening cyclic ether formation. On the basis of our structural and computational studies, we propose a general mechanism for the enzymatic catalysis of polyether natural product biosynthesis. [ABSTRACT FROM AUTHOR]

The article presents a study which describes the total biosynthesis of Aphidicolin (1) as well as its intermediates by heterologous expression of the biosynthetic genes of fungal diterpernoids. The study uses Aspergillus oryzae and Saccharomyces cerevisiae as hosts to investigate the expression of aphidicolin biosynthetic genes. Results revealed that production of fungal bioactive natural products can be attained by developing an efficient method for the introduction of multiple genes.

The biosynthetic pathway of the off-flavour terpenoid alcohol 2-methylisoborneol (2-MIB) requires geranyl pyrophosphate methyltransferase (GPPMT) to methylate GPP before the cyclization reaction. GPPMT is the first example of an S-adenosyl- l-methionine-dependent methyltransferase that acts on general intermediates such as geranyl pyrophosphate and farnesyl pyrophosphate in isoprenoid biosynthetic pathways. In this study, recombinant GPPMT was overproduced, purified and crystallized in the absence and presence of cofactor, cofactor analogue and substrate. Well diffracting crystals of apo GPPMT containing one molecule in the asymmetric unit were obtained and the structure of this form was solved by the molecular-replacement method. Two crystal forms of the tertiary complex with GPP and sinefungin were also obtained. Structure analysis of these crystals is currently under way in order to understand the enzyme reaction mechanism. [ABSTRACT FROM AUTHOR]

The article presents a study which identifies the lasalocid gene cluster and the biosynthetic pathway with genetic information. It says that naturally occurring polyether metabolites, such as ionophore antibiotics and marine triterpenes, are believed to be constructed via a biogenetic pathway; however, the details of the polyether formation are unknown. The study suggests that one difficulty in the reaction mechanism for polyether formation is the involvement of complex modification reactions.

The article discusses a study which identified the two diterpene biosynthesis gene clusters in the fusicoccin-producing fungus, Phomopsis amygdali. The identification was conducted using genome walking from PaGGS1 and PGGS4 which encode the geranylgeranyl diphosphate (GGDP) synthases. The study has isolated the novel diterpenoid, phyllocladan-11alpha,16alpha,18-triol, which is a possible metabolite of phyllocladan-16alpha-ol in the mycelia.

The article examines the later stage of the biosynthesis of pleuromutilin, a diterpene antibiotic. According to the authors, mutilin and deoxy analogs are biosynthetic precursors of pleuromutilin in the later stage of biosynthesis. They add that feeding experiments with the 2H-labeled precursors confirmed their microbial conversion into pleuromutilin.

Nonribosomal peptides (NRPs) are a class of microbial secondary metabolites that have a wide variety of medicinally important biological activities, such as antibiotic (vancomycin), immunosuppressive (cyclosporin A), antiviral (luzopeptin A) and antitumor (echinomycin and triostin A) activities. However, many microbes are not amenable to cultivation and require time-consuming empirical optimization of incubation conditions for mass production of desired secondary metabolites for clinical and commercial use. Therefore, a fast, simple system for heterologous production of natural products is much desired. Here we show the first example of the de novo total biosynthesis of biologically active forms of heterologous NRPs in Escherichia coli. Our system can serve not only as an effective and flexible platform for large-scale preparation of natural products from simple carbon and nitrogen sources, but also as a general tool for detailed characterizations and rapid engineering of biosynthetic pathways for microbial syntheses of novel compounds and their analogs. [ABSTRACT FROM AUTHOR]

The article discusses the results of a study investigating the characteristics of a rice gene encoding type-A diterpene cyclases. Members of the gene family are believed to be responsible for gibberellin biosynthesis. A theory was developed suggesting that the gene OsKS3 may be a pseudo-gene from which the translated product is a truncated enzyme

Rice ( Oryza sativa L.) produces ent-copalyl diphosphate ( ent-CDP) and syn-CDP as precursors for several classes of phytoalexins and the phytohormones, gibberellins (GAs). It has recently been shown that a loss-of-function mutation of OsCPS1, a gene encoding a putative ent-CDP synthase, results in a severely GA-deficient dwarf phenotype in rice. To clarify the biological functions of the ent- and syn-CDP synthases involved in the biosynthesis of phytoalexins and/or GAs, we isolated two cDNAs, OsCyc1 and OsCyc2, encoding putative diterpene cyclases from ultraviolet (UV)-irradiated rice leaves (cv. Nipponbare). The production of phytoalexins in rice leaves is known to be highly induced by UV treatment. Using a bacterial expression system, we demonstrated that OsCyc1 encodes syn-CDP synthase and that OsCyc2 and OsCPS1 encode ent-CDP synthase. The level of expression of the OsCyc1 and OsCyc2 transcripts in rice leaves increased drastically in response to UV treatment, whereas expression of the OsCPS1 transcript was not induced by UV light. These results suggest that OsCyc1, OsCyc2 and OsCPS1 are responsible for the biosynthesis of momilactones A and B and oryzalexin S, oryzalexins A–F and phytocassanes A–E, and GAs, respectively. Our results strongly suggest the presence of two ent-CDP synthase isoforms in rice, one that participates in the biosynthesis of GAs and a second that is involved in the biosynthesis of phytoalexins. [ABSTRACT FROM AUTHOR]

Identifies the genes encoding the type-A diterpene cyclases 9beta-primara-7,15-diene synthase and ent-sandaracopimaradiene synthase which are involved in the biosynthesis of momilactones A, B and oryzalexins A-F respectively. Increase in the transcript levels of the two genes after ultraviolet (UV) treatment; Elevated production of phytoalexins by UV; Suggestion that the genes might prove to be powerful tools for understanding plant defense mechanisms in rice.

Explores a reliable identification method for the biosynthetic gene cluster in fungal diterpenoids by cloning the biosynthetic gene cluster of the diterpene aphidicolin. Application of a simple polymerase chain reaction (PCR) method for genome walking; Indication that simple PCR-based genome walking without constructing a genomic DNA library is useful for identification of a small gene cluster.

The biosynthesis of the antitumor agent GKK1032A[sub 2] (1) has been investigated by administration of isotopically labeled ([sup 13]C and ²H) precursors to Penicillium sp. GKK1032. These studies showed that the backbone of 1 is constructed from L-tyrosine and a nonaketide chain flanked with five methyl groups probably by a polyketide synthase and a nonribosomal peptide synthetase hybrid. On the basis of the oxidation level of the starter unit and unusual 13-membered macroether formation between the tyrosine hydroxy group and the polyketide chain, novel cyclization mechanisms on the formation of a tricarbocyclic system and a macroether have been proposed. Involvement of a similar type of cyclization in the biosynthesis of structurally related metabolites is discussed. [ABSTRACT FROM AUTHOR]

A wide variety of enzymatic pathways that produce specialized metabolites in bacteria, fungi and plants are known to be encoded in biosynthetic gene clusters. Information about these clusters, pathways and metabolites is currently dispersed throughout the literature, making it difficult to exploit. To facilitate consistent and systematic deposition and retrieval of data on biosynthetic gene clusters, we propose the Minimum Information about a Biosynthetic Gene cluster (MIBiG) data standard., Chemistry and Chemical Biology

Review: [application of a newly developed method to reconstitute biosynthetic genes in a heterologous host, involving 17 enzymatic reactions; 69 refs. [ABSTRACT FROM AUTHOR]

Reports on the first example of the incorporation of precursors containing both diene and dienophile moieties into a group of the fungal metabolites solanopyrones. Biosynthetic origins of solanopyrone produced by Alternaria solani; Incorporation of the acyclic trienes prosolanapyrones; Conversion of the derived solanapyrone to the corresponding diastereomers.

Echinomycin, a bis-intercalator antitumor cyclic peptide, is biosynthesized by a unique nonribosomal peptide synthetase (NRPS). Successful heterologous expression of the whole gene cluster of echinomycin in Escherichia coli let us to investigate a further application of echinomycin NRPS. To construct a cyclic peptide library, our approach through both chemoenzymatic and rational genetic engineering has been successfully demonstrated. These achievements provided the further support that E. coli-based system can serve as a flexible yet robust platform for producing complex natural products and their analogs. [Copyright &y& Elsevier]

Abstract: The biosynthetic pathway of a potent antifungal agent, FR-900848, has been examined by administration of several 13C-labeled precursors to Streptoverticillium fervens HP-891. Although none of the 13C-labeled acetate was incorporated into FR-900848, the labeling pattern of FR-900848 derived from d-[U-13C6]glucose revealed that the fatty acid backbone of FR-900848 has been biosynthesized via a polyketide pathway. These unusual results strongly show that the major pathway to provide acetyl-CoA in this microorganism is glycolysis. Feeding experiments with d-[U-13C6]glucose, [1,3-13C2]glycerol, and l-[Me-13C]methionine provided information on the biosynthetic origin of structurally unusual parts (polycyclopropane and aminonucleoside) in this antibiotic. [Copyright &y& Elsevier]

Abstract: Incorporation of labeled acetate and l-serine into PF1140 in Eupenicillium sp. indicated that the skeleton of PF1140 is derived from five acetates and a l-serine. Upon administration of [1,3-13C2]glycerol, a precursor of biotransformation into l-[1,3-13C2]serine, the isotopic labels became contiguous in the resultant 2-pyridone of PF1140. Based on the feeding experiments, a novel and potentially general biosynthetic pathway for a 2-pyridone framework has been proposed, in which an acyl tetramic acid precursor could be converted via a ring expansion with loss of the hydroxyl group. [Copyright &y& Elsevier]

[Display omitted] Oxidative modifications are key biosynthetic processes responsible for expanding the structural diversity of indole diterpenes (IDTs). In this study, we focused on the function of prenyltransferases and flavoprotein oxidases for the synthesis of nodulisporic acid-type and shearinine-type bicyclic rings found on the indole moiety. An in vitro enzymatic reaction of a prenyltransferase JanD, which mediates diprenylation at the C5- and C6-positions, revealed that JanD recognizes a C13‑hydroxy group on the diterpene moiety. Subsequent enzymatic reactions with flavoprotein oxidases, JanO, and NodO, indicated that JanO can accommodate penta/hexacyclic IDTs, while NodO exhibits strict substrate specificity toward pentacyclic IDTs. The broad substrate tolerance of JanD and JanO provides opportunities for the synthesis of unnatural IDTs based on artificial reconstitution in a heterologous host. [ABSTRACT FROM AUTHOR]

Biosynthetic assembly lines of tetrahydroisoquinoline alkaloids employ the tyrosine derivative, ( S )-2-amino-3-(3-hydroxy-4-methoxy-5-methylphenyl)propanoic acid, as a common amino acid building block. A catalytic asymmetric synthetic route to the common amino acid component has been developed by making use of Maruoka’s chiral phase transfer alkylation of a glycine derivative with the requisite benzyl bromide. [ABSTRACT FROM AUTHOR]

We recently reported the function of paxD, which is involved in the paxilline (compound 1) biosynthetic gene cluster in Penicillium paxilli. Recombinant PaxD catalyzed a stepwise regular-type diprenylation at the 21 and 22 positions of compound 1 with dimethylallyl diphosphate (DMAPP) as the prenyl donor. In this study, atmD, which is located in the aflatrem (compound 2) biosynthetic gene cluster in Aspergillus flavus and encodes an enzyme with 32% amino acid identity to PaxD, was characterized using recombinant enzyme. When compound 1 and DMAPP were used as substrates, two major products and a trace of minor product were formed. The structures of the two major products were determined to be reversely monoprenylated compound 1 at either the 20 or 21 position. Because compound 2 and β-aflatrem (compound 3), both of which are compound 1-related compounds produced by A. flavus, have the same prenyl moiety at the 20 and 21 position, respectively, AtmD should catalyze the prenylation in compound 2 and 3 biosynthesis. More importantly and surprisingly, AtmD accepted paspaline (compound 4), which is an intermediate of compound 1 biosynthesis that has a structure similar to that of compound 1, and catalyzed a regular monoprenylation of compound 4 at either the 21 or 22 position, though the reverse prenylation was observed with compound 1. This suggests that fungal indole diterpene prenyltransferases have the potential to alter their position and regular/reverse specificities for prenylation and could be applicable for the synthesis of industrially useful compounds. [ABSTRACT FROM AUTHOR]

Highlights: [•] Enzymatic polyether assembly mechanism in ionophore antibiotic lasalocid. [•] Anti-Baldwin cyclic ether formation catalyzed by polyether biosynthetic enzyme Lsd19. [•] Crystal structure of Lsd19 catalyzing polyether epoxide opening cascade. [ABSTRACT FROM AUTHOR]

Abstract: Cytochalasins are an important class of fungal natural products in view of structural diversity and biological activities. Although their biosynthetic studies have been examined extensively, the detailed molecular assembly mechanism remains to be solved. We have succeeded to heterologously express the cytochalasin polyketide synthase–non-ribosomal peptide synthetase (PKS–NRPS) hybrid gene ccsA and the trans-acting enoyl-CoA reductase gene ccsC in Aspergillus oryzae. The resultant transformant produced a novel metabolite possessing the cytochalasin backbone. This established that CcsA is capable of constructing the octaketide connected with phenylalanine in collaboration with CcsC, and that CcsA R domain catalyzes reductive cleavage of the thio-tethered PKS–NRPS product. [Copyright &y& Elsevier]

Abstract: Enzymatic epoxide-opening cascade is one of the key biosynthetic processes for constructing structurally diverse polyethers. Here we report the first in vitro analysis of the cyclization catalyzed by two epoxide hydrolases, MonBI and MonBII involved in monensin biosynthesis, using simple epoxy-alcohols and the unprecedented synergistic effect on the epoxide-opening activity between these epoxide hydrolases. [Copyright &y& Elsevier]

Natural products display impressive activities against a wide range of targets, including viruses, microbes, and tumors. However, their clinical use is hampered frequently by their scarcity and undesirable toxicity. Not only can engineering Escherichia coli for plasmid-based pharmacophore biosynthesis offer alternative means of simple and easily scalable production of valuable yet hard-to-obtain compounds, but also carries a potential for providing a straightforward and efficient means of preparing natural product analogs. The quinomycin family of nonribosomal peptides, including echinomycin, triostin A, and SW-163s, are important secondary metabolites imparting antibiotic antitumor activity via DNA bisintercalation. Previously we have shown the production of echinomycin and triostin A in E. coli using our convenient and modular plasmid system to introduce these heterologous biosynthetic pathways into E. coli. However, we have yet to develop a novel biosynthetic pathway capable of producing bioactive unnatural natural products in E. coli. Here we report an identification of a new gene cluster responsible for the biosynthesis of SW-163s that involves previously unknown biosynthesis of (+)-(1S, 2S)-norcoronamic acid and generation of aliphatic side chains of various sizes via iterative methylation of an unactivated carbon center. Substituting an echinomycin biosynthetic gene with a gene from the newly identified SW-163 biosynthetic gene cluster, we were able to rationally re-engineer the plasmid-based echinomycin biosynthetic pathway for the production of a novel bioactive compound in E. coli. [ABSTRACT FROM AUTHOR]

The presence of the geranylgeranyl diphosphate synthase (GGS) gene is a common feature of gene clusters for diterpene biosynthesis. We demonstrated identification of a diterpene gene cluster using homology-based PCR of GGS genes and the subsequent genome walking in the fungus Phomopsis amygdali N2. Structure determination of a novel diterpene hydrocarbon phomopsene provided by enzymatic synthesis with the recombinant terpene synthase PaPS and screening of fungal broth extracts with reference to characteristic NMR signals of phomopsene allowed us to isolate a new diterpene, methyl phomopsenonate. The versatility of the gene-based screening of unidentified diterpenes is discussed in regard to fungal genomic data. [ABSTRACT FROM AUTHOR]

Abstract: In the biosynthesis of a polyether ionophore antibiotic, lasalocid A, the cyclic ether skeleton composed of a tetrahydrofuran linked to a tetrahydropyran could be constructed by oxidative cyclization of linear dodecaketide diene precursor. Hence, we hypothesized a prelasalocid having (E,E)-trisubstituted olefins as the dodecaketide biosynthetic precursor. A stereo-controlled synthetic route to the prelasalocid has been devised in a highly convergent manner entailing installation of a variety of substituents at the trisubstituted olefins. [Copyright &y& Elsevier]

The article presents the chemical structure of biosynthesis of Polycyclopropanated Polyketide.