Enzymes in biosynthesis

• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2022, 18, 1131–1132, doi:10.3762/bjoc.18.116

• proceed through multistep cationic cascade reactions and usually produce a polycyclic terpene hydrocarbon or alcohol with multiple stereogenic centers. While these transformations require only a single enzyme, polyketide and nonribosomal peptide biosyntheses are catalyzed by megasynthases that follow an

• assembly line logic, with individual domains for each single step [2]. Furthermore, the domains are organized into modules, each of which is responsible for the incorporation of one extender unit into the growing polyketide or peptide chain. With our knowledge today, the function of these large enzyme

A Streptomyces P450 enzyme dimerizes isoflavones from plants

• Run-Zhou Liu,
• Shanchong Chen and
• Lihan Zhang

Beilstein J. Org. Chem. 2022, 18, 1107–1115, doi:10.3762/bjoc.18.113

• [1][10][11][12][13][14]. In plants and fungi, laccases and cytochrome P450 monooxygenases play pivotal roles in the biaryl bond formation of various polyketide dimers [10][15][16]. In contrast, in bacteria, P450 enzymes are the dominant catalysts, but no laccases have been reported for dimerization

• clustered into the CYP158 clade that reportedly catalyzes dimerization of type III polyketide synthase (T3PKS) products, such as naphthols. Considering the similar biosynthetic pathway of isoflavones shared, this enzyme was expressed in E. coli and purified for in vitro biochemical assay together with four

• . Interestingly, we found that CYP158C1 clusters together with a T3PKS gene in the S. cattleya genome, which is similar to the biflaviolin [30] and naringenin [31] biosynthetic gene clusters. The native function of these type-III polyketide synthase products is believed to be involved in the protection of the

Bioinspired tetraamino-bisthiourea chiral macrocycles in catalyzing decarboxylative Mannich reactions

• Hao Guo,
• Yu-Fei Ao,
• De-Xian Wang and
• Qi-Qiang Wang

Beilstein J. Org. Chem. 2022, 18, 486–496, doi:10.3762/bjoc.18.51

• cavity could resemble the circumstance of the catalytic triad of Polyketide synthases (PKSs) [40][41][42] (Figure 1). On the other hand, the organocatalytic asymmetric decarboxylative addition reactions of MAHTs to imines provide an efficient means for accessing valuable chiral β-amino esters [43][44][45

Unsaturated fatty acids and a prenylated tryptophan derivative from a rare actinomycete of the genus Couchioplanes

• Shun Saito,
• Kanji Indo,
• Naoya Oku,
• Hisayuki Komaki,
• Masashi Kawasaki and
• Yasuhiro Igarashi

Beilstein J. Org. Chem. 2021, 17, 2939–2949, doi:10.3762/bjoc.17.203

• metabolites of Pseudosporangium sp. RD062863, a strain available at the culture collection of the Biological Resource Center, National Institute of Technology and Evaluation (NBRC) [20], and discovered a novel cyclopeptide pseudosporamide along with three new oligomycin-class polyketide [21]. In addition, the

• metabolite with a methyl-branched C9 unsaturated acyl chain [31]. Moreover, salinipyrones, produced by a Salinispora strain, were shown to be biosynthetic byproducts of the rosamicin polyketide synthase [32]. Though not a result from Micromonosporaceae, another example of truncated polyketides is citreodiol

• , a similarly methyl-branched unsaturated fatty acid ester, which is produced by type I polyketide synthase in a Streptomyces strain by a heterologous expression experiment [33]. These facts suggest that 1–5 could be byproducts from the biosynthesis of larger polyketides, but further investigation is

Nomimicins B–D, new tetronate-class polyketides from a marine-derived actinomycete of the genus Actinomadura

• Zhiwei Zhang,
• Tao Zhou,
• Taehui Yang,
• Keisuke Fukaya,
• Enjuro Harunari,
• Shun Saito,
• Katsuhisa Yamada,
• Chiaki Imada,
• Daisuke Urabe and
• Yasuhiro Igarashi

Beilstein J. Org. Chem. 2021, 17, 2194–2202, doi:10.3762/bjoc.17.141

• cytotoxicity against P388 murine leukemia cells with IC50 values of 33 and 89 μM, respectively. Keywords: Actinomadura; nomimicin; polyketide; spirotetronate; Introduction Actinomycetes are a valuable source of bioactive compounds, accounting for approximately two thirds of all known antibiotics, and more

• collection sites [12]. Furthermore, we found that the DSW of Sagami Bay (Pacific Ocean side of Honshu Island, Japan) contained more unknown actinomycete species than other sea areas, which eventually led to the discovery of akazamicin, a new cytotoxic aromatic polyketide from Nonomuraea [13] and akazaoxime

• , nomimicin A (4) [15]. From the extract of the fermentation broth cultured in A11M medium, an additional new tetronate polyketide, nomimicin D (3), was isolated (Figure 1). Nomimicin B (1) was obtained as a colorless amorphous solid. The molecular formula was determined to be C30H40O8, based on the

On the application of 3d metals for C–H activation toward bioactive compounds: The key step for the synthesis of silver bullets

• Renato L. Carvalho,
• Amanda S. de Miranda,
• Mateus P. Nunes,
• Roberto S. Gomes,
• Guilherme A. M. Jardim and
• Eufrânio N. da Silva Júnior

Beilstein J. Org. Chem. 2021, 17, 1849–1938, doi:10.3762/bjoc.17.126

• White’s oxidation method as the final step in the first total synthesis of gracilioether F (75) [157], a natural polyketide with an unusual tricyclic core and five contiguous stereocenters, part of the family of gracilioethers 71–74 (Scheme 26A) extracted from the marine sponge Plakinastrella mamillaris

Natural products in the predatory defence of the filamentous fungal pathogen Aspergillus fumigatus

• Jana M. Boysen,
• Nauman Saeed and
• Falk Hillmann

Beilstein J. Org. Chem. 2021, 17, 1814–1827, doi:10.3762/bjoc.17.124

• , comparable to how Trichoderma virens protects cotton seedlings from its pathogen Pythium ultimum [122]. Trypacidin The spore-born toxin trypacidin (8) is a polyketide that belongs to an anthraquinone-derived class of secondary metabolites (Figure 4) [107]. In A. fumigatus, the trypacidin biosynthetic cluster

• of its biosynthesis are well established: the 19 kb gene cluster contains 6 genes and lies downstream of the conidiation pathway. The polyketide synthase PksP combines the starter units acetyl-CoA and malonyl-CoA into the heptaketide naphthopyrone YWA1 (11). The hydrolytic activity of Ayg1 shortens

Prins cyclization-mediated stereoselective synthesis of tetrahydropyrans and dihydropyrans: an inspection of twenty years

• Asha Budakoti,
• Pradip Kumar Mondal,
• Prachi Verma and
• Jagadish Khamrai

Beilstein J. Org. Chem. 2021, 17, 932–963, doi:10.3762/bjoc.17.77

• with DTBP for the synthesis of polyketide SCH 351448 [43], as shown in Scheme 14. Hart and Bennett have also examined the trifluroacetic acid-catalyzed Prins cyclization of acetal 71 to afford 72 along with side-chain-exchanged product 73 (Scheme 15) [44]. This method was utilized for the synthesis of

¹⁹F NMR as a tool in chemical biology

• Diana Gimenez,
• Aoife Phelan,
• Cormac D. Murphy and
• Steven L. Cobb

Beilstein J. Org. Chem. 2021, 17, 293–318, doi:10.3762/bjoc.17.28

Total synthesis of decarboxyaltenusin

• Lucas Warmuth,
• Aaron Weiß,
• Marco Reinhardt,
• Anna Meschkov,
• Ute Schepers and
• Joachim Podlech

Beilstein J. Org. Chem. 2021, 17, 224–228, doi:10.3762/bjoc.17.22

• compound due to the reduced accessibility of the precursors and since no experimental details have been published for the transformation. To continue our efforts in the total synthesis of mycotoxins [8][9][10][11][12][13][14][15][16][17][18] and to provide larger amounts of the polyketide 1 sufficient for

Nocarimidazoles C and D, antimicrobial alkanoylimidazoles from a coral-derived actinomycete Kocuria sp.: application of ¹J_C,H coupling constants for the unequivocal determination of substituted imidazoles and stereochemical diversity of anteisoalkyl chains in microbial metabolites

• Md. Rokon Ul Karim,
• Enjuro Harunari,
• Amit Raj Sharma,
• Naoya Oku,
• Kazuaki Akasaka,
• Daisuke Urabe,
• Mada Triandala Sibero and
• Yasuhiro Igarashi

Beilstein J. Org. Chem. 2020, 16, 2719–2727, doi:10.3762/bjoc.16.222

• genomic information suggests the presence of biosynthetic genes for nonribosomal peptide synthetase and type III polyketide synthase in some Kocuria strains [18], which leaves a hope for new secondary metabolites. At present, only a few limited structural types of metabolites, including polyamine-derived

Syntheses of spliceostatins and thailanstatins: a review

• William A. Donaldson

Beilstein J. Org. Chem. 2020, 16, 1991–2006, doi:10.3762/bjoc.16.166

• with their complex structure, a number of total syntheses have been reported. This review will compare the synthetic strategies reported through the end of 2019. Keywords: antiproliferative; polyketide natural products; tetrahydropyrans; total synthesis; Introduction The spliceostatins/thailanstatins

• (Figure 1) are a family of linear peptide/polyketide natural products isolated from the bacteria Burkholderia sp. FERM BP-3421 [1][2][3] (originally identified as Pseudomonas sp. No 2663) and Burkholderia sp. MSMB 43 [4][5]. These compounds are of interest due to their ability to bind to a subunit of the

Fabclavine diversity in Xenorhabdus bacteria

• Sebastian L. Wenski,
• Harun Cimen,
• Natalie Berghaus,
• Sebastian W. Fuchs,
• Selcuk Hazir and
• Helge B. Bode

Beilstein J. Org. Chem. 2020, 16, 956–965, doi:10.3762/bjoc.16.84

• ), and polyketide synthases (PKS). Selected Xenorhabdus and Photorhabdus mutant strains were generated applying a chemically inducible promoter in front of the suggested fabclavine (fcl) biosynthesis gene cluster (BGC), followed by the analysis of the occurring fabclavines. Subsequently, known and

• ]. Fabclavines are hexapeptide/polyketide hybrids derived from nonribosomal peptide synthetases (NRPS) and a polyketide synthase (PKS), which are connected to an unusual polyamine derived from polyunsaturated fatty acid (PUFA) synthases [20]. Beside full-length fabclavines, also shortened derivatives were

• (Ala) and the sixth position (R2/R3) between proline (Pro), valine (Val) and threonine (Thr). The polyamine can differ in the length from three to five amine units (m) and is connected via one to three partially reduced polyketide C2 units (n) with the NRPS part. In this work, 22 yet unknown

Two new aromatic polyketides from a sponge-derived Fusarium

• Mada Triandala Sibero,
• Tao Zhou,
• Keisuke Fukaya,
• Daisuke Urabe,
• Ocky K. Karna Radjasa,
• Agus Sabdono,
• Agus Trianto and
• Yasuhiro Igarashi

Beilstein J. Org. Chem. 2019, 15, 2941–2947, doi:10.3762/bjoc.15.289

• polyketide; Fusarium; marine fungus; secondary metabolite; sponge; Introduction Marine organisms have been known as a potential source of prospective bioactive compounds, and sponges are particularly emphasized as the most promising source among all marine invertebrates [1][2]. However, the collection of

Chemical synthesis of tripeptide thioesters for the biotechnological incorporation into the myxobacterial secondary metabolite argyrin via mutasynthesis

• David C. B. Siebert,
• Roman Sommer,
• Domen Pogorevc,
• Michael Hoffmann,
• Silke C. Wenzel,
• Rolf Müller and
• Alexander Titz

Beilstein J. Org. Chem. 2019, 15, 2922–2929, doi:10.3762/bjoc.15.286

• . aeruginosa [18]. Biotechnological engineering of producer strains aims to shutdown the natural substrate production and thereby increase the usually poor yields of the mutasynthesis products [19][20]. For bacterial natural products that originate from a polyketide synthase (PKS) or a nonribosomal peptide

• are quite challenging, e.g., as shown in previous studies on polyketide chain engineering in α-pyrone antibiotic biosynthesis [23]. We assumed that the insufficient/missing processing of the SNAc precursors by the NRPS subunit Arg3 is the main culprit for unsuccessful restoration of the argyrin

Bacterial terpene biosynthesis: challenges and opportunities for pathway engineering

• Eric J. N. Helfrich,
• Geng-Min Lin,
• Christopher A. Voigt and
• Jon Clardy

Beilstein J. Org. Chem. 2019, 15, 2889–2906, doi:10.3762/bjoc.15.283

• thiotemplated assembly lines, such as type I polyketide synthases (PKS) and nonribosomal peptide synthetases (NRPS), are modular, with each module contributing a distinct fragment to the final product’s core structure – a short-chain carboxylic acid (PKS) or an amino acid (NRPS). The modularly defined template

• thiotemplate biosynthetic pathways that enable relatively precise predictions of natural product core structures (e.g., the colinearity rule in NRPSs and cis-acyltransferase polyketide synthases [8]), no such rules exist for the predictions of the cyclic hydrocarbon backbone produced by TCs [1]. This is likely

• assist in refining our understanding of bacterial terpenoid biosynthesis. Examples of bioactive terpenoids. Repetitive electrophilic and nucleophilic functionalities in terpene and type II PKS-derived polyketide biosynthesis. a) Schematic representation. b) Type II PKS-derived polyketide biosynthesis. c

Nanangenines: drimane sesquiterpenoids as the dominant metabolite cohort of a novel Australian fungus, Aspergillus nanangensis

• Heather J. Lacey,
• Cameron L. M. Gilchrist,
• Andrew Crombie,
• John A. Kalaitzis,
• Daniel Vuong,
• Peter J. Rutledge,
• Peter Turner,
• John I. Pitt,
• Ernest Lacey,
• Yit-Heng Chooi and
• Andrew M. Piggott

Beilstein J. Org. Chem. 2019, 15, 2631–2643, doi:10.3762/bjoc.15.256

• ], triterpenoids [10] and prenylated polyketide meroterpenoids [11][12][13][14][15] isolated from soil, endophytes and marine strains. Of this genus, A. ustus [16], A. calidoustus [17], A. insuetus [17], A. insulicola [18], A. bridgeri [18], A. sclerotiorum [19], A. variecolor [19], A. parasiticus [20], A. oryzae

• side chains present in the (iso)nanangenines could be derived either from a fatty acid synthase (FAS) or polyketide synthase (PKS). For example, in aflatoxin biosynthesis, the hexanoyl started unit is supplied by a FAS [31], while in the meroterpenoid fumagillin biosynthesis, the unsaturated acyl chain

Isolation and biosynthesis of an unsaturated fatty acid with unusual methylation pattern from a coral-associated bacterium Microbulbifer sp.

• Amit Raj Sharma,
• Enjuro Harunari,
• Tao Zhou,
• Agus Trianto and
• Yasuhiro Igarashi

Beilstein J. Org. Chem. 2019, 15, 2327–2332, doi:10.3762/bjoc.15.225

• corroborated by 3JHH vicinal coupling constant (JH4,H5 = 15.8 Hz). In fungi and certain kinds of bacteria, methyl substituents in the fatty acid carbon chain or the polyketide chain are derived from the methyl group of S-adenosylmethionine (SAM) (Figure 3A) [13][14]. This methylation reaction usually occurs at

• the nucleophilic carbons originated from the methyl carbon of acetate (C2) since SAM acts as an electrophilic methyl donor. In most of the bacteria including actinomycetes, methyl branching in polyketide chain is derived from methylmalonyl CoA, thereby the methylation position must be also the α

• intermediate, from which deprotonation occurs at C9 to give an internal olefin (Scheme 1). In the case of 1, methylation at the C3 carbon is inconsistent with the regular methylation pattern that occurs in fatty acids synthesized by the FAS (fatty acid synthase) or polyketides from the PKS (polyketide synthase

Synthesis of the polyketide section of seragamide A and related cyclodepsipeptides via Negishi cross coupling

• Jan Hendrik Lang and
• Thomas Lindel

Beilstein J. Org. Chem. 2019, 15, 577–583, doi:10.3762/bjoc.15.53

• Jan Hendrik Lang Thomas Lindel TU Braunschweig, Institute of Organic Chemistry, Hagenring 30, 38106 Braunschweig, Germany 10.3762/bjoc.15.53 Abstract The synthesis of the polyketide section present in the potently cytotoxic marine cyclodepsipeptide jasplakinolide and related natural products

• endeavour, a new synthesis of the polyketide section present in seragamides and most of jasplakinolides and geodiamolides. We also include the synthesis of the protected tripeptide section of seragamide A (2), even if the macrocycle still remains to be assembled. Seragamide A (2) from the marine sponge

• Suberites japonicus (Thiele) has been synthesized only once, with relay ring-closing metathesis being the key step [9]. Characteristically, seragamides A–E exhibit a L-threonine unit at the C-terminus of the peptide moiety. There is a considerable body of work on the synthesis of the C12 polyketide section

Synthesis and SAR of the antistaphylococcal natural product nematophin from Xenorhabdus nematophila

• Frank Wesche,
• Hélène Adihou,
• Thomas A. Wichelhaus and
• Helge B. Bode

Beilstein J. Org. Chem. 2019, 15, 535–541, doi:10.3762/bjoc.15.47

• pathogenic against humans, they are widely used as biocontrol agents in agriculture [9]. Natural products produced by bacteria play an important role in the bacteria/nematode/insect life cycle and most natural products are non-ribosomal peptides (NRP), e.g., rhabdopeptides [10][11] and polyketide–NRP hybrids

Volatiles from the hypoxylaceous fungi Hypoxylon griseobrunneum and Hypoxylon macrocarpum

• Jan Rinkel,
• Alexander Babczyk,
• Tao Wang,
• Marc Stadler and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2018, 14, 2974–2990, doi:10.3762/bjoc.14.277

• derivatives. Their structures could only be unambiguously determined by comparison to all isomers with different substitution patterns. The substitution pattern of the main compound from H. griseobrunneum, the new natural product 2,4,5-trimethylanisole, was explainable by a polyketide biosynthesis mechanism

• (methyl-2H3)methionine. While the methylation pattern of the alternative structure 24c is difficult to understand via a polyketide biosynthesis mechanism, the formation of the assigned structure of 24 by a polyketide synthase (PKS) can be easily rationalised (Scheme 2). The acetate starter unit, bound to

• exhibited the mass spectra shown in Figure 4E and Figure 4F that were similar to database spectra of 2,5-dimethyl-p-anisaldehyde (25) and methyl 2,5-dimethyl-p-anisate (26). The substitution pattern of these compounds is well explained by polyketide biosynthesis logic (Scheme 3). Starting from ACP-bound

Recent advances in hypervalent iodine(III)-catalyzed functionalization of alkenes

• Xiang Li,
• Pinhong Chen and
• Guosheng Liu

Beilstein J. Org. Chem. 2018, 14, 1813–1825, doi:10.3762/bjoc.14.154

• chiral hypervalent iodine catalyst [47][48]. Additionally, mCPBA and trifluoroacetic acid were utilized as terminal oxidants and activators, respectively. This reaction provided a series of 4-oxyisochroman-1-ones, which are found in natural products and bioactive polyketide metabolites. For example, the

Volatiles from the tropical ascomycete Daldinia clavata (Hypoxylaceae, Xylariales)

• Tao Wang,
• Kathrin I. Mohr,
• Marc Stadler and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2018, 14, 135–147, doi:10.3762/bjoc.14.9

• is shown in Scheme 7 that is likely performed by a typical fungal iterative polyketide synthase (PKS). Starting from acyl-carrier-protein (ACP) bound acetate a first elongation step with malonyl-SCoA (Mal-SCoA) catalysed by an acyl transferase (AT) and a ketosynthase (KS) domain yields acetoacetyl

Herpetopanone, a diterpene from Herpetosiphon aurantiacus discovered by isotope labeling

• Xinli Pan,
• Nicole Domin,
• Sebastian Schieferdecker,
• Hirokazu Kage,
• Martin Roth and
• Markus Nett

Beilstein J. Org. Chem. 2017, 13, 2458–2465, doi:10.3762/bjoc.13.242

• . Although the elemental composition does not necessarily exclude a polyketide origin, it perfectly matches a diterpene comprising four intact isoprene units. To obtain sufficient material for structure elucidation, the fermentation of H. aurantiacus 114-95T was repeated on a 50 L scale in VNY medium

Sulfation and amidinohydrolysis in the biosynthesis of giant linear polyenes

• Hui Hong,
• Markiyan Samborskyy,
• Katsiaryna Usachova,
• Katharina Schnatz and
• Peter F. Leadlay

Beilstein J. Org. Chem. 2017, 13, 2408–2415, doi:10.3762/bjoc.13.238

• from Streptomyces mediocidicus), are near-identical giant linear polyenes apparently constructed from, respectively, a 4-guanidinobutanoate or 4-aminobutanoate starter unit and 27 polyketide extender units, and bearing a specific O-sulfonate modification at the C-29 hydroxy group. We show here that

• as donor, efficiently converted mediomycin B to mediomycin A in vitro. Thus, in the final steps of mediomycin A biosynthesis deamidination and sulfotransfer can take place in either order. Keywords: amidinohydrolase; clethramycin; mediomycin; polyketide synthase; sulfotransferase; Introduction

• Bacterial modular polyketide synthases (PKSs) follow an assembly-line paradigm for enzyme catalysis, in which each round of chain extension requires a different set, or module, of enzymatic activities [1][2][3][4]. Among the more remarkable natural products derived by this pathway is the giant linear