Geminal Bismethylation Prevents Polyketide Oxidation and Dimerization in the Benastatin Pathway

Schenk, Angéla; Xu, Zhongli; Pfeiffer, Corina; Steinbeck, Christoph; Hertweck, Christian

doi:10.1002/anie.200702033

Cited by 30 publications

(32 citation statements)

References 29 publications

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“…2 The action of such MTs within PKS modules provides both an alternative route to the α-methyl branched intermediates typically introduced by methylmalonyl-CoA specific acyltransferase (AT) domains as well as the primary route for generating gem -dimethyl functionality. 3,4 …”

Section: Introductionmentioning

confidence: 99%

α-Methylation follows condensation in the gephyronic acid modular polyketide synthase

et al. 2016

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C-methyltransferases (MTs) from modular polyketide synthase assembly lines are relatively rare and unexplored domains that are responsible for installing α-methyl groups into nascent polyketide backbones. The stage at which these synthase-embedded enzymes operate during polyketide biosynthesis has yet to be conclusively demonstrated. In this work we establish the activity and substrate preference for six MTs from the gephyronic acid polyketide synthase and demonstrate their ability to methylate both N-acetylcysteamine- and acyl carrier protein-linked β-ketoacylthioester substrates but not malonyl thioester equivalents. These data strongly indicate that MT-catalyzed methylation occurs immediately downstream of ketosynthase-mediated condensation during polyketide assembly. This work represents the first successful report of MT-catalyzed mono- and dimethylation of simple thioester substrates and provides the groundwork for future mechanistic and engineering studies on this important but poorly understood enzymatic domain.

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Section: Introductionmentioning

confidence: 99%

α-Methylation follows condensation in the gephyronic acid modular polyketide synthase

et al. 2016

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“…1). It should be noted that although no oxygenation is needed in the biosynthesis of benastatin (5), its biosynthetic congener BE43767A (11) contains a C-8 hydroxyl group (15).…”

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confidence: 99%

In Vivo Investigation of the Roles of FdmM and FdmM1 in Fredericamycin Biosynthesis Unveiling a New Family of Oxygenases

Chen

Wendt-Pienkoski

Rajski

et al. 2009

Journal of Biological Chemistry

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Fredericamycin (FDM) A, a highly oxidized aromatic pentadecaketide natural product, exhibits potent cytotoxicity and has been studied as a new anticancer drug lead. The FDM biosynthetic gene cluster has been previously cloned from Streptomyces griseus ATCC 49344 and successfully expressed in the heterologous host Streptomyces albus J1074. The fdmM and fdmM1 genes code for two proteins with high sequence homology to each other but unknown function. In-frame deletion of each of the genes from the fdm cluster was accomplished in the S. albus host. Each mutant failed to produce FDM A and the key biosynthetic intermediate FDM E but produced various new metabolites, the titers of which were dramatically increased via overexpression of an fdm pathway-specific activator fdmR1. The ⌬fdmM mutant strain accumulated three new compounds FDM M-1, FDM M-2, and FDM M-3, whereas the ⌬fdmM1 mutant strain produced one new compound FDM M1-1. Isolation and structural characterization of these compounds enable us to propose that FdmM and FdmM1 catalyze the C-6 and C-8 hydroxylations for FDM biosynthesis, respectively. Homologs of FdmM and FdmM1 can be found in biosynthetic gene clusters of many other aromatic polyketides, ranging from dodecaketides to pentadecaketides, but to date all of them were annotated as proteins of unknown function. Based on the findings reported here for FdmM and FdmM1, we now propose similar functions for those proteins, and FdmM and FdmM1 therefore represent an emerging family of novel oxygenases responsible for hydroxylation of aromatic polyketide natural products.Studies on natural product biosynthetic pathways have uncovered a number of intriguing oxygenases. For instance, the first reported metal-and cofactor-free monooxygenase TcmH is responsible for quinone moiety formation in tetracenomycin D3 and represents a rapidly growing family of antibiotic biosynthetic monooxygenases (1, 2). Another example is DpgC, which is involved in the biosynthesis of vancomycin building block 3, 5-dihydroxyphenylglycine. The crystal structure of DpgC has been used to understand the reaction mechanism of metal-and cofactor-free dioxygenases (3). MomA, involved in mompain biosynthesis (4) is a metal ion-dependent monooxygenase belonging to the cupin superfamily of oxidases bearing no prosthetic group. The discovery of enzymes such as TcmH, DpgC, and MomA continually encourage the community to search for and characterize new oxygenases from proteins of unknown functions involved in natural products biosynthesis.Whereas octaketides (C-16), nonaketides (C-18), and decaketides (C-20) are the most common aromatic polyketide natural products whose biosyntheses have been extensively investigated, aromatic polyketides ranging from dodecaketides (C-24) to pentadecaketides (C-30) are also known including biologically active compounds such as fredericamycin (FDM) 2 A (1) (5, 6), pradimicin A (2) (7), lysolipin X (3) (8), griseorhodin A (4) (9), benastatin A (5) (10), and ␥-rubromycin (6) ( Fig. 1 and Ref. 11). The highly oxidized nat...

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“…6 By analogy, it seemed possible that 1a/b were dimerized precursors in the griseorhodin pathway. Indeed, griseorhodins were also obtained from the culture broth of strain CN48+.…”

Section: Resultsmentioning

confidence: 99%

Griseorhodins D–F, Neuroactive Intermediates and End Products of Post-PKS Tailoring Modification in Griseorhodin Biosynthesis

et al. 2014

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The griseorhodins belong to a family of extensively modified aromatic polyketides that exhibit activities such as inhibition of HIV reverse transcriptase and human telomerase. The vast structural diversity of this group of polyketides is largely introduced by enzymatic oxidations, which can significantly influence the bioactivity profile. Four new compounds, griseorhodins D–F, were isolated from a griseorhodin producer, Streptomyces sp. CN48+, based upon their enhancement of calcium uptake in a mouse dorsal root ganglion primary cell culture assay. Two of these compounds, griseorhodins D1 and D2, were shown to be identical to the major, previously uncharacterized products of a grhM mutant in an earlier griseorhodin biosynthesis study. Their structures enabled the establishment of a more complete hypothesis for the biosynthesis of griseorhodins and related compounds. The other two compounds, griseorhodins E and F, represent new products of post-polyketide synthase tailoring in griseorhodin biosynthesis and showed significant binding activity in a human dopamine active transporter assay.

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Geminal Bismethylation Prevents Polyketide Oxidation and Dimerization in the Benastatin Pathway

Cited by 30 publications

References 29 publications

α-Methylation follows condensation in the gephyronic acid modular polyketide synthase

α-Methylation follows condensation in the gephyronic acid modular polyketide synthase

In Vivo Investigation of the Roles of FdmM and FdmM1 in Fredericamycin Biosynthesis Unveiling a New Family of Oxygenases

Griseorhodins D–F, Neuroactive Intermediates and End Products of Post-PKS Tailoring Modification in Griseorhodin Biosynthesis

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