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In the search for new secondary metabolites from myxobacteria, a strain from the genus Pyxidicoccus was investigated. This led to the identification of a new class of natural products showing structural novelty and interesting biological activity. Isolation and structure elucidation of two analogues led to the identification of pyxipyrrolone A and B, harboring the novel 3-methylene-2,3,4,5,6,7,8,9-octahydro-1H-benzo[e]isoindol-1-one scaffold. Mosher's ester analysis combined with NMR studies allowed the determination of all stereocenters but one. Genome sequencing of the producer strain led to the identification of a putative biosynthetic gene cluster for the pyxipyrrolones. The compounds showed activity against several cancer cell lines (μ m range) with pyxipyrrolone B having 2- to 11-fold higher activity than A, although they differ only by one methylene group. [ABSTRACT FROM AUTHOR]

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Ripostatin is a promising antibiotic that inhibits RNA polymerase by binding to a novel binding site. In this study, the characterization of the biosynthetic gene cluster of ripostatin, which is a peculiar polyketide synthase (PKS) hybrid cluster encoding cis- and trans-acyltransferase PKS genes, is reported. Moreover, an unprecedented mechanism for phenyl acetic acid formation and loading as a starter unit was discovered. This phenyl-C2 unit is derived from phenylpyruvate (phenyl-C3) and the mechanism described herein explains the mysterious loss of one carbon atom in ripostatin biosynthesis from the phenyl-C3 precursor. Through in vitro reconstitution of the whole loading process, a pyruvate dehydrogenase like protein complex was revealed that performs thiamine pyrophosphate dependent decarboxylation of phenylpyruvate to form a phenylacetyl- S-acyl carrier protein species, which is supplied to the subsequent biosynthetic assembly line for chain extension to finally yield ripostatin. [ABSTRACT FROM AUTHOR]

Copyright of Angewandte Chemie is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In the search for new secondary metabolites from myxobacteria, a strain from the genus Pyxidicoccus was investigated. This led to the identification of a new class of natural products showing structural novelty and interesting biological activity. Isolation and structure elucidation of two analogues led to the identification of pyxipyrrolone A and B, harboring the novel 3-methylene-2,3,4,5,6,7,8,9-octahydro-1H-benzo[e]isoindol-1-one scaffold. Mosher's ester analysis combined with NMR studies allowed the determination of all stereocenters but one. Genome sequencing of the producer strain led to the identification of a putative biosynthetic gene cluster for the pyxipyrrolones. The compounds showed activity against several cancer cell lines (μm range) with pyxipyrrolone B having 2- to 11-fold higher activity than A, although they differ only by one methylene group., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Ripostatin is a promising antibiotic that inhibits RNA polymerase by binding to a novel binding site. In this study, the characterization of the biosynthetic gene cluster of ripostatin, which is a peculiar polyketide synthase (PKS) hybrid cluster encoding cis- and trans-acyltransferase PKS genes, is reported. Moreover, an unprecedented mechanism for phenyl acetic acid formation and loading as a starter unit was discovered. This phenyl-C2 unit is derived from phenylpyruvate (phenyl-C3) and the mechanism described herein explains the mysterious loss of one carbon atom in ripostatin biosynthesis from the phenyl-C3 precursor. Through in vitro reconstitution of the whole loading process, a pyruvate dehydrogenase like protein complex was revealed that performs thiamine pyrophosphate dependent decarboxylation of phenylpyruvate to form a phenylacetyl-S-acyl carrier protein species, which is supplied to the subsequent biosynthetic assembly line for chain extension to finally yield ripostatin., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)