Characterization of an Environmental DNA‐Derived Gene Cluster that Encodes the Bisindolylmaleimide Methylarcyriarubin

Abstract

Bisindolylmaleimides represent a naturally occurring class of metabolites that are of interest because of their protein kinase inhibition activity. From a metagenomic library constructed using soil DNA, we identified the four gene mar cluster, a bisindolylmaleimide gene cluster that encodes for methylarcyriarubin (1) production. Heterologous expression of the mar gene cluster in Escherichia coli revealed that the Rieske dioxygenase, MarC, facilitates the oxidative decarboxylation of a chromopyrrolic acid (CPA) intermediate to yield the bisindolylmaleimide core. The characterization of the mar cluster defines a new role for CPA in the biosynthesis of structurally diverse bacterial tryptophan dimers.

Targeted Metagenomics: Finding Rare Tryptophan Dimer Natural Products in the Environment

“…erdasporine), 11 and bisindolylmaleimide ( e.g. arcyriarubin) 17 (Figures 1C). The divergent evolutionary history of the gene clusters that encode these six families of structures is reflected in the fact that CPAS gene phylogeny reproduces the differences seen in TD core structure.…”

Global biogeographic sampling of bacterial secondary metabolism

“…AD and KS amplicon reads were assigned to known biosynthetic gene clusters using the eSNaPD algorithm at an e-value cutoff of 10 −45 ( Reddy et al, 2014 ). At this threshold eSNaPD has been used to successfully assign-and-recover gene clusters that encode congeners of multiple natural product families using only the sequence from a single domain amplicon ( Owen et al, 2013 ; Chang and Brady, 2014 ; Kang and Brady, 2014 ). NRPS/PKS clusters typically have multiple KS or AD domains.…”

Heterologous expression of bacterial natural product biosynthetic pathways

“…Brady and colleagues pioneered the discovery of a number of novel bioactive natural products through metagenomic library screening and subsequent heterologous expression of soil environmental DNA-derived genes in various hosts. [182][183][184][185][186][187][188] For instance, methylarcyriarubin 56 was isolated from E. coli aer expression of the putative mar BGC with an exogenous oxidized tryptophan (IPA imine) synthase encoding gene. This represented the rst report of methylarcyriarubin being isolated as a natural product.…”

“…This represented the rst report of methylarcyriarubin being isolated as a natural product. 182 To overcome limitations in relation to the screening of current eDNA libraries, the same team performed a chemical-biogeographic survey to assess chromopyrrolic acid synthase (CPAS) gene diversity, resulting in the identication of two bioactive tryptophan dimers (TDs): hydroxysporine 57 and reductasporine 58. The latter molecule contains a previously unidentied pyrrolinium indolocarbazole core, which might be correlated to its unusual bioactivity.…”