Biosynthetic Pathway Connects Cryptic Ribosomally Synthesized Posttranslationally Modified Peptide Genes with Pyrroloquinoline Alkaloids

Abstract

Summary In an era where natural product biosynthetic gene clusters can be rapidly identified from sequenced genomes, it is unusual for the biosynthesis of an entire natural product class to remain unknown. Yet, the genetic determinates for pyrroloquinoline alkaloid biosynthesis have remained obscure despite their abundance and deceptive structural simplicity. In this work, we have identified the biosynthetic gene cluster for the ammosamides A-C, pyrroloquinoline alkaloids from Streptomyces sp. CNR-698. Through direct cloning, heterologous expression and gene deletions we have validated the ammosamide biosynthetic gene cluster and demonstrated that these seemingly simple molecules are derived from a surprisingly complex set of biosynthetic genes that are also found in the biosynthesis of lymphostin, a structurally related pyrroloquinoline alkaloid from Salinispora and Streptomyces. Our results implicate a conserved set of genes driving pyrroloquinoline biosynthesis, which consist of genes frequently associated with ribosomal peptide natural product biosynthesis, and whose exact biochemical role remains enigmatic.

Understanding and Improving the Activity of Flavin-Dependent Halogenases via Random and Targeted Mutagenesis

“…Another FDH, which appears to halogenate a precursor of Ammosamide B (Fig. 4A, 10 ), has recently been identified and demonstrates the highest sequence homology to MibH (79). It was originally thought that chlorination of L-Trp by this FDH, Amm3, was the first biosynthetic step for Ammosamide B; however, evidence suggests that Amm3 chlorinates a downstream precursor (79).…”

Another Look at Pyrroloiminoquinone Alkaloids—Perspectives on Their Therapeutic Potential from Known Structures and Semisynthetic Analogues

“…Highlights of important patterns shown in Figure 1 are organized around compounds containing the C 10 N 2 pyrrolo[4,3,2- de ]quinoline. This framework is now considered to be created by ribosomally synthesized and post-translationally modified peptide (RiPP) pathways delivering a C-terminal tryptophan building block [16]. The compilation in Figure 1 also abstracts therapeutic assessment outcomes for eight different lead structures [8,9,10,11,12,13,14,15,17,18,19,20,21,22].…”

Total Synthesis of Damirone C, Makaluvamine O, Makaluvone, Batzelline C and Batzelline D

“…An intramolecular Michael addition, reoxidation of the hydroquinone and halogenation through FADH 2 ‐dependent halogenases or haloperoxidases would lead to the halogenated pyrrolo[4,3,2‐ de ]quinoline alkaloids 1b and 1c ,. Halogenation at an earlier stage of the biosynthesis might also be possible . N ‐methylation of 1b and 1c via a SAM‐dependent methyltransferase would afford the alkaloids 1d and 1e .…”

“…Halogenation at an earlier stage of the biosynthesis might also be possible . N ‐methylation of 1b and 1c via a SAM‐dependent methyltransferase would afford the alkaloids 1d and 1e . The proposed biosynthesis is supported by the fact that the non‐halogenated pyrrolo[4,3,2‐ de ]quinoline alkaloid damirone C ( 1a ) was isolated from Z. fuliginosa …”