Thailandenes, Cryptic Polyene Natural Products Isolated from Burkholderia thailandensis Using Phenotype-Guided Transposon Mutagenesis.

TitleThailandenes, Cryptic Polyene Natural Products Isolated from Burkholderia thailandensis Using Phenotype-Guided Transposon Mutagenesis.
Publication TypeJournal Article
Year of Publication2020
AuthorsPark, J-D, Moon, K, Miller, C, Rose, J, Xu, F, Ebmeier, CC, Jacobsen, JR, Mao, D, Old, WM, DeShazer, D, Seyedsayamdost, MR
JournalACS Chem Biol
Date Published2020 Jan 02
ISSN1554-8937
Abstract

Burkholderia thailandensis has emerged as a model organism for investigating the production and regulation of diverse secondary metabolites. Most of the biosynthetic gene clusters encoded in B. thailandensis are silent, motivating the development of new methods for accessing their products. In the current work, we add to the canon of available approaches using phenotype-guided transposon mutagenesis to characterize a silent biosynthetic gene cluster. Because secondary metabolite biosynthesis is often associated with phenotypic changes, we carried out random transposon mutagenesis followed by phenotypic inspection of the resulting colonies. Several mutants exhibited intense pigmentation and enhanced expression of an iterative type I polyketide synthase cluster that we term org. Disruptions of orgA, orgB, and orgC abolished the biosynthesis of the diffusible pigment, thus linking it to the org operon. Isolation and structural elucidation by HR-MS and 1D/2D NMR spectroscopy revealed three novel, cryptic metabolites, thailandene A-C. Thailandenes are linear formylated or acidic polyenes containing a combination of cis and trans double bonds. Variants A and B exhibited potent antibiotic activity against Staphylococcus aureus and Saccharomyces cerevisiae but not against Escherichia coli. One of the transposon mutants that exhibited an enhanced expression of org contained an insertion upstream of a σ54-dependent transcription factor. Closer inspection of the org operon uncovered a σ54 promoter consensus sequence upstream of orgA, providing clues regarding its regulation. Our results showcase the utility of phenotype-guided transposon mutagenesis in uncovering cryptic metabolites encoded in bacterial genomes.

DOI10.1021/acschembio.9b00883
Alternate JournalACS Chem. Biol.
PubMed ID31816232