Breaking the silence: new strategies for discovering novel natural products

Tang

et al. 2017

mBio

Heterologous expression has become a powerful tool for studying microbial biosynthetic gene clusters (BGCs). Here, we extend the transformation-associated recombination cloning and heterologous expression platform for microbial BGCs to include Gram-negative proteobacterial expression hosts. Using a broad-host-range expression platform, we test the implicit assumption that biosynthetic pathways are more successfully expressed in more closely related heterologous hosts. Cloning and expression of the violacein BGC from Pseudoalteromonas luteoviolacea 2ta16 revealed robust production in two proteobacterial hosts, Pseudomonas putida KT2440 and Agrobacterium tumefaciens LBA4404, but very little production of the antibiotic in various laboratory strains of Escherichia coli, despite their closer phylogenetic relationship. We identified a nonclustered LuxR-type quorum-sensing receptor from P. luteoviolacea 2ta16, PviR, that increases pathway transcription and violacein production in E. coli by ∼60-fold independently of acyl-homoserine lactone autoinducers. Although E. coli harbors the most similar homolog of PviR identified from all of the hosts tested, overexpression of various E. coli transcription factors did not result in a statistically significant increase in violacein production, while overexpression of two A. tumefaciens PviR homologs significantly increased production. Thus, this work not only introduces a new genetic platform for the heterologous expression of microbial BGCs, it also challenges the assumption that host phylogeny is an accurate predictor of host compatibility.

Section: Introductionmentioning

confidence: 99%

Broad-Host-Range Expression Reveals Native and Host Regulatory Elements That Influence Heterologous Antibiotic Production in Gram-Negative Bacteria

Tang

et al. 2017

mBio

“…Nature is an important source of bioactive products and their derivatives (secondary metabolites), which form part of many important drugs formation widely used in the clinic field [1]. In fact, as reported in Newman and Cragg [2], over the last 30 years the great majority of anticancer, anti-infective, and anti-bacterial drugs are represented by natural products and their derivatives, produced by all organisms (from bacteria to plants, invertebrate, and other animals) with different chemical structure and leading to several biological activities [3,4].…”

Section: Introduction On Bioactive Natural Products Isolationmentioning

confidence: 99%

Genome Mining as New Challenge in Natural Products Discovery

et al. 2020

Drug discovery is based on bioactivity screening of natural sources, traditionally represented by bacteria fungi and plants. Bioactive natural products and their secondary metabolites have represented the main source for new therapeutic agents, used as drug leads for new antibiotics and anticancer agents. After the discovery of the first biosynthetic genes in the last decades, the researchers had in their hands the tool to understand the biosynthetic logic and genetic basis leading to the production of these compounds. Furthermore, in the genomic era, in which the number of available genomes is increasing, genome mining joined to synthetic biology are offering a significant help in drug discovery. In the present review we discuss the importance of genome mining and synthetic biology approaches to identify new natural products, also underlining considering the possible advantages and disadvantages of this technique. Moreover, we debate the associated techniques that can be applied following to genome mining for validation of data. Finally, we review on the literature describing all novel natural drugs isolated from bacteria, fungi, and other living organisms, not only from the marine environment, by a genome-mining approach, focusing on the literature available in the last ten years.

“…In recent years, the discovery of natural products from bacterial sources has shown an increasingly high repetition rate [ 3 ]. In laboratory conditions, most of the environmental bacteria cannot be cultured [ 4 ], and the majority of natural product biosynthetic gene clusters on bacterial genomes are silent [ 5 ]. Currently, a metagenomic approach has been applied for the discovery of novel natural products from uncultured bacteria [ 6 ], and methods including the change in growth conditions [ 7 ], manipulation of the pathway-specific regulators [ 8 ], clustered regularly interspersed short palindromic repeats (CRISPR)-Cas9 strategy [ 9 ], and heterologous expression [ 10 ] have been used to activate the silent biosynthetic gene clusters.…”

Section: Introductionmentioning

confidence: 99%

Salumycin, a New Pyrazolequinone from a Streptomyces albus J1074 Mutant Strain

Tao

Cao

et al. 2020

Molecules

Heterocyclic natural products with various bioactivities play significant roles in pharmaceuticals. Here, we isolated a heterocyclic compound salumycin (1) from a Streptomyces albus J1074 mutant strain. The structure of (1) was elucidated via single-crystal X-ray diffraction, mass spectrometry (MS), fourier transform infrared spectrometer (FTIR), and nuclear magnetic resonance (NMR) data analysis. Salumycin (1) contained a novel pyrazolequinone ring, which had never been previously reported in a natural product. Salumycin (1) exhibited moderate 2,2′-diphenyl-1-picrylhydrazyl (DPPH)-radical scavenging activity (EC50 = 46.3 ± 2.2 μM) compared with tert-butylhydroquinone (EC50 = 4.7 ± 0.3 μM). This study provides a new example of discovering novel natural products from bacteria.