Marine sponges host bacteria that produce diverse bioactive compounds. Here, the authors conduct a large-scale metagenomic, single-bacterial and biochemical study to reveal the untapped biosynthetic p...

Recent advances in metabolomics are accelerating natural product (NP) drug discovery. NPs possess diverse biological relevance and comprise a signific…

The methylenomycins are highly functionalized cyclopentanone antibiotics produced by Streptomyces coelicolor A3(2). A biosynthetic pathway to the methylenomycins has been proposed based on sequence analysis of the proteins encoded by the methylenomycin biosynthetic gene cluster and the incorporation of labeled precursors. However, the roles played by putative biosynthetic enzymes remain experimentally uninvestigated. Here, the biosynthetic functions of enzymes encoded by mmyD, mmyO, mmyF, and mmyE were investigated by creating in-frame deletions in each gene and investigating the effect on methylenomycin production. No methylenomycin-related metabolites were produced by the mmyD mutant, consistent with the proposed role of MmyD in an early biosynthetic step. The production of methylenomycin A, but not methylenomycin C, was abolished in the mmyF and mmyO mutants, consistent with the corresponding enzymes catalyzing the epoxidation of methylenomycin C, as previously proposed. Expression of mmyF and mmyO in a S. coelicolor M145 derivative engineered to express mmr, which confers methylenomycin resistance, enabled the resulting strain to convert methylenomycin C to methylenomycin A, confirming this hypothesis. A novel metabolite (premethylenomycin C), which readily cyclizes to form the corresponding butanolide (premethylenomycin C lactone), accumulated in the mmyE mutant, indicating the corresponding enzyme is involved in introducing the exomethylene group into methylenomycin C. Remarkably, both premethylenomycin C and its lactone precursor were one to two orders of magnitude more active against various Gram-positive bacteria, including antibiotic-resistant Staphylococcus aureus and Enterococcus faecium isolates, than methylenomycins A and C, providing a promising starting point for the development of novel antibiotics to combat antimicrobial resistance.

Culture-independent metagenomic approaches have proven to be effective tools for identifying previously hidden biosynthetic gene clusters (BGCs) encoding novel natural products with potential medical relevance. However, producing these compounds remains challenging as metagenomic BGCs often originate from organisms phylogenetically distant from available heterologous hosts. Lasso peptides, a subclass of ribosomally synthesized and post-translationally modified peptide (RiPP) natural products, exhibit diverse bioactivities, yet no lasso peptide has previously been discovered directly from a metagenome. Here, we report the discovery and heterologous expression of the first soil metagenome-derived lasso peptide. Expression of its biosynthetic gene cluster in Escherichia coli, followed by mass spectrometry analysis, strongly supported the predicted amino acid sequence and lasso structure of the peptide. Notably, this lasso peptide is the first to feature asparagine as the ring-forming residue at position one. Taxonomic analysis of the corresponding BGC identified an uncultivated member of the Steroidobacterales family (Gammaproteobacteria) as the closest known relative of the potential native host. These findings underscore the potential of metagenomic genome mining to reveal structurally novel RiPPs and to expand our understanding of the natural diversity of lasso peptides.

An advanced metabolomic workflow featuring expert knowledge-tailored mass spectral queries and multi-informative molecular networking was applied to French DNA-barcoded collections of Amanita species ...

Covering: 2013 to 2023 In this review, we analyzed the scientific literature of the period 2013–2023 that reported novel specialized metabolites from the Actinomycetes, one of the most prolific…

Phylogenetic analysis is widely used to predict enzyme function, yet building annotated and reusable trees is labor-intensive and requires extensive knowledge about the specific enzymes. Existing reso...

Phylogenetic analysis is widely used to predict enzyme function, yet building annotated and reusable trees is labor-intensive and requires extensive knowledge about the specific enzymes. Existing reso...

Covering: 2000 to 2025The Lamiaceae family, the sixth largest among angiosperms, is renowned for its rich diversity of terpenoids, many of which exhibit remarkable bioactivities, including anti-inflam...

Halogenated indole natural products have been isolated from a variety of organisms, including plants, marine algae, marine invertebrates, and bacteria. Aquatic cyanobacteria, in particular, are rich producers of brominated indoles, but their cognate biosynthetic enzymes have only been successfully linked in a limited number of natural products, such as the eagle-killing toxin aetokthonotoxin (AETX). The biosynthetic pathway for AETX involves five enzymes, two of which were previously undescribed due to incomplete annotations as hypothetical proteins. Our recent elucidation of AETX biosynthesis established functions of the two previously unknown proteins as enzymes responsible for tryptophan halogenation (AetF) and nitrile synthesis (AetD). Given their sequence novelty, we queried metagenomic data sets for these two enzymes and identified two new cyanobacterial haloindole biosynthetic gene clusters (BGCs) from marine sediment in Moorea, French Polynesia, and soil-derived samples in Maunawili Falls, Hawaii. We characterized the recovered BGCs by biochemically validating a new AetF homologue that exclusively halogenates free indole, rather than tryptophan as observed in AETX biosynthesis, and a new AetD homologue that harbors distinct substrate preferences, expanding the scope of nitrile biosynthesis. Additional characterization of core and accessory enzymes within these AETX-like BGCs highlights the breadth and diversity of haloindole biosynthetic machinery in cyanobacteria.

Nature Communications - Withanolides are plant steroids with potent bioactivities found in many medicinal plants including Withania somnifera, but their biosynthetic pathway is largely unknown....

Grayson et al. report the genomic discovery and biochemical characterization of a widely distributed gene cluster family for briarane diterpenoid biosynthesis in metazoans. This study expands our unde...

Background Soil ecosystems have long been recognized as hotspots of microbial diversity, but most estimates of their complexity remain speculative, relying on limited data and extrapolation from shall...

Goethe University Frankfurt am Main invites applications for the position of Professor (W3) in Organic Synthesis at the Faculty of Biochemistry, Ch...

Nature - A new lasso peptide antibiotic exhibits broad-spectrum activity against Gram-negative and Gram-positive bacteria by interfering with bacterial protein synthesis, is unaffected by common...