While an immense number of natural products have been screened for bioactivity using a variety of phenotypic assays, elucidation of their protein targets remains a significant bottleneck limiting furt...

Bacteria have been long proposed to harbor ancestral forms of the bifunctional terpene synthases found in plants. Recent studies described the first identification of these fused bacterial diterpene…

Covering: up to 2025 para-Quinone methides (p-QMs) are highly reactive Michael acceptors with broad applications in organic synthesis, drug development, and materials science. Nature ingeniously…

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.

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

Eunicellane diterpenoids, characterized by a 6,10-bicyclic core, are prone to undergo further cyclization into gersemiane diterpenoids via acid- or epoxidation-mediated protonation. However, it…

The structural complexity of natural products arises from the complexity of their biosynthetic pathways and directly contributes to their biological activities. Guided by this principle, we screened 5...

AbstractBackground. Soil ecosystems have long been recognised as hotspots of microbial diversity, but most estimates of their microbial and functional comp

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.

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Covering: up to December 2024 Microbial metabolic pathways, including those of endophytic fungi, offer significant potential for synthesizing secondary metabolites, regardless of their ecological…

Harziane diterpenoids constitute a unique class of diterpenoids distinguished by their intricate 6/5/7/4 carbocyclic scaffold, presenting notable structural complexity. Since the first harziane…