Genome-based analysis of the type II PKS biosynthesis pathway of xanthones in Streptomyces caelestis and their antifungal activity

Structural identification of pyridinopyrone compounds with anti-neuroinflammatory activity from streptomyces sulphureus DSM 40104

This study investigated the chemical composition and biosynthesis pathway of compounds produced by Streptomyces sulphureus DSM 40104. With the guild of molecular networking analysis, we isolated and identified six uncommon structural characteristics of compounds, including four newly discovered pyridinopyrones. Based on genomic analysis, we proposed a possible hybrid NRPS-PKS biosynthesis pathway for pyridinopyrones. Notably, this pathway starts with the use of nicotinic acid as the starting unit, which is a unique feature. Compounds 1-3 exhibited moderate anti-neuroinflammatory activity against LPS-induced BV-2 cell inflammation. Our study demonstrates the diversity of polyene pyrone compounds regarding their chemical structure and bioactivity while providing new insights into their biosynthesis pathway. These findings may lead to the development of new treatments for inflammation-related diseases.

Isolation, Biosynthesis, and Biological Activity of Polycyclic Xanthones From Actinomycetes

Natural products from actinomycetes serve as a crucial source of clinical pharmaceuticals, especially antibiotics and anticancer agents. Among them, polycyclic xanthones belong to a growing group of highly oxygenated aromatic polyketides with a xanthone-containing angular hexacyclic framework. These biosynthetically unique small molecules are of great interest due to their wide spectrum of biological activities, especially the remarkable antibacterial activity against gram-positive bacteria and the significant antineoplastic effects toward various cancer cells at nanomolar concentrations. Their complex structures and significant bioactivities have aroused considerable attention in the chemical and biological communities in recent decades. This review covers the isolation, the biosynthesis, and the biological studies toward these structurally complex and biologically active molecules.

Great diversity of KSα sequences from bat-associated microbiota suggests novel sources of uncharacterized natural products

Polyketide synthases (PKSs) are multidomain enzymes in microorganisms that synthesize complex, bioactive molecules. PKS II systems are iterative, containing only a single representative of each domain: ketosynthase alpha (KS[Formula: see text]), ketosynthase beta and the acyl carrier protein. Any gene encoding for one of these domains is representative of an entire PKS II biosynthetic gene cluster (BGC). Bat skin surfaces represent an extreme environment prolific in Actinobacteria that may constitute a source for bioactive molecule discovery. KS[Formula: see text] sequences were obtained from culturable bacteria from bats in the southwestern United States. From 467 bat bacterial isolates, we detected 215 (46%) had KS[Formula: see text] sequences. Sequencing yielded 210 operational taxonomic units, and phylogenetic placement found 45 (21%) shared <85% homology to characterized metabolites. Additionally, 16 Actinobacteria genomes from the bat microbiome were analyzed for biosynthetic capacity. A range of 69-93% of the BGCs were novel suggesting the bat microbiome may contain valuable uncharacterized natural products. Documenting and characterizing these are important in understanding the susceptibility of bats to emerging infectious diseases, such as white-nose syndrome. Also noteworthy was the relationship between KS [Formula: see text] homology and total BGC novelty within each fully sequenced strain. We propose amplification and detection of KS[Formula: see text] could predict a strain's global biosynthetic capacity.