Nocathioamides, Uncovered by a Tunable Metabologenomic Approach, Define a Novel Class of Chimeric Lanthipeptides

The increasing number of available genomes, in combination with advanced genome mining techniques, unveiled a plethora of biosynthetic gene clusters (BGCs) coding for ribosomally synthesized and post-translationally modified peptides (RiPPs). The products of these BGCs often represent an enormous resource for new and bioactive compounds, but frequently, they cannot be readily isolated and remain cryptic. Here, we describe a tunable metabologenomic approach that recruits a synergism of bioinformatics in tandem with isotope- and NMR-guided platform to identify the product of an orphan RiPP gene cluster in the genomes of Nocardia terpenica IFM 0406 and 0706T . The application of this tactic resulted in the discovery of nocathioamides family as a founder of a new class of chimeric lanthipeptides I.

New Nocobactin Derivatives with Antimuscarinic Activity, Terpenibactins A-C, Revealed by Genome Mining of Nocardia terpenica IFM 0406

We report a genomics-guided exploration of the metabolic potential of the brasilicardin producer strain Nocardia terpenica IFM 0406. Bioinformatics analysis of the whole genome sequence revealed the presence of a biosynthetic gene cluster presumably responsible for the generation of formerly unknown nocobactin derivatives. Mass spectrometry-assisted isolation led to the identification of three new siderophores, terpenibactins A (1), B (2) and C (3), which belong to the class of nocobactins. Their structures were elucidated by employing spectroscopic techniques. Compounds 1-3 demonstrated inhibitory activity towards the muscarinic M3 receptor, while exhibiting only a low cytotoxicity.

Functional Characterisation of ClpP Mutations Conferring Resistance to Acyldepsipeptide Antibiotics in Firmicutes

Acyldepsipeptide (ADEP) is an exploratory antibiotic with a novel mechanism of action. ClpP, the proteolytic core of the caseinolytic protease, is deregulated towards unrestrained proteolysis. Here, we report on the mechanism of ADEP resistance in Firmicutes. This bacterial phylum contains important pathogens that are relevant for potential ADEP therapy. For Staphylococcus aureus, Bacillus subtilis, enterococci and streptococci, spontaneous ADEP-resistant mutants were selected in vitro at a rate of 10-6 . All isolates carried mutations in clpP. All mutated S. aureus ClpP proteins characterised in this study were functionally impaired; this increased our understanding of the mode of operation of ClpP. For molecular insights, crystal structures of S. aureus ClpP bound to ADEP4 were determined. Well-resolved N-terminal domains in the apo structure allow the pore-gating mechanism to be followed. The compilation of mutations presented here indicates residues relevant for ClpP function and suggests that ADEP resistance will occur at a lower rate during the infection process.