ZURJC28, a Novel Nonribosomal Peptide Analog, Disrupts Membranes of Drug-Resistant Gram-Positive Bacteria

The escalating global crisis of antibiotic resistance necessitates the urgent discovery of novel antimicrobial agents. Nonribosomal peptides (NRPs) are a class of natural products with potent biological activities, but traditional discovery methods are hampered by the difficulty in culturing many microorganisms and the 'silent' nature of many antibiotic biosynthetic genes. This creates a significant gap in identifying new NRP scaffolds. A synthetic bioinformatic natural product (syn-BNP) approach offers a promising avenue to overcome these limitations by integrating computational prediction with chemical synthesis to unlock previously inaccessible therapeutic candidates.

Researchers employed a synthetic bioinformatic natural product (syn-BNP) discovery approach, combining bioinformatics and chemical synthesis. They mined a novel nonribosomal peptide synthetase (NRPS) gene cluster from the genome of Rhodococcus erythropolis D-1 to predict a putative NRP scaffold. Through iterative chemical synthesis and four rounds of structure-activity relationship (SAR) studies, a library of 37 NRP analogs was generated. The primary endpoint involved screening these analogs for antimicrobial activity against various Gram-positive bacteria, followed by mechanistic studies and metabolomics analyses to elucidate their mode of action, and cytotoxicity/hemolytic assays for preliminary safety assessment.

Among the 37 synthesized analogs, ZURJC28 emerged as a lead compound, demonstrating potent activity against multiple Gram-positive bacteria, notably including two drug-resistant strains. Mechanistic investigations and metabolomics analyses revealed a distinct mode of action for ZURJC28. It primarily exerts membrane-disruptive activity, which is strongly associated with its interaction with phosphatidylglycerol (PG)-enriched Gram-positive bacterial membranes. This interaction leads to significant membrane damage and subsequent widespread metabolic dysregulation within the bacterial cells. Importantly, preliminary safety profiling indicated that ZURJC28 exhibits low cytotoxicity and low hemolytic activity in in vitro models, suggesting a favorable initial safety profile for further development. This combination of potent antimicrobial efficacy against resistant strains and a novel membrane-targeting mechanism positions ZURJC28 as a compelling candidate.

ZURJC28 effectively disrupted bacterial membranes by interacting with phosphatidylglycerol (PG), leading to widespread metabolic dysregulation and potent activity against two drug-resistant Gram-positive strains.