Marine-inspired antimicrobial peptides disrupt gene expression on DNA level

ABSTRACT: Genome mining of Streptomyces sp. H-KF8 combined with sequence engineering yielded two serum-stable, non-cytotoxic, non-lytic antimicrobial peptides, L3 and L3-K. Initial studies in uropathogenic Escherichia coli suggested membrane effects and nucleoid relaxation, prompting a comprehensive investigation of their mode of action. Tandem mass tag (TMT)-based quantitative proteomics revealed extensive proteome remodelling, with 175 and 120 differentially expressed proteins (DEPs) after treatment with L3 and L3-K, respectively. L3 induced predominantly upregulated responses linked to metabolism, RNA processing, transport, and homeostasis, whereas L3-K mainly caused downregulation of proteins involved in metabolism, transport, and cell structure. Both peptides disrupted ABC transporter–mediated nutrient uptake and elicited stress responses, while L3 specifically perturbed the mal regulon, indicative of broader transcriptional dysregulation. Complementary fluorescent dye displacement and in vitro transcription/translation assays demonstrated non-specific DNA binding, stronger for L3 than L3-K, and potent inhibition of transcriptional and translational processes. Strikingly, inhibitory concentrations paralleled their minimum inhibitory concentrations, directly linking DNA binding and interference with central information processing to antimicrobial activity. Taken together, these findings reveal that L3 and L3-K primarily act by targeting DNA and interfering with the transcription–translation machinery. Beyond offering mechanistic insights, this study also underscores their promise as scaffolds for developing next-generation antimicrobial peptides with DNA-binding, non-membrane-lytic activity.

INSTRUMENT(S):

ORGANISM(S): Escherichia Coli

SUBMITTER: Liisa Arike  

LAB HEAD: Luisa Beyer

PROVIDER: PXD068455 | Pride | 2026-01-23

REPOSITORIES: Pride