Abstract Description

Lanthipeptides are ribosomally synthesized and post-translationally modified peptides (RiPPs) with remarkable structural diversity and bioactive potential, making them promising candidates for drug discovery. While most characterized lanthipeptides are derived from Gram-positive bacteria, lanthipeptides from Gram-negative organisms are less common and remain understudied. Marine sponge microbiomes are a rich source of untapped chemical diversity, providing novel biosynthetic gene clusters (BGCs) with potential for the discovery of new therapeutically relevant compounds. Here, we mined a sponge-derived metagenome for novel RiPPs and identified a putative Class III lanthipeptide BGC. The precursor peptides were heterologously expressed in Escherichia coli BL21 (DE3) using a dual-plasmid system, with the precursor and pathway-specific modifying enzyme encoded on one plasmid and the cognate peptidase provided on a separate plasmid to enable proper post-translational maturation and leader peptide cleavage. Preliminary antimicrobial activity assays showed potent antibacterial activity when assessed using the peptide mixture. Both Gram-positive and Gram-negative strains treated with the peptides showed significant reduction in viability. This work expands on the limited reports of bioactive lanthipeptides derived from Gram-negative bacteria and highlights the potential for further investigation of class III lanthipeptides as novel antimicrobial candidates.