Abstract
Marine organisms serve as a rich source of bioactive natural compounds, including antimicrobial agents. Jellyfish, which are ancient marine invertebrates with hundreds of millions of years of evolutionary history, have been in continuous contact with a diverse array of pathogenic microorganisms from seawater, which may give rise to a distinctive innate immune system and related defensive molecules. However, it is difficult and inefficient to isolate active ingredients directly from jellyfish for enrichment, though few jellyfish-sourced antimicrobial peptides (AMPs) have been reported. In this study, we utilized transcriptomic big data with bioinformatic tools to dig deeper into potential antimicrobial components in jellyfish, and identified a new AMP JFP-2826 from Rhopilema esculentum. The 20-mer peptide exhibited an alpha-helix structure and showed antimicrobial activity against selected bacterial strains; more importantly, JFP-2826 demonstrated good selectivity for marine-specific Vibrio including Vibrio vulnificus. Sequence analysis of the full-length protein of JFP-2826 revealed that it is derived from the housekeeping gene glyceraldehyde-3-phosphate dehydrogenase (GAPDH), which is probably produced through enzymatic cleavage of the N-terminal fragment. This suggests that GAPDH of jellyfish might have a newly discovered antimicrobial-related function that is conducted by releasing JFP-2826-like cryptic peptides. JFP-2826 can be subjected to further structural modifications and optimizations to potentially become a potent lead peptide for the development of novel antimicrobial drugs treating infections of marine pathogens.