Trematocine, a Novel Antimicrobial Peptide from the Antarctic Fish Trematomus bernacchii: Identification and Biological Activity

Antimicrobial peptides (AMPs) are short peptides active against a wide range ofpathogens and, therefore, they are considered a useful alternative to conventional antibiotics. Wehave identified a new AMP in a transcriptome derived from the Antarctic fish Trematomusbernacchii. This peptide, named Trematocine, has been investigated for its expression both at thebasal level and after in vivo immunization with an endemic Antarctic bacterium (Psychrobacter sp.TAD1). Results agree with the expected behavior of a fish innate immune component, therefore wedecided to synthesize the putative mature sequence of Trematocine to determine the structure, theinteraction with biological membranes, and the biological activity. We showed that Trematocinefolds into a α-helical structure in the presence of both zwitterionic and anionic charged vesicles. Wedemonstrated that Trematocine has a highly specific interaction with anionic charged vesicles andthat it can kill Gram-negative bacteria, possibly via a carpet like mechanism. Moreover,Trematocine showed minimum inhibitory concentration (MIC) and minimum bactericidalconcentration (MBC) values against selected Gram-positive and Gram-negative bacteria similar toother AMPs isolated from Antarctic fishes. The peptide is a possible candidate for a new drug as itdoes not show any haemolytic or cytotoxic activity against mammalian cells at the concentrationneeded to kill the tested bacteria.