The structure and behavior of the NA-CATH antimicrobial peptide with liposomes

Abstract

Naja atra cathelicidin (NA-CATH) is a 34-amino acid highly cationic peptide identified in Chinese cobras to possess potent toxicity against gram-negative and gram-positive bacteria and low toxicity against host cells. Here, we report the NMR solution structure of the full-length NA-CATH peptide and its interaction with liposomes. The structure shows a well-defined α-helix between residues Phe3 to Lys23, on which one surface is lined by the side-chains of one arginine and 11 lysine residues, while the other side is populated by hydrophobic residues. The last eleven amino acids, which are predominately aromatic and hydrophobic in nature, have no defined structure. NMR data reveal that these residues do not interact with the hydrophobic residues of the helix, indicating that the C-terminal residues have random conformations. Fluorescence requenching experiments, in which liposomes serve as a mimic of the bacterial membranes, result in fluorophore leakage that is consistent with a membrane thinning or transient pore formation mechanism. NMR titration studies of the peptide-liposome interaction reveal that the peptide is in fast exchange with the liposome, consistent with the fluorescent studies. These data indicate that full length NA-CATH possesses a helical segment and unstructured C-terminal tail that disrupts the bilayer to induce leakage and lysing.

Mechanisms of bacterial membrane permeabilization by crotalicidin (Ctn) and its fragment Ctn(15–34), antimicrobial peptides from rattlesnake venom

“…Interestingly, the related NA-CATH cathelicidin seems to switch its mechanism of action from membrane disruption to pore-based lysis in a biphasic model, mimicking the E. coli membrane with an impact on kinetics similar to that described for Ctn (49). Given the high structural similarities between both peptides (an N-terminal ␣-helical segment followed by a disordered tail) (27,53), it is plausible that Ctn may act similarly, and such behavior would explain the complex cell death kinetic pattern here reported. This dual behavior might be tentatively related to the composite structure (␣-helix plus random tail) of both NA-CATH and Ctn, each moiety of the peptide embed-ding into the membrane in a different fashion, as suggested for NA-CATH (49).…”

Antibacterial properties of snake venom components

“…BF-30, cathelicidin-type peptide derived from B. fasciatus is very effective against diverse antibiotic-resistant bacteria, including those that cause wounds (MRSA) (Chen et al 2011a). It was shown that it reduces number of bacteria at the wound, but also prevents inflammation and accelerates wound healing (Zhou et al 2011;Du et al 2015). Cathelicidin (OH-CATH) from Ophiophagus hannah and its analogs exert strong antibacterial and weak hemolytic activity.…”

Hitchhiking with Nature: Snake Venom Peptides to Fight Cancer and Superbugs

“…Du et al postulated that Na-CATH is able to disrupt bacterial membrane-like liposomes via membrane thinning or transient-pore formation [118]. This hypothesis was further confirmed in vitro by Gupta el al.…”

“…Structurally, Na-CATH folds into a well-defined amphipathic α-helix between residues Phe3 and Lys23 in the presence of trifluoroethanol. The remaining 11-residue tail, consisting mostly of aromatic and hydrophobic residues, does not present a defined structure, but appears to interact with lipid membranes [118]. Na-CATH contains an 11-residue sequence [KR(F/A)KKFFKK(L/P)K] known as an ATRA motif, repeated twice and almost totally shared by other SV-CATHs ( Table 2).…”