Ion channel-like activity of the antimicrobial peptide tritrpticin in planar lipid bilayers

Abstract

The cationic peptide tritrpticin (VRRFPWWWP-FLRR, Trp3) has a broad action spectrum, acting against Gram-positive and Gram-negative bacteria, as well as some fungi, while also displaying hemolytic activity. We have studied the behavior of Trp3 in planar lipid bilayers (or black lipid membrane -BLM) and were able to demonstrate its ion channel-like activity. Channel-like activity was observed in negatively charged azolectin BLM as a sudden appearance of discrete current fluctuations upon application of a constant voltage across the membrane. Trp3 formed large conductance channels (500-2000 pS) both at positive and negative potentials. In azolectin bilayers, the predominant ionchannel activity was characterized by very regular and discrete current steps (corresponding to openings) of uniform amplitude, which exhibited relatively long residence times (of the order of seconds). Occasionally, multiple conductance steps were observed, indicating the simultaneous presence of more than one open pore. In bilayers of zwitterionic diphytanoylphosphatidyl choline (DPhPC) Trp3 also showed ion-channel activity, but in a much less frequent and less prominent way. Studies of ion selectivity indicated that Trp3 forms a cation-selective channel. These results should contribute to the understanding of the molecular interactions and mechanism of action of Trp3 in lipid bilayers and biological membranes.

Fuscopeptins, antimicrobial lipodepsipeptides from Pseudomonas fuscovaginae, are channel forming peptides active on biological and model membranes

“…This was indeed the case for other related LDPs so far analyzed, like SRE [23][24][25][26]32] and SP25A [22]. Nevertheless, cationic selectivity seems to be a common characteristic of positively charged channel forming peptides, like mastoparan and mast cell degranulation peptide [33,34], the antimicrobial cathelicidin tritrpticin [35], gaegurin from frog skin [36], synthetic basic α-helical peptides [37], a segment of the sodium channel polypeptide [38] (see also the excellent review of Sansom [33], and that more recent of Kourie [39]).…”

Mechanism of Action of Surface Immobilized Antimicrobial Peptides Against Pseudomonas aeruginosa

“…allowing the charged resdiues to intricate with membranes (Salay et al, 2004). This in turn may induce a positive curvature in the lipid matrix which can result in displacement of membrane lipids to a greater extent (Vogel et al, 2002).…”