Interaction of antimicrobial dermaseptin and its fluorescently labeled analogs with phospholipid membranes

Abstract

Dermaseptin, a 34 amino-acid residue antimicrobial polypeptide [Mor, A., Nguyen, V. H., Delfour, A., Migliore-Samour, D., & Nicolas, P. (1991) Biochemistry 30, 8824-8830] was synthesized and selectively labeled at its N-terminal amino acid with either 7-nitrobenz-2-oxa-1,3-diazole-4-yl (NBD), rhodamine, or fluorescein. The fluorescent emission spectra of the NBD-labeled dermaseptin displayed a blue-shift upon binding to small unilamellar vesicles (SUV), reflecting the relocation of the fluorescent probe to an environment of increased apolarity. Titrations of solutions containing NBD-labeled dermaseptin with SUV composed of zwitterionic or acidic phospholipids were used to generate binding isotherms, from which were derived surface partition constants of (0.66 +/- 0.06) x 10(4) M-1 and (2.8 +/- 0.3) x 10(4) M-1, respectively. The shape of the binding isotherms, as well as fluorescence energy transfer measurements, suggests that some aggregation of membrane-bound peptide monomers occurs in acidic but not in zwitterionic vesicles. The preferential susceptibility of the peptide to proteolysis when bound to zwitterionic but not to acidic SUV suggests that these aggregates might then penetrate a relatively short distance into the hydrophobic region of the acidic membrane. Furthermore, the results provide good correlation between the peptide's strong binding and its ability to permeate membranes composed of acidic phospholipids, as revealed by a dissipation of diffusion potential and a release of entrapped calcein from SUV.

Interaction of wheat α‐thionin with large unilamellar vesicles

“…This detergent-like property has been described for other small peptides such as magainins 1 and 2 (Matsuzaki et al, 1989(Matsuzaki et al, , 1991, dermaseptin (Pouny et al, 1992), or melittin (Katsu et al, 1989;Benachir & Lafleur, 1995) and larger proteins like the bacterial toxin a-haemolysin secreted by Escherichia coli (Ostolaza et al, 1993) or CytA, a 27 kDa protein belonging to the family of &endotoxins occumng in parasporal crystals of Bacillus thuringiensis var. israelensis (Butko et al, 1996(Butko et al, , 1997.…”

Alpha-helical cationic antimicrobial peptides: relationships of structure and function

“…In the carpet model (Pouny et al, 1992), the peptides initially associate with the membrane and align parallel to the surface of bilayer, covering the surface in a carpet-like fashion. This orientation destabilizes the packing of phospholipids and causes a change in membrane fluidity because of the displacement of phospholipids by peptides.…”

“…Multiple studies demonstrated that peptide helicity might be more important for toxicity (neutral membrane) than antimicrobial activity (negatively charged membrane) of AMPs (Pouny et al, 1992;Dathe et al, 1996). The most convincing evidences are from D-amino acid substitution on model peptides.…”

Antibacterial activity of secretolytin, a chromogranin B‐derived peptide (614–626), is correlated with peptide structure

“…The charged and polar groups are grouped together suggesting that the basic amino acids could interact with the negatively charged phospholipids of the bacterial membranes. Both models predict a hydrophobic domain covering approximatively one third of the molecule which is likely to orientate the peptide towards the hydrophobic core of membranes [24]. Furthermore, several possibilities of internal interactions between charged groups exist.…”