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Proceedings Paper

Toxins and antimicrobial peptides: interactions with membranes
Author(s): Diana E. Schlamadinger; Jonathan E. Gable; Judy E. Kim
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Paper Abstract

The innate immunity to pathogenic invasion of organisms in the plant and animal kingdoms relies upon cationic antimicrobial peptides (AMPs) as the first line of defense. In addition to these natural peptide antibiotics, similar cationic peptides, such as the bee venom toxin melittin, act as nonspecific toxins. Molecular details of AMP and peptide toxin action are not known, but the universal function of these peptides to disrupt cell membranes of pathogenic bacteria (AMPs) or a diverse set of eukaryotes and prokaryotes (melittin) is widely accepted. Here, we have utilized spectroscopic techniques to elucidate peptide-membrane interactions of alpha-helical human and mouse AMPs of the cathelicidin family as well as the peptide toxin melittin. The activity of these natural peptides and their engineered analogs was studied on eukaryotic and prokaryotic membrane mimics consisting of <200-nm bilayer vesicles composed of anionic and neutral lipids as well as cholesterol. Vesicle disruption, or peptide potency, was monitored with a sensitive fluorescence leakage assay. Detailed molecular information on peptidemembrane interactions and peptide structure was further gained through vibrational spectroscopy combined with circular dichroism. Finally, steady-state fluorescence experiments yielded insight into the local environment of native or engineered tryptophan residues in melittin and human cathelicidin embedded in bilayer vesicles. Collectively, our results provide clues to the functional structures of the engineered and toxic peptides and may impact the design of synthetic antibiotic peptides that can be used against the growing number of antibiotic-resistant pathogens.

Paper Details

Date Published: 21 August 2009
PDF: 13 pages
Proc. SPIE 7397, Biosensing II, 73970J (21 August 2009); doi: 10.1117/12.827439
Show Author Affiliations
Diana E. Schlamadinger, Univ. of California, San Diego (United States)
Jonathan E. Gable, Univ. of California, San Diego (United States)
Judy E. Kim, Univ. of California, San Diego (United States)


Published in SPIE Proceedings Vol. 7397:
Biosensing II
Manijeh Razeghi; Hooman Mohseni, Editor(s)

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