Microbial membranes and the action of antimicrobial peptides.

Since their discovery, antimicrobial peptides (AMPs) have excited researchers worldwide, mainly due to their wide spectrum of activity and rapid action. As for the latter feature, it is believed to be a consequence of their membrane-targeting properties. In the present chapter we will describe this fine-tuned interaction between peptides and lipids in a biophysical context. We took advantage of the antimicrobial peptide database to identify physicochemical properties of AMPs based on their target microorganisms. In spite of the fact that cell envelopes of microorganisms present different molecular composition, as well as molecular organization, the physicochemical properties of membrane-interacting AMPs have been found to be similar. The interactions of AMPs with different components of the cell envelope and their consequence for the peptide's toxicity are discussed. In addition, membrane-peptide interactions are described with a focus on bacterial membranes, since they vary for different bacterial species and can contribute to the efficacy of some AMPs. Finally, we will outline novel strategies for using the interaction of AMPs with components of the microbial membranes both directly as antimicrobial agents, and by altering membrane properties so as to sensitize microorganisms to different cytotoxic drugs.