Anionic Antimicrobial Peptides from Eukaryotic Organisms and their Mechanisms of Action

Anionic antimicrobial peptides (AAMPs) are important components of the innate immune system and here, we review recent research into these peptides. As examples, we refer to two major families of AAMPs: those that adopt cysteine stabilized β-sheet structure, such as plant cyclotides, and those that are encrypted in larger proteins, such as bovine kappacins. This review shows that AAMPs use a diverse range of antimicrobial mechanisms, which in some cases, such as ovine SAAPs, involves translocation across the membrane to utilize intracellular sites of antimicrobial action. In other cases, the membrane itself is the major site of action for AAMPs as in the case of cyclotides, which permeabilize membranes via pore formation, and human β-defensins, which induce the disintegration of membranes via carpet-type mechanisms prior to action against intracellular targets. These AAMPs show the potential for development as antiviral agents, insecticides, topical biocides, fertility control agents, therapeutically useful antibiotics, decontaminants food preservatives and agents against dental and periodontal diseases.