Antimicrobial Peptides

Antimicrobial peptides (AMPs) are a diverse group of peptides that evolved across all kingdoms of life. Gramicidin, daptomycin, bacitracin, and colistin are notable examples of clinically used AMPs. Antimicrobial peptides are attracted to negatively charged bacterial membranes via coulombic attraction. AMPs disrupt the cell membrane via mechanisms described as the carpet model, toroidal pore model, and barrel stave model. The membrane disruptions formed will lead to the exudation of cytoplasmic contents and the death of the bacterium. Membrane localization can be observed via fluorescence microscopy involving the use of fluorescently tagged AMPs. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) can be used to visualize membrane damage caused by AMP. Simple radioassays can be used to track small-molecule leakage from the bacterial cytoplasm. Secondary metabolic inhibitory effects of AMPs also contribute to their mechanism of action. Resistance mechanisms to AMPs include proteolytic enzymes, changing the membrane charge, formation of biofilms, and the use of multidrug efflux pumps.