Membrane phase characteristics control NA-CATH activity.

Our studies presented in this report focus on the behavior of NA-CATH， an α-helical cathelicidin antimicrobial peptide， originally discovered in the Naja atra snake. It has demonstrated high potency against gram-positive and gram-negative bacteria with minimal hemolysis. Here we examine the kinetics， behaviors and potential mechanisms of the peptide in the presence of membrane liposome， modeling Escherichia coli， whose membrane exhibits distinct lipid phases. To understand NA-CATH interactions， the role of lipid phases is critical. We test three different lipid compositions to detangle the effect of phase on NA-CATH's activity using a series of leakage experiments. From these studies， we observe that NA-CATH changes from membrane disruption to pore-based lysing， depending on phases and lipid composition. This behavior also plays a major role in its kinetics.