Lipid Membrane Deformation Induced by Transmembrane Peptides

Abstract

The plasma membrane has an essential role in life activities of living cells. For example, the lipid membrane enables to enclose molecules in inner compartment to isolate from outer environment. Inner/outer molecules are sometimes exchanged by dynamic membrane deformation as endo- or exocytosis. Extensive proteins including membrane proteins complicatedly interact in the deformation event. Matrix-2 (M2) protein in influenza A virus mediates a part of infection pathway by budding and scission. It was reported that the partial sequence of M2 protein has the deformability to liposome which contains model cell-membrane. Besides, a few studies reported that melittin, one of antimicrobial peptides (AMPs), also induced liposome deformation, but the detailed mechanism of the deformation-induced peptides has been still unclear. In this study, as the first step to elucidate the mechanism, we focus on short membrane binding peptide, AMPs, and cell-penetrating peptides (CPPs), and evaluate their deformability. The AMPs are known as pore-formation in plasma membrane, and CPPs translates across the lipid membrane. In our experiments, we prepared liposome, added peptides to liposome solution, observed them by microscopy, and then performed the 2D shape-deforming analysis. Also, we developed planner lipid membrane and measured temporal membrane capacitance (Cm). In this paper, we will discuss on (a) these peptides have deformability (b) the deformability difference among each peptide. We believe that our methods will be a useful tool to elucidate the peptide deforming mechanism.