Time influence on the interaction between Cyt2Aa2 and lipid/cholesterol bilayers

Abstract

© 2016 Wiley Periodicals, Inc. Protein–membrane interactions are still an important topic of investigation. One of the suitable experimental techniques used by the scientific community to address such question is atomic force microscopy. In a previous work, we have reported that the binding mechanism between the cytolytic and antimicrobial protein (Cyt2Aa2) and lipid/cholesterol bilayers was concentration-dependent, leading to either the formation of holes in the bilayer or aggregates. Here we study such binding mechanism as a function of time at low protein concentrations (10 µg/mL). We demonstrate that although holes are formed during the first stages of the protein–lipid interaction, a reparation process due to molecular mobility in the bilayer leads to a homogenous and isotropic protein–lipid/cholesterol layer within 3 hr. The combination of imaging, force spectroscopy, and phase contrast delivered information about topography dynamics (molecular mobility), layer thickness, and mechanical properties of the protein–lipid/cholesterol system. These results highlight the importance of the observation time in (such type of) protein–lipid interactions (at low protein concentrations).