(634b) Supported Bilayers Composed of Bacterial Outer Membranes for the Study of Lipopolysaccharide Interaction with Antimicrobial Peptides

The bacterial outer membrane is a critical barrier that contains membrane proteins and liposaccharides that fulfill crucial biological activities for the bacteria, but also protect it from harsh environments and compounds intended to kill the bacteria. With the advent of drug-resistant bacteria, new methods must be developed to understand the functional role of this membrane and its constituents to enable novel drug designs to treat Gram-negative infection. In this study, we report a simple method to form a bacteria-like supported lipid bilayer (BLSB), which incorporates native lipids and membrane proteins of gram-negative bacterial outer membrane. BLSBs are assembled with outer membrane vesicles (OMVs), proteoliposomes released from the outer membrane. We first characterize the formation of BLSBs by performing quartz crystal microbalance with dissipation monitoring (QCM-D) and fluorescent recovery after photobleaching (FRAP). By monitoring the formation process of BLSBs, we are able to control the amount of native components incorporated and determine the quality of the bilayers. As a demonstration of BLSBs platform, we characterize antimicrobial peptides (AMPs) interactions with bacterial outer membranes.  We employ QCM-D to probe the interactions between BLSB and polymyxin B, a cationic peptide used for treating Gram-negative infection. With the multiple signatures obtained from the QCM-D studies, a detailed antibacterial mechanism of polymyxin B towards outer membrane has been further unraveled and will be presented here.