Liposomes as Membrane Models in Studies of Bacterial Toxins

Publisher Website
Google Scholar
Abstract
Liposomes have become important research tools in biology and medicine, not only because of their usefulness as models of cell membranes, but also for their potential role as drug delivery vehicles. It is as a membrane model system that these structures have been most useful in understanding the interaction between bacterial toxins and the cell membrane. In this review, liposome studies with two major groups of bacterial toxins will be considered. The first group includes the subunit toxins such as cholera toxin and diphtheria toxin, in which the B subunit or fragment of the molecule binds to membrane receptors, and a different portion of the molecule, the A component, then crosses the cell membrane to produce alterations of physiological processes in the cell. Both the binding and internalization steps have been studied with liposomes, and in addition, liposomes have been used to deliver the diphtheria toxin A fragment directly to the cytoplasm, bypassing the initial binding step. The toxins in the second group, known as cytolytic toxins, are thought to act directly on the cell membrane, producing changes in the permeability barrier that result in cell lysis. Liposomes have been useful in helping to define the membrane target of some of the toxins in this group.