Transferrins selectively cause ion efflux through bacterial and artificial membranes

Serum transferrin, ovotransferrin and lactoferrin constitute the most notable members of the transferrin family. Among their multiple biological functions, they possess an important antibacterial activity. These proteins can permeate the Escherichia coli outer membrane, reaching the inner membrane where they selectively cause permeation of ions, resulting in dissipation of the electrical potential without affecting the pH gradient. Similar results were obtained using artificial liposomes, suggesting a direct action of the proteins on the lipid bilayer, which was mediated by detectable conformational changes in their structures. (C) 2003 Federation of European Biochemical Societies. Published by Elsevier Science B.V. All rights reserved.