Binding sites on tau proteins as components for antimicrobial peptides.

To design new antimicrobial peptides, we have focused on various proteins which are not essential for self-defense but carry important responsibilities for biosystems. Previously, we reported that highly efficient antimicrobial properties or antiviral properties are inherent in the nuclear translocation signals and binding sites on laminin receptors. Here we introduce microtubule binding sites on tau proteins as new components for antimicrobial peptides. Strong antimicrobial activities against Staphylococcus aureus and Escherichia coli were found in tandem sequences of the binding sites on tau proteins. Moreover, the binding sites obtained significantly strong antimicrobial activities against bacteria and fungi when combined with a nuclear localization signal (NLS) and/or a peptide derived from a binding site of a laminin receptor. The antimicrobial activities of some of the tau-derived peptides were not affected by salt, cations, or serum that simulate the natural environment present in blood. Tau proteins so far have only been known as one of the microtubule-associated proteins (MAPs) which are especially abundant in the central nervous system within the brain. Our finding demonstrates that the binding sites on tau proteins possess high potential for becoming components in antimicrobial peptides. Designs based on binding sites of various proteins could become a useful method in peptide antibiotic research.