GALACTOSE OXIDASE-GLUCAN BINDING DOMAIN FUSION PROTEINS AS TARGETING INHIBITORS OF DENTAL PLAQUE BACTERIA

In order to inhibit the growth of bacteria present in the human oral c avity, a novel system which targets antimicrobial agents to dental pla que has been developed, This system involves a hybrid protein consisti ng of a peptide expressing the bactericidal properties of galactose ox idase (GAG) fused to the glucan binding domain (GBD) of the Streptococ cus mutans glucosyltransferase-S enzyme. A gene encoding GAO from the fungus Fusarium sp, has been inserted into an Escherichia coli express ion vector and fused to sequences encoding the GBD, which binds to the glucans synthesized by oral streptococci. Bacterial extracts expressi ng the hybrid protein were tested for their ability to target the GAO activity to an in vitro plaque model consisting of streptococcal cells bound to microtiter plate wells. The binding of the hybrid protein to the streptococcal cells through its GBD and the dependence of binding on the production of glucans by bacteria were demonstrated, Furthermo re, killing of three different species of oral streptococci by bound h ybrid protein in conjunction with the galactose-lactoperoxidase-iodide cytotoxic system has been demonstrated, These results suggest a novel strategy for controlling dental plaque formation as well as dental ca ries in humans.