Bioaccumulation of heavy metals by fimbrial designer adhesins

Naturally occurring adhesins bind to specific molecular targets in a lock-a nd-key fashion due to the composition of the binding domain of the adhesin. By introduction of random peptide libraries in a suitable surface exposed carrier protein it is possible to create and select designer adhesins with novel binding affinities. Type 1 fimbriae are surface organelles of Escheri chia coli which, mediate D-mannose sensitive binding to different host surf aces through the FimH adhesin, an integral part of these organelles. We hav e studied the ability of the FimH adhesin to display random peptide sequenc es. By serial selection and enrichment procedures specific sequences were i dentified which conferred the ability on recombinant cells to adhere to var ious metal oxides (PbO2, CoO, MnO2, Cr2O3 ) The properties inherent in thes e sequences permitted the distinct recognition of metals to varying degrees , indicating that this system allows for the isolation of peptide sequences with a variety of binding avidities. These studies demonstrate the potenti al and versatility of the FimH display system for presenting random peptide sequences. In addition, the possibility exists for the construction of mic roorganisms for the bioaccumulation of heavy metals from the environment. ( C) 1999 Federation of European Microbiological Societies. Published by Else vier Science B.V. All rights reserved.