Engineered iron oxide-adhesion mutants of the Escherichia coli phage lambda receptor.

Escherichia coli able to specifically adhere to iron oxide and not adhere to other metal oxides were constructed by genetic engineering. Concatamers of random oligonucleotides were introduced into a portion of a plasmid-borne lamB gene encoding an external domain of the phage lambda receptor. Bacteria able to adhere to iron oxide were selected by serial enrichment from the population of plasmid transformants. The concatameric nature of the inserted DNA allows a genetic analysis analogous to exons shuffling. Results of this genetic analysis indicate that in some isolates, part of the binding site is encoded by flanking vector sequences. This strategy may prove generally useful for identifying protein sequences able to recognize specific surfaces.