FIG. 4.

In vivo expression analysis of in vitro-selected peptides. Assessment of in vivo expression by inserting 19 clones identified by in vitro selection into loop 5 of the fhuA gene. Recombinant E. coli was induced for fhuA expression, and extracts were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blotting with antibodies against FhuA. As controls, wild-type fhuA (positive control) and two clones (SA0835 and SA0334, indicated by an asterisk) containing a stop codon in the library fragment (negative controls), respectively, are shown.