FIG. 2.

DNA sequence comparison of the invertible element of E. coli K-12 (GenBank accession number X00981) and strains used in this study. O157:H7 and O157:H⁻ strains have completely identical sequences. Dots indicate identity; stars indicate gaps. These sequences are shown in phase-off orientation. The inverted repeats that border the fim switch and the fimA promoter (1) are overlined and allow for the indication of the direction of transcription. Binding sites for IHF (4) and Lrp (38) are also shown.