Fig. 2.

The 5′ UTR region of the fliC gene. (A) The RNA sequence of the 5′ UTR region of fliC from the +1 site of transcription through 12 bases after the translation-initiating AUG codon was subjected to the mfold RNA-folding program of Zucker (www.bioinfo.rpi.edu/applications/mfold). Five potential SL structures (SL1–SL5) were identified, corresponding to the two lowest-energy folds. SL3 and SL4 are competing SL structures and are depicted in Upper and Lower, respectively. The translation-initiating AUG codon is boxed. (B) Mutational changes in the fliC 5′ UTR that allow fliC-lacZ expression (Lac⁺) in cells expressing the FljA protein. Mutations in green were isolated in this study, and mutations in the fliC 5′ UTR that allow fliC⁺ expression (motility) in cells expressing the FljA protein (10) are depicted in black. The regions of the two duplications are highlighted in red [DUP-(−15 to −19)] and orange [DUP-(−13 to +15)].