FIG. 5.

Functions of nucleotide sequences downstream and upstream from pcaU. (A) Two open reading frames, designated orf1 and orf2, encode amino acid sequences closely resembling those of enzymes associated with β-oxidation of fatty acids. Dashed arrows below gene designations show directions of transcription. The other dashed arrows indicate positions of inverted repetitions that were depicted in Fig. 4 and shown in later experiments to be within sites where PcaU binds to DNA. To provide a frame of reference for subsequent observations, the position of the nucleotide substitution causing the pcaP1 mutation also is shown here, as is the EcoRI site between pcaU and pcaI. (B) Alignment of nucleotide sequences containing inverted repetitions downstream and upstream from pcaU. Identical residues in the aligned sequences are in shaded boxes.