Fig. 3.

(A) Amplification of the A. hydrophila AH-3 pomA₂ and flrA cDNA 5′ end performed using the 5′ RACE System, version 2.0 (Invitrogen). An amplicon was obtained by nested PCR using primers AUAP (abridged universal amplification primer) and GSP3-PomA₂ (pomA₂p) and by primary PCR using primers AAP (abridged anchor primer) and GSP2-FlrA (flrAp). Lanes 1, primary PCR template; lanes 2, PCR negative control; and lanes 3, molecular size standard (Ecogen). Underlined sequences show start codons, italics indicate the ribosome binding sites, asterisks show locations of the transcriptional start sites, and bold nucleotides show potential consensus sequences. (B) Alignment in silico of σ²⁸ and σ⁵⁴ promoter elements in A. hydrophila polar-flagellum promoters. The consensus σ²⁸ sequence is from Kutsukake (22). The consensus σ⁵⁴ sequence is from Barrios et al. (4).