Analysis of the paaL promoter region. (a) Promoter structure of the archetypal σ54 factor dependent promoter employed by GenomeMatScan to predict the P. putida KT2440 sigmulon. The upstream activating sequence UAS is indicated, flanked by distal/proximal enhancer binding protein sites displaying diverse spatial positioning upstream of σ54-RNA polymerase promoter complex formation. Schematic originally proposed by Cases et al, . (b) Annotated nucleotide sequence of the 456 bp intergenic region between the paaG stop codon, (X), and the paaL start codon (M) in P. putida CA-3. Nucleotide positions are indicated in italics. An imperfect integration host factor (IHF) binding site is highlighted in bold italics with a tetrameric palindrome indicated by directional arrows. Both consensus GG-N10-GC σ54 factor binding sites are highlighted in grey, with the primer extension mapped transcriptional start site indicated numerically (+1). (c) RACE directed RT-PCR amplification of the paaL transcriptional start site. Lanes; 1 = 465 bp RACE product, 2 = negative control, (adapter ligated RNA), and M = Hyperladder II DNA marker (Bioline).