Nucleotide sequence of the acrAB regulatory region. The transcription initiation site (+ 1) of the acrAB operon is capitalized and indicated by a bent arrow. The CTAG IS5 target site, the putative ribosome binding site (RBG) for acrA, and the ATG start codons for acrR and acrAB are shaded. The promoter regions (− 10 and − 35) (Martin et al.1999) and marbox (Su et al.2007) are underlined. The bold arrow above the sequence indicates the insertion site of IS5.