Alignment and RNA secondary structures of the leuA upstream regions (LEU elements). The stem at the base is highlighted in grey, helices forming the pseudoknot are underlined and double underlined, leucine and stop codons are set in bold, the candidate Shine-Dalgarno boxes of the leuA are set in capitals. The last sequence is that of the transposase from B. longum (see the text). Sequences for M. bovis (Mb) and M. tuberculosis spp. (Mt and Rv) coincide.