The nucleotide sequence of the promoter, 16S rRNA and spacer region of the ribosomal RNA operon of Mycobacterium tuberculosis and comparison with Mycobacterium leprae precursor rRNA.

Mycobacterium tuberculosis H37Rv has a single rrn (ribosomal RNA) operon. The operon was cloned and a region of 1536 nucleotides was sequenced, starting 621 bp upstream from the 5'-end of the 16S rRNA coding region and continuing to the start of the 23S rRNA coding region. The 16S rRNA sequence inferred from the gene sequence was found to differ in one position from Mycobacterium bovis (nucleotide 1443) and from Mycobacterium microti (nucleotide 427). A single putative promoter was identified on the basis of similarities with the sequence of rrn operons of Bacillus subtilis and Escherichia coli. The regions of similarity include a -35 box, a -10 box, a stringent response element, antitermination signals, potential RNAase III processing sites and features of precursor rRNA secondary structure. Sequences upstream from the 5'-end of Mycobacterium leprae 16S rRNA were also investigated. Homologous schemes of secondary structure were deduced for precursor rRNA of both M. tuberculosis and M. leprae; although the principal features are common to both species there are notable differences.