Cloning and characterization of the Mycobacterium leprae putative ribosomal RNA promoter in Escherichia coli

Abstract

The putative promoter region of the 16S ribosomal RNA-encoding gene (rRNA) of Mycobacterium leprae was cloned and characterized in Escherichia coli. A 932-bp HaeIII restriction fragment, containing the 5' end of the 16S rRNA gene and flanking upstream region, was cloned in front of a promoterless reporter gene in the shuttle vector, pMH109, to generate the plasmid, pYA1101. This clone exhibits promoter activity both in Gram-(E. coli) and Gram+ (Bacillus subtilis) bacteria. Sequence analysis and primer extension experiments with mRNA derived from the M. leprae clone were used to determine the structure and the location of the promoter, as well as the transcription start point in E. coli. The promoter region contains sequences that resemble the -35 and -10 consensus sequences found in many bacteria. A region located 34 bp distal to the promoter is a putative rRNA processing signal, based on sequence homology with processing signals involved in the maturation of the rRNA precursor in B. subtilis and several Mycoplasma species.