Organization and Characterization of the Promoter Elements of the rRNA Operons in the Slow-Growing Pathogen .

The slow-growing, nontuberculous mycobacterium possesses two rRNA operons, and , located downstream from the and genes, respectively. Here, we report the sequence and organization of the promoter regions of these two operons. In the operon, transcription can be initiated from the two promoters, named P1 and PCL1, while in , transcription can only start from one, called P1 . Both operons show a similar organization to the one described in and . Furthermore, by qRT-PCR analyses of the products generated from each promoter, we report that stress conditions such as starvation, hypoxia, and cellular infection affect the contribution of each operon to the synthesis of pre-rRNA. It was found that the products from the PCL1 promoter of play a pivotal role in rRNA synthesis during all stress conditions. Interestingly, the main participation of the products of transcription from the P1 promoter of was found during hypoxic conditions at the NRP1 phase. These results provide novel insights into pre-rRNA synthesis in mycobacteria, as well as the potential ability of to produce latent infections.