Mycobacterium tuberculosis expresses ftsE gene through multiple transcripts

Bacterial FtsE gene codes for the ATP-binding protein, FtsE, which in complex with the transmembrane protein, FtsX, participates in diverse cellular processes. Therefore, regulated expression of FtsE and FtsX might be critical to the human pathogen, Mycobacterium tuberculosis, under stress conditions. Although ftsX gene of M. tuberculosis (MtftsX) is known to be transcribed from a promoter inside the upstream gene, ftsE, the transcriptional status of ftsE gene of M. tuberculosis (MtftsE) remains unknown. Therefore, the authors initiated transcriptional analyses of MtftsE, using total RNA from M. tuberculosis cells that were grown under stress conditions, which the pathogen is exposed to, in granuloma in tuberculosis patients. Primer extension experiments showed the presence of putative transcripts, T1, T2, T3, and T4. T1 originated from the intergenic region between the upstream gene, MRA_3135, and MtftsE. T2 and T3 were found initiated from within MRA_3135. T4 was transcribed from a region upstream of MRA_3135. RT-PCR confirmed co-transcription of MRA_3135 and MtftsE. The cloned putative promoter regions for T1, T2, and T3 elicited transcriptional activity in Mycobacterium smegmatis transformants. T1, T2, and T3, but no new transcript, were present in the M. tuberculosis cells that were grown under the stress conditions, which the pathogen is exposed to in granuloma in tuberculosis patients. It showed lack of modulation of MtftsE transcripts under the stress conditions tested, indicating that ftsE may not have a stress response-specific function in M. tuberculosis.