Comparative study of the promoter activity of metabolism-related pabB and lpdA genes between Mycobacterium tuberculosis strains H37Rv and H37Ra

Abstract:

Abstract: [Objective] Comparative genomic study revealed mutations at the promoter regions of pabB and lpdA in avirulent Mycobacterium tuberculosis strain H37Ra compared to its virulent counterpart strain H37Rv. LacZ reporter system was used to test whether those mutations will affect promoter activity and its potential relationship to virulence attenuation of H37Ra. [Methods] Promoter regions of pabB and lpdA were predicted by the “Neural Network Promoter Prediction” method (http://www.fruitfly.org/seq_tools/promoter.html). Promoter sequences were PCR amplified and cloned into mycobacterial promoterless probe vector pMC210. Resultant recombinant plasmids were transformed into M. smegmatis by electroporation. The transcription activity of lacZ under the control of cloned promoters were monitored by Quantitative Real-Time RT-PCR. [Results] Quantitative Real Time PCR results showed that the promoter activity of H37Ra pabB was six times more than that of H37Rv pabB (p < 0.05), while the promoter activity of the H37Rv lpdA was two fold of that of H37Ra lpdA (p < 0.05). [Conclusion] The mutations in pabB and lpdA promoters affect its expression activity. The T-A mutation in lpdA promoter may be related to virulence attenuation of H37Ra.