Fig 1.

prrA and prrB transcription and PrrA levels during in vitro growth. (A) Quantitation of prrA and prrB transcripts during M. tuberculosis H37Rv in vitro exponential growth in supplemented Middlebrook 7H9 broth with glycerol. The optical density at 600 nm of the cultures is indicated by the solid line and scaled on the right y axis. (B) qRT-PCR comparison of prrA and prrB expression in logarithmic and stationary phases of M. tuberculosis growth in supplemented Middlebrook 7H9 broth without glycerol. Normalized expression of prrA and prrB with respect to 16S rRNA expression is presented as the mean ± SD of data from three independent experiments. The decrease in prrA and prrB expression during stationary phase is presented relative to the logarithmic-phase expression, which is set at 1.0. ∗∗∗, P < 0.0001. (C) Western blot analyses of PrrA in total M. tuberculosis H37Rv protein (20 μg) collected from logarithmic (lane 1) and stationary (lane 2) growth phases and detected using anti-PrrA antibodies. Lane 3 represents the purified His-tagged PrrA protein (40 ng). (D) Northern analysis of M. tuberculosis H37Rv with prrA and prrB single-stranded RNA probes. RNA samples were collected from exponential-phase cultures of M. tuberculosis H37Rv grown in Middlebrook 7H9 broth with glycerol. (E) Diagram of the prrA-prrB region of the chromosome, drawn to scale and showing the prrA and prrB gene lengths.