FIG 3.

PabB was regulated directly by σ^B in M. tuberculosis H37Ra. (A) Comparison of the transcriptional level of the gene pabB during the exponential phase in H37Ra (WT) and H37RaΔsigB (KO) strains by qRT-PCR. The expression levels of GAPDH mRNA were normalized as an endogenous control. Data are representative of three experiments, and the statistical significance is indicated by an asterisk: *, P < 0.01. (B) Comparison of the expressional level of PabB during the exponential phase in H37Ra, H37RaΔsigB, and H37RaΔsigB(pMV261::sigB) as determined by a Western blot assay. Experiments were repeated at least three times, and representative results are shown. (a) Total protein was normalized to 20 μg of each strain and then electrophoresed by SDS-PAGE and stained by Coomassie brilliant blue. Lane M, the prestained protein marker; lane 1, total protein of H37Ra; lane 2, total protein of H37RaΔsigB; lane 3, total protein of H37RaΔsigB(pMV261::sigB). (b) Western blot analysis of total protein immunoblotted with mice antisera of anti-PabB. Lane 1, anti-PabB immunoblotted to the total protein of H37RaΔsigB; lane 2, anti-PabB immunoblotted to the total protein of H37RaΔsigB; lane 2, anti-PabB immunoblotted to the total protein of H37RaΔsigB(pMV261::sigB). (C) [³²P]RNA products synthesized in the in vitro transcription assay from the indicated promoter of pabB. Transcription was performed by RNAP holoenzyme containing σ^B.