Effect of σB and σB-controlled SpoVG on esxA expression. A. Transcriptional activity of the esxA promoter in strain Newman (squares), SM148 (triangles), and IK184 (diamonds). Growth was followed by measuring the optical density at 600 nm [OD600] (open signs), and the activity of the esxA promoter was determined by the luciferase activity of pesxAp-luc+ (filled signs). B. Northern blot analysis of esxA transcription in Newman, the ΔyabJ-spoVG mutant (SM148) and the ΔrsbUVW-sigB mutant (IK184) over growth. C. Northern blot showing esxA transcription in Newman, the ΔyabJ-spoVG mutant (SM148) and the ΔrsbUVW-sigB mutant (IK184) complemented with pBus1, pyabJ, pspoVG or pyabJspoVG after 5 h of growth. Ethidium bromide-stained 16S rRNA patterns are shown as an indication of RNA loading.