FIG. 1.
The RNAP α-CTD is not required for ExsA-dependent activation of transcription. (A) E. coli strain GS162 carrying the indicated transcriptional reporters (PexsC-lacZ, PexsD-lacZ, or PexoT-lacZ) was transformed with a vector control (pJN105) or a constitutive ExsA expression plasmid (p2UY21, labeled pExsA in the figure). The resulting strains were grown in LB to an OD600 of 0.6 and assayed for β-galactosidase activity (reported in Miller units). (B) E. coli GS162 carrying a PluxI-lacZ reporter and a LuxR expression plasmid (p2UY21-luxR) and the reporter strains from panel A were transformed with a plasmid expressing the native α or αΔCTD subunit. The resulting strains were grown in LB to an OD600 of 0.6 and assayed for β-galactosidase activity. The reporter activities obtained in cells expressing αΔCTD were normalized to the same strain expressing native (WT) α and reported as the percentage of native activity. The results represent the averages for three independent experiments, and error bars represent the standard errors of the means.