FIG. 3.
Transcriptional activation by λcI-AlgQ in the presence of the α-ς70PA chimera. (A) Replacement of the RNAP α-CTD by a C-terminal fragment of P. aeruginosa ς70 (residues 532 to 617) permits interaction with the AlgQ moiety of a λcI-AlgQ chimera bound to DNA. The diagram depicts the test promoter placOR2-62, which bears the λ operator OR2 centered 62 bp upstream from the transcriptional start site of the lac core promoter. In reporter strain KS1 the placOR2-62 test promoter is located on the chromosome and drives expression of a linked lacZ gene. (B) Effect of λcI-AlgQ on transcription in vivo from placOR2-62 in the presence of the α-ς70PA or α-ς70PA(R600H) chimera. KS1 cells harboring compatible plasmids expressing the indicated proteins were grown in the presence of different concentrations of IPTG and assayed for β-galactosidase activity.