Fig 5.
The mob genes are transcribed constitutively from pLYL72, and the excision proteins Xis2d and Exc are required for sufficient enhancement of transcription upon Tc induction. RT-qPCR was performed to localize potential regulators of mob transcription; the relative fold changes in transcription measuring mobB relative to the levels in the absence of tetracycline (−) are shown. Fold changes were calculated using the Pfaffl ΔΔCT equation, and samples were normalized using the reference marker rpoD (20). The observations described above were also confirmed using qualitative RT-PCR (not shown). The mob genes were transcribed constitutively from pLYL72, and the excision operon in trans was sufficient for transcriptional activation. A deletion of xis2C appears to have no deleterious effect on mob transcription, whereas a deletion in either xis2d or exc drops transcription to the levels determined for constitutive empty vector.