FIG. 2.

Controls for PspA inhibition of pspA transcription. (A) In vitro transcription reaction mixtures contained either supercoiled pJD10 (wild-type pspA promoter) or supercoiled pGZ119EH (tac promoter). PspF was included at 4 nM in lanes 1 and 2. ς⁵⁴ and core RNAP were omitted from the reaction mixture, and ς⁷⁰-RNAP holoenzyme was included instead at 13 nM. PspA (300 nM) was included in lanes 2 and 4. (B) In vitro transcription reaction mixtures contained supercoiled pJD10 (wild-type pspA promoter) and PspF at 4 nM. PspA (300 nM) was included in lane 2. Lane 3 contains a fraction from a purification of a strain carrying only the expression vector (see the text for more details).