Figure 3.

No autoregulation of CRP. a) LacZ fusion reporter. A promoter-proximal region of crp was cloned into pRW50 and transformed into WT or Δcrp to determine their promoter activities, respectively. This figure shows the increased mean fold for the activity in Δcrp relative to WT. b) Primer extension. Primer extension assay was performed for crp using total RNAs from WT or Δcrp. On the right side, DNA sequences are shown from the bottom (5') to the top (3'), and the transcription start sites are underlined. c) DNase I footprinting. The labeled upstream DNA fragment of crp was incubated with 0, 5, 10, 15, and 20 pmol of purified His-CRP in lanes 1 to 5, respectively, in the presence of 2 mM cAMP. No footprint region was detected.