FIG. 4.

EMSA demonstrating the binding of purified CRP to the traJ promoter region. (A) Migration of the ³²P-end-labeled 226-bp PCR traJ promoter fragment (ptraJ) in the absence and presence of different concentrations of purified CRP as determined by polyacrylamide gel electrophoresis and autoradiography. The arrows indicate the positions of the traJ region and the shifted protein-DNA complex. (B) Migration in an agarose gel of the 226-bp PCR traJ promoter fragment (ptraJ) after addition of different concentrations of CRP in the presence of the 100-bp DNA ladder. Note the specificity of the shift of the ptraJ fragment (arrow) in the presence of CRP. Lane M contained the 100-bp DNA marker.