Figure 4.

Binding of GadX to btuB promoter. ³²P-labeled DNA fragments PbtuB, PgadA, PgadB, and Ppal containing the promoters of btuB, gadA, gadB, and pal, respectively, were incubated with GadX fused to the maltose binding protein (MalE-GadX) at 0, 2, 4, or 6 pmoles. The reaction mixtures were electrophoresed in a 5% native polyacrylamide gel. Band shift due to GadX binding was visualized by autoradiography. Arrows indicate bands of DNA probes not bound by GadX.