FIG. 3.

EMSAs identifying the two protein-binding sites of erp operator DNAs. All assays used protein extracts of B. burgdorferi cultured at 34°C. Experimental data shown in panels A, B, and C were obtained with a labeled probe extending from +18 to −330, while those for panel D were obtained with a probe spanning −31 to −89. For all panels, lanes contained either free DNA or DNA, poly(dI-dC), protein extract, and the DNA competitor noted above the lane. (A and B) Short and long exposures of the same EMSA indicating DNA competition of protein binding to site 2 (A) and site 1 (B). (C) Identification of maximal boundary of site 1. (D) Identification of maximal boundary of site 2. As previously observed (8), complex 1 was less abundant than complex 2, and longer exposure times were required to detect complex 1 on X-ray film. As a result, signals from complex 2 often saturated films that were used to detect complex 1.