FIGURE 2.

TcpP cytoplasmic domain binding to DNA in vitro. (A) The cytoplasmic domain of TcpP WT or C58S including the first 135 amino acids of the N termini was purified under non-reducing conditions. Proteins treated with (+) or without (–) DTT were separated using SDS-PAGE and subjected to Western blotting using an anti-TcpP antibody. P, polymer; O, oligomer; D, dimer; M, monomer. (B) Gel shift assays using purified TcpP_cyto WT or C58S and DNA containing ∼400 bp of the regulatory regions identified in toxT promoter. (C) Free thiol group assay of TcpP_cyto WT protein by AMS trapping. One hundred ng of protein was precipitated using 10% TCA and proteins containing free thiol groups were trapped with AMS. TcpP_cyto was detected by Western blot using anti-TcpP antibody.