FIGURE 1.

A, schematic drawing of the domain arrangement of tripartite sensor kinases and TodS. Tm, transmembrane region; RRR, response regulator receiver domain. The domain arrangement for tripartite sensor kinases is taken from ArcB, the best studied family member, and the figure is adapted from Kwon et al. (8). The phosphorelay is indicated. The TodS domains were predicted by SMART (30). B, summary of truncated TodS versions used in this study. The ends of recombinant fragments were determined according to the domain annotation by SMART (30) and secondary structure prediction of TodS using the consensus method (38). Fragment ends were placed in regions for which a turn or coil secondary structure was predicted. All fragments were produced as His tag fusion proteins and purified as detailed for TodS in Lacal et al. (15). For further information see Table 1 and “Experimental Procedures.”