Comparison of CbpM with transcriptional activators from MerR-like family.

<p><b>A)</b> The overall structures of the CbpM dimer (in light/lime green) and MtaN dimer (in salmon/magenta) with different orientation of the coiled-coils; <b>B)</b> Superposition of the first three helices of CbpM (in green) with MtaN (in salmon; PDB code 1R8D); <b>C)</b> Sequence alignment of CbpM from <i>K. pneumonia, E. coli</i> and HspR from <i>H. pylori</i>, along with the structure based alignment with the first 60 residues of the transcriptional regulator MtaN from <i>Bacillus Subtilis</i> (PDB code 1R8D). The residues forming helices are shown in green (experimental) with letter <i>h</i> above/below or in yellow (predicted). The coiled-coil location in <i>E. coli</i> CbpM and <i>H. pylori</i> HspR as predicted by Coil program <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0100441#pone.0100441-Lupas1" target="_blank">[42]</a> is indicated by underlined sequence. The conserved residues in CbpM, which are different from the DNA binding residues in transcriptional regulators, are shown in bold; <b>D)</b> Mechanistic model explaining how HspR (salmon/magenta) and CbpM (green) structures could evolve from each other. An arrow indicates the position where the two structures diverge. For simplicity, only one monomer of CbpM is shown. DNA bound to MtaN is shown in light gray.