Figure 2.

Overall structure of the MtlR-HPr complex and surface-properties of the MtlR dimer. (A) Ribbon diagrams showing two orthogonal views of the MtlR-HPr complex. The MtlR-HPr complex is a heterotetramer composed of two MtlR and two HPr molecules. MtlR and HPr are shown in green and yellow, respectively. α-Helices of MtlR are labeled and His15 of HPr is shown in a magenta stick. (B) Hydrophobicity of the surface amino acids in the MtlR dimer. The ecMtlR dimer was colored according to the Eisenberg hydrophobicity scale³⁶ and the “Color h” script in the Pymol program. (C) Conservation of the surface amino acids in the MtlR dimer. The conservation rate of each residue of MtlR was calculated by multiple sequence alignment as described in the Materials and Methods section. Twenty-one non-Enterobacteriaceae MtlR sequences were aligned and shown as surface presentation. The color bar indicates the conservation rate. (D) The conserved w-shaped groove formed by the binding of HPr (yellow) to MtlR.