Fig. 5.

CheY_ArcA•BeF₃⁻•Mn²⁺ does not display steric obstruction of the BeF₃⁻. Both panels are from the perspective of a nucleophilic water molecule, looking straight down the line connecting the beryllium atom and Asp57 Oδ1 atom. The same general modeling scheme described in Fig. 2a, with only residues 14, 59, and 89 colored, applies. BeF₃⁻ is orange and Mn²⁺ is marked by a sphere in the color of the parent molecule. (a) Overlay of CheY_ArcA•BeF₃⁻•Mn²⁺ (cyan) and wild type CheY•BeF₃⁻•Mn²⁺ (magenta, pdb 1FQW). (b) Close-up view illustrating the packing of CheY_ArcA•BeF₃⁻•Mn²⁺ residues Trp58, Asn59, and Arg89. Cation-π interactions are represented with red dotted lines and the hydrogen bond between Asn59 and Arg89 is illustrated as a green dotted line. (c) Overlay of CheY_ArcA•BeF₃⁻•Mn²⁺ (cyan) and ArcA•BeF₃⁻•Mg²⁺ (blue, pdb 1XHF).