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![[Figure 2]](ni5011fig2mag.jpg)
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Figure 2
Activation of VanRSc. (a) A view from above the site of phosphorylation. The phosphoryl acceptor Asp51 lies at the end of the third β-strand and is shown bound to the beryllium fluoride phosphomimetic. The F atoms (pale blue) interact with the side chains of Thr79 and Lys101 and the backbone carbonyl of Asp53. A magnesium ion (shown in teal) is also present at the phosphorylation site, and is octahedrally coordinated by the side chains of Asp8, Glu7 and Asp51, the backbone carbonyl of Asp53 and two water molecules (shown as red spheres). (b) 2Fo − Fc electron-density map showing the site of phosphorylation. A σA-weighted map (Read, 1986  ) contoured at 1.6σ is shown. A stereo version of this panel can be found in Supplementary Fig. S2. (c) The activated dimer, shown in both surface and cartoon representation. One protomer is colored cyan and the other is colored slate blue. The boxed region highlights the dimer interface that forms around α4–β5–α5. Hydrophobic contacts along the outer edges of the dimer interface stabilize dimer formation; the amino-acid side chains responsible for these contacts are shown as spheres. (d) Stereoview of polar contacts stabilizing the core of the dimer interface. The orientation shown is rotated 90° about a horizontal axis relative to the orientation shown in (c). (e) Conservation of dimer-interface residues for OmpR/PhoB response regulators. Hydrophobic residues are highlighted in lime green and polar residues are highlighted in pink. The brackets below the sequences indicate the typical salt bridges formed within the interface, while the brackets above indicate interactions that are specific to VanRSc. Because VanRSc contains a glycine at position 92 (circled), it does not form the typical 92–113 interaction (represented by the red dashed line); instead, an alternative hydrogen-bond interaction is formed between Tyr98 and Arg111. Numbering for the VanRSc sequence is shown at the top. For convenience, the brackets representing interactions are drawn connecting two residues within a single stretch of sequence; however, the actual interactions occur between two different protomers, across the dimer interface. |
![[Figure 2]](ni5011fig2.jpg)
 | STRUCTURAL BIOLOGY |
ISSN: 2059-7983
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