Figure 3.
Alignment and stereoviews showing the superposition of BeF
⋅PSP and BeF
⋅CheY. Structurally homologous β-strand residues (PSP: 7–11, 94–98, 116–120, 162–167, 180–182, and CheY: 53–57, 82–86, 104–108, 8–13, 34–36) were used for the superposition. PSP and CheY are colored purple and yellow, respectively. (A) Diagram of the circular permutation required to align the conserved active site residues of PSP and CheY (29). (B) Ribbon structures of PSP and CheY. The molecules are oriented with the H4-β5-H5 face of CheY directed toward the reader. The N and C termini of CheY are denoted. Some PSP residues that have no structural counterparts in CheY are not shown. (C) A top-down view of the superimposed active sites. This orientation was obtained by applying a −90° rotation around the x-axis starting from the orientation in B. The active site residues of PSP and CheY are labeled in purple and black, respectively. The sidechains are shown in ball-and-stick form with carbon, nitrogen, and oxygen atoms colored green, blue, and red, respectively. BeF
is represented by red balls with orange bonds. The cyan- and blue-green-colored balls, lower and upper, respectively, adjacent to BeF
represent the Mg2+ ions in the PSP and CheY structures, respectively. The purple arrow points to D167 of PSP.