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. 2012 May 16;287(28):23381–23396. doi: 10.1074/jbc.M112.362913

FIGURE 1.

FIGURE 1.

Structural model of pesticin from Y. pestis. A, Pst structure in schematic representation is displayed from two different views related to each other by a rotation of 180° around the y axis. The N-terminal (NT) 12 residues, including the TonB box (TBB) and residues 30–34, are not visible in the crystal structure due to disorder. Pst consists of three domains as follow: the translocation domain (T), marked in red; the receptor binding domain (R), marked in blue, and the activity domain (A), marked in orange. The secondary structure assignment is given for β-strands (β1–β8) and α-helices (α1–α11). Two independent PstAD1 and PstAD2 domains connected by α7 helix form the basis of the subdomains of the T4 lysozyme-like structure. The interface residues between the R (blue) and A domain (orange) are highlighted in the box below the structure. One particular hydrogen bond used for the construction of PstS89C/S285C is marked with dashed lines. The R domain includes a mixed α/β-fold, and the A domain is α-helical with three short conserved β-strands (β8–β10, see also Fig. 2A). The R domain displays a new fold that is drawn schematically below the structure (β-strands in blue and α-helices in red). The domain composition together with domain residue boundaries is given in the schematic bar below the structures. B, surface charge representation of Pst illustrated from the same orientations as in A. The active site (marked by a black star) is flanked by two patches of positively charged residues that are further surrounded by extended patches of negatively charged residues. C, activity domain in the same orientation as A is displayed from two sides related by a rotation of 180° around the y axis to illustrate conservation of residues. The structure is shown as a schematic model together with the surface representation of conserved (color coded in blue) and highly conserved residues (in yellow) (see also the alignment in supplemental Fig. S6B for comparison). Single residues lining the active site are more strongly conserved and marked with residue type and number. Residues Glu-178, Thr-201, and Asp-207 are particularly important as they form part of the active site (these residues are marked with large yellow dots).