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. 2013 Jul 25;9(7):e1003159. doi: 10.1371/journal.pcbi.1003159

Figure 3. Electrostatic potentials at the allosteric sites of PYKs.

Figure 3

The electrostatic potential is mapped on the molecular surface of each enzyme. Negative potentials are displayed in red, positive potentials in blue on a scale from −2 to +2 kT/e. Panel A shows a section of the crystallographically resolved Saccharomyces cerevisiae PYK (PDB id: 1A3W, chain A) in cartoon representation with the activator FBP bound in the allosteric site in stick representation. The electrostatic potentials displayed in panels B to D correspond to the same regions of the structure as shown in panel A. Panel B represents the electrostatic potential computed for the Saccharomyces cerevisiae PYK, panels C and D show the electrostatic potentials computed for the models of PYKs from Streptococcus pyogenes and Lactobacillus plantarum, respectively. The Saccharomyces cerevisiae PYK displays a broad region of positive potential at the allosteric binding site, whereas in the LAB PYKs, a rather negative potential is observed in parts of the allosteric binding site and in its proximity (panels C and D). These negatively charged regions may hinder electrostatic steering of allosteric activators to the allosteric site.