Figure 6.

Simulated structural ensemble of phosphorylated Syt 1 IDR core. (A) Representative conformers are shown of the peptide at a dielectric constant of 80. Secondary structure probability per residue is shown below (histogram). Note the reduced helicity compared to unphosphorylated peptide. (B) Representative conformers of the peptide at a dielectric constant of 20 are shown. Secondary structure probability per residue is shown below (histogram). Note that residues 107–118, which formed a continuous helix in the unphosphorylated peptide, are disrupted by coil secondary structure immediately adjacent to phosphorylation site. (C) Closeup shown of example salt bridge that distorts peptide backbone and limits helix formation in low dielectric environment. (D) IDR core region sequence shows salt-bridge interactions inhibitory toward helices at a dielectric constant of ε = 20. Green residues are those that occupy helical conformers during the trajectory. (E) Heat map shows change in salt-bridge interactions in going from dielectric 80 to dielectric 20. An increased frequency of interaction between two charged residues is indicated by gradations of blue, whereas decreased interactions are indicated by gradations of red. To see this figure in color, go online.