Interaction of E6CT11 with hDlgPDZ2.

<p><b>A</b> Combined ¹H and ¹⁵N chemical shift perturbation (as detailed in SI) of 100 µM hDlgPDZ2 in complex with 300 µM E6CT11 peptide versus 300 µM E6CT6 peptide. Residues without observable amide shifts are denoted with X. The inset of a region of the corresponding HSQC spectra show unperturbed as well as perturbed signals. Red contours: hDlgPDZ2 complexed with E6CT11, blue contours: hDlgPDZ2 complexed with E6CT6. Note that the side chain amide signals of Asn339 were also perturbed by more than 2× the average value. <b>B</b> Structure of the hDlgPDZ2-E6CT11 complex. The bundle of 20 best E6CT11 structures (residues 141 to 151, dark grey) is shown together with a ribbon of the closest-to-mean hDlgPDZ2 structure (hDlg residues 318–406). Peptide structures were fitted to residues 143 to 151 and the termini are indicated. Secondary structure elements are labeled. The boxed inset depicts per-residue backbone order parameters of the complexed E6CT11 peptide. <b>C</b> Details of the hDlgPDZ2-E6CT11 complex. hDlgPDZ2 backbone trace depicted in light gray. PDZ side chains (heavy atoms) of residues showing most perturbed combined amide group chemical shifts (backbone and Asn339 side chain; <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0062584#pone-0062584-g006" target="_blank">Figure 6a</a>) are depicted in green and labeled, while the closest-to-mean E6CT11 peptide structure (heavy atoms, residues 143–151) is presented in dark gray. <b>D</b> Schematic depiction of intermolecular hydrogen bonds and salt bridges in the clostest-to-mean complex structure. Indicated side-chains start at the Cβ atom. Hydrogen bonds are indicated as dashed lines. Secondary structure elements β* and β2 are emphasized by arrows; hDlgPDZ2 residues appear gray, while peptide residues are depicted in black.