Figure 4
The quaternary complex of SdgB (SdgBquaternary) with UDP, GlcNAc and GlcNAcylated 9-mer SD-repeat peptide. (a) The electrostatic potential surface view of SdgBquaternary. UDP and the cleaved GlcNAc were observed in the cleft between the DBD and ABD, and the buried region was visualized in an enlarged view (left). The GlcNAcylated SD peptide attached inside the dimerization domain is shown as a stick and cartoon model (right). (b, c) Detailed binding modes of UDP and GlcNAc in the donor-binding site (b) and the GlcNAcylated product in the dimerization domain shown as a stereoview (c). The ligands are shown in ball-and-stick representation. The key residues for ligand binding are presented as lines with labels and the key interactions are shown as black dotted lines. The left panel in (b) highlights the interactions between UDP and GlcNAc, and the C atoms of GlcNAc are numbered. In (b) and (c), mFo − DFc omit maps of ligands are contoured at 3.0σ as green mesh. The C atoms of UDP, GlcNAc and the SDR peptide are colored gray, light green and black, respectively. O atoms, N atoms and phosphates are colored red, blue and orange, respectively. |