Figure 6
An unusual pair of MAN-1,2-MAN torsions in PDB entry 4j0m (She et al., 2013). The mannose–mannose pair is well supported by the electron density, indicating that the unusual conformation of the linkage (red asterisk in the bottom panel) may be stabilized by interactions, electrostatic in this case, with surrounding side chains. The MAN (chain ID and sequence number D5)–MAN (chain ID and sequence number D6) linkage of PDB entry 4j0m (pink) is identified as an outlier (φ = 82.9°, ψ = −179.9°). The carbohydrate linkage is represented by a ball-and-stick model (C, green; O, red; N, blue). Residues identified as interacting with the linkage are represented by a cylindrical model (C, pink). Hydrogen bonds (black dashed line) and electrostatic interactions (within 4.5 Å, blue line) are shown with the distance between atoms in Å. 2Fo − Fc electron density (grey) is displayed for the linkage contoured to 1σ. Possible electrostatic interactions were identified for residues within 4.5 Å of the linkage and can be seen between Arg260 NH1 and MAN5 O3, His286 NE2 and MAN5 O3, Asn332 ND2 and MAN5 O4, and Asn332 ND2 and MAN5 O6. This linkage has a Z-score of −1.06. The top image was produced using CCP4mg. Bottom: SNFG notation output from Privateer. |