Figure 1
Monomeric Uhgb_MP fold, substrates and interacting residues. Like other GH130 enzymes, the Uhgb_MP monomer has a five-bladed β-propeller fold with a central catalytic furrow. The Pi, mannose and N-acetylglucosamine molecules present at the catalytic site are shown as sticks, while interacting residues are shown as lines. The catalytic Asp104 is shown in red, Pi-interacting residues in green, mannose-interacting residues in blue and N-acetylglucosamine-interacting residues in orange. The Asn44 and Asp104 side chains are shown in the B conformation, i.e. the conformation that is catalytically active. Water molecules 436, 457 and 656, which mediate interactions between the N-acetylglucosamine and residues Lys212 and Tyr242, Asp304 and His235, respectively, are shown as black crosses. Protein–Pi interactions: NH2 of Arg150 is contacting Pi O4 and O2, while NH2 of Asn151 contacts Pi O4. ωNH2 of the Arg168 side chain binds to Pi O1 and its ω′NH2 is interacting with Pi O2. The side-chain amine of Lys212 binds to Pi O2 and His231 N∊2 is at a hydrogen-bond distance from Pi O1. Finally, the hydroxyl of the Tyr242 side chain is in contact with Pi O3. |