Fig. 3.

Structure-based comparison of the MtDUT^WT-Stl^NTand MtDUT^Δloop–dUPNPP complexes. (a) Overall structure of MtDUT^WT–Stl^NT complex. MtDUT^WT is represented as blue cartoon, Stl^NT is represented as orange cartoon. (b) MtDUT^WT active site interactions with Stl^NT. Substrate analogue interacting residues are displayed as blue stick, while residues interacting only with Stl^NT are represented as grey sticks, Stl^NT interacting residues are shown as orange sticks. Interactions are indicated as dashed black (polar), π- π stacking interaction is shown as dashed green line (with distances measured in Å). (c) Interactions of Stl^NT α5 helix with MtDUT^WT. Interacting residues are shown as sticks. Colouring of the proteins are the same as in panel (a). Interactions are shown as dashed purple lines (with distances measured in Å). (d) Overall structure of MtDUT^Δloop in complex with dUPNPP substrate analogue. MtDUT^Δloop is displayed as blue cartoon, substrate analogue is represented as sticks. (e) Active site interactions of MtDUT^Δloop in complex with dUPNPP. MtDUT^Δloop is represented as surface. The representation of interacting residues is the same as on panel (b). The omit map around substrate analogue and Mg²⁺-ion (green sphere) is contoured in green isomesh at 3.0σ level. Interactions are indicated as dashed black (polar) and purple (hydrophobic) lines (with distances measured in Å). Individual panels were created using PyMOL 2.5.4 (Schrodinger, LLC; https://www.pymol.org/). The figure was assembled using CorelDRAW 2020 (Corel Corporation; https://www.coreldraw.com).