Structural elements of the preQ1 binding pocket. (A) Van der Waals representation of preQ1 in the binding pocket. (B) Stick representation showing interactions between A35-A51 and A50-U19, with hydrogen bonds shown as dashed lines (side view). (C) Sphere representation of C8-preQ1-U19-A50 interactions, illustrating a van der Waals interaction among A50, U19, and preQ1. (D–F) Stick representations of nucleotide interactions in the binding pocket: U10-A52-U17 (D), U9-A51-U18-A35 (E), and C8-preQ1-U19-A50 (F).