Fig. 5: Three-dimensional structure of S-2L DatZ.

a Ribbon representation of a DatZ monomer in a light blue-dark blue gradient, with bound dA in stick (yellow). The Zn²⁺ ion is shown as a grey sphere. b A close-up on the catalytic pocket of DatZ with the experimental 2F_o-F_c electron density contoured at 2.5 sigmas around bound ligands: dA and Zn²⁺ (black mesh). Additionally, the anomalous density at Zn²⁺ absorption edge (red mesh) is contoured at 10 sigmas. Residue I22 (orange) provides direct specificity towards the adenine nucleobase, creating a steric hindrance for chemical groups in position 2 of the purine ring. Other residues highlighted in the text are Zn²⁺-coordinating ones (purple), W20 (magenta) and P79 (lime). c Structure of the full DatZ hexamer, top and side views, in surface representation. Blue and purple protomers form a compact, particularly stable disc in an alternating, zigzagging pattern. Two of the six symmetrical cavities leading to buried dA molecules (yellow) are visible in the side view and highlighted by the white dotted circles. d Surface representation of DatZ hexamer coloured by the experimental B-factors (dark red-yellow gradient, hydrogen atoms omitted), with the scale bar below. The highest temperature factors map to the flexible loop above dA.