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Figure 4
The active site of SaTatD. (a) Electrostatic surface potential view of SaTatD. The acidic active-site pocket is marked with a white box, and basic (blue) and acidic (red) surfaces composed of Loop2–Loop3 and Loop1, respectively, are marked in dotted circles. (b) Metal-binding site of SaTatD. The key residues and two phosphates coordinating Ni2+ ions are labeled and shown as lines and in ball-and-stick representation, respectively. The interactions are shown as red dotted lines. The distance between the Ni2+ ions is labeled and is shown as a black dotted line. (c) The key residues contributing to the binding of phosphates are labeled and shown as lines. The distance between the P atoms of the phosphates is labeled and is shown as a black dotted line. (d) Superimposed view of SaTatD and the E. coli TatD–DNA complex (PDB entry 4pe8), revealing that the two phosphates of SaTatD resemble the scissile phosphates of DNA in E. coli TatD. T, thymine; C, cytosine; G, guanine. In (b–d), 2mFo − DFc electron-density maps contoured at 2.0σ are shown as a blue mesh.

IUCrJ
Volume 7| Part 3| May 2020| Pages 509-521
ISSN: 2052-2525
https://doi.org/10.1107/S2052252520003917