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Figure 4
Structural differences in the proton channel and structural preservation of the alternative electron transfer route between Hd1NES1NiR and HdA3151NiR. (a) Proton channel of Hd1NES1NiR colored green and cyan for each monomer superimposed on HdA3151NiR colored yellow for all monomers for simplicity. The T2Cu ion in the core domain is represented by a deep-blue sphere. The water molecules for Hd1NES1NiR and HdA3151NiR are represented by red and yellow spheres, respectively, and the bridging water is indicated by a black arrow. Coordination to the T2Cu ion is shown by a red broken line and the interaction is shown by a black broken line. (b) Alternative electron transfer route of Hd1NES1NiR colored green and cyan for each monomer superimposed on the extra cupredoxin domain of HdA3151NiR colored yellow for all monomers for simplicity. The T1CuN ion in the extra cupredoxin domain and T2Cu ion in the core domain are represented by deep-blue spheres. The mediation water molecules (W2 and W3) and ligand water molecule (W1) for Hd1NES1NiR and HdA3151NiR are shown by red and yellow spheres, respectively. Coordination to the T1CuN and T2Cu ions is shown by a red broken line and the interaction is shown by a black broken line. The distance between Val30 and Thr36 is indicated (∼20 Å).

IUCrJ
Volume 7| Part 3| May 2020| Pages 557-565
ISSN: 2052-2525
https://doi.org/10.1107/S2052252520005230