Figure 3
Zn2+ coordination around the active site of E. coli RNase HI: (a) RNH_Zn_1, (b) RNH_Zn_2. Zinc ions are shown as purple spheres. 2Fo − Fc maps (gray mesh, 1.3σ) of the RNase HI side chain and water molecule coordinated by Zn2+ and anomalous maps [orange mesh, 7σ in (a) and 6σ in (b)] of the Zn2+ ion are shown. Pseudo-bonds representing coordination are shown as purple dashed lines and the distances (in Å) between Zn2+ and coordinating ligand molecules are also given. (c) RNase HI–Mg (RNH_Mg_3, cyan), RNase HI–Mn (PDB entry 1g15, salmon) and RNase HI–Zn (RNH_Zn_1, cornflower blue) are superimposed. The loop structure of residue 122–125 in PDB entry 1g15 was disordered and not included in the structure model. |