Fig. 4: The active sites of Mtb-RNase J.

a The active sites of Mtb-RNase J. Residues involved in metal chelation were shown as stick models. The Zn²⁺ were shown as gray spheres. Yellow dashed lines indicated Zn²⁺ coordination. The bridging water was shown as a red sphere. The electron density map was contoured to 2.0 σ. b Sequence alignment of the active sites among different RNase J proteins: Mtb (Mycobacterium tuberculosis), Msm (Mycobacterium smegmatis), Tth (Thermus thermophilus), Bsu (Bacillus subtilis), Ddr (Deinococcus deserti), and Dra (Deinococcus radiodurans). The conserved binding sites are shown in red. c The ribonuclease activities of Mtb-RNase J and mutants were assayed with a 20-nt ssRNA as the substrate.