Figure 2

Structure comparison of SA1388. (A) Superimposed structures of SA1388 (shown in cyan) with two homologs, E. coli ybgI (PDB id: 1nmo; colored red) and SP1609 from Streptococcus pneumoniae (PDB id: 2fyw; colored yellow). The two bound Zn atoms of SA1388 are shown as spheres and superimposed on the two equivalent Fe atoms of ybgI. For clarity, only the strands of SA1388 are numbered using the same scheme as β1–16 of Figure 1A. Sidechains of three conserved residues that mediate metal binding in the three structures are shown in ball-and-stick representations with the numbering corresponding to that in SA1388. (B) Comparison of the PII domain of SA1388 (left) and a canonical PII domain seen in E. coli GlnK (PDB id: 2gnk) shown in a similar orientation. Colors are ramped from N terminus (blue) to C terminus (red) in both structures and the bound ATP of GlnK is shown in ball-and-stick representation. The disordered T-loop in the two structures is indicated by the dotted line.