E37 or E39 of YjiA could coordinate nucleotide-associated
Mg(II).
GTP analogue-bound HypB (cyan carbons, PDB entry 2HF8(18)) is superimposed onto the structure of Zn(II)-bound WT
YjiA (green carbons). Bound GTPγS is shown with cyan carbons,
and GTPγS-associated Mg(II) is shown as an orange sphere. D75
of HypB is involved in Mg(II) coordination. Both E37 and E39 of YjiA
are in the proximity of the modeled Mg(II), as indicated by the purple
dashed lines, raising the possibility that these residues are involved
in Mg(II) coordination in YjiA. Notably, E37 is also involved in binding
Zn(II) (purple sphere). E39 was truncated to the Cβ atom because of a lack of electron density for the side chain.