Fig. 3.

Magnesium ions facilitate ATP recognition by LysRS. (A) Electron density map of the first magnesium and ATP analog, AMPcPP, in LysRS pocket 2 (state 2). (B) Superimposition of the state 2 structure (cyan) with the human LysRS structure (pdb: 3BJU, orange) at the complete state for ATP binding. (C) Superimposition of the state 2 structure (cyan) with the human LysRS structure (pdb: 4DPG, pink) at another intermediate state for ATP binding (state 3). (D) Superimposition of the state 3 structure (pink) with the complete state structure (orange) for ATP binding. (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)