Structure and mechanism of the polynucleotide kinase component of the bacterial Pnkp-Hen1 RNA repair system

Atomic contacts in the active site. Stereoviews of the phosphate donor site of the A protomers of the SeMet-kinase•ATP•Mg²⁺ substrate complex (panel A) and the native kinase•ADP•Mg²⁺ product complex (panel B). Amino acids and ATP/ADP are shown as stick models with beige and gray carbons, respectively. Mg²⁺ is depicted a magenta sphere in the center of an octahedral coordination complex. Waters in the metal coordination complex are denoted by red spheres. Atomic contacts are indicated by dashed lines.