Structural insight into nucleotide recognition by human death-associated protein kinase

Death-associated protein kinase (DAPK) is a member of the Ca ²⁺/calmodulin-regulated family of serine/threonine protein kinases. The role of the kinase activity of DAPK in eukaryotic cell apoptosis and the ability of bioavailable DAPK inhibitors to rescue neuronal death after brain injury have made it a drug-discovery target for neurodegenerative disorders. In order to understand the recognition of nucleotides by DAPK and to gain insight into DAPK catalysis, the crystal structure of human DAPK was solved in complex with ADP and Mg²⁺ at 1.85 Å resolution. ADP is a product of the kinase reaction and product release is considered to be the rate-limiting step of protein kinase catalytic cycles. The structure of DAPK-ADP-Mg²⁺ was compared with a newly determined DAPK-AMP-PNP-Mg²⁺ structure and the previously determined apo DAPK structure (PDB code 1jks). The comparison shows that nucleotide-induced changes are localized to the glycine-rich loop region of DAPK.