Purification and crystallization of the N-terminal domain from the human doublecortin-like kinase

The unique doublecortin-like tandem of two homologous domains is found in certain microtubule-associated proteins such as doublecortin (DCX) and doublecortin-like kinase (DCLK). It is responsible for interactions with tubulin/microtubules and regulates microtubule dynamics. Here, the expression and purification of the tandem from human DCLK (residues 49–280) and of the isolated domains (residues 49–154 and 176–280) and the successful crystallization of the N-terminal domain (N-DCLK) are reported. High-quality wild-type crystals were obtained and a complete native data set was collected to 1.5 Å resolution. The crystals belong to space group C2, with unit-cell parameters a = 85.98, b = 29.62, c = 40.33 Å, β = 101.3°. Crystals of SeMet-substituted N-DCLK (Leu120Met) were also obtained, but they exhibit the symmetry of space group P2₁, with unit-cell parameters a = 38.81, b = 29.43, c = 40.1 Å, β = 115.7°.