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 wildtype crystals were obtained and a complete native data set was collected to 1.5 Angstrom resolution. The crystals belong to space group C2, with unit-cell parameters a = 85.98, b = 29.62, c = 40.33 Angstrom, beta = 101.3degrees. Crystals of SeMet-substituted N-DCLK (Leu120Met) were also obtained, but they exhibit the symmetry of space group P2(1), with unit-cell parameters a = 38.81, b = 29.43, c = 40.1 Angstrom, beta = 115.7degrees.