Preliminary crystallographic analysis of the kinase domain of SAD-1, a protein essential for presynaptic differentiation in Caenorhabditis elegans.

SAD-1 is a serine/threonine kinase which plays an important role in the regulation of both neuronal polarity and synapse formation in Caenorhabditis elegans. The kinase domain of SAD-1 from C. elegans was overexpressed in Escherichia coli BL21 (DE3) cells and purified to homogeneity using nickel-nitrilotriacetic acid metal-affinity, ion-exchange and gel-filtration chromatography. Diffraction-quality crystals were grown using the sitting-drop vapour-diffusion technique from a condition consisting of 1 M CAPSO pH 9.6, 10%(w/v) polyethylene glycol 3350. The crystals belonged to the monoclinic space group C2, with unit-cell parameters a = 205.4, b = 57.1, c = 71.7 Å, β = 106.1°. X-ray diffraction data were recorded to 3.0 Å resolution from a single crystal using synchrotron radiation.