Preliminary crystallographic analysis of the N-­terminal domain of FILIA, a protein essential for embryogenesis

FILIA is a component of the subcortical maternal complex that is essential for early stage embryogenesis. Its 6×His-tagged N-terminal domain was expressed in Escherichia coli and purified to homogeneity. Two types of crystals formed under different crystallization conditions during screening. Orthorhombic crystals appeared in a solution containing 1.4 M ammonium sulfate, 0.1 M Tris pH 8.2 and 12% glycerol, while tetragonal crystals were obtained using 15% PEG 4000 mixed with 0.1 M HEPES pH 7.5 and 15% 2-propanol. High-quality diffraction data were collected from the two crystal forms to resolutions of 1.8 and 2.2 Å, respectively, using synchrotron radiation. The Matthews coefficients indicated that the P2₁2₁2₁ and P4₁2₁2 crystals contained two molecules and one molecule per asymmetric unit, respectively. A selenomethionine-substituted sample failed to crystallize under the native conditions, but another ortho­rhombic crystal form was obtained under different conditions and anomalous diffraction data were collected.