Crystallization and preliminary X-ray crystallographic studies of Drep-3, a DFF-related protein from Drosophila melanogaster.

During apoptosis, DNA fragmentation is mainly mediated by the caspase-activated DFF40 nuclease. DFF40 exists as a heterodimeric complex with its inhibitor DFF45. Upon apoptosis induction, DFF45 is cleaved by caspases to allow DFF40 activation. Drep-3 is a recently identified regulator of the DFF40 system in Drosophila melanogaster. Here, Drep-3 was expressed with a C-terminal His tag in Escherichia coli and the protein was purified to homogeneity. Multi-angle light-scattering analysis showed that Drep-3 is a homotetramer in solution. Native and selenomethionine-substituted Drep-3 proteins were crystallized at 293 K and X-ray diffraction data were collected to 2.8 and 3.0 A resolution, respectively. The crystals belong to space group P2(1)2(1)2(1), with unit-cell parameters a = 56.9, b = 125.4, c = 168.7 A. The asymmetric unit is estimated to contain one homotetramer.