Crystallization and crystal-packing studies of Chlorella virus deoxyuridine triphosphatase

The 141-amino-acid deoxyuridine triphosphatase (dUTPase) from the algal Chlorella virus IL-3A and its Glu81Ser/Thr84Arg-mutant derivative Mu-22 were crystallized using the hanging-drop vapor-diffusion method at 298 K with polyethylene glycol as the precipitant. An apo IL-3A dUTPase with an amino-terminal T7 epitope tag and a carboxy-terminal histidine tag yielded cubic P2(1)3 crystals with unit-cell parameter a = 106.65 Å. In the presence of dUDP, the enzyme produced thin stacked orthorhombic P222 crystals with unit-cell parameters a = 81.0, b = 96.2, c = 132.8 Å. T7-histidine-tagged Mu-22 dUTPase formed thin stacked rectangular crystals. Amino-terminal histidine-tagged dUTPases did not crystallize but formed aggregates. Glycyl-seryl-tagged dUTPases yielded cubic P2(1)3 IL-3A crystals with unit-cell parameter a = 105.68 Å and hexagonal P6(3) Mu-22 crystals with unit-cell parameters a = 132.07, c = 53.45 Å, γ = 120°. Owing to the Thr84Arg mutation, Mu-22 dUTPase had different monomer-to-monomer interactions to those of IL-3A dUTPase.