Crystallographic study of intein homing endonuclease II encoded in the archaeal DNA polymerase gene

Intein homing endonucleases are proteins spliced out from a precursor protein and site-specific enzymes that make double-strand breaks in inteinless alleles. Crystals of intein homing endonuclease II from the hyperthermophilic archaeon Pyrococcus kodakaraensis strain KOD1 (PI-PkoII) have been grown at room temperature using ammonium sulfate as a precipitant. The diffraction pattern of the crystal extends to 3.0 Å resolution at room temperature upon exposure to synchrotron X-rays at KEK-PF, Japan. The crystals have symmetry consistent with space group C222₁, with unit-cell parameters a = 107.6, b = 150.5, c = 146.8 Å. A full set of X-ray diffraction data were collected to 3.0 Å Bragg spacing from a native crystal with an overall R_merge of 4.8% and a completeness of 96.6%.