Crystallization and preliminary crystallographic analysis of the nickel-responsive regulator NikR from Pyrococcus horikoshii

The nickel-responsive repressor from Pyrococcus horikoshii OT3 (PhNikR) has been crystallized in the apo form (PhNikR-apo) and two nickel-bound forms (PhNikR-Ni-1 and PhNikR-Ni-2). The PhNikR-apo crystals belong to space group P21, with unit-cell parameters a = 75.78, b = 54.32, c = 77.28 A, β = 116.07°, and diffract to 2.2 A. The PhNikR-Ni-1 crystals belong to space group P41212, with unit-cell parameters a = b = 99.89, c = 97.98 A, and diffract to 3.0 A and the PhNikR-Ni-2 crystals belong to space group P3121 or P3221, with unit-cell parameters a = b = 109.95, c = 79.0 A, and diffract to 2.1 A. The crystals obtained were suitable for detailed structural studies.