Crystallization and preliminary X-ray crystallographic analyses of Nur, a nickel-responsive transcription regulator from Streptomyces coelicolor.

Nickel ions serve in the correct folding and function of microbial enzymes implicated in metabolic processes. Although nickel ions are indispensable for the survival of cells, the intracellular level of nickel ions needs to be properly maintained as excessive levels of nickel ions are toxic. Nur, a nickel-uptake regulator belonging to the Fur family, is a nickel-responsive transcription factor that controls nickel homeostasis and antioxidative response in Streptomyces coelicolor. Nur was purified and crystallized at 295 K. A 2.4 A native data set and a 3.0 A Ni-MAD data set were collected using synchrotron radiation. The Nur crystals belong to space group P3(1), with unit-cell parameters a = b = 78.17, c = 50.39 A. Assuming the presence of two molecules in the asymmetric unit, the solvent content is estimated to be about 54.7%.