Crystallization and preliminary X-ray studies of ferric uptake regulator from Magnetospirillum gryphiswaldense

Magnetosomes in magnetotactic bacteria have been widely used in studies of magnetic domains and in commercial applications. The iron content of magnetotactic bacteria is similar to 100 times higher than that of Escherichia coli. Magnetospirillum gryphiswaldense MSR-1 can still take up iron even at high intracellular concentrations. Ferric uptake regulator (Fur) is a global iron-responsive regulator that affects magnetosome formation, iron transport and oxygen metabolism. However, the mechanism of iron uptake and homeostasis by M. gryphiswaldense MSR-1 Fur is not clear. Here, the expression, purification and crystallization of apo and SeMet Fur from M. gryphiswaldense MSR-1 are reported. The crystals belonged to space group C2. Matthews coefficient analysis and size-exclusion chromatography showed that the asymmetric unit probably contains one dimer of Fur. Diffraction data were optimized to 1.58 angstrom resolution for apo Fur and to 1.9 angstrom resolution for SeMet Fur.