Purification, crystallization and preliminary X-ray diffraction analysis of the FeoB G domain from Methanococcus jannaschii.

The transmembrane protein FeoB plays a key role in ferrous iron acquisition in prokaryotes. The N-terminal domain of FeoB from Methanococcus jannaschii was overproduced, purified to homogeneity and crystallized in the presence of GTP and magnesium. The native protein crystallized in a tetragonal space group and the crystals diffracted to beyond 2.2 A resolution, with unit-cell parameters a = b = 84.77, c = 137.90 A. The Matthews coefficient and the solvent content were estimated to be 2.65 A(3) Da(-1) and 53.64%, respectively, which corresponds to the presence of two molecules per asymmetric unit. To obtain initial phases, selenomethionyl-substituted protein was overproduced, purified and crystallized.