Crystallization and preliminary X-ray diffraction studies of the ISC-like [2Fe-2S] ferredoxin (FdxB) from Pseudomonas putida JCM 20004.

The iron-sulfur (Fe-S) cluster-biosynthesis (ISC) system of the gamma-proteobacterium Pseudomonas putida JCM 20004 contains a constitutively expressed vertebrate-type [2Fe-2S] ferredoxin, FdxB, which lacks the conserved free cysteine residue near the Fe-S cluster site that has been proposed to function in the catalysis of biological Fe-S cluster assembly in other bacterial homologues. Recombinant FdxB was heterologously overproduced in Escherichia coli, purified and crystallized in its oxidized form by the hanging-drop vapour-diffusion and streak-seeding methods using 1.6 M trisodium citrate dihydrate pH 6.5. The thin needle-shaped crystals diffract to 1.90 A resolution and belong to the hexagonal space group P6(1)22, with unit-cell parameters a = 87.58, c = 73.14 A. The asymmetric unit contains one protein molecule.