Crystallization and preliminary X-ray studies on the molbindin ModG from Azotobacter vinelandii

Crystals of the molbindin ModG (subunit M-r = 14359 Da), a cytoplasmic moly bdate-binding protein from Azotobacter vinelandii, were grown by vapour dif fusion. Both apo and tungstate-bound forms were crystallized and X-ray data were collected at 100 K. Apo-ModG crystallizes in space group P6(3)22, wit h unit-cell dimensions a = b = 90.62, c = 79.46 Angstrom. Native data to a resolution of 2.5 Angstrom were collected from a single crystal, which show ed a marked improvement in diffraction quality after annealing. Data from a single-site gold derivative were also collected at 2.7 Angstrom resolution . Crystals of the ligand-bound form of ModG belong to space group P321, wit h unit-cell parameters a = b = 50.57, c = 79.29 Angstrom. X-ray data to a r esolution of 2.0 Angstrom were collected.