Crystallization and Preliminary X-ray Diffraction Studies of New Crystal Forms of Escherichia coli P_II Complexed with Various Ligands

New crystals of the signal-transducing protein P_II have been obtained in the presence of a number of different effector ligands. Various crystal forms are observed depending on the nature of the ligand(s). Co-crystallization with 2-ketoglutarate, glutamate and pyrophosphate produces hexagonal crystals similar to the wild type, ATP yields cubic crystals and ATP in conjunction with 2-ketoglutarate or glutamate yields orthorhombic crystal forms. All of the above crystals have been characterized by X-ray diffraction analysis. The hexagonal crystals belong to space group P6₃, cubic crystals to either I23 or I2₁3 and orthorhombic crystals to I222. A molecular-replacement solution for the P_II/ATP/2-ketoglutarate crystals has been obtained giving us an initial model for a trimer in the orthorhombic crystal form.