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 cr ystal forms are observed depending on the nature of the ligand(s). Co- crystallization with 2-ketoglutarate, glutamate and pyrophosphate prod uces hexagonal crystals similar to the wild type, ATP yields cubic cry stals and ATP in conjunction with 2-ketoglutarate or glutamate yields orthorhombic crystal forms. All of the above crystals have been charac terized by X-ray diffraction analysis. The hexagonal crystals belong t o space group P6(3), cubic crystals to either I23 or I2(1)3 and orthor hombic crystals to I222. A molecular-replacement solution for the P-II /ATP/2-ketoglutarate crystals has been obtained giving us an initial m odel for a trimer in the orthorhombic crystal form.