Crystallization and preliminary X-ray diffraction analysis of the dimerization domain of the tumour suppressor ING4

Inhibitor of growth protein 4 (ING4) belongs to the ING family of tumour suppressors and is involved in chromatin remodelling, in growth arrest and, in cooperation with p53, in senescence and apoptosis. Whereas the structure and histone H3-binding properties of the C-terminal PHD domains of the ING proteins are known, no structural information is available for the N-terminal domains. This domain contains a putative oligomerization site rich in helical structure in the ING2-5 members of the family. The N-terminal domain of ING4 was overexpressed in Escherichia coli and purified to homogeneity. Crystallization experiments yielded crystals that were suitable for high-resolution X-ray diffraction analysis. The crystals belonged to the orthorhombic space group C222, with unit-cell parameters a = 129.7, b = 188.3, c = 62.7 angstrom. The self-rotation function and the Matthews coefficient suggested the presence of three protein dimers per asymmetric unit. The crystals diffracted to a resolution of 2.3 angstrom using synchrotron radiation at the Swiss Light Source (SLS) and the European Synchrotron Radiation Facility (ESRF).