Purification and crystallization of yeast Ent1 ENTH domain

Members of the Epsin protein family regulate the ubiquitin/clathrin-dependent trafficking of transmembrane proteins. The yeast Epsin-1 (ent1) gene was cloned and expressed in Escherichia coli. The protein product of a construct containing the ENTH-UIM modules was purified to homogeneity and subjected to crystallization screening using the sitting-drop vapour-diffusion method. Refined conditions containing polyethylene glycol 3350 and Tacsimate yielded thin rod-like crystals. X-ray analysis revealed that the crystallographic symmetry is primitive orthorhombic, space group P222, with unit-cell parameters a = 32.7, b = 35.5, c = 110.6 Å and a diffraction limit of 2.3 Å. Matthews coefficient calculations suggested that the crystal contained only the ENTH domain. This was corroborated by Coomassie Blue-stained SDS-PAGE analysis of dissolved crystals.