Purification, crystallization and preliminary X-ray analysis of Caenorhabditis elegans ubiquitin-conjugation enzyme...

M7.1 is a class IV ubiquitin-conjugation enzyme (UBC) that belongs to the ubiquitination cascade in Caenorhabditis elegans. The clone for this UBC has been overexpressed in Escherichia coli and the 16.7 kDa protein was purified from the soluble fraction. M7.1 was crystallized by sitting-drop vapor diffusion in 10% ethanol, 1.5 M NaCl at 277.5 K. Crystals diffracted to 1.75 A and belong to the orthorhombic space group P2(1)2(1)2(1), with unit-cell parameters a = 44.3, b = 54.3, c = 60.2 A. The asymmetric unit contains a single monomer. A molecular-replacement model has been determined and refinement is in progress.