Crystal structure of an Xrcc4–DNA ligase IV complex

摘要: A complex of two proteins, Xrcc4 and DNA ligase IV, plays a fundamental role in non-homologous end joining (NHEJ), cellular function required for double-strand break repair V(D)J recombination. Here we report the crystal structure human bound to polypeptide that corresponds IV sequence linking its BRCA1 C-terminal (BRCT) domains. In complex, single chain binds asymmetrically an dimer. The helical tails undergo substantial conformational change relative uncomplexed protein, forming coiled coil unwinds upon binding, leading flat interaction surface. buried network charged hydrogen bonds surrounded by extensive hydrophobic contacts explains observed tightness interaction. strong conservation residues at interface between proteins provides evidence mode has been maintained NHEJ throughout evolution.