Crystal Structure of Human XLF: A Twist in Nonhomologous DNA End-Joining

DNA double-strand breaks represent one of the most severe forms of DNA damage in mammalian cells. One pathway for repairing these breaks occurs via nonhomologous end-joining (NHEJ) and depends on XRCC4, LigaseIV, and Cernunnos, also called XLF. Although XLF stimulates XRCC4/LigaseIV to ligate mismatched and noncohesive DNA ends, the mechanistic basis for this function remains unclear. Here we report the structure of a partially functional 224 …