A YAC CONTIG ENCOMPASSING THE XRCC5 (KU80) DNA-REPAIR GENE AND COMPLEMENTATION OF DEFECTIVE CELLS BY YAC PROTOPLAST FUSION

The Chinese hamster ovary xrs mutants are sensitive to ionizing radiat ion, defective in DNA double-strand break rejoining, and unable to car ry out V(D)J recombination effectively. Recently, the gene defective i n these mutants, XRCC5, has been shown to encode Ku80, a component of the Ku protein and DNA-dependent protein kinase. We present here a YAC contig involving 25 YACs mapping to the region 2q33-q34, which encomp asses the XRCC5 gene. Eight new markers for this region of chromosome 2 are identified. YACs encoding the Ku80 gene were transferred to xrs cells by protoplast fusion, and complementation of all the defective p henotypes has been obtained with two YACs. We discuss the advantages a nd disadvantages of this approach as a strategy for cloning human gene s complementing defective rodent cell lines. (C) 1995 Academic Press, Inc.