The Saccharomyces cerevisiae DNA damage checkpoint is required for efficient repair of double strand breaks by non-homologous end joining

In this work we report that the Saccharomyces cerevisiae RAD9, RAD24, RAD17 , MEC1, MEC3 and RAD53 checkpoint genes are required for efficient non-homo logous end joining (NHEJ), RAD9 and RAD24 function additionally in this pro cess. Defective NHEJ in rad9 Delta-rad24 Delta, but not yku80 Delta cells, is only partially rescued by imposing G1 or G2/M delays. Thus, checkpoint f unctions other than transient cell cycle delays may be required for normal levels of NHEJ, Epistasis anal,;sis also indicated that YKU80 and R4D9/RAD2 4 function in the same pathway for repair of lesions caused by MMS and gamm a-irradiation, Unlike NHEJ, the checkpoint pathway is not required for effi cient site-specific integration of plasmid DNA into the yeast genome, which is RAD52-dependent, but RAD51-independent, (C) 2000 Federation of European Biochemical Societies.