YEAST CHECKPOINT GENES IN DNA-DAMAGE PROCESSING - IMPLICATIONS FOR REPAIR AND ARREST

Yeast checkpoint control genes were found to affect processing of DNA damage as well as cell cycle arrest. An assay that measures DNA damage processing in vivo showed that the checkpoint genes RAD17, RAD24, and MEC3 activated an exonuclease that degrades DNA. The degradation is p robably a direct consequence of checkpoint protein function, because R AD17 encodes a putative 3'-5' DNA exonuclease. Another checkpoint gene , RAD9, had a different role: It inhibited the degradation by RA17, RA D24, and MEC3. A model of how processing of DNA damage may be linked t o both DNA repair and cell cycle arrest is proposed.