FHA domain boundaries of the Dun1p and Rad53p cell cycle checkpoint kinases

Dun1p and Rad53p of the budding yeast Saccharomyces cerevisiae are members of a conserved family of cell cycle checkpoint protein kinases that contain forkhead-associated (FHA) domains. Here, we demonstrate that these FHA dom ains contain 130-140 residues, and are thus considerably larger than previo usly predicted by sequence comparisons (55-75 residues), In vivo, expressio n of the proteolytically defined Dun1p FHA domain, but not a fragment conta ining only the predicted domain boundaries, inhibited the transcriptional i nduction of repair genes following replication blocks, This indicates that the non-catalytic FI-IA domain plays an important role in the transcription al function of the Dun1p protein kinase. (C) 2000 Federation of European Bi ochemical Societies.