Identification and characterization of the genes for two topoisomerase I-interacting proteins from Saccharomyces cerevisiae

The two-hybrid system was used to identify yeast genes encoding proteins th at interact with DNA topoisomerase I. Two new genes were found and named TO F1 and TOF2. The Tof1 protein has 1238 amino acids and no obvious homologue s in databases. The Tof2 protein has 771 amino acids; it is quite closely r elated to another yeast protein, the product of an uncharacterized ORF. Bot h tof1 and tof2 null mutants, and tof1-tof2 double mutants, grow normally a nd have normal levels of topoisomerase I activity. TOF2 shows various genet ic interactions with TOPI and HPR1. The implications of these interactions for TOF2 function are discussed. Copyright (C) 1999 John Wiley & Sons, Ltd.