Coordination of expression of DNA synthesis genes in budding yeast by a cell-cycle regulated trans factor.

All of the DNA synthesis genes of budding yeast examined so far are periodically expressed and hence under cell-cycle control (Table 1). Expression occurs near the G1/S phase boundary and the genes seem to be coordinately regulated (reviewed in ref. 4). The upstream promoter sequences of these genes have only a hexamer element, ACGCGT (an MluI restriction site), in common. Here we show that this hexamer is able to impart periodic expression to a heterologous gene and, significantly, this expression occurs coincidentally with that of CDC9, one of the DNA synthesis genes (Table 1). We have also identified a protein that binds specifically to these sequences in a similar periodic manner. These ACGCGT sequences and the transcription factor that binds to them therefore seem to be the elements controlling both the periodic expression and coordinate regulation of the DNA synthesis genes.