Transcriptional Regulation of the Cell Cycle-Dependent Thymidylate Synthase Gene of Saccharomyces cerevisiae

Abstract

We have previously shown that transcript levels expressed from the yeast TMP1 gene fluctuate periodically during the yeast cell cycle. However, it was not known whether periodic expression resulted from a regulatory mechanism acting at the level of transcription or a regulatory mechanism acting at the level of cell cycle stage-dependent changes in the stability of the TMP1 transcript. In this report we now show that the periodic expression of TMP1 transcript is primarily controlled at the level of its transcription by sequences which are upstream of its transcription initiation sites. We also localized the upstream sequences necessary for periodic transcription to a 150-base-pair region and show that this region encodes an element(s) with the properties of a periodic upstream activating sequence. The regulatory region defined in this study apparently does not contain consensus sequences similar to those reported for the cell cycle-regulated HO endonuclease or for the histone H2A and H2B genes of Saccharomyces cerevisiae.