INVOLVEMENT OF SRE ELEMENT OF TY1 TRANSPOSON IN TEC1-DEPENDENT TRANSCRIPTIONAL ACTIVATION

Some Ty1 transposable element insertion mutations of Saccharomyces cerevisiae activate transcription of adjacent genes in a cell-type dependent manner. This activation requires at least STE12 and TEC1 gene products. The binding site for the STE12 protein is located in the sterile responsive element (SRE), which is just downstream the 5' LTR of Ty1 and contains one copy of the pheromone response element (PRE). This report defines the sequences in Ty1 required for TEC1-dependent activation using a TDH3::lacZ reporter gene in which the UAS was replaced by different portions of a Ty1 or Ty2 element. The Ty1 SRE seems to be sufficient to ensure the TEC1 and STE12-mediated activation whereas Ty2 SRE can activate the expression of the adjacent genes in the absence of both proteins. Adjacent to the PRE element, there is a region (PAE) with extensive sequence divergence in Ty1 and Ty2 SREs. Swapping experiments between Ty1 and Ty2 sequences show that Tyl PAE is required for the activation of adjacent gene expression in a TEC1 and STE12-dependent manner. The use of a LexA::TEC1 construct indicates that the chimeric protein has no activation ability suggesting that TEC1 could act in conjunction with another factor.