To understand how transcription factor family members perform slightly different functions within a transcriptional complex, we study Met31 and Met32, very similar transcription factors in yeast. MET31 and MET32 arose from a gene duplication and have diverged to have some specialized functions. While they bind identical DNA sequences, they exhibit different expression profiles, which could be due to different promoters. To test the effect of the promotor in allowing for their specialized roles, we are examining a strain of yeast in which the native MET31 promoter is replaced by the promoter from MET32, while deleting MET32 in its entirety. We are then analyzing protein and RNA levels of Met31/MET31 in the met32 delete strain where MET31 is driven by its native promoter or by the MET32 promoter. This replacement allows us to study the role of the promoter in defining Met31 function. Ultimately, we can characterize how this change plays a role in the transcription and expression of the target genes. We are also characterizing the expression of other transcription factors that interact with Met31 (such as Met4, Met28, and Cbf1) to regulate its target genes. Exploring the outcomes of this promoter replacement will help answer questions as to the evolution of transcription factor families and how members become specialized. Since Met31 and Met32 are part of the well-defined sulfur metabolism system we are able to isolate the effects of the promoter replacement.
