Date of Award
Mary J. Clancy
In the yeast Saccharomyces cerevisiae, m6A methylation regulates the stability and translation of mRNA. Ime4, which is highly active in meiotic cells, recognizes consensus methyl sites in pre-mRNA and adds methyl groups to a small fraction of adenosine residues, whereas Pho92 binds to such methylated sites and promotes subsequent degradation. PHO5 transcripts expression is upregulated when IME4 and PHO92 are deleted. In the PHO5 transcript, near the stop codon of the open reading frame (ORF), there is a potential consensus methyl site that is predicted to be methylated, based on its location and excellent match to the consensus methylation sequence (Schwartz et al. 2013). We believe that this 3’ region, containing potential methyl site, may be involved in the transcript regulation. We tested this hypothesis by examining the change in expression of GFP-Pho5 fusion proteins under the control of ADH1 promoter. These experiments were done using Δime4, Δpho92 and Δime4 Δpho92 deletions in haploid and vegetative growing Saccharomyces cerevisiae. Although the results of these experiments were inconclusive for Ime4, we confirmed that Pho92 cannot act solely on the 3’ region; it needs the PHO5 ORF to promote its activity. We suggest that Pho92 promotes PHO5 transcript degradation by an alternative pathway, which is not dependent on methylation of the target transcript.
Shah, Krishna, "Role of Ime4 and Pho92 Proteins in Pho5 Regulation" (2017). Senior Honors Theses. 93.