Drug Study on Saccharomyces Cerevisiae

3371 WordsJan 30, 201814 Pages
In Saccharomyces cerevisiae, lysine methyltransferase Set1 protein is a member of COMPASS, a protein complex that catalyzes methyl transfer from methyl donor S-adenosylmethionine to lysine 4 of histone 3. Methylation of lysine 4 of histone 3 regulates gene expression and gene silencing. In order to develop a screen to identify important residues for silencing by Set1, single amino acid substitutions were introduced into the SET domain. Two different missense mutations were introduced to code for either a phenylalanine (Y967F) or an alanine (Y967A). In the mutant strains, set1 gene silencing was assessed by measuring the transcription level of the HIS3 gene in the rDNA. The mutant strains were grown on sc-his plate, which allowed cells that transcribe high levels of HIS3 to grow quicker. However, there was not a clear difference on the spot plate assay, thus a HIS3 gene product inhibitor, 3-amino-1,2,4-triazole was used to better assess growth differences between the mutant yeast strains. The findings indicate that Y967F set1 showed similar growth patterns to the wild type SET1, while Y967A set1 showed similar growth to the set1Δ (1). However, the growth patterns for SET1 and set1Δ were the opposite of what was expected. The wild type strain contains a set1 gene, which causes HIS3 silencing, so it is expected that the SET1 strain to have more growth defects than the set1Δ, which lacks the set1 gene. These growth differences are due to changes beyond loss of silencing
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