Biochemistry | Molecular Genetics


Gene expression is a multi-faceted phenomenon, governed not only by the sequence of nucleotides, but also by the extent to which a particular gene gets transcribed, how the transcript is processed, and whether or not the transcript ever makes it out of the nucleus. Rrp6p is a 5’-3’ exonuclease that can function independently and as part of the nuclear exosome in Saccharomyces cerevisiae (Portin, 2014). It degrades various types of aberrant RNA species including small nuclear RNAs, small nucleolar RNAs, telomerase RNA, unspliced RNAs, and RNAs that have not been properly packaged for export (Butler & Mitchell, 2010). This exosome mediated degradation is important as the accumulation of unprocessed mRNA transcripts can be harmful to the cell. These experiments sought to quantify changes in RNA levels in rrp6-Δ strains grown in glucose versus those grown in galactose compared to wild type strains grown in each of the carbon sources. The goal was to determine if there was an interplay between the genes regulated by Rrp6p and the genes involved in the switch from glucose metabolism to galactose metabolism. Based on the data, it appears that the absence of Rrp6p increases transcription in glucose while, in galactose, the absence of Rrp6p increases transcription to a significantly lesser degree than in glucose and in some cases decreases transcription.