The exosome is a highly conserved multimeric enzymatic complex with an exoribonucleolytic 3'-5' activity. It plays a fundamental role in RNA processing and degradation both in the cytoplasm and nucleus, being involved in rRNA, snoRNA and snRNA maturation. In Saccharomyces cerevisiae, in addition to the 9 subunits-core, it presents two catalytic subunits: Rrp44 and Rrp6. The mechanisms that regulate its activity are not yet completely understood. Nop53 and Nop8, two nucleolar proteins involved in ribosomal 60S subunit biogenesis, were demonstrated to interact and affect the exosome activity. Interestingly, in vivo and in vitro assays showed the ability of these proteins to interact with Rrp6. This work aim at evaluating the effect of Nop53 and Nop8 on the stability and levels of expression of Rrp6 in S. cerevisiae, depicting an alternative way by which nucleolar proteins could modulate the exosome activity. We are going to analyse whether Rrp6 expression is modulated by Nop8 or Nop53 depletion. These results might contribute to better understand the regulation of this important enzymatic complex, as well as allow further functional characterization of these two nucleolar proteins implicated in ribosome biogenesis.
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