Roles of TRAMP complex on aberrant rRNA degradation in Saccharomyces cerevisiae

• Grant number: 25/06224-5
• Support Opportunities: Scholarships in Brazil - Master
• Start date: August 01, 2025
• End date: January 31, 2027
• Field of knowledge: Biological Sciences - Biochemistry - Molecular Biology
• Principal Investigator: Carla Columbano de Oliveira
• Grantee: Rebeca Barcelos Jantsch
• Host Institution: Instituto de Química (IQ). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated research grant: 20/00901-1 - Posttranscriptional control of gene expression: pre-rRNA processing, mRNA degradation, splicing and snoRNP assembly in Saccharomyces cerevisiae, AP.TEM

Abstract

The processing of ribosomal RNA occurs through meticulous maturation steps coordinated by protein cofactors and ribonucleoproteins, which act from the nucleolus until the complete maturation of rRNA in the cytoplasm. In the final stages of 7S pre-rRNA processing, the Nop53 protein recruits the exosome complex for the processing of the 3' end of 7S pre-rRNA through the RNA helicase Mtr4, giving rise to the mature 5.8S rRNA, which will be part of the large ribosomal subunit. Our group previously demonstrated that the absence of Nop53 leads to an accumulation of 7S rRNA in the 60S pre-ribosomal particle and the assembled 80S ribosome. This indicates that this rRNA is being transported to the cytoplasm but is degraded during the first rounds of translation by cytoplasmic complexes responsible for ribosome quality control. Interestingly, recent experiments in our laboratory have shown that the depletion of proteins from the TRAMP complex, which is involved in RNA quality control in the nucleus, leads to the accumulation of 7S in cytoplasmic ribosomes, similarly to what occurs with the depletion of proteins involved in cytoplasmic quality control. This raises the hypothesis that 7S pre-rRNA undergoes a nuclear quality control step that has not yet been described and is likely mediated by the TRAMP complex. Therefore, this project aims to identify proteins involved in the nuclear degradation of 7S to determine the quality control mechanism of this pre-rRNA. (AU)