Influence of the phosphorylation of proteins from the 90s preribosome complex on the recruitment of exosome and its role in signaling during the processing and quality control of pre-rRNAS

• Grant number: 21/14620-7
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: March 01, 2022
• End date: March 20, 2023
• Field of knowledge: Biological Sciences - Biochemistry - Molecular Biology
• Principal Investigator: Carla Columbano de Oliveira
• Grantee: Felipe Astolpho de Almeida
• 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

Protein phosphorylation regulates the activity, localization, stability, and interaction with other ligands. The process of ribosomal biogenesis is highly complex, being dynamically controlled by the action of specific protein-protein and RNA-protein interactions, which are essential for the control of gene expression. The RNase called exosome has been the central focus of research of our lab, but the factors controlling the recruitment of this complex remain mostly unknown. This project aims to identify and characterize the phosphorylation sites of exosome subunit proteins and study the role of these modifications in the control the recruitment of this complex to pre-ribosomal particles. The chosen strategy will be the pre-fractionation of the exosome nuclear subunits of Saccharomyces cerevisiae, followed by the purification and enrichment of the phosphopeptides by various chromatography steps, and identification by mass spectrometry using ETD (Electron Transfer Dissociation) ionization. These approaches show potential to generate unprecedented results and identify yet unreported phosphoproteins, as well as characterize their phosphorylation sites, during the processing of rRNAs. Given the evolutionary conservation of these processes in eukaryotes, these results can be extrapolated to humans, in which diseases have already been identified as being caused by mutations in the genes of orthologous proteins studied by this research group. (AU)