Understanding the mechanism of the RNA Exosome subunits nuclear transport in Saccharomyces cerevisiae

• Grant number: 22/16740-2
• Support Opportunities: Scholarships abroad - Research Internship - Post-doctor
• Start date: September 01, 2023
• End date: August 31, 2024
• Field of knowledge: Biological Sciences - Biochemistry - Biochemistry of Microorganisms
• Principal Investigator: Carla Columbano de Oliveira
• Grantee: Valdir Gomes Neto
• Supervisor: Olivier Gadal
• Host Institution: Instituto de Química (IQ). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Institution abroad: Centre de Biologie Intégrative de Toulouse (CBI Toulouse), France
• Associated to the scholarship: 22/00071-4 - Identification of karyopherins involved in the nuclear import of exosome subunits in Saccharomyces cerevisiae, BP.PD

Abstract

The exosome is a multiprotein complex that plays an important role in the processing and degradation of all classes of RNAs in the nucleus and cytoplasm. In Saccharomyces cerevisiae cells, it is formed by 10 subunits in the cytosol (EXO10), and by 11 subunits in the nucleus (EXO11). In the cytosol, the EXO10 acts in the regulation of specific RNA expression levels associated with the Ski complex, while in nuclei the EXO11acts in the maturation of various RNAs and degradation of unstable pre-mRNAs. In the nucleus, the exosome is highly concentrated in the nucleolus, where it participates in rRNA processing, more specifically in the maturation of 5.8 S rRNA and degradation of the spacer 5'-ETS. The mechanism responsible for the exosome transport to the nucleus and its targeting to the nucleolus is still unknown. To better understand the nuclear import of this complex, our research group has studied the transport of the catalytic subunits (Rrp6 and Rrp44). The catalytic subunits contain nuclear localization sequences (NLS) and the importins Kap95 (importin ²) and Srp1 (Importin ±) are the key players involved in the nuclear transport of those subunits. In this work, we propose to study the transport of core exosome proteins (6 subunits) and cap exosome proteins (3 subunits). Dr. Gadal's expertise in the use of high-resolution microscopy to study rRNA transcription and nucleolar protein localization in yeast will help us determine the exosome subunits localization in karyopherin mutants, and identify which of the core subunits of the complex are responsible for its nuclear import. (AU)