Functional correlation of eIF5A with the Quality Control (RQC) complex

• Grant number: 18/19854-3
• Support Opportunities: Scholarships abroad - Research
• Start date: February 01, 2019
• End date: January 31, 2020
• Field of knowledge: Biological Sciences - Biochemistry - Molecular Biology
• Principal Investigator: Cleslei Fernando Zanelli
• Grantee: Cleslei Fernando Zanelli
• Host Investigator: Judith Frydman
• Host Institution: Faculdade de Ciências Farmacêuticas (FCFAR). Universidade Estadual Paulista (UNESP). Campus de Araraquara. Araraquara , SP, Brazil
• Institution abroad: Stanford University, United States

Abstract

The translation factor 5A (eIF5A) is highly conserved in archaea and eukaryotes and is essential for cell viability in all organisms tested so far. eIF5A undergoes a unique post-translational modification which essential for its function, wherein a lysine residue is converted into a hypusine. eIF5A and its functional counterpart in bacteria, EF-P, associate between the peptidyl (P) and the exit sites (E) of tRNAs in the ribosome, aiding in the correct positioning of the peptidyl-tRNA at the peptidyl transferase (PTC) center of the ribosome and, therefore, facilitating the formation of peptide bond between proline and other amino acid residues in contexts that may cause a type of stalling. Consecutive proline sequences cause spatial restriction which reflects in their greatest difficulty for peptide bond formation. However, not all proline-rich sequences appear to require EF-P / eIF5A for translation and the reason for other sequences of 3 or more residues of amino acids to require EF-P / eIF5A is not yet elucidated. Previous results from our laboratory have demonstrated that stalling caused by eIF5A-dependent sequences does not appear to trigger the Ribosome Quality Control (RQC) complex. This complex acts to resolve other stalling events caused by premature mRNA cleavage or absence of a termination codon, for example. On the other hand, depletion of eIF5A directly affected the functioning of the RQC complex. Thus, this project aims at confirming and extending the preliminary data of our laboratory, determining how eIF5A affects the functioning of RQC, more specifically, the activity of Rqc2 in 60S, which leads to the formation of peptide bonds between alanines and threonines independently of mRNA and 40S.