Venue: FIAS Seminar Room 0.101

Our next "CMMS Talks" event with a talk by Dr. Irene Lamberti will take place on Thursday, 31 October 2024 at 3 p.m. in the FIAS Seminar Room 0.101.

Abstract:

EIF5A (Eukaryotic Initiation Factor 5A) is a highly expressed and conserved elongation factor: first identified as an initiation factor, it was later shown to relieve ribosome stalling in proline-rich amino acid sequences. Its unique post-translational modification, called hypusination, is important for its catalytic function. We aimed at investigating the role of EIF5A on different codon sequences by imaging translation of single mRNAs over time in living cells, with a protein-tagging technique called SunTag. We developed a Bayesian inference framework based on a low-density approximation of the Totally Asymmetric Exclusion Process (TASEP) to analyze single intensity traces and infer kinetic parameters. Our results indicate a strong correlation between initiation and elongation rates across different transcripts, indicative of a feedback mechanism where elongation influences initiation to prevent ribosome crowding. Pharmacological depletion of hypusinated EIF5A (hEIF5A) had ubiquitous effects, not limited to proline amino acids, implying a broader role of EIF5A in translation elongation, consistent with recent results in ribosome profiling data. Genetic knockout of EIF5A led to significant reduction in ribosome density, shorter ribosome stalling and altered bursting dynamics with respect to hEIF5A depletion, suggesting a role of non-hypusinated EIF5A in protecting slow-elongating ribosomes from degradation. Our findings extend the current knowledge on the interplay between elongation and initiation as well as the role of EIF5A in translation, and propose new methodologies for analyzing SunTag traces, contributing to the broader understanding of translation regulation.