RRM
2013 Rustbelt RNA Meeting
RRM
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Poster abstracts
Abstract:
The function and core structure of ribosomes are conserved in all kingdoms of life. Consistent with the increased complexity of their function, eukaryotic ribosomes are larger than their bacterial counterparts. Eukaryote-specific extensions of ribosomal proteins (r-proteins) and expansion segments of rRNAs account for this size difference. These additions are thought to have roles in translation regulation and may increase the stability of ribosomes through extra protein-protein and protein-rRNA interactions. However, specific roles have been assigned to only a few of extensions. Interestingly, some regions within extensions are structurally disordered and transition to an ordered state upon binding their ligand, but the significance of this structural feature in ribosome assembly is yet to be determined. Our goal is to investigate whether eukaryotic extensions have roles in ribosome assembly. Previous data have shown that depletion of each ribosomal protein has a specific effect on the pre-rRNA processing pathway for the large subunit. However, depletion of an essential ribosomal protein may cause destabilization of this multi-component system and abort assembly. Thus, truncation of eukaryote-specific extensions has the potential to reveal more specific functions of r-proteins. We have systematically truncated and introduced single mutations in the eukaryote-specific extensions of six r-proteins (L4, L6, L7, L8, L25, L35) in Saccharomyces cerevisiae 60S subunits. While in vivo expression of some truncated r-proteins resulted in depletion phenotypes, we were able to identify several mutants with distinct defects. Our approach promises to assign specific roles to the eukaryote-specific extensions of r-proteins in ribosome assembly and reveal the significance of intrinsically disordered domains in processing and folding of rRNAs, as well as binding of r-proteins.
Keywords: ribosome assembly , ribosomal proteins
