Ribosomal protein eL24, involved in two intersubunit bridges, stimulates translation initiation and elongation

Abstract

Interactions between subunits in the Saccharomyces cerevisiae ribosome are mediated by universal and eukaryote-specific intersubunit bridges. Universal bridges are positioned close to the ribosomal functional centers, while eukaryote-specific bridges are mainly located on the periphery of the ribosome. Two bridges, eB13 and B6, are formed by the ribosomal protein eL24. The eukaryotic eL24 is composed of an N-terminal domain, a linker region and a C-terminal α-helix. Here, the functions of different domains of eL24 in the S. cerevisiae ribosome were evaluated. The C-terminal domain and the linker region of the eL24 form eukaryote-specific eB13 bridge. Phenotypic characterization of the eL24 deletion mutants indicated that the functional integrity of the eB13 bridge mainly depends on the protein–protein contacts between eL24 and eS6. Further investigation showed importance of the eB13 bridge in the subunit joining in vivo and in vitro. In vitro translation assay demonstrated the role of the eB13 bridge in both initiation and elongation steps of translation. Intriguingly, results of in vitro translation experiment suggest involvement of the N-terminal domain of eL24 in the translation initiation. Therefore, eL24 performs number of tasks required for the optimal ribosome functionality.

Functional Interactions of Ribosomal Intersubunit Bridges in Saccharomyces cerevisiae

“…Construction of strains TYSC360 and TYSC488, and plasmids pRS315-rpl19 1-146 and pRS314-rpl24 1-65 has been described previously (Kisly et al 2016(Kisly et al , 2019. Strains TYSC517 and TYSC523 were constructed by a one-step PCR-based gene disruption method (Janke et al 2004).…”

“…Further analysis utilizing a cell-free translation system has demonstrated the role of the eukaryote-specific sequence of eL24 in both the initiation and elongation steps of translation. Parallel analysis of the importance of the N-terminal domain of eL24 suggests the involvement of this domain in the initiation step of translation (Kisly et al 2019).…”

“…The r-proteins eL19 and eL24 contain the domains that are conserved in archaeal and eukaryotic ribosomes. In addition, they have eukaryotespecific extensions that carry out specific functions (Kisly et al 2016(Kisly et al , 2019. eL41 is the smallest r-protein in the ribosomes (Planta and Mager 1998).…”

“…Mutational analysis of eL24 demonstrated that the interaction between eL24 and eS6 is a key component of the eB13 bridge, indicating the importance of protein-protein contacts (Kisly et al 2019).…”

“…The eukaryote-specific extensions of eL24, namely the linker and a-helix, form the eB13 bridge. Analysis of yeast mutants has revealed that this bridge is important for subunit joining in vitro and in vivo (Kisly et al 2019). Further analysis utilizing a cell-free translation system has demonstrated the role of the eukaryote-specific sequence of eL24 in both the initiation and elongation steps of translation.…”