Abstract
Protein biosynthesis is essential for any organism, yet how this process is regulated is not fully understood at the molecular level. During evolution, ribosomal RNA expanded in specific regions, referred to as rRNA expansion segments (ES). First functional roles of these expansions have only recently been discovered. Here we address the role of ES7La located in the large ribosomal subunit for factor recruitment to the yeast ribosome and the potential consequences for translation. Truncation of ES7La has only minor effects on ribosome biogenesis, translation efficiency and cell doubling. Using yeast rRNA deletion strains coupled with ribosome-specific mass spectrometry we analyzed the interactome of ribosomes lacking ES7La. Three aminoacyl-tRNA synthetases showed reduced ribosome association. Synthetase activities however remained unaltered suggesting that the pool of aminoacylated tRNAs is unaffected by the ES deletion. These results demonstrated that aminoacylation activities of tRNA synthetases per se do not rely on ribosome association. These findings suggest a role of ribosome-associated aminoacyl-tRNA synthetase beyond their core enzymatic functions.
Highlights
Protein biosynthesis is essential for life and belongs to the most central and probably most ancient biochemical processes that exist
Of special interest are substantial expansions of specific ribosomal RNA (rRNA) helices ranging from 7–210 nucleotides in the budding yeast S. cerevisiae up to expansions of several hundred nucleotides in mammalian rRNAs [5]
In this study we investigated the general role of ES7La in yeast ribosome biology and in factor recruitment during translation
Summary
Protein biosynthesis is essential for life and belongs to the most central and probably most ancient biochemical processes that exist This fact is mirrored in the machinery performing the task of sequential addition of amino acids to a growing nascent chain, translation. Of special interest are substantial expansions of specific rRNA helices ranging from 7–210 nucleotides in the budding yeast S. cerevisiae up to expansions of several hundred nucleotides in mammalian rRNAs [5] Some of these so-called expansion segments (ES) have established roles in ribosome biogenesis [5] and inter-subunit bridge formation and all of them are located at the periphery of the ribosomal subunits and face towards the cytosol [6]. Recent studies suggest a role of ES7L in factor recruitment to eukaryotic ribosomes, more precisely, aminoacyl-tRNA synthetases (AARS) [13]. This ribosome-association of AARS is dispensable for tRNA charging efficiency and delivery to the ribosome
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