Mitochondria contain a complete translation machinery that is used to translate its internally transcribed mRNAs. This machinery uses a distinct set of tRNAs that are charged with cognate amino acids inside the organelle. Interestingly, charging is executed by aminoacyl tRNA synthetases (aaRS) that are encoded by the nuclear genome, translated in the cytosol, and need to be imported into the mitochondria. Here, we review import mechanisms of these enzymes with emphasis on those that are localized to both mitochondria and cytosol. Furthermore, we describe RNA recognition features of these enzymes and their interaction with tRNA and non-tRNA molecules. The dual localization of mitochondria-destined aaRSs and their association with various RNA types impose diverse impacts on cellular physiology. Yet, the breadth and significance of these functions are not fully resolved. We highlight here possibilities for future explorations.
Aminoacyl tRNA synthetases (aaRS) are well studied for their roles in tRNA charging with cognate amino acid. Nevertheless, numerous lines of evidence indicate that these proteins have roles other than tRNA charging. These include coordination of cellular signaling cascades, induction of cytokines outside the cell and transcription regulation. Herein, we focus on their roles in post‐transcriptional regulation of mRNA expression. We describe functions that are related to antitermination of transcription, RNA splicing and mRNA translation. Cases were recognition of mRNA by the aaRS involves recognition of tRNA‐like structures are described. Such recognition may be achieved by repurposing tRNA‐binding domains or through domains added to the aaRS later in evolution. Furthermore, we describe cases in which binding by aaRS is implicated in autogenous regulation of expression. Overall, we propose RNA‐mimicry as a common mode of interaction between aaRS and mRNA which allows efficient expression regulation.
This article is categorized under:
RNA Processing > tRNA Processing
RNA Interactions with Proteins and Other Molecules > Protein–RNA Recognition
RNA Interactions with Proteins and Other Molecules > Protein–RNA Interactions: Functional Implications
Translation > Translation Regulation
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