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Nucleic Acids Res. 2018 Sep 28;46(17):9170-9180. doi: 10.1093/nar/gky593.

Small but large enough: structural properties of armless mitochondrial tRNAs from the nematode Romanomermis culicivorax.

Author information

1
Institute for Biochemistry, Leipzig University, Brüderstrasse 34, 04103 Leipzig, Germany.
2
Architecture et Réactivité de l'ARN, Université de Strasbourg, CNRS, IBMC, 67084 Strasbourg, France.
3
Institute of Molecular Biosciences, Goethe-University and Center of Biomolecular Magnetic Resonance (BMRZ), Frankfurt/M., Max-von-Laue-Strasse 9, 60438, Frankfurt, Germany.

Abstract

As adapter molecules to convert the nucleic acid information into the amino acid sequence, tRNAs play a central role in protein synthesis. To fulfill this function in a reliable way, tRNAs exhibit highly conserved structural features common in all organisms and in all cellular compartments active in translation. However, in mitochondria of metazoans, certain dramatic deviations from the consensus tRNA structure are described, where some tRNAs lack the D- or T-arm without losing their function. In Enoplea, this miniaturization comes to an extreme, and functional mitochondrial tRNAs can lack both arms, leading to a considerable size reduction. Here, we investigate the secondary and tertiary structure of two such armless tRNAs from Romanomermis culicivorax. Despite their high AU content, the transcripts fold into a single and surprisingly stable hairpin structure, deviating from standard tRNAs. The three-dimensional form is boomerang-like and diverges from the standard L-shape. These results indicate that such unconventional miniaturized tRNAs can still fold into a tRNA-like shape, although their length and secondary structure are very unusual. They highlight the remarkable flexibility of the protein synthesis apparatus and suggest that the translational machinery of Enoplea mitochondria may show compensatory adaptations to accommodate these armless tRNAs for efficient translation.

PMID:
29986062
PMCID:
PMC6158502
DOI:
10.1093/nar/gky593
[Indexed for MEDLINE]
Free PMC Article

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