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Nat Struct Mol Biol. 2017 Sep;24(9):778-782. doi: 10.1038/nsmb.3449. Epub 2017 Aug 7.

Hydroxylation of a conserved tRNA modification establishes non-universal genetic code in echinoderm mitochondria.

Author information

1
Department of Chemistry and Biotechnology, Graduate School of Engineering, University of Tokyo, Tokyo, Japan.
2
Department of Applied Life Sciences, School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Tokyo, Japan.

Abstract

The genetic code is not frozen but still evolving, which can result in the acquisition of 'dialectal' codons that deviate from the universal genetic code. RNA modifications in the anticodon region of tRNAs play a critical role in establishing such non-universal genetic codes. In echinoderm mitochondria, the AAA codon specifies asparagine instead of lysine. By analyzing mitochondrial (mt-) tRNALys isolated from the sea urchin (Mesocentrotus nudus), we discovered a novel modified nucleoside, hydroxy-N6-threonylcarbamoyladenosine (ht6A), 3' adjacent to the anticodon (position 37). Biochemical analysis revealed that ht6A37 has the ability to prevent mt-tRNALys from misreading AAA as lysine, thereby indicating that hydroxylation of N6-threonylcarbamoyladenosine (t6A) contributes to the establishment of the non-universal genetic code in echinoderm mitochondria.

PMID:
28783151
DOI:
10.1038/nsmb.3449
[Indexed for MEDLINE]

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