Substrate selection mechanism and function of human cytoplasmic tRNA t6A modification

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Among all RNA molecules in cells, tRNA contains the most dense and diverse post-transcriptional modifications
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Up to now, about 120 post-transcriptional modifications of tRNA have been found

In this study, the researchers purified 14 cytoplasmic tRNAs that decoded ANN codons from human cells, and UPLC-MS/MS identified that these 14 tRNAs contained ^t6A modification ; The determination of t ⁶ A modification activity of ^the KEOPS complexes ^{of the} Cellular eukaryotes (human and nematode, etc.

) t ⁶ A modification machinery uses C33 as a reverse recognition element, and then evolves tRNA Meti containing C33 in multicellular eukaryotes ; the system reveals that human KEOPS accurately recognizes tRNA ^substrates tRNA elements are required for specific tRNA elements, including C32 and two conserved base pairs in the D stem, but the function of the universal CCA terminus in t6A modification is species ^- specific and diverse; elucidates the major localization of human KEOPS In the cytoplasm, t ⁶ A modification can only be mediated on mature tRNAs without introns ; a knockdown cell line of the catalytic subunit OSGEP was further constructed and found that t ⁶ AThe modification defect does not affect the steady-state levels of all tRNAs, nor does it affect the aminoacylation levels of the vast majority of tRNAs, but both in vivo and in vitro experiments demonstrate that the t6A modification is recognized by cytoplasmic isoleucyl ^- tRNA synthetase (hIleRS ) A key recognition element of tRNA ^Ile ; by constructing a fluorescent reporter system for mRNA translation, it was demonstrated that the t6A modification is important for precise codon-anticodon pairing, preventing +1 frameshift ^mutations .

This study clarified that all human ANN-decoding tRNAs have t ⁶ A modification, found the co-evolution of t ⁶ A modification machinery and tRNA ^Met i, elucidated for the first time the molecular mechanism of eukaryotic KEOPS recognizing tRNA substrates, and revealed that t ⁶ A modification is a hIleRS recognizes key recognition elements of tRNA ^Ile and further elucidates the critical role of t ⁶ A modification in mRNA translation
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These findings provide a theoretical basis for understanding the molecular mechanism of human cytoplasmic tRNAt ⁶ A modification, and revealing the mechanism of modification enzymes and tRNA mutation-related human diseases

Wang Jintao and Zhou Jingbo, Ph.

D.

Article link: https://academic.

Co-evolution of the eukaryotic KEOPS complex and the initiating tRNA ^{Met and its cellular function}