Société Française de Biochimie et Biologie Moléculaire


Marcel-Joseph Yared - Article of the month July

IBPC, Paris Different modification pathways for m1A58 incorporation in yeast elongator and initiator tRNAs
Nucleic Acids Research, Volume 51, Issue 19, 27 October, Pages 10653–10667.
https://doi.org/10.1093/nar/gkad722

Marcel-Joseph Yared, Yasemin Yoluç, Marjorie Catala, Carine Tisné, Stefanie Kaiser and Pierre Barraud

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Marcel-Joseph Yared studied Biochemistry and Molecular Biology at the Lebanese University (Lebanon) and at Sorbonne University (France). He is currently working in the group of Dr C. Tisné, as a PhD student (PSL University, France) under the supervision of Dr P. Barraud. His research focuses on tRNA modifications circuits in yeast and in E. coli.

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Résumé de l'article

As essential components of the protein synthesis machinery, tRNAs undergo a tightly controlled biogenesis process, which include the incorporation of numerous posttranscriptional modifications. Defects in these tRNA maturation steps may lead to the degradation of hypomodified tRNAs by the rapid tRNA decay (RTD) and nuclear surveillance pathways. We previously identified m1A58 as a late modification introduced after modifications Ψ55 and T54 in yeast elongator tRNAPhe. However, previous reports suggested that m1A58 is introduced early during the tRNA modification process, in particular on primary transcripts of initiator tRNAiMet, which prevents its degradation by RNA decay pathways. Here, aiming to reconcile this apparent inconsistency on the temporality of m1A58 incorporation, we examined its introduction into yeast elongator and initiator tRNAs. We used specifically modified tRNAs to report on the molecular aspects controlling the Ψ55 → T54 → m1A58 modification circuit in elongator tRNAs. We also show that m1A58 is efficiently introduced on unmodified tRNAiMet, and does not depend on prior modifications. Finally, we show that m1A58 has major effects on the structural properties of initiator tRNAiMet, so that the tRNA elbow structure is only properly assembled when this modification is present. This observation provides a structural explanation for the degradation of hypomodified tRNAiMet lacking m1A58 by the nuclear surveillance and RTD pathways.