Leszczyńska, GrażynaLeonczak, PiotrWoźniak, KarolinaMałkiewicz, Andrzej2016-02-012016-02-012014RNA, Vol. 20, nr 6, s. 938-9471355-8382ISSN (online) 1469-9001http://hdl.handle.net/11652/1031http://rnajournal.cshlp.org/content/20/6/938.full5-Taurinomethyluridine (τm5U) and 5-taurinomethyl-2-thiouridine (τm5s2U) are located at the wobble position of human mitochondrial (hmt) tRNALeu(UUR) and tRNALys, respectively. Both hypermodified units restrict decoding of the third codon letter to A and G. Pathogenic mutations in the genes encoding hmt-tRNALeu(UUR) and hmt-tRNALys are responsible for the loss of the discussed modifications and, as a consequence, for the occurrence of severe mitochondrial dysfunctions (MELAS, MERRF). Synthetic oligoribonucleotides bearing modified nucleosides are a versatile tool for studying mechanisms of genetic message translation and accompanying pathologies at nucleoside resolution. In this paper, we present site-specific chemical incorporation of τm5U and τm5s2U into 17-mers related to the sequence of the anticodon arms hmt-tRNALeu(UUR) and hmttRNALys, respectively employing phosphoramidite chemistry on CPG support. Selected protecting groups for the sulfonic acid (4-(tert-butyldiphenylsilanyloxy)-2,2-dimethylbutyl) and the exoamine function (-C(O)CF3) are compatible with the blockage of the canonical monomeric units. The synthesis of τm5s2U-modified RNA fragment was performed under conditions eliminating the formation of side products of 2-thiocarbonyl group oxidation and/or oxidative desulphurization. The structure of the final oligomers was confirmed by mass spectroscopy and enzymatic cleavage data.enhuman mitochondrial tRNAmodified ribonucleosides5-taurinomethyluridine5-taurinomethyl-2-thiouridinephosphoramidite chemistryArtykuł