Čapková Pavlíková Zuzana, Miletínová Petra, Roithová Adriana, Pospíšilová Klára, Záhonová Kristína, Kachale Ambar, Becker Thomas, Durante Ignacio M, Lukeš Julius, Paris Zdeněk, Beznosková Petra, Valášek Leoš Shivaya
Laboratory of Regulation of Gene Expression, Institute of Microbiology, Czech Academy of Sciences, Prague, Czech Republic.
Faculty of Science, Charles University, Prague, Czech Republic.
Nat Struct Mol Biol. 2025 Apr;32(4):662-674. doi: 10.1038/s41594-024-01450-z. Epub 2025 Jan 13.
Transfer RNAs (tRNAs) serve as a dictionary for the ribosome translating the genetic message from mRNA into a polypeptide chain. In addition to this canonical role, tRNAs are involved in other processes such as programmed stop codon readthrough (SC-RT). There, tRNAs with near-cognate anticodons to stop codons must outcompete release factors and incorporate into the ribosomal decoding center to prevent termination and allow translation to continue. However, not all near-cognate tRNAs promote efficient SC-RT. Here, with the help of Saccharomyces cerevisiae and Trypanosoma brucei, we demonstrate that those tRNAs that promote efficient SC-RT establish critical contacts between their anticodon stem (AS) and ribosomal proteins Rps30/eS30 and Rps25/eS25 forming the decoding site. Unexpectedly, the length and well-defined nature of the AS determine the strength of these contacts, which is reflected in organisms with reassigned stop codons. These findings open an unexplored direction in tRNA biology that should facilitate the design of artificial tRNAs with specifically altered decoding abilities.
转运RNA（tRNA）充当核糖体的“字典”，将遗传信息从信使RNA（mRNA）翻译成多肽链。除了这一经典作用外，tRNA还参与其他过程，如程序性终止密码子通读（SC-RT）。在该过程中，与终止密码子具有近同源反密码子的tRNA必须胜过释放因子，并进入核糖体解码中心以防止终止并使翻译继续进行。然而，并非所有近同源tRNA都能促进高效的SC-RT。在此，借助酿酒酵母和布氏锥虫，我们证明那些促进高效SC-RT的tRNA在其反密码子茎（AS）与构成解码位点的核糖体蛋白Rps30/eS30和Rps25/eS25之间建立了关键接触。出乎意料的是，AS的长度和明确性质决定了这些接触的强度，这在重新分配了终止密码子的生物体中得到体现。这些发现为tRNA生物学开辟了一个未被探索的方向，应该有助于设计具有特定改变解码能力的人工tRNA。
