Guo Wei, Kaczmarczyk Igor, Kopietz Kevin, Flegler Florian, Russo Stefano, Cigirgan Ege, Chramiec-Głąbik Andrzej, Koziej Łukasz, Cirzi Cansu, Peschek Jirka, Reuter Klaus, Helm Mark, Glatt Sebastian, Tuorto Francesca
Faculty of Biosciences, Heidelberg University, Heidelberg, Germany.
Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, Heidelberg, Germany.
Nat Commun. 2025 Jul 31;16(1):7044. doi: 10.1038/s41467-025-62220-z.
Each newly transcribed tRNA molecule must undergo processing and receive modifications to become functional. Queuosine (Q) is a tRNA modification present at position 34 of four tRNAs with "GUN" anticodons. Among these, the precursor of tRNA carries an intronic sequence within the anticodon loop that is removed by an essential non-canonical splicing event. The functional and temporal coupling between tRNA-splicing and Q-incorporation remains elusive. Here, we demonstrate in vitro and in vivo that intron-containing precursors of tRNA are modified with Q or with the Q-derivative galactosyl-queuosine (galQ) before being spliced. We show that this order of events is conserved in mouse, human, flies and worms. Using single particle cryo-EM, we confirm that pre-tRNA is a bona fide substrate of the QTRT1/2 complex, which catalyzes the incorporation of Q into the tRNA. Our results elucidate the hierarchical interplay that coordinates Q-incorporation and splicing in eukaryotic tRNAs, providing a relevant but unappreciated aspect of the cellular tRNA maturation process.
每个新转录的tRNA分子都必须经过加工并接受修饰才能发挥功能。 queuosine（Q）是一种存在于四种带有“GUN”反密码子的tRNA的第34位的tRNA修饰。其中，tRNA的前体在反密码子环内携带一个内含子序列，该序列通过一个必需的非经典剪接事件被去除。tRNA剪接与Q掺入之间的功能和时间耦合仍然难以捉摸。在这里，我们在体外和体内证明，含内含子的tRNA前体在剪接之前会被Q或Q衍生物半乳糖基-queuosine（galQ）修饰。我们表明，这种事件顺序在小鼠、人类、果蝇和蠕虫中是保守的。使用单颗粒冷冻电镜，我们证实前体tRNA是QTRT1/2复合物的真正底物，该复合物催化Q掺入tRNA。我们的结果阐明了协调真核生物tRNA中Q掺入和剪接的层次相互作用，揭示了细胞tRNA成熟过程中一个相关但未被重视的方面。
