Arjun Prabhakar, Natalie Krahn, Jingji Zhang, Oscar Vargas-Rodriguez, Miri Krupkin, Ziao Fu, Francisco J Acosta-Reyes, Xueliang Ge, Junhong Choi, Ana Crnković, Måns Ehrenberg, Elisabetta Viani Puglisi, Dieter Söll, Joseph Puglisi
Nucleic Acids Research, gkac576, https://doi.org/10.1093/nar/gkac576
Continued expansion of the genetic code has required the use of synthetic tRNAs for decoding. Some of these synthetic tRNAs have unique structural features that are not observed in canonical tRNAs. Here, the authors applied single-molecule, biochemical and structural methods to determine whether these distinct features were deleterious for efficient protein translation on the ribosome. With a focus on selenocysteine insertion, the authors explored an allo-tRNA with a 9/3 acceptor domain. They observed a translational roadblock that occurred in A- to P-site tRNA translocation. This block was mediated by a tertiary interaction across the tRNA core, directing the variable arm position into an unfavorable conformation. A single-nucleotide mutation disrupted this interaction, providing flexibility in the variable arm and promoting efficient protein production.