Selective profiling of translationally active tRNAs and their dynamics under stress

Abstract

During translation, transfer RNAs (tRNAs) deliver specific amino acids to the ribosome in a coordinated manner with the sequence encoded by the mRNA. Despite their central role in protein synthesis, their precise contribution to the modulation of translation remains poorly understood, primarily due to lack of methods to characterise tRNA abundances and their modifications from actively translating ribosomes. Here we develop tRIBO-seq, a simple and robust nanopore-based method to selectively capture ribosome-associated native tRNA populations (ribo-tRNAs) from actively translating ribosomes, providing tRNA abundance, modification and fragmentation information from a single experiment. Using tRIBO-seq, we find that ribo-tRNAs, but often not total tRNAs, are significantly altered upon stress. Notably, we find that tRNAome alterations strongly vary depending on the stress type: while viral infection and leucine deprivation leads to changes in ribo-tRNA abundances, methionine starvation causes a dramatic loss of methyl-based tRNA modifications. By contrast, we find that arsenite exposure does not alter tRNA abundances nor modification patterns, but rather causes major fragmentation events in selected subsets of ribo-tRNAs. Altogether, tRIBO-seq offers a robust and reproducible approach to map the full tRNA landscape -capturing tRNA abundance, modification and fragmentation patterns-, across both total and actively translating tRNA populations, revealing the dynamics of the tRNAome with unprecedented resolution, in a single experiment.