Identification of RNA helicases with unwinding activity on angiogenin-processed tRNAs

Stress-induced tRNA fragmentation upon environmental insult is a conserved cellular process catalysed by endonucleolytic activities targeting mature tRNAs. The resulting tRNA-derived small RNAs (tsRNAs) have been implicated in various biological processes that impact cell-to-cell signalling, cell survival as well as gene expression regulation during embryonic development. However, how endonuclease-targeted tRNAs give rise to individual and potentially biologically active tsRNAs remains poorly understood. Here, we report on the in vivo identification of proteins associated with stress-induced tsRNAs-containing protein complexes, which, together with a 'tracer tRNA' assay, were used to uncover enzymatic activities that can bind and process specific endonuclease-targeted tRNAs in vitro. Among those, we identified conserved ATP-dependent RNA helicases which can robustly separate tRNAs with endonuclease-mediated 'nicks' in their anticodon loops. These findings shed light on the existence of cellular pathways dedicated to producing individual tsRNAs after stress-induced tRNA hydrolysis, which adds to our understanding as to how tRNA fragmentation and the resulting tsRNAs might exert physiological impact.

Automated summary

Stress-induced tRNA fragmentation, catalyzed by endonucleolytic activities, produces tRNA-derived small RNAs (tsRNAs) that play important roles in cell signaling, survival, and gene expression regulation. However, the process by which specific endonuclease-targeted tRNAs are processed into individual and potentially biologically active tsRNAs remains poorly understood. In this study, we identified proteins associated with stress-induced tsRNAs and discovered ATP-dependent RNA helicases that can separate tRNAs with endonuclease-mediated nicks. These findings provide insights into the cellular pathways involved in producing individual tsRNAs and their physiological impact.