Trypanosomes regulate their gene expression mostly at the post-transcriptional level as they barely regulate transcription of their genes. Fragments derived from tRNAs are more and more recognized as regulators of cellular processes. The Polacek and Schneider labs now found that tRNAThr-3'-half fragments are generated upon nutritional stress in mitochondria and accumulate there. Upon release of the nutritional stress, the tRNAThr-3'-half fragments bind to mitochondrial ribosomes and boost their translational activity leading to increased activity of the mitochondrium and thereby giving the cell increased energy production capability. Their results haven been published in the article "A ribosome-bound tRNA half stimulates mitochondrial translation during stress recovery in Trypanosoma brucei" in the journal Cell Reports.
Highlights
- tRNA-derived RNAs accumulate in the mitochondria of T. brucei exposed to nutritional stress
- Most tRNA-derived RNAs detected during exponential growth are found in the cytosol
- The enzymatic activity generating tDRs is detected in mitochondria
- tRNAThr-3'-half binds to mitochondrial ribosomes promoting translation and stress survival
Summary
The protozoan parasite Trypanosoma brucei and its disease-causing relatives are among the few organisms that barely regulate the transcription of protein-coding genes. Yet, alterations in its gene expression are essential to survive in different host environments. Recently, tRNA-derived RNAs have been implicated as regulators of many cellular processes within and beyond translation. Previously, we identified the tRNAThr-3'-half (AGU) as a ribosome-associated non-coding RNA able to enhance global translation. Here we report that the tRNAThr-3'-half is generated upon starvation inside the mitochondria. The tRNAThr-3'-half associates with mitochondrial ribosomes and stimulates translation during stress recovery, positively affecting mitochondrial activity and, consequently, cellular energy production capacity. Our results describe an organelle ribosome-associated ncRNA involved in translation regulation to boost the central hub of energy metabolism as an immediate stress recovery response.
Read the Article in Cell Reports (Open Access)
Figure, highlights, summary and title from Brogli et al (2023) Cell Reports published under a CC BY-NC-ND 4.0 license.