tRNA genes rapidly change in evolution to meet novel translational demands

Abstract

Changes in expression patterns may occur when organisms are presented with new environmental challenges, for example following migration or genetic changes. To elucidate the mechanisms by which the translational machinery adapts to such changes, we perturbed the tRNA pool of Saccharomyces cerevisiae by tRNA gene deletion. We then evolved the deletion strain and observed that the genetic adaptation was recurrently based on a strategic mutation that changed the anticodon of other tRNA genes to match that of the deleted one. Strikingly, a systematic search in hundreds of genomes revealed that anticodon mutations occur throughout the tree of life. We further show that the evolution of the tRNA pool also depends on the need to properly couple translation to protein folding. Together, our observations shed light on the evolution of the tRNA pool, demonstrating that mutation in the anticodons of tRNA genes is a common adaptive mechanism when meeting new translational demands.DOI: http://dx.doi.org/10.7554/eLife.01339.001

High-resolution mapping of transcriptional dynamics across tissue development reveals a stable mRNA–tRNA interface

“…Further, the expression of the anticodon isoacceptor families, relative to each other, was stable across mammalian development. In yeast, tRNA genes can compensate for changing levels of expression of another member of their isoacceptor family, an effect demonstrated by systematic deletion of tRNA genes (Yona et al 2013;Bloom-Ackermann et al 2014). Our data are a first direct indication that a compensatory mechanism must also operate dynamically in mammals to stabilize the collective expression of a given isoacceptor family.…”

Large gene overlaps and tRNA processing in the compact mitochondrial genome of the crustaceanArmadillidium vulgare

“…Such constraint is more likely to be too stringent for protein-coding genes overlaps. In contrast, tRNA gene sequences evolve rapidly and recent evidence showed that a simple secondary structure coupled with a specific anticodon may be sufficient to generate a functional tRNA, 47,48 or that incomplete cloverleaf structure may be repaired post-transcriptionally (e.g., tRNA His in this study).…”

Evolution of initiator tRNAs and selection of methionine as the initiating amino acid

“…Evolutionary importance of changes in the tRNA gene and energy efficiency with bacterial growth has already been well characterized. 20,54,55 The occurrence of Met in proteins is very infrequent (Fig. 6a), its internal occurrence would mean a higher metabolic cost.…”