Plants, as sessile organisms, have evolved intricate mechanisms to adapt
to various environmental changes and challenges. Considering that various types of stress trigger significant decrease in global translation rates we examined stress-related expression of aminoacyl-tRNA synthetases (aaRSs), enzymes that participate in the first step of protein translation. We have analyzed promoters of genes encoding cytosolic seryl-tRNA synthetase (SerRS), cytosolic aspartyl-tRNA synthetase (AspRS) and cytosolic cysteinyl-tRNA synthetase
(CysRS) in Arabidopsis thaliana L., and examined SerRS, AspRS and CysRS
gene expression in the seedlings exposed to different abiotic stressors. Although global translation levels are repressed by stress, our results show that plant aaRSs expression is not decreased by osmotic, salt and heavy metal/cadmium stress. Moreover, during exposure to stress conditions we detected increased AspRS and CysRS transcript levels. SerRS gene expression did not change, however participation of SerRS in stress response could be regulated at the protein level. Expression of the examined aaRS genes in stress correlated well with the
length of their predicted promoters and a number of available binding sites for the stress related transcription factors. It thus appears that
during the stress it is important to keep steady state levels of aaRSs for translation of specific stress related mRNAs and furthermore to rapidly continue with translation when stress conditions cease. Importantly, increased levels of plant aaRSs during stress may serve as a
pool of aaRS proteins that can participate directly in stress responses
through their noncanonical activities.
The Role of Orthogonality in Genetic Code Expansion