tRNA modifications as regulators of bacterial virulence and stress responses

Bacteria are recognized for their ability to adapt their lifestyle to the environment. Specifically, when considering pathogenic bacteria, their capacity to respond to stress and switch to a virulent state through gene regulation is crucial. One of the mechanisms that enables regulation of gene expression at the translational level is RNA modification. These chemical changes produced by specific enzymes are present on all types of RNAs and can modulate translational efficiency by influencing the structure of RNA molecules, the codon usage bias, the interaction with other molecules, or the efficiency of ribosome action. Transfer RNA (tRNA) is the most modified RNA in the cell, with modifications in the core body of the tRNA primarily affecting the stability and flexibility of the structure while modifications in the anticodon stem-loop (ASL) are more involved in decoding, as well as the efficiency and fidelity of translation. Given the impacts of these modifications on the translation process and the critical role of modulating translation fidelity during bacterial stress responses and host interactions, tRNA modifications play an important role in regulating the expression of virulence factors in bacterial pathogens, resulting in changes in various phenotypes. This review aims to establish a comprehensive landscape of tRNA modifications and their direct impact on the translation process, emphasizing their significant role in bacterial virulence and stress responses.