tRNAs as toxin targets in phage defence and a focus of counter-defence against abortive infection

Shutoff of host translation is a common immunity strategy employed by bacteria to defend against predatory bacteriophages. Many bacterial toxin-antitoxin systems specifically target and inactivate tRNAs to achieve translational inhibition, potentially in response to phage infection. Common modes of action include modification, cleavage or re-allocation of target tRNAs. Recent studies have also identified key determinants of specificity for tRNA-targeting toxins. Herein, we discuss toxin action and specificity in the context of phage defence. As a counterpoint, we consider virally encoded tRNAs as counter-defences and drivers of phage evolution.