TRNAIle-lysidine synthase (EC 6.3.4.19, TilS, mesJ (gene), yacA (gene), isoleucine-specific transfer ribonucleate lysidine synthetase, tRNAIle-lysidine synthetase) is an enzyme with systematic name L-lysine:(tRNAIle2)-cytidine34 ligase (AMP-forming). This enzyme catalyses the following chemical reaction[tRNAIle2]-cytidine34 + L-lysine + ATP [tRNAIle2]-lysidine34 + AMP + diphosphate + H2O