lysylAMP

LysylAMP, also known as lysyl-adenylate, is a transient reaction intermediate formed during the enzymatic charging of transfer RNA with lysine by the enzyme lysyl-tRNA synthetase (LysRS). In the first step of the LysRS-catalyzed reaction, lysine and ATP react to form lysyl-AMP and pyrophosphate. The lysyl-AMP intermediate is typically bound within the enzyme’s active site, where the lysine moiety is activated as an acyl-adenylate.

In the second step, the activated lysine is transferred from the lysyl-AMP to the 3′-terminal adenosine of tRNA^Lys, yielding lysyl-tRNA^Lys and releasing AMP. The formation and turnover of lysyl-AMP are tightly coordinated with tRNA binding, ensuring that aminoacylation occurs specifically on the correct tRNA.

LysylAMP is a representative member of the acyl-adenylate intermediates used by aminoacyl-tRNA synthetases, a broad family of enzymes that couple amino acids to their cognate tRNAs. The intermediate is typically short-lived and may be stabilized in crystal structures or captured in kinetic experiments under pre-steady-state conditions. Its existence highlights the two-substep mechanism common to many aminoacylation reactions and underpins the fidelity of protein translation.