aminoacyltRNALys

Aminoacyl-tRNALys, also written as Lys-tRNA^Lys, is the charged form of tRNA^Lys in which the amino acid lysine is covalently attached to the 3' end of the tRNA by the enzyme lysyl-tRNA synthetase (LysRS). The charging reaction occurs in two steps: first lysine is activated with ATP to form lysyl-AMP, and then lysine is transferred to the 3' CCA terminus of tRNA^Lys, yielding Lys-tRNA^Lys and releasing AMP.

This aminoacyl-tRNA species serves as the substrate for protein synthesis during translation. Lys-tRNA^Lys recognizes the lysine codons AAA and AAG on the mRNA, delivering lysine to the growing polypeptide chain. In bacteria and eukaryotes, the charged tRNA is delivered to the ribosome by the elongation factor EF-Tu (in bacteria) or eEF1A (in eukaryotes) in a GTP-dependent manner, and is released upon correct codon-anticodon pairing.

Genes encoding lysyl-tRNA synthetase and the tRNA^Lys isoacceptors exhibit species-specific variation. Many organisms possess two lysine codons, AAA and AAG, each recognized by a distinct isoacceptor of tRNA^Lys with anticodons UUU (for AAA) and CUU (for AAG). The fidelity of aminoacylation and subsequent decoding is maintained by the interplay between LysRS specificity, tRNA identity elements, and cellular proofreading mechanisms.

Aminoacyl-tRNALys is essential for accurate lysine incorporation into proteins and for maintaining translational efficiency and fidelity across all domains of life.