tRNALeu

tRNALeu, or tRNA-Leu, is a transfer RNA that carries the amino acid leucine to the ribosome during protein synthesis. In most organisms there are multiple tRNA^Leu genes encoding isoacceptor tRNAs that differ in their anticodon sequence to recognize the six leucine codons (UUA, UUG, CUU, CUC, CUA, CUG).

Like other tRNAs, tRNA^Leu is about 75–90 nucleotides long and adopts the conserved Cloverleaf secondary structure, with the 3' CCA end supplied posttranscriptionally where leucine is attached by the aminoacyl-tRNA synthetase LeuRS. Leucyl-tRNA synthetase specifically charges tRNA^Leu with leucine and contains an editing function that hydrolyzes misacylated amino acids such as isoleucine when attached to tRNA^Leu, a fidelity mechanism to prevent amino acid misincorporation.

tRNA^Leu genes are widespread across bacteria, archaea, and eukaryotes. In many species, there are several tRNA^Leu isoacceptors, and organelles such as mitochondria and chloroplasts encode their own tRNA^Leu genes in addition to nuclear copies.

tRNA^Leu is essential for translation and protein synthesis. Its study informs understanding of translation fidelity, tRNA gene evolution, and organellar gene expression. Defects in tRNA processing or in LeuRS can lead to cellular dysfunction and are topics of ongoing research.