Cysteine–tRNA ligase

In enzymology, a cysteine–tRNA ligase (EC 6.1.1.16) is an enzyme that catalyzes the chemical reaction:

ATP + L-cysteine + tRNA^Cys ${\displaystyle \rightleftharpoons }$ AMP + diphosphate + L-cysteinyl-tRNA^Cys

The three substrates of this enzyme are ATP, L-cysteine, and tRNA^Cys, whereas its three products are AMP, diphosphate, and L-cysteinyl-tRNA^Cys.

There are two isozymes in humans, encoded by the genes CARS1 (cytoplasmic) and CARS2 (mitochondrial). This enzyme belongs to the family of ligases, specifically those forming carbon–oxygen bonds in aminoacyl-tRNA and related compounds. The systematic name of this enzyme class is L-cysteine:tRNA^Cys ligase (AMP-forming). Other names in common use include cysteinyl-tRNA synthetase, cysteinyl-transferRNA synthetase, cysteinyl-transfer ribonucleate synthetase, and cysteine translase. This enzyme participates in cysteine metabolism and aminoacyl-tRNA biosynthesis.

Structural studies

As of late 2007, three structures have been solved for this class of enzymes, with PDB accession codes PDB: 1LI5​, PDB: 1LI7​, and PDB: 1U0B​.

References

• Mccorquodale DJ (December 1964). "The separation and partial purification of aminoacyl-RNA synthetases from Escherichia coli". Biochimica et Biophysica Acta (BBA) - Specialized Section on Nucleic Acids and Related Subjects. 91 (4). Elsevier: 541–8. doi:10.1016/0926-6550(64)90001-5. ISSN 0926-6550. PMID 14262440.