Aminoacyl-tRNA synthetase(AARS), also known as tRNA ligases, are a family of enzymes that are responsible for adding amino acids to their cognate tRNA molecules. There are 21 AARS in the human body, one enzyme for each amino acid, with the exception of lysine, for which there are two AARS. In addition to these 21 AARS for protein amino acids, there are also AARS for non-protein amino acids, such as pyrrole lysyl tRNA synthetase and phosphoserine tRNA synthetase. Each tRNA has a specific AARS to activate it. When tRNA is aminoacylated, the ribosome can transfer amino acids from the tRNA to the peptide being synthesized according to the genetic code. Thus, the process of aminoacyl tRNA plays an important role in RNA translation and gene expression of proteins.
Figure 1. The aaRS·tRNA complex (PDB:1f7u) and the architecture of its active site.(K, Florian.;et al. 2020)
The process of AARS aminoacylation occurs in two steps:
Figure 2. Amino acid activation by aminoacyl tRNA synthetase and attachment to tRNA.
Aminoacyl-tRNA synthetases are highly accurate, and some synthetases also mediate editing reactions to hydrolyze away incorrect tRNA additions to ensure high fidelity and specificity of the tRNA aminoacyl process.
AARS enzymes are divided into two main classes, including class I and class II.
Class I AARS has two highly conserved sequence motifs, HIGH and KMSKS, which are aminoacylated at the 2'-OH of the terminal adenosine nucleotide of the tRNA. Class I enzymes are generally monomeric or dimeric.
Class II AARS has multiple highly conserved sequence motifs that are amidated at the 3'-OH of the terminal adenosine of the tRNA. Class II enzymes are usually dimers or tetramers.
Aminoacyl tRNA synthetases play important roles in RNA translation, gene expression, cellular metabolism, signaling, and disease mechanisms. BOC Sciences offers a wide range of aminoacyl tRNA synthetases with different structures and functions to aid you in your research on potential drug targets for the treatment of various diseases.
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AARS enzymes are divided into Class I and Class II based on structural features and catalytic mechanisms, with Class I charging at the 2'-OH position and Class II at the 3'-OH position of tRNA adenosine.
AARS enzymes employ precise substrate recognition, editing mechanisms to hydrolyze mischarged tRNAs, and proofreading functions to maintain high fidelity in protein synthesis.
We utilize structural biology methods, enzymatic activity assays, binding studies, and computational modeling to analyze AARS specificity and catalytic mechanisms.
Yes, certain AARS enzymes can charge tRNAs with non-proteinogenic amino acids, expanding the genetic code for research applications in synthetic biology and protein engineering.
Specificity is determined by tRNA identity elements, amino acid recognition sites, editing domains, and structural features that distinguish between similar amino acids and tRNA isoforms.
We characterize AARS through kinetic analysis, substrate specificity profiling, structural determination, and functional validation in translation systems.
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