Alanyl tRNA Synthetase (AARS)

The AARS gene encodes alanyl-tRNA synthetase. Each of the amino acid synthetases catalyzes the attachment of their respective amino acids to the appropriate tRNA. The class II Escherichia coli and human alanyl-tRNA synthetases cross-acylate their respective tRNAs and require, for aminoacylation, an acceptor helix G3:U70 basepair that is conserved in evolution. The N-terminal 498 amino acids of the 968-residue polypeptide showed 41% identity with the E. coli protein. The human protein contains the class-defining domain of the E. coli enzyme, which includes the part needed for recognition of the acceptor helix G3:U70 basepair as an RNA signal for alanine. The authors concluded that mutagenesis, modeling, domain organization, and biochemical characterization of the E. coli protein are valid as a template for the human protein.