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Hati, S, Ziervogel, B, Sternjohn, J, Wong, FC, Nagan, MC, Rosen, AE, Siliciano, PG, Chihade, JW and Musier-Forsyth, K (2006) Pre-transfer editing by class II prolyl-tRNA synthetase: role of aminoacylation active site in "selective release" of noncognate amino acids. J. Biol. Chem. 281:27862-72


Aminoacyl-tRNA synthetases catalyze the attachment of cognate amino acids to specific tRNA molecules. To prevent potential errors in protein synthesis caused by misactivation of noncognate amino acids, some synthetases have evolved editing mechanisms to hydrolyze misactivated amino acids (pre-transfer editing) or misacylated tRNAs (post-transfer editing). In the case of post-transfer editing, synthetases employ a separate editing domain that is distinct from the site of amino acid activation, and the mechanism is believed to involve shuttling of the flexible CCA-3' end of the tRNA from the synthetic active site to the site of hydrolysis. The mechanism of pre-transfer editing is less well understood, and in most cases, the exact site of pre-transfer editing has not been conclusively identified. Here, we probe the pre-transfer editing activity of class II prolyl-tRNA synthetases from five species representing all three kingdoms of life. To locate the site of pre-transfer editing, truncation mutants were constructed by deleting the insertion domain characteristic of bacterial prolyl-tRNA synthetase species, which is the site of post-transfer editing, or the N- or C-terminal extension domains of eukaryotic and archaeal enzymes. In addition, the pre-transfer editing mechanism of Escherichia coli prolyl-tRNA synthetase was probed in detail. These studies show that a separate editing domain is not required for pre-transfer editing by prolyl-tRNA synthetase. The aminoacylation active site plays a significant role in preserving the fidelity of translation by acting as a filter that selectively releases non-cognate adenylates into solution, while protecting the cognate adenylate from hydrolysis.


PubMed Online version:10.1074/jbc.M605856200


Adenosine Monophosphate/metabolism; Adenosine Triphosphate/metabolism; Amino Acids/metabolism; Amino Acyl-tRNA Synthetases/chemistry; Amino Acyl-tRNA Synthetases/physiology; Binding Sites; Hydrolysis; Protein Structure, Tertiary; RNA Editing; Transfer RNA Aminoacylation



Gene product Qualifier GO Term Evidence Code with/from Aspect Extension Notes Status



GO:0006433: prolyl-tRNA aminoacylation

ECO:0000314: direct assay evidence used in manual assertion


Seeded From UniProt




GO:0004827: proline-tRNA ligase activity

ECO:0000314: direct assay evidence used in manual assertion


Seeded From UniProt


See also


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