PMID:14596614
| Citation |
Nordin, BE and Schimmel, P (2003) Transiently misacylated tRNA is a primer for editing of misactivated adenylates by class I aminoacyl-tRNA synthetases. Biochemistry 42:12989-97 |
|---|---|
| Abstract |
The genetic code depends on amino acid fine structure discrimination by aminoacyl-tRNA synthetases. For isoleucyl- (IleRS) and valyl-tRNA synthetases (ValRS), reactions that hydrolyze misactivated noncognate amino acids help to achieve high accuracy in aminoacylation. Two editing pathways contribute to aminoacylation fidelity: pretransfer and post-transfer. In pretransfer editing, the misactivated amino acid is hydrolyzed as an aminoacyl adenylate, while in post-transfer editing a misacylated tRNA is deacylated. Both reactions are dependent on a tRNA cofactor and require translocation to a site located approximately 30 A from the site of amino acid activation. Using a series of 3'-end modified tRNAs that are deficient in either aminoacylation, deacylation, or both, total editing (the sum of pre- and post-transfer editing) was shown to require both aminoacylation and deacylation activities. These and additional results with IleRS are consistent with a post-transfer deacylation event initiating formation of an editing-active enzyme/tRNA complex. In this state, the primed complex processively edits misactivated valyl-adenylate via the pretransfer route. Thus, misacylated tRNA is an obligatory intermediate for editing by either pathway. |
| Links |
PubMed Online version:10.1021/bi035052q |
| Keywords |
3' Flanking Region; Acylation; Adenine Nucleotides/chemistry; Adenosine Triphosphatases/chemistry; Escherichia coli Proteins/chemistry; Hydrolysis; Isoleucine-tRNA Ligase/chemistry; RNA Editing; RNA, Bacterial/chemistry; RNA, Transfer, Amino Acyl/chemistry; Substrate Specificity; Valine-tRNA Ligase/chemistry |
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