Section 44
Chapter 43,936

Phenylalanyl-tRNA synthetase and isoleucyl-tRNA Phe : a possible verification mechanism for aminoacyl-tRNA

Yarus, M.

Proceedings of the National Academy of Sciences of the United States of America 69(7): 1915-1919


ISSN/ISBN: 0027-8424
PMID: 4558664
DOI: 10.1073/pnas.69.7.1915
Accession: 043935021

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The synthesis of isoleucyl-tRNA(Phe) (Escherichia coli) proceeds at an appreciable rate under normal in vitro conditions in the presence of isoleucyl-tRNA synthetase (EC from E. coli. The misacylated product is shown here to be hydrolyzed by highly purified phenylalanyl-tRNA synthetase from E. coli, with release of isoleucine and active tRNA(Phe). Thus, phenylalanyl-tRNA synthetase possesses a previously unrecognized activity, which deacylates a mistakenly acylated tRNA(Phe); the enzyme is inactive toward correctly matched aminoacyl tRNAs. Such a mechanism could serve to verify aminoacyl-tRNAs, deacylating those that are misacylated. Thus, a common generalization needs to be modified: an amino acid is not necessarily committed to a given (incorrect) anticodon when it is incorporated into aminoacyl-tRNA. It may be possible to correct it thereafter.

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