Aminoacyl-tRNA synthesis by pre-translational amino acid modification.

Liang Feng, Kelly Sheppard, Suk Namgoong, Alexandre Ambrogelly, Carla Polycarpo, Lennart Randau, Debra Tumbula-Hansen, Dieter Söll

Research output: Contribution to journalReview articlepeer-review

23 Scopus citations


Aminoacyl-tRNAs (aa-tRNAs) are essential substrates for ribosomal translation, and are generally synthesized by aminoacyl-tRNA synthetases (aaRSs). It was expected earlier that every organism would contain a complete set of twenty aaRSs, one for each canonical amino acid. However, analysis of the many known genome sequences and biochemical studies revealed that most organisms lack asparaginyl- and glutaminyl-tRNA synthetases, and thus are unable to attach asparagine and glutamine directly onto their corresponding tRNA. Instead, a pretranslational amino acid modification is required to convert Asp-tRNA(Asn) and Glu-tRNA(Gln) to the correctly charged Asn-tRNA(Asn) and Gln-tRNA(Gln), respectively. This transamidation pathway of amide aa-tRNA synthesis is common in most bacteria and archaea. Unexpected results from biochemical, genetic and genomic studies showed that a large variety of different bacteria rely on tRNA-dependent transamidation for the formation of the amino acid asparagine. Pretranslational modifications are not restricted to asparagine and glutamine but are also found in the biosynthesis of some other aa-tRNAs, such as the initiator tRNA fmet-tRNA(Met)(i) and Sec-tRNA(Sec) specifying selenocysteine, the 21(st) cotranslationally inserted amino acid. tRNA-dependent amino acid modification is also involved in the generation of aminolevulinic acid, the first precursor for porphyrin biosynthesis in many organisms.

Original languageEnglish (US)
Pages (from-to)15-19
Number of pages5
JournalRNA Biology
Issue number1
StatePublished - May 2004
Externally publishedYes

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology


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