Document Detail

Aminoacyl-tRNA synthesis by pre-translational amino acid modification.
MedLine Citation:
PMID:  17194933     Owner:  NLM     Status:  MEDLINE    
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.
Liang Feng; Kelly Sheppard; Suk Namgoong; Alexandre Ambrogelly; Carla Polycarpo; Lennart Randau; Debra Tumbula-Hansen; Dieter Söll
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, U.S. Gov't, Non-P.H.S.; Review     Date:  2004-05-28
Journal Detail:
Title:  RNA biology     Volume:  1     ISSN:  1555-8584     ISO Abbreviation:  RNA Biol     Publication Date:  2004 May 
Date Detail:
Created Date:  2006-12-29     Completed Date:  2007-02-12     Revised Date:  2010-01-15    
Medline Journal Info:
Nlm Unique ID:  101235328     Medline TA:  RNA Biol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  16-20     Citation Subset:  IM    
Department of Molecular Biophysics, Yale University, New Haven, Connecticut 06520-8114, USA.
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MeSH Terms
Amino Acids / chemistry
Amino Acyl-tRNA Synthetases / chemistry,  physiology*
Archaea / metabolism
Asparagine / chemistry
Bacillus subtilis / metabolism
Chlorophyll / chemistry
Escherichia coli / metabolism
Glutamine / chemistry
Heme / chemistry
Models, Biological
Porphyrins / chemistry
Protein Modification, Translational*
RNA, Transfer, Amino Acyl*
Species Specificity
Reg. No./Substance:
0/Amino Acids; 0/Porphyrins; 0/RNA, Transfer, Amino Acyl; 1406-65-1/Chlorophyll; 14875-96-8/Heme; 56-85-9/Glutamine; 7006-34-0/Asparagine; EC 6.1.1.-/Amino Acyl-tRNA Synthetases

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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