Structural elements defining elongation factor Tu mediated suppression of codon ambiguity.
Nucleic Acids Res
; 35(10): 3420-30, 2007.
Article
en En
| MEDLINE
| ID: mdl-17478519
ABSTRACT
In most prokaryotes Asn-tRNA(Asn) and Gln-tRNA(Gln) are formed by amidation of aspartate and glutamate mischarged onto tRNA(Asn) and tRNA(Gln), respectively. Coexistence in the organism of mischarged Asp-tRNA(Asn) and Glu-tRNA(Gln) and the homologous Asn-tRNA(Asn) and Gln-tRNA(Gln) does not, however, lead to erroneous incorporation of Asp and Glu into proteins, since EF-Tu discriminates the misacylated tRNAs from the correctly charged ones. This property contrasts with the canonical function of EF-Tu, which is to non-specifically bind the homologous aa-tRNAs, as well as heterologous species formed in vitro by aminoacylation of non-cognate tRNAs. In Thermus thermophilus that forms the Asp-tRNA(Asn) intermediate by the indirect pathway of tRNA asparaginylation, EF-Tu must discriminate the mischarged aminoacyl-tRNAs (aa-tRNA). We show that two base pairs in the tRNA T-arm and a single residue in the amino acid binding pocket of EF-Tu promote discrimination of Asp-tRNA(Asn) from Asn-tRNA(Asn) and Asp-tRNA(Asp) by the protein. Our analysis suggests that these structural elements might also contribute to rejection of other mischarged aa-tRNAs formed in vivo that are not involved in peptide elongation. Additionally, these structural features might be involved in maintaining a delicate balance of weak and strong binding affinities between EF-Tu and the amino acid and tRNA moieties of other elongator aa-tRNAs.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Codón
/
ARN de Transferencia de Asparagina
/
Aminoacil-ARN de Transferencia
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Factor Tu de Elongación Peptídica
/
Aminoacilación de ARN de Transferencia
Tipo de estudio:
Prognostic_studies
Idioma:
En
Revista:
Nucleic Acids Res
Año:
2007
Tipo del documento:
Article
País de afiliación:
Francia