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Mol Cell. 2007 Oct 26;28(2):228-39.

The transamidosome: a dynamic ribonucleoprotein particle dedicated to prokaryotic tRNA-dependent asparagine biosynthesis.

Author information

1
UPR Architecture et Réactivité de l'ARN, Université Louis Pasteur de Strasbourg, CNRS, Institut de Biologie Moléculaire et Cellulaire, 15, Rue René Descartes, F-67084 Strasbourg Cédex, France.

Abstract

Asparagine, one of the 22 genetically encoded amino acids, can be synthesized by a tRNA-dependent mechanism. So far, this type of pathway was believed to proceed via two independent steps. A nondiscriminating aspartyl-tRNA synthetase (ND-DRS) first generates a mischarged aspartyl-tRNAAsn that dissociates from the enzyme and binds to a tRNA-dependent amidotransferase (AdT), which then converts the tRNA-bound aspartate into asparagine. We show herein that the ND-DRS, tRNAAsn, and AdT assemble into a specific ribonucleoprotein complex called transamidosome that remains stable during the overall catalytic process. Our results indicate that the tRNAAsn-mediated linkage between the ND-DRS and AdT enables channeling of the mischarged aspartyl-tRNAAsn intermediate between DRS and AdT active sites to prevent challenging of the genetic code integrity. We propose that formation of a ribonucleoprotein is a general feature for tRNA-dependent amino acid biosynthetic pathways that are remnants of earlier stages when amino acid synthesis and tRNA aminoacylation were coupled.

PMID:
17964262
DOI:
10.1016/j.molcel.2007.08.017
[Indexed for MEDLINE]
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