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Publication Abstract from PubMed

Four out of the 22 aminoacyl-tRNAs (aa-tRNAs) are systematically or alternatively synthesized by an indirect, two-step route requiring an initial mischarging of the tRNA followed by tRNA-dependent conversion of the non-cognate amino acid. During tRNA-dependent asparagine formation, tRNA(Asn) promotes assembly of a ribonucleoprotein particle called transamidosome that allows channelling of the aa-tRNA from non-discriminating aspartyl-tRNA synthetase active site to the GatCAB amidotransferase site. The crystal structure of the Thermus thermophilus transamidosome determined at 3 A resolution reveals a particle formed by two GatCABs, two dimeric ND-AspRSs and four tRNAs(Asn) molecules. In the complex, only two tRNAs are bound in a functional state, whereas the two other ones act as an RNA scaffold enabling release of the asparaginyl-tRNA(Asn) without dissociation of the complex. We propose that the crystal structure represents a transient state of the transamidation reaction. The transamidosome constitutes a transfer-ribonucleoprotein particle in which tRNAs serve the function of both substrate and structural foundation for a large molecular machine.

Crystal structure of a transfer-ribonucleoprotein particle that promotes asparagine formation.,Blaise M, Bailly M, Frechin M, Behrens MA, Fischer F, Oliveira CL, Becker HD, Pedersen JS, Thirup S, Kern D EMBO J. 2010 Sep 15;29(18):3118-29. Epub 2010 Aug 17. PMID:20717102^[1]

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