Crystal structure of a transfer-ribonucleoprotein particle that promotes asparagine formation

EMBO J. 2010 Sep 15;29(18):3118-29. doi: 10.1038/emboj.2010.192. Epub 2010 Aug 17.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Asparagine / biosynthesis*
  • Crystallization
  • Nitrogenous Group Transferases / metabolism
  • Protein Conformation
  • RNA, Transfer, Asn / metabolism*
  • Ribonucleoproteins / chemistry*
  • Ribonucleoproteins / isolation & purification
  • Ribonucleoproteins / metabolism
  • Thermus thermophilus / metabolism
  • Transfer RNA Aminoacylation


  • RNA, Transfer, Asn
  • Ribonucleoproteins
  • Asparagine
  • Asp-tRNA(Asn) amidotransferase
  • Nitrogenous Group Transferases

Associated data

  • PDB/3KFU