2ake: Difference between revisions

[[Image:2ake.gif|left|200px]]<br /><applet load="2ake" size="350" color="white" frame="true" align="right" spinBox="true"  

Aminoacyl-tRNA synthetases (aaRSs) are a family of enzymes responsible for the covalent link of amino acids to their cognate tRNAs. The selectivity and species-specificity in the recognitions of both amino acid and tRNA by aaRSs play a vital role in maintaining the fidelity of protein synthesis. We report here the first crystal structure of human tryptophanyl-tRNA synthetase (hTrpRS) in complex with tRNA(Trp) and Trp which, together with biochemical data, reveals the molecular basis of a novel tRNA binding and recognition mechanism. hTrpRS recognizes the tRNA acceptor arm from the major groove; however, the 3' end CCA of the tRNA makes a sharp turn to bind at the active site with a deformed conformation. The discriminator base A73 is specifically recognized by an alpha-helix of the unique N-terminal domain and the anticodon loop by an alpha-helix insertion of the C-terminal domain. The N-terminal domain appears to be involved in Trp activation, but not essential for tRNA binding and acylation. Structural and sequence comparisons suggest that this novel tRNA binding and recognition mechanism is very likely shared by other archaeal and eukaryotic TrpRSs, but not by bacterial TrpRSs. Our findings provide insights into the molecular basis of tRNA specificity and species-specificity.

2AKE is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Bos_taurus Bos taurus] and [http://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens] with <scene name='pdbligand=SO4:'>SO4</scene> and <scene name='pdbligand=TRP:'>TRP</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Tryptophan--tRNA_ligase Tryptophan--tRNA ligase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=6.1.1.2 6.1.1.2] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2AKE OCA].  

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