1tke
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(New page: 200px<br /><applet load="1tke" size="450" color="white" frame="true" align="right" spinBox="true" caption="1tke, resolution 1.46Å" /> '''Crystal structure of...)
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Revision as of 01:13, 21 November 2007
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Crystal structure of the editing domain of threonyl-tRNA synthetase complexed with serine
Overview
The fidelity of aminoacylation of tRNA(Thr) by the threonyl-tRNA, synthetase (ThrRS) requires the discrimination of the cognate substrate, threonine from the noncognate serine. Misacylation by serine is corrected, in a proofreading or editing step. An editing site has been located 39 A, away from the aminoacylation site. We report the crystal structures of, this editing domain in its apo form and in complex with the serine, product, and with two nonhydrolyzable analogs of potential substrates: the, terminal tRNA adenosine charged with serine, and seryl adenylate. The, structures show how serine is recognized, and threonine rejected, and, provide the structural basis for the editing mechanism, a water-mediated, hydrolysis of the mischarged tRNA. When the adenylate analog binds in the, editing site, a phosphate oxygen takes the place of one of the catalytic, water molecules, thereby blocking the reaction. This rules out a, correction mechanism that would occur before the binding of the amino acid, on the tRNA.
About this Structure
1TKE is a Single protein structure of sequence from Escherichia coli with SER as ligand. Active as Threonine--tRNA ligase, with EC number 6.1.1.3 Full crystallographic information is available from OCA.
Reference
Achieving error-free translation; the mechanism of proofreading of threonyl-tRNA synthetase at atomic resolution., Dock-Bregeon AC, Rees B, Torres-Larios A, Bey G, Caillet J, Moras D, Mol Cell. 2004 Nov 5;16(3):375-86. PMID:15525511
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