1tky
From Proteopedia
Crystal structure of the editing domain of threonyl-tRNA synthetase complexed with seryl-3'-aminoadenosine
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
1TKY is a Single protein structure of sequence from Escherichia coli. 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 Page seeded by OCA on Sat May 3 10:04:42 2008
