2hl2
From Proteopedia
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Crystal structure of the editing domain of threonyl-tRNA synthetase from Pyrococcus abyssi in complex with an analog of seryladenylate
Overview
To ensure a high fidelity during translation, threonyl-tRNA synthetases, (ThrRSs) harbor an editing domain that removes noncognate L-serine, attached to tRNAThr. Most archaeal ThrRSs possess a unique editing domain, structurally similar to D-aminoacyl-tRNA deacylases (DTDs) found in, eubacteria and eukaryotes that specifically removes D-amino acids attached, to tRNA. Here, we provide mechanistic insights into the removal of, noncognate L-serine from tRNAThr by a DTD-like editing module from, Pyrococcus abyssi ThrRS (Pab-NTD). High-resolution crystal structures of, Pab-NTD with pre- and post-transfer substrate analogs and with L-serine, show mutually nonoverlapping binding sites for the seryl moiety. Although, the pre-transfer editing is excluded, the analysis reveals the importance, of main chain atoms in proper positioning of the post-transfer substrate, for its hydrolysis. A single residue has been shown to play a pivotal role, in the inversion of enantioselectivity both in Pab-NTD and DTD. The study, identifies an enantioselectivity checkpoint that filters opposite chiral, molecules and thus provides a fascinating example of how nature has subtly, engineered this domain for the selection of chiral molecules during, translation.
About this Structure
2HL2 is a Single protein structure of sequence from Pyrococcus abyssi with SSA as ligand. Active as Threonine--tRNA ligase, with EC number 6.1.1.3 Full crystallographic information is available from OCA.
Reference
Post-transfer editing mechanism of a D-aminoacyl-tRNA deacylase-like domain in threonyl-tRNA synthetase from archaea., Hussain T, Kruparani SP, Pal B, Dock-Bregeon AC, Dwivedi S, Shekar MR, Sureshbabu K, Sankaranarayanan R, EMBO J. 2006 Sep 6;25(17):4152-62. Epub 2006 Aug 10. PMID:16902403
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