1n9w
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(New page: 200px<br /><applet load="1n9w" size="450" color="white" frame="true" align="right" spinBox="true" caption="1n9w, resolution 2.3Å" /> '''Crystal structure of ...)
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Revision as of 20:40, 24 November 2007
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Crystal structure of the non-discriminating and archaeal-type aspartyl-tRNA synthetase from Thermus thermophilus
Overview
In most organisms, tRNA aminoacylation is ensured by 20 aminoacyl-tRNA, synthetases (aaRSs). In eubacteria, however, synthetases can be duplicated, as in Thermus thermophilus, which contains two distinct AspRSs. While, AspRS-1 is specific, AspRS-2 is non-discriminating and aspartylates, tRNA(Asp) and tRNA(Asn). The structure at 2.3 A resolution of AspRS-2, the, first of a non-discriminating synthetase, was solved. It differs from that, of AspRS-1 but has resemblance to that of discriminating and archaeal, AspRS from Pyrococcus kodakaraensis. The protein presents non-conventional, features in its OB-fold anticodon-binding domain, namely the absence of a, helix inserted between two beta-strands of this fold and a peculiar L1, loop differing from the large loops known to interact with tRNA(Asp), identity determinant C36 in conventional AspRSs. In AspRS-2, this loop is, small and structurally homologous to that in AsnRSs, including, conservation of a proline. In discriminating Pyrococcus AspRS, the L1, loop, although small, lacks this proline and is not superimposable with, that of AspRS-2 or AsnRS. Its particular status is demonstrated by a, loop-exchange experiment that renders the Pyrococcus AspRS, non-discriminating.
About this Structure
1N9W is a Single protein structure of sequence from Thermus thermophilus. Full crystallographic information is available from OCA.
Reference
Non-discriminating and discriminating aspartyl-tRNA synthetases differ in the anticodon-binding domain., Charron C, Roy H, Blaise M, Giege R, Kern D, EMBO J. 2003 Apr 1;22(7):1632-43. PMID:12660169
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