1u7d
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(New page: 200px<br /><applet load="1u7d" size="450" color="white" frame="true" align="right" spinBox="true" caption="1u7d, resolution 2.65Å" /> '''crystal structure of...)
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Revision as of 01:46, 21 November 2007
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crystal structure of apo M. jannashii tyrosyl-tRNA synthetase
Overview
The Methanococcus jannaschii tRNA(Tyr)/TyrRS pair has been engineered to, incorporate unnatural amino acids into proteins in E. coli. To reveal the, structural basis for the altered specificity of mutant TyrRS for, O-methyl-L-tyrosine (OMeTyr), the crystal structures for the apo wild-type, and mutant M. jannaschii TyrRS were determined at 2.66 and 3.0 A, respectively, for comparison with the published structure of TyrRS, complexed with tRNA(Tyr) and substrate tyrosine. A large conformational, change was found for the anticodon recognition loop 257-263 of wild-type, TyrRS upon tRNA binding in order to facilitate recognition of G34 of the, anticodon loop through pi-stacking and hydrogen bonding interactions. Loop, 133-143, which is close to the tRNA acceptor stem-binding site, also, appears to be stabilized by interaction with the tRNA(Tyr). Binding of the, substrate tyrosine results in subtle and cooperative movements of the side, chains within the tyrosine-binding pocket. In the OMeTyr-specific mutant, synthetase structure, the signature motif KMSKS loop and acceptor, stem-binding loop 133-143 were surprisingly ordered in the absence of, bound ATP and tRNA. The active-site mutations result in altered hydrogen, bonding and steric interactions which favor binding of OMeTyr over, L-tyrosine. The structure of the mutant and wild-type TyrRS now provide a, basis for generating new active-site libraries to evolve synthetases, specific for other unnatural amino acids.
About this Structure
1U7D is a Single protein structure of sequence from Methanocaldococcus jannaschii. Active as Tyrosine--tRNA ligase, with EC number 6.1.1.1 Full crystallographic information is available from OCA.
Reference
Crystal structures of apo wild-type M. jannaschii tyrosyl-tRNA synthetase (TyrRS) and an engineered TyrRS specific for O-methyl-L-tyrosine., Zhang Y, Wang L, Schultz PG, Wilson IA, Protein Sci. 2005 May;14(5):1340-9. PMID:15840835
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