1vbn

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spinqualitylabelsall models 1vbn, resolution 2.70Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

Escherichia coli tyrosyl-tRNA synthetase mutant complexed with Tyr-AMS

Overview

The genetic code in a eukaryotic system has been expanded by the, engineering of Escherichia coli tyrosyl-tRNA synthetase (TyrRS) with the, Y37V and Q195C mutations (37V195C), which specifically recognize, 3-iodo-L-tyrosine rather than L-tyrosine. In the present study, we, determined the 3-iodo-L-tyrosine- and L-tyrosine-bound structures of the, 37V195C mutant of the E. coli TyrRS catalytic domain at 2.0-A resolution., The gamma-methyl group of Val-37 and the sulfur atom of Cys-195 make van, der Waals contacts with the iodine atom of 3-iodo-L-tyrosine. The Val-37, and Cys-195 side chains are rigidly fixed by the neighboring residues, forming the hydrophobic core of the TyrRS. The major roles of the two, mutations are different for the 3-iodo-L-tyrosine-selective recognition in, the first step of the aminoacylation reaction (the amino acid activation, step): the Y37V mutation eliminates the fatal steric repulsion with the, iodine atom, and the Q195C mutation reduces the L-tyrosine misrecognition., The structure of the 37V195C mutant TyrRS complexed with an, L-tyrosyladenylate analogue was also solved, indicating that the, 3-iodo-L-tyrosine and L-tyrosine side chains are similarly discriminated, in the second step (the aminoacyl transfer step). These results, demonstrate that the amino acid-binding pocket on the 37V195C mutant is, optimized for specific 3-iodo-L-tyrosine recognition.

About this Structure

1VBN is a Single protein structure of sequence from Escherichia coli with YSA as ligand. Active as Tyrosine--tRNA ligase, with EC number 6.1.1.1 Full crystallographic information is available from OCA.

Reference

Structural basis of nonnatural amino acid recognition by an engineered aminoacyl-tRNA synthetase for genetic code expansion., Kobayashi T, Sakamoto K, Takimura T, Sekine R, Kelly VP, Kamata K, Nishimura S, Yokoyama S, Proc Natl Acad Sci U S A. 2005 Feb 1;102(5):1366-71. Epub 2005 Jan 25. PMID:15671170

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