PMID:11243794
| Citation |
Serre, L, Verdon, G, Choinowski, T, Hervouet, N, Risler, JL and Zelwer, C (2001) How methionyl-tRNA synthetase creates its amino acid recognition pocket upon L-methionine binding. J. Mol. Biol. 306:863-76 |
|---|---|
| Abstract |
Amino acid selection by aminoacyl-tRNA synthetases requires efficient mechanisms to avoid incorrect charging of the cognate tRNAs. A proofreading mechanism prevents Escherichia coli methionyl-tRNA synthetase (EcMet-RS) from activating in vivo L-homocysteine, a natural competitor of L-methionine recognised by the enzyme. The crystal structure of the complex between EcMet-RS and L-methionine solved at 1.8 A resolution exhibits some conspicuous differences with the recently published free enzyme structure. Thus, the methionine delta-sulphur atom replaces a water molecule H-bonded to Leu13N and Tyr260O(eta) in the free enzyme. Rearrangements of aromatic residues enable the protein to form a hydrophobic pocket around the ligand side-chain. The subsequent formation of an extended water molecule network contributes to relative displacements, up to 3 A, of several domains of the protein. The structure of this complex supports a plausible mechanism for the selection of L-methionine versus L-homocysteine and suggests the possibility of information transfer between the different functional domains of the enzyme. |
| Links |
PubMed Online version:10.1006/jmbi.2001.4408 |
| Keywords |
Allosteric Regulation; Allosteric Site; Amino Acid Sequence; Binding, Competitive; Crystallization; Crystallography, X-Ray; Escherichia coli/enzymology; Homocysteine/metabolism; Hydrogen Bonding; Methionine/chemistry; Methionine/metabolism; Methionine-tRNA Ligase/chemistry; Methionine-tRNA Ligase/metabolism; Models, Molecular; Molecular Sequence Data; Protein Structure, Secondary; Protein Structure, Tertiary; Sequence Alignment; Substrate Specificity; Water/chemistry; Water/metabolism |
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