2ag6
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Crystal structure of p-bromo-l-phenylalanine-tRNA sythetase in complex with p-bromo-l-phenylalanine
OverviewOverview
Recently, tRNA aminoacyl-tRNA synthetase pairs have been evolved that allow one to genetically encode a large array of unnatural amino acids in both prokaryotic and eukaryotic organisms. We have determined the crystal structures of two substrate-bound Methanococcus jannaschii tyrosyl aminoacyl-tRNA synthetases that charge the unnatural amino acids p-bromophenylalanine and 3-(2-naphthyl)alanine (NpAla). A comparison of these structures with the substrate-bound WT synthetase, as well as a mutant synthetase that charges p-acetylphenylalanine, shows that altered specificity is due to both side-chain and backbone rearrangements within the active site that modify hydrogen bonds and packing interactions with substrate, as well as disrupt the alpha8-helix, which spans the WT active site. The high degree of structural plasticity that is observed in these aminoacyl-tRNA synthetases is rarely found in other mutant enzymes with altered specificities and provides an explanation for the surprising adaptability of the genetic code to novel amino acids.
About this StructureAbout this Structure
2AG6 is a Single protein structure of sequence from Methanocaldococcus jannaschii with as ligand. Active as Tyrosine--tRNA ligase, with EC number 6.1.1.1 Full crystallographic information is available from OCA.
ReferenceReference
Structural plasticity of an aminoacyl-tRNA synthetase active site., Turner JM, Graziano J, Spraggon G, Schultz PG, Proc Natl Acad Sci U S A. 2006 Apr 25;103(17):6483-8. Epub 2006 Apr 17. PMID:16618920
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