title: Incorporation of azides into recombinant proteins for chemoselective modification by the Staudinger ligation.
abstract: The introduction of chemically unique groups into proteins by means of non-natural amino acids has numerous applications in protein engineering and functional studies. One method to achieve this involves the utilization of a non-natural amino acid by the cell's native translational apparatus. Here we demonstrate that a methionine surrogate, azidohomoalanine, is activated by the methionyl-tRNA synthetase of Escherichia coli and replaces methionine in proteins expressed in methionine-depleted bacterial cultures. We further show that proteins containing azidohomoalanine can be selectively modified in the presence of other cellular proteins by means of Staudinger ligation with triarylphosphine reagents. Incorporation of azide-functionalized amino acids into proteins in vivo provides opportunities for protein modification under native conditions and selective labeling of proteins in the intracellular environment.
authors.affiliation: Department of Polymer Science and Engineering, University of Massachusetts, Amherst, MA 01003, USA.
authors.forename: Kristi L
authors.initials: KL
authors.lastname: Kiick
authors.forename: Eliana
authors.initials: E
authors.lastname: Saxon
authors.forename: David A
authors.initials: DA
authors.lastname: Tirrell
authors.forename: Carolyn R
authors.initials: CR
authors.lastname: Bertozzi
mesh_terms: D000818:Animals; D001386:Azides / Q000737:chemistry*; D001671:Biochemistry / Q000379:methods*; D015153:Blotting, Western; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000201:enzymology; D007700:Kinetics; D013058:Mass Spectrometry; D008715:Methionine / Q000737:chemistry; D008718:Methionine-tRNA Ligase / Q000737:chemistry; D051379:Mice; D008956:Models, Chemical; D008958:Models, Molecular; D010455:Peptides / Q000737:chemistry; D014176:Protein Biosynthesis; D011487:Protein Conformation; D011993:Recombinant Fusion Proteins / Q000737:chemistry*; D013696:Temperature; D013762:Tetrahydrofolate Dehydrogenase / Q000737:chemistry
chemical_list: D001386:Azides; D010455:Peptides; D011993:Recombinant Fusion Proteins; D008715:Methionine; D013762:Tetrahydrofolate Dehydrogenase; D008718:Methionine-tRNA Ligase