Diversified sequences of peptide epitope for same-RNA recognition.
We replaced an essential RNA-binding, 30-amino acid helix-loop in an Escherichia coli tRNA synthetase with an inactive and simplified "generic" sequence having 23 of the 30 amino acids as alanine and serine. Wild-type residues were restored in random combinations to generate a library with a sequence complexity of about 1.9 x 10(7). Active molecules were obtained by genetic selection at a frequency of approximately 1% and contained variants with as many as 11 alanine/serine replacements and a total of 17 alanine/serine residues. These variants have activities which are thermodynamically competitive with that of the native protein and therefore are functionally and, most likely, conformationally equivalent.
Kim
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Department of Biology, Massachusetts Institute of Technology, Cambridge 02139.
Ribas de Pouplana
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Schimmel
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D000926:Anticodon / Q000378:metabolism; D001665:Binding Sites; D002151:Calorimetry; D000939:Epitopes / Q000737:chemistry; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics; D005798:Genes, Bacterial; D014644:Genetic Variation; D001411:Geobacillus stearothermophilus / Q000201:enzymology; D008718:Methionine-tRNA Ligase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D016297:Mutagenesis, Site-Directed; D017354:Point Mutation; D017433:Protein Structure, Secondary; D012441:Saccharomyces cerevisiae / Q000201:enzymology; D017384:Sequence Deletion; D017386:Sequence Homology, Amino Acid; D016963:Thermus thermophilus / Q000201:enzymology
D000926:Anticodon; D000939:Epitopes; D008718:Methionine-tRNA Ligase