The nucleotide sequence of the structural gene for Escherichia coli tryptophanyl-tRNA synthetase.

The complete nucleotide sequence of trpS, the structural gene for Escherichia coli tryptophanyl-tRNA synthetase, was determined using a plasmid carrying the structural gene. From the single open reading frame of correct length and orientation we deduced an amino acid sequence consistent with the amino acid composition of the purified protein. In addition, previously sequenced peptides representing 52% of the protein were readily aligned with regions of the deduced sequence. The deduced amino acid sequence of the E. coli enzyme is 60% homologous with the sequence of the enzyme from Bacillus stearothermophilus. Using currently available procedures we predicted the secondary structure for the enzyme from each organism and compared these structures to those of the two aminoacyl-tRNA synthetases whose three-dimensional structures have been determined. We used a convenient plasmid recombination procedure to map the regional locations of missense mutations within trpS that have characteristic effects on the properties of the enzyme.