Isolation and characterization of a Chinese hamster lung cell tryptophanyl-tRNA synthetase mutant

A novel type of temperature-sensitive protein synthetic mutant was isolated from V-79 Chinese hamster lung cells using an amino acid analog suicide selection. The expression of the temperature sensitive phenotype of the mutant is greatly affected by the concentration of tryptophan in the culture medium. In addition, the activity of tryptophanyl-tRNA synthetase is undetectable in cell-free extracts prepared from the mutant cells. The results suggest that the mutant has an alteration in the structural gene encoding tryptophanyl-tRNA synthetase.