Screening for mutants temperature sensitive in protein synthesis by using methionine analogues

Two new mutants are described which are temperature sensitive in protein synthesis. The mutants were obtained by a screening procedure using methionine analogues. The method is based on two findings: a) that in E. coli, and in other members of the Enterobacteriaceae, sensitivity to methionine analogues increases with the growth temperature, and b) that cells which are not synthesizing proteins during treatment with methionine analogues have a shorter lag in resuming growth subsequent to removal of the analogue.