A mutant of Escherichia coli with temperature-sensitive streptomycin protein.

The temperature-sensitive mutation in our Escherichia coli strain C1714 appears to be in a ribosomal protein. The mutation maps at the streptomycin locus. Protein synthesis in intact cells stops immediately when the temperature is shifted from 30 to 42 degrees C. Analysis of polyribosome distributions after shift-up suggests that initiation of protein synthesis is defective at the high temperature. In vitro protein synthesis in extracts from C1714 is temperature sensitive when directed by natural mRNA, but not when directed by poly U.