Natural premature protein synthesis termination can be reduced in Escherichia coli by decreased translation rates.

Peptidyl tRNA hydrolase is an essential enzyme for normal growth inasmuch as a mutant strain of Escherichia coli with a temperature-sensitive hydrolase cannot continue protein synthesis at the non-permissive temperature. In the absence of hydrolase peptidyl tRNA rapidly accumulates. Why peptidyl tRNA should be formed is the subject of this report. The rapid rate of protein synthesis is likely one mechanism of formation of peptidyl tRNA. A strA mutant of the hydrolase (pth-1) mutant strain that has a 40% reduction in amino acid polymerization rate can grow at 42 degrees C. StrA mutants with normal polymerization rates, however, cannot grow at 42 degrees C when pth-1 is present. Furthermore, addition of low levels of chloramphenicol (2--4 micrograms/ml) but not several other tested drugs, phenotypically suppressed pth-1 at 42 degrees C. Chloramphenicol, at these concentrations, was found to reduce the amino acid polymerization rate 30--40%. On the other hand, no evidence could be found that amino acyl tRNA selection errors are incorporated into pseudo revertants of the pth-1 strain.