Inhibition of Messenger Ribonucleic Acid Synthesis in Escherichia coli by Thiolutin

Abstract

Thiolutin, at concentrations of 5 to 40 μg/ml, inhibited the induced synthesis of β-galactosidase in Escherichia coli CA8000. Thiolutin had no effect on the rate of in vitro hydrolysis of o -nitrophenyl-β- d -galactoside by purified β-galactosidase. Examination of the effects of thiolutin on the kinetics of appearance of β-galactosidase in the presence and absence of rifampin in induced E. coli cells indicated that thiolutin interferes with the transcription process at the level of elongation of messenger ribonucleic acid (mRNA) chains. The data indicated that, in the presence of thiolutin, β-galactosidase mRNA has a half-life of 1.6 min and that the first completed β-galactosidase mRNA is produced about 1.5 min after induction. These data are consistent with estimates of transcription time and messenger half-life obtained by conventional means, and suggest that thiolutin does not affect translation of mRNA or its breakdown in vivo. After removal of thiolutin, cells fully regained the ability to be induced for synthesis of β-galactosidase within 10 min, but mRNA which was incomplete at the time of thiolutin addition did not subsequently become functional.