RNA synthesis and ribosome production in puromycin-treated cells

Abstract

1. 1. Puromycin is an effective inhibitor of protein synthesis in Escherichia coli 15T when treatment takes place in a medium lacking magnesium. Although incorporation of labelled amino acid is prevented in this system, incorporation of nucleic acid precursors continues. RNA, from cells treated with puromycin, labelled with [8- 14C]adenine and separated on a sucrose density gradient exhibits the same sedimentation profile as the RNA from normal cells. The RNA accumulated during treatment with puromycin is stable after removal of the inhibitor, provided glucose is added to the medium in which the bacteria are resuspended. The ribosomal RNA, furthermore, can be incorporated into ribosomal particles during recovery from puromycin treatment. 2. 2. During this recovery phase there appears to be a preferential synthesis of ribosomal protein. Thus, the simultaneous sysnthesis of ribosomal RNA and ribosomal protein is not a necessary requirement for the formation of ribosome particles. 3. 3. In resting cell cultures (absence of glucose) nucleic acid formation, as measured by [8- 14C]adenine incorporation is increased by the addition of puromycin to the incubation medium.