Lack of dependance of transcription-induced cytosine deaminations on protein synthesis.

Transcription-induced mutations (TIM) is a phenomenon in Escherichia coli in which transcription promotes C to T and other mutations in a strand-specific manner. Because the processes of transcription and translation are coupled in prokaryotes and some models regarding creating a hypermutagenic state in E. coli require new protein synthesis, we tested the possibility that TIM was dependent on efficient synthesis of proteins. We used puromycin to reversibly inhibit protein synthesis and found that it had little effect on mRNA synthesis, plasmid copy-number or TIM. Our results show that TIM is not dependent on efficient translation of mRNA and this helps eliminate certain models concerning the mechanism underlying TIM.