Transcription of Native and Denatured DNA Preparations by Bacteriophage T3 Induced RNA Polymerase

Abstract

It is now well established that the expression of genetic information in bacteriophages, as well as in more complex organisms, is subject to temporal control; not all genes are expressed simultaneously. Early- and late–functioning cistrons have been distinguished in λ, T-even, and other bacteriophages. In these viruses, temporal regulation of gene expression seems to occur at the transcriptional level. At a certain time after infection, mRNA synthesis, originally specific for early phage proteins, is altered to produce RNA that directs the synthesis of late phage proteins. Evidence for this control mechanism has been reviewed (1,2). The change in transcription specificity leading to the synthesis of late mRNA may be achieved either by modification of the host RNA polymerase or by de novo synthesis of a new RNA polymerase coded by the viral genome. The modified or the new RNA polymerase can initiate RNA synthesis corresponding to late bacteriophage genes.