Transcription of bacteriophage T4 DNA by Escherichia coli RNA polymerase in vitro: Identification of some immediate-early and delayed-early genes

Abstract

Transcription of bacteriophage T4 DNA by Escherichia coli RNA polymerase has been studied in vitro. RNA synthesis was initiated at sigma-specific promotor loci by forming rifampicin-resistant initiation complexes before the onset of polymerization and specific termination accomplished by the addition of rho factor. The RNA synthesized in the presence and absence of rho was analyzed for gene-specific messenger RNA's. The eight genes studied could be grouped into three classes: (1) those which were transcribed in the presence or absence of rho (genes 42 and 30); (2) those which were transcribed only in the absence of rho (genes 43, e, rIIA and rIIB); and (3) those which could not be transcribed in vitro even in the absence of rho (genes 41 and 40). It is concluded that genes 42 and 30 belong to the immediate-early class and genes 43, rIIA and rIIB to the delayed-early class. The transcription of the lysozyme gene in vitro resembles that of the delayed-early genes. The inability to transcribe gene 41 in vitro even in the absence of rho implies a rho-independent termination site between genes 42 and 41 and a positive control element to turn on gene 41.