Sequence of a region near the left end of bacteriophage T3 DNA that contains three promoters for theE. ColiRNA polymerase

Abstract

The early genes of bacteriophages T7 and T3 are transcribed by E. coli RNA polymerase from a cluster of three promoters that lie near the left end of the genome (1 ,2). We have sequenced the early control region of T3 DNA and have compared it with the corresponding region of T7 DNA (Fig. 1). Three potential promoters for the E. coli RNA polymerase (designated Al, A2 and A3) are apparent from their homology to the Al, A2 and A3 promoters of T7, as well as by their homology to the consensus sequence for other E. coli promoters (4).

Expression of the cloned coliphage T3 S-adenosylmethionine hydrolase gene inhibits DNA methylation and polyamine biosynthesis in Escherichia coli

“…1) and our repeated inability to clone it. Our suspicions have recently been confirmed, as the HpaI boundary of the HM fragment is 66 bases upstream from the complete published A3 promoter (9). These data therefore presumably imply that uncontrolled, prolonged transcription of the gene or high levels of production of the AdoMetase activity, or both, are detrimental to the cell or at least to M13 metabolism.…”

“…Figure 1A shows these T7 elements and some of their T3 homologs superimposed on the 2,350-base-pair T3 MboI G fragment, the 5'-terminal MboI restriction fragment (4). A sequencing study (9) Fig. 1.…”