IN vitro transcription of bacteriophage T4 tRNA gene cluster from two different promoters.

Analysis of primary transcripts made by Escherichia coli RNA polymerase on T4 DNA containing an intact or partially deleted tRNA gene cluster demonstrates that the T4 tRNA genes are transcribed from two promoters differing in their strength. The stronger (P1) and the weaker (P2) promoters are located at distances of 1 kb and 1.5 kb from the tRNA genes, respectively. Selective initiation of individual transcripts with dinucleotides shows that P1 and P2 promoters contain the sequences TAT and CAC respectively. The two-promoter organisation of the tRNA cluster may reflect two superimposed mechanisms of gene expression in T4-infected bacteria.