A transcriptional map of the bacteriophage SP01 genome. I. The major early promoters.

Bacteriophage SP01 early transcripts come predominantly from the terminally repeated 12-kilobase-pair segments of its genome. Much less early RNA comes from a relatively large region of the genome which surrounds the early regulatory gene 28. (The gene 28 protein positively regulates viral middle gene expression.) The major sites at which Bacillus subtilis RNA polymerase holoenzyme binds to SP01 DNA and initiates RNA synthesis have been mapped and the direction of transcription from each of these promoter sites has been determined. There are 12 such sites spanning 11.1 kilobase pairs at each end of the SP01 genome and each set of 12 sites defines a complex set of convergent transcription units.