TRANSCRIPTION ANALYSIS OF THE PROLATE-HEADED LACTOCOCCAL BACTERIOPHAGE-C2

A detailed transcription map of the prolate-headed lactococcal phage c 2 has been constructed. Transcription of about one-third of the genome , encoding 22 open reading frames, began within the first 2 min of inf ection and produced at least 12 overlapping transcripts that persisted until lysis occurred at 30 min after initiation of infection. The rem aining two-thirds of the genome, encoding 17 open reading frames, was divergently transcribed, beginning between 4 and 6 min after initiatio n of infection, and resulted in at least 18 overlapping transcripts th at persisted until lysis. Five very strong, simultaneously active, and probably unregulated early promoters and a single positively regulate d late promoter were identified. The late promoter had an extended -10 sequence, had a significant basal level of activity in the uninduced state, and was induced to high activity by a phage gene product. The c omplex overlapping pattern of transcripts resulted from the action of the multiple early promoters, inefficient termination of transcription , and (possibly) processing of a late precursor transcript(s). Phage p roteins were not required for these processes, and the host RNA polyme rase was probably used for both early and late transcription.