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.