In vivo transcription of bacteriophage phi 29 DNA: transcription termination

Abstract

The main early and late transcription termination sites in vivo in bacteriophage 429 DNA were determined by nuclease Si mapping. Transcription of the +29 early genes located at the left end of the viral genome terminated at the very end of the DNA molecule and within the HindIlI G fragment of the viral DNA. Transcription termination of the early genes located at the right end of the genome and that of the late viral genes overlapped in a specific region of the +29 DNA within the EcoRI D fragment. Stem-loop structures followed by uridine-rich tails could be derived close to the 3' ends of early and late mRNAs, suggesting Rho-independent transcription termination in 429 DNA.

DNA bending and looping in the transcriptional control of bacteriophage φ29

“…Viral gene expression in vegetative cells is regulated in an orderly sequence; immediately after infection, the host RNAP transcribes early genes located at the two DNA ends, whereas transcription of the late genes, located at the middle of the genome, requires early gene expression Sogo et al, 1979). Transcription initiation and termination sites were mapped in vivo and in vitro; the corresponding early promoters were named A1, A2b, A2c, B1, B2, C1 and C2 and the only late promoter A3 (Kawamura & Ito, 1977;Sogo et al, 1979;Murray & Rabinowitz, 1982;Dobinson & Spiegelman, 1985;Barthelemy et al, 1986Barthelemy et al, , 1987Mellado et al, 1986a, b).…”

Resolution of head-on collisions between the transcription machinery and bacteriophage Phi 29 DNA polymerase is dependent on RNA polymerase translocation

“…The A2b promoter, located very close to the A2c promoter and that gives rise to transcripts of almost the same length, is at least 50 times weaker under our reaction conditions (not shown). The A1 promoter is a relatively strong promoter, but transcripts from this promoter are only 321 nt long (Barthelemy et al, 1987). Transcripts from the weak A1IV promoter are not detected under our reaction conditions (not shown).…”

“…Transcripts produced at different times from the main promoter in the ClaI B DNA fragment, A2c, were analysed by primer extension, as described in Materials and methods ( Figure 6B). Transcripts originating at the A2c promoter could interfere most with replication; this promoter is strong, and the transcripts generated from it can be as long as 5000 nt, although approximately half of the transcripts are shorter (~1100 nt) due to premature termination at the TA1 transcriptional terminator (this study; Barthelemy et al, 1987). The A2b promoter, located very close to the A2c promoter and that gives rise to transcripts of almost the same length, is at least 50 times weaker under our reaction conditions (not shown).…”

Compartmentalization of prokaryotic DNA replication

“…In addition, gene 1 would be transcribed from the weak promoter A1IV, which is located within gene 2 [148][149][150]. A Rho-independent transcriptional terminator, named TA1, is located within gene 4 [151]. With the exception of gene 4, which encodes a transcriptional regulator protein (p4) [146,147], the left early genes are involved in phage DNA replication.…”

“…Late genes encode components of the viral capsids, proteins involved in phage morphogenesis, and those required for cell lysis. A Rho-independent bidirectional transcription terminator (TD1) is located downstream gene 16 [151].…”