The chromosome of bacteriophage T5. III. Patterns of transcription from the single-stranded DNA fragments

S. Diane Hayward, M. G. Smith

Research output: Contribution to journalArticlepeer-review


To map the regions on the bacteriophage T.5st(O) DNA molecule transcribed in vivo, we hybridized samples of T5 messenger RNA with an excess of each of the four major single-stranded fragments of T5 DNA. These experiments showed that the intact strand (35 million mol. wt fragment) and the 17 million molecular weight fragment form the major templates for transcription. Thus, regions of both complementary DNA strands direct RNA synthesis in phage T5. Transcription of almost all pre-early and most early class RNA species occurs from the intact strand, while at late times RNA is synthesized extensively on both the 35 and 17 million molecular weight fragments. The 14·5 and 3·8 million molecular weight fragments have little or no template activity. We also annealed pulse-labelled T5 RNA to isolated fractions of sheared T5 DNA and to DNA fractionated by the CsCl-poly(G) technique. Pre-early RNA hybridized to both ends of the intact strand, thus suggesting that first-step transfer DNA sequences occur at both ends of the DNA molecule and that T5 DNA contains a large terminal repetition. The experiments using sheared DNA also revealed that two separate regions of the intact strand are transcribed during the synthesis of both early and late class RNA. As with many other phages, a correlation exists between poly(G)-binding properties and DNA template activity; the 35 and 17 million molecular weight fragments occur in the heavy band in CsCl-poly(G) density gradients and virtually all T5 messenger RNA hybridizes to this heavy band.

Original languageEnglish (US)
Pages (from-to)345-348,IN7,349-359
JournalJournal of molecular biology
Issue number2
StatePublished - Oct 25 1973

ASJC Scopus subject areas

  • Structural Biology
  • Molecular Biology


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