Preferred Site for Initiation of RNA Transcription by Escherichia coli RNA Polymerase Within the Simian Virus 40 DNA Segment of the Nondefective Adenovirus-Simian Virus 40 Hybrid Viruses Ad2 + ND 1 and Ad2 + ND 3

Abstract

The DNA of simian virus 40 (SV40) was transcribed into RNA by Escherichia coli RNA polymerase at 18 to 24 C after synchronization of the initiation of RNA synthesis. After a brief synthetic period the RNA product contained relatively large amounts of sequences derived from a limited segment of SV40 DNA. The source for this pulse-labeled RNA was found to be a portion of the segment of SV40 DNA included within the nondefective adenovirus (Ad)-SV40 hybrid viruses, Ad2 + ND 1 and Ad2 + ND 3 . After synthesis with [γ- 32 P ] ATP, Ad2 + ND 1 and Ad2 + ND 3 DNA transcripts contained an initial sequence missing from Ad2 transcripts. This sequence was identified as an initiation sequence for polymerase transcription of the SV40 DNA. Thus, there is a preferred site for initiation of in vitro transcription on the segment of SV40 DNA common to the nondefective Ad2 + ND 1 and Ad2 + ND 3 hybrid viruses.