The sv40 transcription complex. II. Non-dissociation of protein from SV40 chromatin during transcription.

A small fraction of the SV40 chromatin isolated from infected monkey cell cultures by the Triton method contains active RNA polymerase which had initiated transcription in vivo. This viral transcription complex (VTC) was utilized to answer the question of whether proteins dissociate from chromatin during transcription in vitro. 3H-RNA was synthesized by the VTC under conditions such that over half the label was in transcripts which were longer than half the length of the SV40 genome. Virtually all of the 3H-RNA remained associated with the SV40 chromatin, causing an increase in sedimentation rate from 55S to 78S. The density of the VTC-3H-RNA complex indicated that less than 5% of the original protein dissociated from the SV40 DNA which served as a template for transcription. We conclude that SV40 chromatin can be transcribed while the proteins remain associated with the DNA.