Multiple discrete sites for premature RNA chain termination late in adenovirus-2 infection: enhancement by 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole.

Discrete-sized short RNA chains that contain the distinctive oligonucleotides, including the 5'-capped oligonucleotide, characteristic of the first 600 nucleotides of the adenovirus type 2 (Ad-2) large, late, rightward-reading transcriptional unit (16.4-99) accumulate in Ad-2-infected HeLa cells. In the presence of 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole the accumulation of these chains is enhanced, as is the accumulation of short chains from a neighbouring rightward-reading transcriptional unit (3.0-10.7). These short chains appear to represent prematurely terminated transcripts. Late in infection there is a marked increase in RNA synthesis, including that of prematurely terminated short chains, from the large late transcriptional unit. This suggests that the increase in transcription and mRNA production from this region late in infection is not due to reduced "attenuation" of RNA synthesis.