Origin and Metabolic Properties of the RNA Species Formed During the Replication Cycle of Virus 2C

Abstract

When short pulses of [ 3 H]uracil were administered to Bacillus subtilis infected with phage 2C, the main species of labeled RNA was a 10 S component that hybridized chiefly, but not exclusively, with the heavy strand of 2C DNA. After long pulses, most of the radioactivity was found in the 23 S , 16 S , and 5 S rRNA's, which are coded for by the cell genome. Formation of such RNA species was reduced but not suppressed upon infection, the extent of inhibition being proportional to the virus-to-cell ratio. When bacteria were incubated with virginiamycin, an inhibitor of protein synthesis, and then infected with phage 2C, formation of virus-specific RNA decreased. This antibiotic also reduced the preferential transcription of the heavy strand of 2C DNA. The methylation pattern of rRNA remained unchanged upon infection with phage 2C. Virginiamycin reduced both the methylation and stability of rRNA in uninfected cells; this effect, however, was clearly reduced during the viral cycle. It can be concluded that in 2C-infected B. subtilis , cellular and viral RNA species are simultaneously synthesized and a preferential transcription of viral message depends not only on the number of available copies of viral template, but also on their translation. Moreover, virus-dictated proteins are responsible for the inhibition of cellular RNA formation as well as for the asymmetrical transcription of phage genome. Finally, virginiamycin and phage 2C have antagonistic, nonoverlapping effects on the metabolism and function of the RNA of the host cell.