Poliovirus-induced modification of host cell RNA polymerase IIO is prevented by cycloheximide and zinc

Infection of HeLa cells with poliovirus results in a decrease in the level of RNA polymerase IIO, the transcriptionally active form of the enzyme, and a shutdown of host transcription (Rangel, L. M., Fernández-Tomas, C., Dahmus, M. E., and Gariglio, P. (1987) J. Virol. 61, 1002-1006). The effect of cycloheximide on poliovirus-induced modification of host RNA polymerase IIO was investigated. The inhibition of protein synthesis, at sequential stages during viral replication, prevents the modification of both total and chromatin-bound RNA polymerase IIO. Furthermore, the inclusion of zinc at a concentration that inhibits the proteolytic post-translational processing of viral polyprotein also prevents the modification of RNA polymerase IIO. These results suggest that host cell enzyme modification depends on the synthesis and processing of protein(s) encoded by the viral genome.