Inhibition of rRNA synthesis by poliovirus: specific inactivation of transcription factors.
Synthesis of rRNA by RNA polymerase I is almost completely inhibited soon after infection of human cells with poliovirus. We show that extracts prepared from poliovirus-infected HeLa cells are severely inhibited in their ability to transcribe from a human rDNA promoter compared with extracts from mock-infected cells. Two lines of evidence presented here suggest that a specific transcriptional activity required for rDNA transcription in vitro is impaired in virus-infected cells. First, fractionation of individual transcriptional components by phosphocellulose chromatography and subsequent reconstitution experiments showed that the specific transcriptional activity of fraction C (0.8 M KCl eluate) from virus-infected cells was reduced three- to fourfold relative to that isolated from mock-infected cells. The activities of other transcription factors needed for in vitro transcription from the rDNA promoter were unaffected. Second, fraction C derived from mock-infected cells specifically restored transcription in extracts prepared from virus-infected cells. Fraction C contained both a nonspecific RNA polymerase I elongation activity and a specific factor activity which was needed for accurate transcription initiation. It is the specific transcriptional activity and not the nonspecific chain elongation activity of fraction C that is affected in cells infected with poliovirus.
Rubinstein
S J
SJ
Department of Microbiology and Immunology, UCLA School of Medicine.
Dasgupta
A
A
D002472:Cell Transformation, Viral; D004275:DNA, Ribosomal / Q000037:antagonists & inhibitors / Q000235:genetics*; D006367:HeLa Cells / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D010957:Plasmids; D017955:Poliovirus / Q000235:genetics*; D012318:RNA Polymerase I / Q000037:antagonists & inhibitors*; D012335:RNA, Ribosomal / Q000096:biosynthesis; D014157:Transcription Factors / Q000037:antagonists & inhibitors*; D014158:Transcription, Genetic
D004275:DNA, Ribosomal; D012335:RNA, Ribosomal; D014157:Transcription Factors; D012318:RNA Polymerase I