Association of Herpes Simplex Virus Type 1 ICP8 and ICP27 Proteins with Cellular RNA Polymerase II Holoenzyme

Abstract

Herpes simplex virus 1 (HSV-1) infection causes the shutoff of host gene transcription and the induction of a transcriptional program of viral gene expression. Cellular RNA polymerase II is responsible for transcription of all the viral genes, but several viral proteins stimulate viral gene transcription. ICP4 is required for all delayed-early and late gene transcription, ICP0 stimulates transcription of viral genes, and ICP27 stimulates expression of some early genes and transcription of at least some late viral genes. The early DNA-binding protein, ICP8, also stimulates late gene transcription. We therefore investigated which HSV proteins interact with RNA polymerase II. Using immunoprecipitation and Western blotting methods, we observed the coprecipitation of ICP27 and ICP8 with RNA polymerase II holoenzyme. The association of ICP27 with RNA polymerase II was detectable as early as 3 h postinfection, while ICP8 association became evident by 5 h postinfection, and the association of both was independent of viral DNA synthesis. Infections with ICP27 gene mutant viruses revealed that ICP27 is required for the association of ICP8 with RNA polymerase II, while studies with ICP8 gene deletion mutants showed no apparent role for ICP8 in the association of ICP27 with RNA polymerase II. The association of ICP27 and ICP8 with RNA polymerase II holoenzyme appeared to be independent of nucleic acids. We hypothesize that the interaction of ICP27 with RNA polymerase II holoenzyme reflects its role in stimulating early and late gene expression and/or its role in inhibiting host transcription and that the interaction of ICP8 with RNA polymerase II holoenzyme reflects its role in stimulating late gene transcription

Herpes Simplex Virus Virion Host Shutoff Protein: Immune Evasion Mediated by a Viral RNase?

“…Second, infection displaces the essential general transcription factor TFIIE from the RNAP II holoenzyme (19). Third, several HSV proteins, including ICP4, ICP27, and ICP8, have been reported to associate with RNAP II in either the holoenzyme complex (71) or a smaller complex found in infected cells (19). Jenkins and Spencer (19) suggest that these alterations may act in combination to selectively impair transcription of chromatin-associated templates, thus repressing cellular genes and favoring transcription of the nonchromatinized viral genome.…”

Human Cytomegalovirus Tegument Protein pp71 Directs Long-Term Gene Expression from Quiescent Herpes Simplex Virus Genomes

“…However, the experiments also raise the possibility that the action of pp71 is indirect. The HSV-1 IE proteins ICP22 and ICP27, encoded by US1 and UL54, respectively, have each been implicated in transcriptional regulation (1,34,58,63,64); thus, it could be these proteins that mediated the long-term expression, either alone or in combination with pp71. To resolve whether this was the case, derivatives of in1312 with an additional deletion of US1 or UL54 were constructed.…”

Herpes simplex virus ICP27 regulates alternative pre-mRNA polyadenylation and splicing in a sequence-dependent manner

“…(ICP27), an immediate early (IE) gene (among those first expressed after virus enters the cells) that is required for expression of some early and late viral genes as well as for virus growth, is highly conserved between HSV-1 and -2, two closely related neurotropic herpesviruses (1). ICP27 has a role in transcriptional regulation through association with the C-terminal domain of RNA polymerase II (2,3), forms homodimers (4,5), interacts with U1 small nuclear ribonucleoprotein (snRNP) through its C-terminal domain, and colocalizes with U1 and U2 snRNPs (6,7). It also interacts with splicing factors such as SRSF3, SRSF1, SRSF7, and SRSF2 (8)(9)(10)(11), and is involved in nuclear export of some viral transcripts (12,13).…”