title: Occupancy of RNA Polymerase II Phosphorylated on Serine 5 (RNAP S5P) and RNAP S2P on Varicella-Zoster Virus Genes 9, 51, and 66 Is Independent of Transcript Abundance and Polymerase Location within the Gene.
abstract: Regulation of gene transcription in varicella-zoster virus (VZV), a ubiquitous human neurotropic alphaherpesvirus, requires coordinated binding of multiple host and virus proteins onto specific regions of the virus genome. Chromatin immunoprecipitation (ChIP) is widely used to determine the location of specific proteins along a genomic region. Since the size range of sheared virus DNA fragments governs the limit of accurate protein localization, particularly for compact herpesvirus genomes, we used a quantitative PCR (qPCR)-based assay to determine the efficiency of VZV DNA shearing before ChIP, after which the assay was used to determine the relationship between transcript abundance and the occupancy of phosphorylated RNA polymerase II (RNAP) on the gene promoter, body, and terminus of VZV genes 9, 51, and 66. The abundance of VZV gene 9, 51, and 66 transcripts in VZV-infected human fetal lung fibroblasts was determined by reverse transcription-linked quantitative PCR. Our results showed that the C-terminal domain of RNAP is hyperphosphorylated at serine 5 (S5(P)) on VZV genes 9, 51, and 66 independently of transcript abundance and the location within the virus gene at both 1 and 3 days postinfection (dpi). In contrast, phosphorylated serine 2 (S2(P))-modified RNAP was not detected at any virus gene location at 3 dpi and was detected at levels only slightly above background levels at 1 dpi.
  
  
  OBJECTIVE
  Regulation of herpesvirus gene transcription is an elaborate choreography between proteins and DNA that is revealed by chromatin immunoprecipitation (ChIP). We used a quantitative PCR-based assay to determine fragment size after DNA shearing, a critical parameter in ChIP assays, and exposed a basic difference in the mechanism of transcription between mammalian cells and VZV. We found that hyperphosphorylation at serine 5 of the C-terminal domain of RNAP along the lengths of VZV genes (the promoter, body, and transcription termination site) was independent of mRNA abundance. In contrast, little to no enrichment of serine 3 phosphorylation of RNAP was detected at these virus gene regions. This is distinct from the findings for RNAP at highly regulated host genes, where RNAP S5(P) occupancy decreased and S2(P) levels increased as the polymerase transited through the gene. Overall, these results suggest that RNAP associates with human and virus transcriptional units through different mechanisms.
authors.affiliation: Center for Math & Science, Community College of Denver, Denver, Colorado, USA.
authors.forename: Heather H
authors.initials: HH
authors.lastname: Henderson
authors.affiliation: Department of Integrative Biology, University of Colorado Denver, Denver, Colorado, USA.
authors.forename: Kensey B
authors.initials: KB
authors.lastname: Timberlake
authors.affiliation: Department of Integrative Biology, University of Colorado Denver, Denver, Colorado, USA.
authors.forename: Zoe A
authors.initials: ZA
authors.lastname: Austin
authors.affiliation: Department of Neurology, University of Colorado School of Medicine, Aurora, Colorado, USA.
authors.forename: Hussain
authors.initials: H
authors.lastname: Badani
authors.affiliation: Department of Neurology, University of Colorado School of Medicine, Aurora, Colorado, USA.
authors.forename: Bridget
authors.initials: B
authors.lastname: Sanford
authors.affiliation: Department of Neurology, University of Colorado School of Medicine, Aurora, Colorado, USA.
authors.forename: Keriann
authors.initials: K
authors.lastname: Tremblay
authors.affiliation: Department of Neurology, University of Colorado School of Medicine, Aurora, Colorado, USA.
authors.forename: Nicholas L
authors.initials: NL
authors.lastname: Baird
authors.affiliation: Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, Colorado, USA.
authors.forename: Kenneth
authors.initials: K
authors.lastname: Jones
authors.affiliation: Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado, USA.
authors.forename: Joel
authors.initials: J
authors.lastname: Rovnak
authors.affiliation: School of Biological Sciences, University of Northern Colorado, Greeley, Colorado, USA.
authors.forename: Seth
authors.initials: S
authors.lastname: Frietze
authors.affiliation: Department of Neurology, University of Colorado School of Medicine, Aurora, Colorado, USA Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, Colorado, USA.
authors.forename: Don
authors.initials: D
authors.lastname: Gilden
authors.affiliation: Department of Neurology, University of Colorado School of Medicine, Aurora, Colorado, USA Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, Colorado, USA randall.cohrs@ucdenver.edu.
authors.forename: Randall J
authors.initials: RJ
authors.lastname: Cohrs
mesh_terms: D002478:Cells, Cultured; D047369:Chromatin Immunoprecipitation; D004279:DNA, Viral / Q000737:chemistry*; D005347:Fibroblasts / Q000821:virology; D014645:Herpesvirus 3, Human / Q000502:physiology*; D006801:Humans; D010766:Phosphorylation; D011499:Protein Processing, Post-Translational; D012319:RNA Polymerase II / Q000032:analysis*; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014158:Transcription, Genetic
chemical_list: D004279:DNA, Viral; D012319:RNA Polymerase II