HSV-1 infection induces a downstream shift of promoter-proximal pausing linked to H2A.Z-containing +1 nucleosomes
Herpes simplex virus 1 (HSV-1) infection exerts a profound shut-off of host gene expression at multiple levels. Recently, HSV-1 infection was reported to also impact promoter-proximal RNA Polymerase II (Pol II) pausing, a key step in the eukaryotic transcription cycle, with decreased and increased Pol II pausing observed for activated and repressed genes, respectively. Here, we demonstrate that HSV-1 infection induces more complex alterations in promoter-proximal pausing than previously suspected for the vast majority of cellular genes. While pausing is generally retained, it is shifted to more downstream and less well-positioned sites for most host genes. We exclude that this is an artefact of alternative de novo transcription initiation at downstream sites or read-in transcription originating from disruption of transcription termination for upstream genes. Use of downstream 2nd pause sites associated with +1 nucleosomes was previously observed upon NELF depletion. However, downstream shifts of Pol II pausing upon HSV-1 infection are much more pronounced than observed upon NELF depletion. Thus, our study reveals a novel aspect in which HSV-1 infection fundamentally reshapes host transcriptional processes with implications for our understanding of maintenance of promoter-proximal Pol II pausing in eukaryotic cells.