title: Essential role of protein kinase R antagonism by TRS1 in human cytomegalovirus replication.
abstract: Human cytomegalovirus (HCMV) lacking TRS1 and IRS1 (HCMV[ΔI/ΔT]) cannot replicate in cell culture. Although both proteins can block the protein kinase R (PKR) pathway, they have multiple other activities and binding partners. It remains unknown which functions are essential for HCMV replication. To investigate this issue, we first identified a TRS1 mutant that is unable to bind to PKR. Like HCMV[ΔI/ΔT], a recombinant HCMV containing this mutant (HCMV[TRS1-Mut 1]) did not replicate in wild-type cells. However, HCMV[ΔI/ΔT] did replicate in cells in which PKR expression was reduced by RNA interference. Moreover, HCMV[ΔI/ΔT] and HCMV[TRS1-Mut 1] replicated to similar levels as virus containing wild-type TRS1 in cell lines in which PKR expression was knocked out by CRISPR/Cas9-mediated genome editing. These results demonstrate that the sole essential function of TRS1 is to antagonize PKR and that its other activities do not substantially enhance HCMV replication, at least in cultured human fibroblasts.
authors.affiliation: Department of Microbiology, University of Washington Seattle, WA 98115, United States; Divisions of Human Biology and Clinical Research, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, United States. Electronic address: jbraggin@uw.edu.
authors.forename: Jacquelyn E
authors.initials: JE
authors.lastname: Braggin
authors.affiliation: Divisions of Human Biology and Clinical Research, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, United States. Electronic address: schild@fhcrc.org.
authors.forename: Stephanie J
authors.initials: SJ
authors.lastname: Child
authors.affiliation: Department of Microbiology, University of Washington Seattle, WA 98115, United States; Divisions of Human Biology and Clinical Research, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, United States; Department of Medicine, University of Washington, Seattle, WA 98115, United States. Electronic address: ageballe@fhcrc.org.
authors.forename: Adam P
authors.initials: AP
authors.lastname: Geballe
mesh_terms: D003587:Cytomegalovirus / Q000235:genetics / Q000502:physiology*; D003586:Cytomegalovirus Infections / Q000201:enzymology* / Q000235:genetics / Q000821:virology; D006367:HeLa Cells; D006801:Humans; D011485:Protein Binding; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism*; D014779:Virus Replication; D019892:eIF-2 Kinase / Q000235:genetics / Q000378:metabolism*
chemical_list: C072216:TRS1 protein, Human herpesvirus 5; D014764:Viral Proteins; D019892:eIF-2 Kinase
keywords: Cytomegalovirus; Double-stranded RNA; Host defense; IRS1; PKR; TRS1; Translation