title: US3 of herpes simplex virus type 1 encodes a promiscuous protein kinase that phosphorylates and alters localization of lamin A/C in infected cells.
abstract: The herpes simplex virus type 1 (HSV-1) US3 gene encodes a serine/threonine kinase that, when inactivated, causes capsids to aggregate aberrantly between the inner and outer nuclear membranes (INM and ONM, respectively) within evaginations/extensions of the perinuclear space. In both Hep2 cells and an engineered cell line derived from Hep2 cells expressing lamin A/C fused to enhanced green fluorescent protein (eGFP-lamin A/C), lamin A/C localized mostly in a reticular pattern with small regions of the INM devoid of eGFP-lamin A/C when they were either mock infected or infected with wild-type HSV-1(F). Cells infected with HSV-1(F) also contained some larger diffuse regions lacking lamin A/C. Proteins UL31 and UL34, markers of potential envelopment sites at the INM and perinuclear virions, localized within the regions devoid of lamin A/C and also in regions containing lamin A/C. Similar to previous observations with Vero cells (S. L. Bjerke and R. J. Roller, Virology 347:261-276, 2006), the proteins UL34 and UL31 localized exclusively in very discrete regions of the nuclear lamina lacking lamin A/C in the absence of US3 kinase activity. To determine how US3 alters lamin A/C distribution, US3 was purified and shown to phosphorylate lamin A/C at multiple sites in vitro, despite the presence of only one putative US3 kinase consensus site in the lamin A/C sequence. US3 kinase activity was also sufficient to invoke partial solubilization of lamin A/C from permeabilized Hep2 cell nuclei in an ATP-dependent manner. Two-dimensional electrophoretic analyses of lamin A/C revealed that lamin A/C is phosphorylated in HSV-infected cells, and the full spectrum of phosphorylation requires US3 kinase activity. These data suggest that US3 kinase activity regulates HSV-1 capsid nuclear egress at least in part by phosphorylation of lamin A/C.
authors.affiliation: Department of Microbiology and Immunology, C5143 Veterinary Education Center, Cornell University, Ithaca, NY 14853, USA.
authors.forename: Fan
authors.initials: F
authors.lastname: Mou
authors.forename: Tom
authors.initials: T
authors.lastname: Forest
authors.forename: Joel D
authors.initials: JD
authors.lastname: Baines
mesh_terms: D000818:Animals; D016367:Baculoviridae / Q000378:metabolism; D002460:Cell Line; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000378:metabolism; D015180:Electrophoresis, Gel, Two-Dimensional; D015967:Gene Expression Regulation, Viral; D006801:Humans; D007313:Insecta; D034904:Lamin Type A / Q000737:chemistry*; D034882:Lamins / Q000737:chemistry; D008856:Microscopy, Fluorescence; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry* / Q000502:physiology*; D014764:Viral Proteins / Q000737:chemistry* / Q000502:physiology*
chemical_list: D034904:Lamin Type A; D034882:Lamins; D014764:Viral Proteins; C440308:lamin C; D017346:Protein Serine-Threonine Kinases; C095207:US3 protein, Human herpesvirus 1