title: Herpes Simplex Virus 1 UL37 Protein Tyrosine Residues Conserved among All Alphaherpesviruses Are Required for Interactions with Glycoprotein K, Cytoplasmic Virion Envelopment, and Infectious Virus Production.
abstract: The herpes simplex virus 1 (HSV-1) UL37 protein functions in virion envelopment at trans-Golgi membranes, as well as in retrograde and anterograde transport of virion capsids. Recently, we reported that UL37 interacts with glycoprotein K (gK) and its interacting partner protein UL20 (N. Jambunathan, D. Chouljenko, P. Desai, A. S. Charles, R. Subramanian, V. N. Chouljenko, and K. G. Kousoulas, J Virol 88:5927-5935, 2014, http://dx.doi.org/10.1128/JVI.00278-14), facilitating cytoplasmic virion envelopment. Alignment of UL37 homologs encoded by alphaherpesviruses revealed the presence of highly conserved residues in the central portion of the UL37 protein. A cadre of nine UL37 site-specific mutations were produced and tested for their ability to inhibit virion envelopment and infectious virus production. Complementation analysis revealed that replacement of tyrosines 474 and 480 with alanine failed to complement the UL37-null virus, while all other mutated UL37 genes complemented the virus efficiently. The recombinant virus DC474-480 constructed with tyrosines 474, 476, 477, and 480 mutated to alanine residues produced a gK-null-like phenotype characterized by the production of very small plaques and accumulation of capsids in the cytoplasm of infected cells. Recombinant viruses having either tyrosine 476 or 477 replaced with alanine produced a wild-type phenotype. Immunoprecipitation assays revealed that replacement of all four tyrosines with alanines substantially reduced the ability of gK to interact with UL37. Alignment of HSV UL37 with the human cytomegalovirus and Epstein-Barr virus UL37 homologs revealed that Y480 was conserved only for alphaherpesviruses. Collectively, these results suggest that the UL37 conserved tyrosine 480 residue plays a crucial role in interactions with gK to facilitate cytoplasmic virion envelopment and infectious virus production.
  
  
  OBJECTIVE
  The HSV-1 UL37 protein is conserved among all herpesviruses, functions in both retrograde and anterograde transport of virion capsids, and plays critical roles in cytoplasmic virion envelopment by interacting with gK. We show here that UL37 tyrosine residues conserved among all alphaherpesviruses serve critical roles in cytoplasmic virion envelopment and interactions with gK.
authors.affiliation: Division of Biotechnology and Molecular Medicine and Department of Pathobiological Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, Louisiana, USA.
authors.forename: Dmitry V
authors.initials: DV
authors.lastname: Chouljenko
authors.affiliation: Division of Biotechnology and Molecular Medicine and Department of Pathobiological Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, Louisiana, USA.
authors.forename: Nithya
authors.initials: N
authors.lastname: Jambunathan
authors.affiliation: Division of Biotechnology and Molecular Medicine and Department of Pathobiological Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, Louisiana, USA.
authors.forename: Vladimir N
authors.initials: VN
authors.lastname: Chouljenko
authors.affiliation: Department of Biological Sciences, College of Basic Sciences, Louisiana State University, Baton Rouge, Louisiana, USA.
authors.forename: Misagh
authors.initials: M
authors.lastname: Naderi
authors.affiliation: Department of Biological Sciences, College of Basic Sciences, Louisiana State University, Baton Rouge, Louisiana, USA.|Center for Computation & Technology, Louisiana State University, Baton Rouge, Louisiana, USA.
authors.forename: Michal
authors.initials: M
authors.lastname: Brylinski
authors.affiliation: Division of Biotechnology and Molecular Medicine and Department of Pathobiological Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, Louisiana, USA.|Center for Computation & Technology, Louisiana State University, Baton Rouge, Louisiana, USA.
authors.forename: John R
authors.initials: JR
authors.lastname: Caskey
authors.affiliation: Division of Biotechnology and Molecular Medicine and Department of Pathobiological Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, Louisiana, USA vtgusk@lsu.edu.
authors.forename: Konstantin G
authors.initials: KG
authors.lastname: Kousoulas
mesh_terms: D000409:Alanine / Q000378:metabolism; D000818:Animals; D002213:Capsid / Q000378:metabolism; D002522:Chlorocebus aethiops; D003593:Cytoplasm / Q000378:metabolism; D006561:Herpes Simplex / Q000378:metabolism / Q000821:virology; D018259:Herpesvirus 1, Human / Q000378:metabolism*; D004854:Herpesvirus 4, Human / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D010641:Phenotype; D014443:Tyrosine / Q000378:metabolism; D014709:Vero Cells; D014764:Viral Proteins / Q000378:metabolism*; D015678:Viral Structural Proteins / Q000378:metabolism*; D014771:Virion / Q000378:metabolism
chemical_list: C084763:UL37 protein, Human herpesvirus 1; C072448:UL53 protein, Human herpesvirus 1; D014764:Viral Proteins; D015678:Viral Structural Proteins; D014443:Tyrosine; D000409:Alanine