title: Functional characterization of the essential tail anchor of the herpes simplex virus type 1 nuclear egress protein pUL34.
abstract: Release of herpes simplex virus type 1 (HSV-1) nucleocapsids from the host nucleus relies on the nuclear egress complex consisting of the two essential proteins pUL34 and pUL31. The cytoplasmically exposed N-terminal region of pUL34 interacts with pUL31, while a hydrophobic region followed by a short luminal part mediates membrane association. Based on its domain organization, pUL34 was postulated to be a tail-anchor (TA) protein. We performed a coupled in vitro transcription/translation assay to show that membrane insertion of pUL34 occurs post-translationally. Transient transfection and localization experiments in mammalian cells were combined with HSV-1 bacterial artificial chromosome mutagenesis to reveal the functional properties of the essential pUL34 TA. Our data show that a minimal tail length of 15 residues is sufficient for nuclear envelope targeting and pUL34 function. Permutations of the pUL34 TA with orthologous regions of human cytomegalovirus pUL50 or Epstein-Barr virus pBFRF1 as well as the heterologous HSV-1 TA proteins pUL56 or pUS9 or the cellular TA proteins Bcl-2 and Vamp2 revealed that nuclear egress tolerates TAs varying in sequence and hydrophobicity, while a non-α-helical membrane anchor failed to complement the pUL34 function. In conclusion, this study provides the first mechanistic insights into the particular role of the TA of pUL34 in membrane curving and capsid egress from the host nucleus.
authors.affiliation: Max von Pettenkofer-Institut, Ludwig-Maximilians-Universität München, Pettenkoferstr. 9a, 80336 München, Germany.
authors.forename: Melanie
authors.initials: M
authors.lastname: Ott
authors.affiliation: Technische Biochemie, Universität des Saarlandes, Saarbrücken, Germany.
authors.forename: Georg
authors.initials: G
authors.lastname: Tascher
authors.affiliation: Medizinische Biochemie und Molekularbiologie, Universität des Saarlandes, Homburg, Germany.
authors.forename: Sarah
authors.initials: S
authors.lastname: Haßdenteufel
authors.affiliation: Medizinische Biochemie und Molekularbiologie, Universität des Saarlandes, Homburg, Germany.
authors.forename: Richard
authors.initials: R
authors.lastname: Zimmermann
authors.affiliation: Division of Pathway Medicine, University of Edinburgh, UK.|Max von Pettenkofer-Institut, Ludwig-Maximilians-Universität München, Pettenkoferstr. 9a, 80336 München, Germany.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Haas
authors.affiliation: Max von Pettenkofer-Institut, Ludwig-Maximilians-Universität München, Pettenkoferstr. 9a, 80336 München, Germany.
authors.forename: Susanne M
authors.initials: SM
authors.lastname: Bailer
mesh_terms: D000818:Animals; D019084:Fluorescent Antibody Technique, Indirect / Q000379:methods; D017353:Gene Deletion; D018259:Herpesvirus 1, Human / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D009154:Mutation; D009685:Nuclear Envelope / Q000737:chemistry* / Q000378:metabolism / Q000821:virology*; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D010957:Plasmids; D014709:Vero Cells; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism*; D014779:Virus Replication
chemical_list: D009687:Nuclear Proteins; C403420:UL34 protein, Human herpesvirus 1; D014764:Viral Proteins