title: Nuclear trafficking of the human cytomegalovirus pp71 (ppUL82) tegument protein.
abstract: The human cytomegalovirus tegument protein pp71 localizes to the nucleus immediately upon infection, and functions to initiate viral gene expression. Analysis of a series of random insertion mutations revealed that sequences within the mid region (MR) of pp71 are important for localization to the nucleus. Fusion of MR sequences with eGFP revealed that amino acids 94 to 300 were sufficient to target proteins to the nucleus. Random substitution mutagenesis within this domain resulted in two double substitution mutants, pp71P203T/T223M and pp71T228M/L275Q, with a predominantly cytoplasmic localization. Disruption of nuclear targeting resulted in relocalization of the fusion proteins to a distinct perinuclear region. Using tandem mass spectrometry, we determined that threonine 223 can be phosphorylated. Mutation of this residue to a phosphomimetic amino acid resulted in abrogation of nuclear targeting. These results strongly suggest that the intracellular trafficking of pp71 is regulated by phosphorylation.
authors.affiliation: Department of Microbiology and Molecular Cell Biology, Eastern Virginia Medical School, Norfolk, VA 23507, USA.
authors.forename: Weiping
authors.initials: W
authors.lastname: Shen
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Westgard
authors.forename: Liqun
authors.initials: L
authors.lastname: Huang
authors.forename: Michael D
authors.initials: MD
authors.lastname: Ward
authors.forename: Jodi L
authors.initials: JL
authors.lastname: Osborn
authors.forename: Nha H
authors.initials: NH
authors.lastname: Chau
authors.forename: Lindsay
authors.initials: L
authors.lastname: Collins
authors.forename: Benjamin
authors.initials: B
authors.lastname: Marcum
authors.forename: Margaret A
authors.initials: MA
authors.lastname: Koach
authors.forename: Jennifer
authors.initials: J
authors.lastname: Bibbs
authors.forename: O John
authors.initials: OJ
authors.lastname: Semmes
authors.forename: Julie A
authors.initials: JA
authors.lastname: Kerry
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution / Q000235:genetics; D019677:Artificial Gene Fusion; D002467:Cell Nucleus / Q000737:chemistry*; D003587:Cytomegalovirus / Q000502:physiology*; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D020125:Mutation, Missense; D019913:Nuclear Localization Signals; D010766:Phosphorylation; D021381:Protein Transport; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D053719:Tandem Mass Spectrometry; D013912:Threonine / Q000378:metabolism; D014763:Viral Matrix Proteins / Q000737:chemistry / Q000378:metabolism*
chemical_list: D019913:Nuclear Localization Signals; D011993:Recombinant Fusion Proteins; D014763:Viral Matrix Proteins; C047015:cytomegalovirus matrix protein, pp 64-69; D049452:Green Fluorescent Proteins; D013912:Threonine