title: Characterization of the nuclear export signal in the coronavirus infectious bronchitis virus nucleocapsid protein.
abstract: The nucleocapsid (N) protein of infectious bronchitis virus (IBV) localizes to the cytoplasm and nucleolus and contains an eight-amino-acid nucleolar retention motif. In this study, a leucine-rich nuclear export signal (NES) (291-LQLDGLHL-298) present in the C-terminal region of the IBV N protein was analyzed by using alanine substitution and deletion mutagenesis to investigate the relative contributions that leucine residues make to nuclear export and where these residues are located on the structure of the IBV N protein. The analysis indicated that Leu296 and Leu298 are required for efficient nuclear export of the protein. Structural information indicated that both of these amino acids are available for interaction with protein complexes involved in this process. However, export of N protein from the nucleus/nucleolus was not inhibited by leptomycin B treatment, indicating that N protein nuclear export is independent of the CRM1-mediated export pathway.
authors.affiliation: Institute of Molecular and Cellular Biology, Faculty of Biology Sciences, Garstang Building, University of Leeds, Leeds LS2 6JT, United Kingdom.
authors.forename: Mark L
authors.initials: ML
authors.lastname: Reed
authors.forename: Gareth
authors.initials: G
authors.lastname: Howell
authors.forename: Sally M
authors.initials: SM
authors.lastname: Harrison
authors.forename: Kelly-Anne
authors.initials: KA
authors.lastname: Spencer
authors.forename: Julian A
authors.initials: JA
authors.lastname: Hiscox
mesh_terms: D019943:Amino Acid Substitution; D000818:Animals; D002522:Chlorocebus aethiops; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005231:Fatty Acids, Unsaturated / Q000494:pharmacology; D001351:Infectious bronchitis virus / Q000502:physiology*; D028884:Karyopherins / Q000187:drug effects; D008856:Microscopy, Fluorescence; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D049790:Nuclear Export Signals; D019590:Nucleocapsid Proteins / Q000235:genetics* / Q000378:metabolism*; D018160:Receptors, Cytoplasmic and Nuclear / Q000187:drug effects; D017384:Sequence Deletion; D014709:Vero Cells; D000097606:Exportin 1 Protein
chemical_list: D004791:Enzyme Inhibitors; D005231:Fatty Acids, Unsaturated; D028884:Karyopherins; D049790:Nuclear Export Signals; D019590:Nucleocapsid Proteins; D018160:Receptors, Cytoplasmic and Nuclear; D000097606:Exportin 1 Protein; C038753:leptomycin B