title: Characterization of the nucleocytoplasmic shuttle of the matrix protein of influenza B virus.
abstract: Influenza B virus is an enveloped negative-strand RNA virus that contributes considerably to annual influenza illnesses in human. The matrix protein of influenza B virus (BM1) acts as a cytoplasmic-nuclear shuttling protein during the early and late stages of infection. The mechanism of this intracellular transport of BM1 was revealed through the identification of two leucine-rich CRM1-dependent nuclear export signals (NESs) (3 to 14 amino acids [aa] and 124 to 133 aa), one bipartite nuclear localization signal (NLS) (76 to 94 aa), and two phosphorylation sites (80T and 84S) in BM1. The biological function of the NLS and NES regions were determined through the observation of the intracellular distribution of enhanced green fluorescent protein (EGFP)-tagged signal peptides, and wild-type, NES-mutant, and NLS-mutant EGFP-BM1. Furthermore, the NLS phosphorylation sites 80T and 84S, were found to be required for the nuclear accumulation of EGFP-NLS and for the efficient binding of EGFP-BM1 to human importin-α1. Moreover, all of these regions/sites were required for the generation of viable influenza B virus in a 12-plasmid virus rescue system.
  
  
  OBJECTIVE
  This study expands our understanding of the life cycle of influenza B virus by defining the dynamic mechanism of the nucleocytoplasmic shuttle of BM1 and could provide a scientific basis for the development of antiviral medication.
authors.affiliation: Center for Molecular Virology, CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.
authors.forename: Shuai
authors.initials: S
authors.lastname: Cao
authors.affiliation: Center for Molecular Virology, CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China School of Life Sciences, University of Science and Technology of China, Hefei, China.
authors.forename: Jingwen
authors.initials: J
authors.lastname: Jiang
authors.affiliation: Center for Molecular Virology, CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Li
authors.affiliation: Center for Molecular Virology, CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Li
authors.affiliation: Center for Molecular Virology, CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.
authors.forename: Limin
authors.initials: L
authors.lastname: Yang
authors.affiliation: Center for Molecular Virology, CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.
authors.forename: Shanshan
authors.initials: S
authors.lastname: Wang
authors.affiliation: Center for Molecular Virology, CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.
authors.forename: Jinghua
authors.initials: J
authors.lastname: Yan
authors.affiliation: Center for Molecular Virology, CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China School of Life Sciences, University of Science and Technology of China, Hefei, China Graduate University of Chinese Academy of Sciences, Beijing, China China-Japan Joint Laboratory of Molecular Immunology and Molecular Microbiology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China Research Network of Immunity and Health, Beijing Institutes of Life Science, Chinese Academy of Sciences, Beijing, China Office of Director-General, Chinese Center for Disease Control and Prevention, Beijing, China.
authors.forename: George F
authors.initials: GF
authors.lastname: Gao
authors.affiliation: Center for Molecular Virology, CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China School of Life Sciences, University of Science and Technology of China, Hefei, China Graduate University of Chinese Academy of Sciences, Beijing, China China-Japan Joint Laboratory of Molecular Immunology and Molecular Microbiology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China liuwj@im.ac.cn.
authors.forename: Wenjun
authors.initials: W
authors.lastname: Liu
mesh_terms: D021581:Active Transport, Cell Nucleus / Q000502:physiology*; D000595:Amino Acid Sequence; D002467:Cell Nucleus / Q000378:metabolism; D002853:Chromatography, Liquid; D003593:Cytoplasm / Q000378:metabolism; D019084:Fluorescent Antibody Technique, Indirect; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D009981:Influenza B virus / Q000502:physiology*; D007251:Influenza, Human / Q000378:metabolism* / Q000821:virology; D028884:Karyopherins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D019913:Nuclear Localization Signals / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation; D010957:Plasmids / Q000235:genetics; D018160:Receptors, Cytoplasmic and Nuclear / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D053719:Tandem Mass Spectrometry; D014763:Viral Matrix Proteins / Q000235:genetics / Q000378:metabolism*; D014779:Virus Replication / Q000502:physiology; D000097606:Exportin 1 Protein
chemical_list: D049452:Green Fluorescent Proteins; D028884:Karyopherins; D019913:Nuclear Localization Signals; D018160:Receptors, Cytoplasmic and Nuclear; D011993:Recombinant Fusion Proteins; D014763:Viral Matrix Proteins; D000097606:Exportin 1 Protein; C545845:M1 matrix protein, influenza B virus; C485184:enhanced green fluorescent protein
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