title: The amino-terminal region of the neuraminidase protein from avian H5N1 influenza virus is important for its biosynthetic transport to the host cell surface.
abstract: Influenza virus neuraminidase (NA) is a major viral envelope glycoprotein, which plays a critical role in viral infection. Although NA functional domains have been determined previously, the precise role of the amino acids located at the N-terminus of avian H5N1 NA for protein expression and intracellular transport to the host plasma membrane is not fully understood. In the present study, a series of N-terminal truncation or deletion mutants of H5N1 NA were generated and their expression and intracellular trafficking were investigated. Protein expression from mutants NAΔ20, NAΔ35, NAΔ40, NAΔ7-20 and NAΔ7-35 was undetectable by immunoblotting and by performing NA activity assays. Mutants NAΔ6, NAΔ11 and NAΔ15-20 showed a marked decreased in protein expression, whereas mutants NAΔ7-15 and NAΔ15 displayed a slight increase in protein expression, compared with that of the native NA protein. These data suggest that amino acid residues 16-20 are vital for NA protein expression, while amino acids 7-15 might suppress NA protein expression. In deletion mutants NAΔ7-15 and NAΔ15 there was an accumulation of NA protein at the juxta-nuclear region, with reduced expression of NA at the cell surface. Although active Cdc42 could promote transport of wild-type NA to the host cell surface, this member of the Rho family of GTPases failed to regulate transport of mutants NAΔ7-15 and NAΔ15. The results of the study reveal that amino acid residues 7-15 of H5N1 NA are critical for its biosynthetic transport to the host cell surface.
authors.affiliation: Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China.
authors.forename: Guomin
authors.initials: G
authors.lastname: Qian
authors.affiliation: Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China.
authors.forename: Song
authors.initials: S
authors.lastname: Wang
authors.affiliation: College of Animal Science, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
authors.forename: Xiaojuan
authors.initials: X
authors.lastname: Chi
authors.affiliation: Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China.
authors.forename: Hua
authors.initials: H
authors.lastname: Li
authors.affiliation: Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China.
authors.forename: Haitao
authors.initials: H
authors.lastname: Wei
authors.affiliation: School of Life Sciences, Anhui University, Hefei 230601, China.
authors.forename: Xiaomei
authors.initials: X
authors.lastname: Zhu
authors.affiliation: Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China.
authors.forename: Yuhai
authors.initials: Y
authors.lastname: Chen
authors.affiliation: Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China; College of Animal Science, Fujian Agriculture and Forestry University, Fuzhou 350002, China. Electronic address: chenjl@im.ac.cn.
authors.forename: Ji-Long
authors.initials: JL
authors.lastname: Chen
mesh_terms: D000595:Amino Acid Sequence; D001692:Biological Transport; D053124:Influenza A Virus, H5N1 Subtype / Q000235:genetics* / Q000378:metabolism*; D009439:Neuraminidase / Q000235:genetics* / Q000378:metabolism; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017384:Sequence Deletion; D014764:Viral Proteins / Q000235:genetics* / Q000378:metabolism
chemical_list: D012333:RNA, Messenger; D014764:Viral Proteins; D009439:Neuraminidase
keywords: Avian influenza virus; Cdc42; H5N1; Neuraminidase; Protein intracellular transport