title: Species specificity of the NS1 protein of influenza B virus: NS1 binds only human and non-human primate ubiquitin-like ISG15 proteins.
abstract: Influenza B viruses, which cause a highly contagious respiratory disease every year, are restricted to humans, but the basis for this restriction had not been determined. Here we provide one explanation for this restriction: the species specificity exhibited by the NS1 protein of influenza B virus (NS1B protein). This viral protein combats a major host antiviral response by binding the interferon-alpha/beta-induced, ubiquitin-like ISG15 protein and inhibiting its conjugation to an array of proteins. We demonstrate that the NS1B protein exhibits species-specific binding; it binds human and non-human primate ISG15 but not mouse or canine ISG15. In both transfection assays and virus-infected cells, the NS1B protein binds and relocalizes only human and non-human primate ISG15 from the cytoplasm to nuclear speckles. Human and non-human primate ISG15 proteins consist of two ubiquitin-like domains separated by a short hinge linker of five amino acids. Remarkably, this short hinge plays a large role in the species-specific binding by the NS1B protein. The hinge of human and non-human primate ISG15, which has a sequence that differs from that of other mammalian ISG15 proteins, including mouse and canine ISG15, is absolutely required for binding the NS1B protein. Consequently, the ISG15 proteins of humans and non-human primates are the only mammalian ISG15 proteins that would bind NS1B.
authors.affiliation: Institute for Cellular and Molecular Biology, Section of Molecular Genetics and Microbiology, University of Texas, Austin, Texas 78712, USA.
authors.forename: Haripriya
authors.initials: H
authors.lastname: Sridharan
authors.forename: Chen
authors.initials: C
authors.lastname: Zhao
authors.forename: Robert M
authors.initials: RM
authors.lastname: Krug
mesh_terms: D000818:Animals; D019556:COS Cells; D002467:Cell Nucleus / Q000378:metabolism / Q000821:virology; D002522:Chlorocebus aethiops; D016207:Cytokines / Q000378:metabolism*; D003593:Cytoplasm / Q000378:metabolism / Q000821:virology; D004285:Dogs; D006367:HeLa Cells; D006801:Humans; D009981:Influenza B virus / Q000276:immunology* / Q000378:metabolism; D007251:Influenza, Human / Q000276:immunology / Q000378:metabolism / Q000821:virology*; D007668:Kidney / Q000166:cytology; D051379:Mice; D009687:Nuclear Proteins / Q000276:immunology / Q000378:metabolism; D009976:Orthomyxoviridae Infections / Q000276:immunology / Q000378:metabolism / Q000821:virology*; D010455:Peptides; D011485:Protein Binding / Q000276:immunology; D016601:RNA-Binding Proteins; D014157:Transcription Factors / Q000276:immunology / Q000378:metabolism; D014452:Ubiquitins / Q000378:metabolism*; D017361:Viral Nonstructural Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*
chemical_list: D016207:Cytokines; C489550:G1p2 protein, mouse; C085820:INS1 protein, influenza virus; C114207:IVNS1ABP protein, human; D009687:Nuclear Proteins; D010455:Peptides; D016601:RNA-Binding Proteins; D014157:Transcription Factors; D014452:Ubiquitins; D017361:Viral Nonstructural Proteins; C120583:transfecting peptide I; C074034:ISG15 protein, human