Features of Nuclear Export Signals of NS2 Protein of Influenza D Virus
Lingcai Zhao,
Huizhi Xia,
Jingjin Huang,
Yiqing Zheng,
Chang Liu,
Juan Su,
Jihui Ping
Affiliations
Lingcai Zhao
MOE Joint International Research Laboratory of Animal Health and Food Safety, Engineering Laboratory of Animal Immunity of Jiangsu Province, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China
Huizhi Xia
MOE Joint International Research Laboratory of Animal Health and Food Safety, Engineering Laboratory of Animal Immunity of Jiangsu Province, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China
Jingjin Huang
MOE Joint International Research Laboratory of Animal Health and Food Safety, Engineering Laboratory of Animal Immunity of Jiangsu Province, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China
Yiqing Zheng
MOE Joint International Research Laboratory of Animal Health and Food Safety, Engineering Laboratory of Animal Immunity of Jiangsu Province, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China
Chang Liu
MOE Joint International Research Laboratory of Animal Health and Food Safety, Engineering Laboratory of Animal Immunity of Jiangsu Province, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China
Juan Su
MOE Joint International Research Laboratory of Animal Health and Food Safety, Engineering Laboratory of Animal Immunity of Jiangsu Province, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China
Jihui Ping
MOE Joint International Research Laboratory of Animal Health and Food Safety, Engineering Laboratory of Animal Immunity of Jiangsu Province, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China
Emerging influenza D viruses (IDVs), the newest member in the genus Orthomyxovirus family, which can infect and transmit in multiple mammalian species as its relatives the influenza A viruses (IAVs). Additional studies of biological characteristics of IDVs are needed; here, we studied the characteristics of IDV nonstructural protein 2 (NS2), which shares the lowest homology to known influenza proteins. First, we generated reassortant viruses via reverse genetics to analyze the segment compatibility and gene interchangeability between IAVs and IDVs. Next, we investigated the locations and exact sequences of nuclear export signals (NESs) of the IDV NS2 protein. Surprisingly, three separate NES regions were found to contribute to the nuclear export of an eGFP fusion protein. Alanine scanning mutagenesis identified critical amino acid residues within each NES, and co-immunoprecipitation experiments demonstrated that their nuclear export activities depend on the CRM1-mediated pathway, particularly for the third NES (136-146aa) of IDV NS2. Interestingly, the third NES was important for the interaction of NS2 protein with CRM1. The findings in this study contribute to the understanding of IDV NS2 protein’s role during nucleocytoplasmic transport of influenza viral ribonucleoprotein complexes (vRNPs) and will also facilitate the development of novel anti-influenza drugs targeting nuclear export signals of IDV NS2 protein.
