Cellular Nuclear Export Factors TAP and Aly Are Required for HDAg-L-mediated Assembly of Hepatitis Delta Virus.
Hepatitis delta virus (HDV) is a satellite virus of hepatitis B virus (HBV). HDV genome encodes two forms of hepatitis delta antigen (HDAg), small HDAg (HDAg-S), which is required for viral replication, and large HDAg (HDAg-L), which is essential for viral assembly. HDAg-L is identical to HDAg-S except that it bears a 19-amino acid extension at the C terminus. Both HDAgs contain a nuclear localization signal (NLS), but only HDAg-L contains a CRM1-independent nuclear export signal at its C terminus. The nuclear export activity of HDAg-L is important for HDV particle formation. However, the mechanisms of HDAg-L-mediated nuclear export of HDV ribonucleoprotein are not clear. In this study, the host cellular RNA export complex TAP-Aly was found to form a complex with HDAg-L, but not with an export-defective HDAg-L mutant, in which Pro205was replaced by Ala. HDAg-L was found to colocalize with TAP and Aly in the nucleus. The C-terminal domain of HDAg-L was shown to directly interact with the N terminus of TAP, whereas an HDAg-L mutant lacking the NLS failed to interact with full-length TAP. In addition, small hairpin RNA-mediated down-regulation of TAP or Aly reduced nuclear export of HDAg-L and assembly of HDV virions. Furthermore, a peptide, TAT-HDAg-L(198-210), containing the 10-amino acid TAT peptide and HDAg-L(198-210), inhibited the interaction between HDAg-L and TAP and blocked HDV virion assembly and secretion. These data demonstrate that formation and release of HDV particles are mediated by TAP and Aly.
From the Department of Applied Science, National Hsinchu University of Education, Hsinchu 30014.
Hsiu-Chen
HC
Huang
the School of Nursing, National Taipei University of Nursing and Health Sciences, Taipei 11219.
Chung-Pei
CP
Lee
the National Research Institute of Chinese Medicine, Ministry of Health and Welfare, Taipei 11221.|the Ph.D Program for Clinical Drug Discovery from Botanical Herbs, Taipei Medical University, Taipei 11031.
Hui-Kang
HK
Liu
the Institute of Biochemistry and Molecular Biology, National Taiwan University College of Medicine, Taipei 10051.
Ming-Fu
MF
Chang
the Department of Chemistry, Chinese Culture University, Taipei 11114.
Yu-Heng
YH
Lai
the Center of Translational Medicine, Taipei Medical University, Taipei 11031.|the Ph.D. Program for Medical Biotechnology, College of Medical Science and Technology, Taipei Medical University, Taipei 11031, and.
Yu-Ching
YC
Lee
the National Research Institute of Chinese Medicine, Ministry of Health and Welfare, Taipei 11221, chengh@nricm.edu.tw.|the Department of Earth and Life Sciences, University of Taipei, Taipei 10048, Taiwan.
Cheng
C
Huang
D018528:ATP-Binding Cassette Transporters / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D021581:Active Transport, Cell Nucleus / Q000187:drug effects / Q000235:genetics; D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism* / Q000821:virology; D056945:Hep G2 Cells; D003698:Hepatitis Delta Virus / Q000502:physiology*; D035923:Hepatitis delta Antigens / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D019913:Nuclear Localization Signals / Q000235:genetics / Q000378:metabolism*; D009687:Nuclear Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D010455:Peptides / Q000494:pharmacology; D000072417:Protein Domains; D016601:RNA-Binding Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D014771:Virion / Q000235:genetics / Q000378:metabolism*; D019065:Virus Assembly / Q000187:drug effects / Q000502:physiology*
C105242:ALYREF protein, human; D018528:ATP-Binding Cassette Transporters; D035923:Hepatitis delta Antigens; D019913:Nuclear Localization Signals; D009687:Nuclear Proteins; D010455:Peptides; D016601:RNA-Binding Proteins; D014157:Transcription Factors; C477327:transporter associated with antigen processing (TAP)
Aly; TAP; hepatitis delta antigen; hepatitis virus; nuclear export factor; nuclear transport; protein translocation; viral replication; virus assembly