Novel nuclear export signal-interacting protein, NESI, critical for the assembly of hepatitis delta virus.
The process of host factor-mediated nucleocytoplasmic transport is critical for diverse cellular events in eukaryotes and the life cycle of viruses. We have previously identified a chromosome region maintenance 1-independent nuclear export signal (NES) at the C terminus of the large form of hepatitis delta antigen (HDAg), designated NES(HDAg-L) that is required for the assembly of hepatitis delta virus (HDV) (C.-H. Lee et al., J. Biol. Chem. 276:8142-8148, 2001). To look for interacting proteins of the NES(HDAg-L), yeast two-hybrid screening was applied using the GAL4-binding domain fused to the NES(HDAg-L) as bait. Among the positive clones, one encodes a protein, designated NESI [NES(HDAg-L) interacting protein] that specifically interacted with the wild-type NES(HDAg-L) but not with the export/package-defective HDAg-L mutant, NES*(HDAg-L), in which Pro-205 has been replaced by Ala. Northern blot analysis revealed NESI as the gene product of a 1.9-kb endogenous mRNA transcript that is present predominantly in human liver tissue. NESI consists of 467 amino acid residues and bears a putative actin-binding site and a bipartite nuclear localization signal. Specific interaction between HDAg-L and NESI was further confirmed by coimmunoprecipitation and immunofluorescence staining. Overexpression of antisense NESI RNAs inhibited the expression of NESI and abolished HDAg-L-mediated nuclear export and assembly of HDV genomic RNA. These data indicate a critical role of NESI in the assembly of HDV through interaction with HDAg-L.
Wang
Yun-Hsin
YH
Institute of Biochemistry and Molecular Biology, National Taiwan University College of Medicine, No. 1, Jen-Ai Road, First Section, Taipei 100, Taiwan.
Chang
Shin C
SC
Huang
Cheng
C
Li
Ya-Ping
YP
Lee
Chia-Huei
CH
Chang
Ming-Fu
MF
D000199:Actins / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D017931:DNA Primers; D003698:Hepatitis Delta Virus / Q000502:physiology*; D035923:Hepatitis delta Antigens / Q000502:physiology; D006801:Humans; D008099:Liver / Q000821:virology; D008840:Microfilament Proteins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D029543:Nucleocytoplasmic Transport Proteins; D010957:Plasmids; D016133:Polymerase Chain Reaction; D021381:Protein Transport; D012367:RNA, Viral / Q000235:genetics; D014158:Transcription, Genetic; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism*; D014779:Virus Replication
D000199:Actins; D017931:DNA Primers; D035923:Hepatitis delta Antigens; C502888:LMBRD1 protein, human; D008840:Microfilament Proteins; D029543:Nucleocytoplasmic Transport Proteins; D012367:RNA, Viral; D014764:Viral Proteins