Close but distinct regions of human herpesvirus 8 latency-associated nuclear antigen 1 are responsible for nuclear targeting and binding to human mitotic chromosomes.
Human herpesvirus 8 is associated with all forms of Kaposi's sarcoma, AIDS-associated body cavity-based lymphomas, and some forms of multicentric Castleman's disease. Herpesvirus 8, like other gammaherpesviruses, can establish a latent infection in which viral genomes are stably maintained as multiple episomes. The latent nuclear antigen (LANA or LNAI) may play an essential role in the stable maintenance of latent episomes, notably by interacting concomitantly with the viral genomes and the metaphase chromosomes, thus ensuring an efficient transmission of the neoduplicated episomes to the daughter cells. To identify the regions responsible for its nuclear and subnuclear localization in interphase and mitotic cells, LNAI and various truncated forms were fused to a variant of green fluorescent protein. This enabled their localization and chromosome binding activity to be studied by low-light-level fluorescence microscopy in living HeLa cells. The results demonstrate that nuclear localization of LNAI is due to a unique signal, which maps between amino acids 24 and 30. Interestingly, this nuclear localization signal closely resembles those identified in EBNA1 from Epstein-Barr virus and herpesvirus papio. A region encompassing amino acids 5 to 22 was further proved to mediate the specific interaction of LNA1 with chromatin during interphase and the chromosomes during mitosis. The presence of putative phosphorylation sites in the chromosome binding sites of LNA1 and EBNA1 suggests that their activity may be regulated by specific cellular kinases.
Service de Microbiologie-EA 2391, Hôpital Rothschild, 75571 Paris Cedex 12, France.
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Piolot
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Tramier
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Coppey
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Nicolas
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Marechal
D021581:Active Transport, Cell Nucleus; D000595:Amino Acid Sequence; D000956:Antigens, Viral; D001402:B-Lymphocytes; D001665:Binding Sites; D002467:Cell Nucleus / Q000378:metabolism*; D002877:Chromosomes, Human / Q000378:metabolism*; D019309:Epstein-Barr Virus Nuclear Antigens / Q000737:chemistry; D006367:HeLa Cells; D019288:Herpesvirus 8, Human / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008856:Microscopy, Fluorescence; D008938:Mitosis; D008969:Molecular Sequence Data; D019913:Nuclear Localization Signals / Q000235:genetics / Q000502:physiology; D009687:Nuclear Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins; D016415:Sequence Alignment; D017384:Sequence Deletion; D014407:Tumor Cells, Cultured; D014764:Viral Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
D000956:Antigens, Viral; D019309:Epstein-Barr Virus Nuclear Antigens; D019913:Nuclear Localization Signals; D009687:Nuclear Proteins; D011993:Recombinant Fusion Proteins; D014764:Viral Proteins; C109540:latency-associated nuclear antigen; C417029:EBV-encoded nuclear antigen 1