The bovine papillomavirus type 1 E2 transactivator and repressor proteins use different nuclear localization signals.
The E2 gene of bovine papillomavirus type 1 encodes at least three nuclear phosphoproteins that regulate viral transcription and DNA replication. All three proteins have a common C-terminal domain that has DNA-binding and dimerization activities. A basic region in this domain forms an alpha helix which makes direct contact with the DNA target. In this study, it is shown that in addition to its role in DNA binding, this basic region functions as a nuclear localization signal both in the E2 DNA-binding domain and in a heterologous protein. Deletion of this signal sequence resulted in increased accumulation of the E2 transactivator and repressor proteins in the cytoplasm, but nuclear localization was not eliminated. In the full-length transactivator protein, another signal, present in the N-terminal transactivation domain, is used for transport to the nucleus, and the C-terminal nuclear localization signal(s) are masked. The use of different nuclear localization signals could potentially allow differential regulation of the subcellular localization of the E2 transactivator and repressor proteins at some stage in the viral life cycle.
Skiadopoulos
M H
MH
Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892-0455, USA.
McBride
A A
AA
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D001692:Biological Transport; D052688:Bovine papillomavirus 1 / Q000378:metabolism*; D002417:Cattle; D002460:Cell Line; D002467:Cell Nucleus / Q000821:virology; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D019084:Fluorescent Antibody Technique, Indirect; D008969:Molecular Sequence Data; D010455:Peptides / Q000378:metabolism; D021382:Protein Sorting Signals / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism*; D012097:Repressor Proteins / Q000378:metabolism*; D017384:Sequence Deletion; D015534:Trans-Activators / Q000378:metabolism*; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism*; D001616:beta-Galactosidase / Q000378:metabolism
D004268:DNA-Binding Proteins; C051550:E2 protein, Bovine papillomavirus; D010455:Peptides; D021382:Protein Sorting Signals; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; D015534:Trans-Activators; D014764:Viral Proteins; D001616:beta-Galactosidase