Adenovirus core protein pVII is translocated into the nucleus by multiple import receptor pathways.
Adenoviruses are nonenveloped viruses with an approximately 36-kb double-stranded DNA genome that replicate in the nucleus. Protein VII, an abundant structural component of the adenovirus core that is strongly associated with adenovirus DNA, is imported into the nucleus contemporaneously with the adenovirus genome shortly after virus infection and may promote DNA import. In this study, we evaluated whether protein VII uses specific receptor-mediated mechanisms for import into the nucleus. We found that it contains potent nuclear localization signal (NLS) activity by transfection of cultured cells with protein VII fusion constructs and by microinjection of cells with recombinant protein VII fusions. We identified three NLS-containing regions in protein VII by deletion mapping and determined important NLS residues by site-specific mutagenesis. We found that recombinant protein VII and its NLS-containing domains strongly and specifically bind to importin alpha, importin beta, importin 7, and transportin, which are among the most abundant cellular nuclear import receptors. Moreover, these receptors can mediate the nuclear import of protein VII fusions in vitro in permeabilized cells. Considered together, these data support the hypothesis that protein VII is a major NLS-containing adaptor for receptor-mediated import of adenovirus DNA and that multiple import pathways are utilized to promote efficient nuclear entry of the viral genome.
Wodrich
Harald
H
Institut de Génétique Moléculaire de Montpellier, UMR 5535 CNRS, 1919 Route de Mende, 34293 Montpellier Cedex 05, France. harald.wodrich@igmm.cnrs.fr
Cassany
Aurelia
A
D'Angelo
Maximiliano A
MA
Guan
Tinglu
T
Nemerow
Glen
G
Gerace
Larry
L
D021581:Active Transport, Cell Nucleus; D000256:Adenoviridae / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D002460:Cell Line; D002522:Chlorocebus aethiops; D003600:Cytosol / Q000378:metabolism; D006801:Humans; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D019913:Nuclear Localization Signals; D011485:Protein Binding; D014758:Viral Core Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
D019913:Nuclear Localization Signals; D014758:Viral Core Proteins