Nuclear import of hepatitis B virus capsids and release of the viral genome.
While studying the import of the hepatitis B virus genome into the nucleus of permeabilized tissue culture cells, we found that viral capsids were imported in intact form through the nuclear pore into the nuclear basket. Import depended on phosphorylation of the capsid protein and was mediated by the cellular transport receptors importin alpha and beta. Virus-derived capsids that contained the mature viral genome were able to release the viral DNA and capsid protein into the nucleoplasm. The uncoating reaction was independent of Ran, a GTP-binding enzyme responsible for dissociating other imported cargo from the inner face of the nuclear pore. Immature capsids that did not contain the mature viral genome reached the basket but did not release capsid proteins nor immature genomes into the nucleoplasm. The different fate of mature and immature capsids after passing the nuclear pore indicates that the outcome of a nuclear import event may be regulated within the nuclear basket.
Rabe
Birgit
B
Institute of Medical Virology, Frankfurter Strasse 107, D-35392 Giessen, Germany.
Vlachou
Angelika
A
Panté
Nelly
N
Helenius
Ari
A
Kann
Michael
M
D021581:Active Transport, Cell Nucleus; D036022:Capsid Proteins / Q000737:chemistry / Q000502:physiology*; D002460:Cell Line; D002467:Cell Nucleus / Q000821:virology; D004279:DNA, Viral / Q000235:genetics / Q000378:metabolism; D016679:Genome, Viral; D006515:Hepatitis B virus / Q000235:genetics* / Q000472:pathogenicity / Q000502:physiology*; D006801:Humans; D010766:Phosphorylation; D028901:alpha Karyopherins / Q000378:metabolism; D028961:beta Karyopherins / Q000378:metabolism; D020931:ran GTP-Binding Protein / Q000378:metabolism
D036022:Capsid Proteins; D004279:DNA, Viral; D028901:alpha Karyopherins; D028961:beta Karyopherins; D020931:ran GTP-Binding Protein