Nuclear import adenovirus DNA in vitro involves the nuclear protein importpathway and hsc70

Adenovirus, a respiratory virus with a double-stranded DNA genome, replicat es in the nuclei of mammalian cells. We have developed a cytosol-dependent in vitro assay utilizing adenovirus nucleocapsids to examine the requiremen ts for adenovirus docking to the nuclear pore complex and for DNA import in to the nucleus. Our assay reveals that adenovirus DNA import is blocked by a competitive excess of classical protein nuclear localization sequences an d other inhibitors of nuclear protein import and indicates that this proces s is dependent on hsc70, Previous work revealed that the hexon (coat) prote in of adenovirus is the only major protein on the surface of the adenovirus nucleocapsid that docks at the nuclear pore complex. This, together with o ur finding that in vitro nuclear import of hexon is inhibited by an excess of classical nuclear localization sequences, suggests a role for the hexon protein in adenovirus DNA import. However, recombinant transport factors th at are sufficient for hexon import in permeabilized cells do not support DN A import, indicating that there are other as yet unidentified factors requi red for this process.