December 12, 2003
Multifunctional protein VI
Adenovirus is a small DNA virus that replicates its genome and assembles new virus particles inside the nucleus of the host cell. One of the viral capsid proteins, protein VI, has near its C terminus both nuclear localization signal (NLS) and nuclear export signal (NES).The major adenovirus capsid protein (hexon) is produced in the cytosol and so must be imported into the nucleus for virus particle assembly. Protein VI binds to it, and carries hexon molecules into the nucleus, using its NLS to hitch a ride on the host nuclear importers, and then return empty-handed to the cytosol via its NES-exporter interaction.
When capsid proteins are sufficiently concentrated in the nucleus to allow for efficient virus assembly, both nuclear transport signals in protein VI are degraded by proteolysis, trapping the protein in the nucleus and uncovering its third function as a structural component of the capsid itself. Pretty nifty for a small protein with about 225 residues.
The complete article can be found at EMBO Journal, 22, 6245 (2003).
Posted by Parag at December 12, 2003 10:40 AM | TrackBack
