Researchers from the European Molecular Biology Laboratory
(EMBL) in Grenoble, France have determined the detailed
3-dimensional structure of part of the flu virus RNA polymerase,
an enzyme that is crucial for influenza virus replication. The
scientists focused on the endonuclease part of the viral RNA
polymerase which is responsible for a unique mechanism called
'cap-snatching' that allows the virus to trick its host cell
into producing viral proteins. In human cells the translation of
messenger RNA (mRNA) strands into proteins requires a special
structure, called the cap, at the beginning of each mRNA. When
the influenza virus infects a host cell its endonuclease
"snatches" that cap from the cell's own mRNA. Another part of
its RNA polymerase then uses it as the starting point for
synthesising viral mRNA. With the correct cap structure at the
beginning, viral mRNA can then hijack the protein-production
machinery of the infected cell to make viral proteins, which
assemble into new viruses that will spread th