Purification, thioredoxin renaturation, and reconstituted activity of the three subunits of the influenza A virus RNA polymerase.

The virion-associated RNA polymerase and the structural nucleoprotein of influenza A virus were separated by sodium dodecyl sulfate/PAGE, electroblotted to a polyvinylidine membrane, and eluted with good recovery from the membrane. After renaturation by incubating with Escherichia coli thioredoxin, these proteins were active in a reconstituted in vitro transcription reaction with purified genomic RNAs. All four proteins (i.e., the three subunits of the RNA polymerase as well as the structural nucleoprotein) were required for activity. The RNA products were plus-strand, mRNA-sized species.