RNA-POLYMERASE OF INFLUENZA-VIRUS .11. PURIFICATION AND MOLECULAR-STRUCTURE OF RNA-POLYMERASE FROM INFLUENZA VIRUS-A/PR8

The RNA-dependent RNA polymerase of influenza virus A/PR/8 was isolated from virus particles by stepwise centrifugation in cesium salts. First, RNP (viral RNA-NP-P proteins) complexes were isolasgted by glycerol gradient centrifugation of detergent-treated viruses and subsequently NP was dissociated from RNP by cesium chloride gradient centrifugation. The P-RNA (P proteins-viral RNA) complexes were further dissociated into P proteins and virasl RNA by cesium trifluoroacetate (CsTFA) gradient centrifugation The nature of P proteins was further analyzed by glycerol gradient centrifugation and immunobloting using monospecific antibodies against each P protein. The three P proteins, PB1, PB2, and PA, sedimented altogether as fast as the marker protein with the molecular weight of about 250, 000 Da. Upon addition of the template vRNA, the RNA-free P protein complex exhibited the activities of capped RNA cleavage and limited RNA synthesis. When a cell line stably expressing cDNAs for three P proteins and NP protein was examined, the three P proteins were found to be co-precipitated by antibodies against the individual P proteins. These results indicate that the influenza virus RNA-dependent RNA polymerase is a heterocomplex composed of one each of the three P proteins and that the RNA-free RNA polymerase can be isolated in an active form from virus particles. Furthermore, the three P proteins form a complex in the absence of vRNA. © 1990 COPYRIGHT, 1990 BY THE JOURNAL OF BIOCHEMISTRY.