title: Limited compatibility of polymerase subunit interactions in influenza A and B viruses.
abstract: Despite their close phylogenetic relationship, natural intertypic reassortants between influenza A (FluA) and B (FluB) viruses have not been described. Inefficient polymerase assembly of the three polymerase subunits may contribute to this incompatibility, especially because the known protein-protein interaction domains, including the PA-binding domain of PB1, are highly conserved for each virus type. Here we show that substitution of the FluA PA-binding domain (PB1-A(1-25)) with that of FluB (PB1-B(1-25)) is accompanied by reduced polymerase activity and viral growth of FluA. Consistent with these findings, surface plasmon resonance spectroscopy measurements revealed that PA of FluA exhibits impaired affinity to biotinylated PB1-B(1-25) peptides. PA of FluB showed no detectable affinity to biotinylated PB1-A(1-25) peptides. Consequently, FluB PB1 harboring the PA-binding domain of FluA (PB1-AB) failed to assemble with PA and PB2 into an active polymerase complex. To regain functionality, we used a single amino acid substitution (T6Y) known to confer binding to PA of both virus types, which restored polymerase complex formation but surprisingly not polymerase activity for FluB. Taken together, our results demonstrate that the conserved virus type-specific PA-binding domains differ in their affinity to PA and thus might contribute to intertypic exclusion of reassortants between FluA and FluB viruses.
authors.affiliation: Department of Virology, University of Freiburg, 70104 Freiburg, Germany.
authors.forename: Kerstin
authors.initials: K
authors.lastname: Wunderlich
authors.forename: Mindaugas
authors.initials: M
authors.lastname: Juozapaitis
authors.forename: Benjamin
authors.initials: B
authors.lastname: Mänz
authors.forename: Daniel
authors.initials: D
authors.lastname: Mayer
authors.forename: Veronika
authors.initials: V
authors.lastname: Götz
authors.forename: Andrea
authors.initials: A
authors.lastname: Zöhner
authors.forename: Thorsten
authors.initials: T
authors.lastname: Wolff
authors.forename: Martin
authors.initials: M
authors.lastname: Schwemmle
authors.forename: Arnold
authors.initials: A
authors.lastname: Martin
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D004285:Dogs; D006801:Humans; D009980:Influenza A virus / Q000378:metabolism*; D009981:Influenza B virus / Q000378:metabolism*; D007700:Kinetics; D008969:Molecular Sequence Data; D009711:Nucleotides / Q000737:chemistry; D010455:Peptides / Q000737:chemistry; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity; D020349:Surface Plasmon Resonance
chemical_list: D009711:Nucleotides; D010455:Peptides; D011994:Recombinant Proteins