title: Functional domains of the influenza A virus PB2 protein: identification of NP- and PB1-binding sites.
abstract: Influenza virus genomic RNA segments are packaged into ribonucleoprotein (RNP) structures by the PB1, PB2, and PA subunits of an RNA polymerase and a single-strand RNA-binding nucleoprotein (NP). Assembly and function of these ribonucleoproteins depend on a complex set of protein-protein and protein-RNA interactions. Here, we identify new functional domains of PB2. We show that PB2 contains two regions that bind NP and also identify a novel PB1 binding site. The regions of PB2 responsible for binding NP and PB1 show considerable overlap, and binding of NP to the PB2 fragments could be outcompeted by PB1. The binding domains of PB2 acted as trans-dominant inhibitors of viral gene expression, and consistent with the in vitro binding data, their inhibitory activity depended on the concentration of wild-type PB2, NP, and PB1. This provides evidence for functionally significant and potentially regulatory interactions between PB2 and NP.
authors.affiliation: Division of Virology, Department of Pathology, University of Cambridge, Cambridge, CB2 1QP, UK.
authors.forename: Emma
authors.initials: E
authors.lastname: Poole
authors.forename: Debra
authors.initials: D
authors.lastname: Elton
authors.forename: Liz
authors.initials: L
authors.lastname: Medcalf
authors.forename: Paul
authors.initials: P
authors.lastname: Digard
mesh_terms: D001665:Binding Sites; D015870:Gene Expression; D009980:Influenza A virus / Q000737:chemistry*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D012367:RNA, Viral / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000378:metabolism*; D012324:RNA-Dependent RNA Polymerase / Q000378:metabolism*; D014764:Viral Proteins / Q000737:chemistry / Q000378:metabolism*
chemical_list: C057027:PB2 protein, Influenzavirus A; D012367:RNA, Viral; D016601:RNA-Binding Proteins; D014764:Viral Proteins; C077346:influenza virus polymerase basic protein 1; D012324:RNA-Dependent RNA Polymerase