title: Molecular Basis of mRNA Cap Recognition by Influenza B Polymerase PB2 Subunit.
abstract: Influenza virus polymerase catalyzes the transcription of viral mRNAs by a process known as "cap-snatching," where the 5'-cap of cellular pre-mRNA is recognized by the PB2 subunit and cleaved 10-13 nucleotides downstream of the cap by the endonuclease PA subunit. Although this mechanism is common to both influenza A (FluA) and influenza B (FluB) viruses, FluB PB2 recognizes a wider range of cap structures including m(7)GpppGm-, m(7)GpppG-, and GpppG-RNA, whereas FluA PB2 utilizes methylated G-capped RNA specifically. Biophysical studies with isolated PB2 cap-binding domain (PB2(cap)) confirm that FluB PB2 has expanded mRNA cap recognition capability, although the affinities toward m(7)GTP are significantly reduced when compared with FluA PB2. The x-ray co-structures of the FluB PB2(cap) with bound cap analogs m(7)GTP and GTP reveal an inverted GTP binding mode that is distinct from the cognate m(7)GTP binding mode shared between FluA and FluB PB2. These results delineate the commonalities and differences in the cap-binding site between FluA and FluB PB2 and will aid structure-guided drug design efforts to identify dual inhibitors of both FluA and FluB PB2.
authors.affiliation: From the Divisions of Protein Sciences.
authors.forename: Lili
authors.initials: L
authors.lastname: Xie
authors.affiliation: Structural and Biophysical Chemistry, Global Discovery Chemistry.
authors.forename: Charles
authors.initials: C
authors.lastname: Wartchow
authors.affiliation: Structural and Biophysical Chemistry, Global Discovery Chemistry.
authors.forename: Steven
authors.initials: S
authors.lastname: Shia
authors.affiliation: From the Divisions of Protein Sciences.
authors.forename: Kyoko
authors.initials: K
authors.lastname: Uehara
authors.affiliation: Structural and Biophysical Chemistry, Global Discovery Chemistry.
authors.forename: Micah
authors.initials: M
authors.lastname: Steffek
authors.affiliation: Virology Lead Discovery.
authors.forename: Robert
authors.initials: R
authors.lastname: Warne
authors.affiliation: Global Discovery Chemistry and.
authors.forename: James
authors.initials: J
authors.lastname: Sutton
authors.affiliation: Virology, Novartis Institutes for BioMedical Research, Emeryville, California 94608-2916.
authors.forename: Gladys T
authors.initials: GT
authors.lastname: Muiru
authors.affiliation: Virology, Novartis Institutes for BioMedical Research, Emeryville, California 94608-2916.
authors.forename: Vincent H J
authors.initials: VH
authors.lastname: Leonard
authors.affiliation: Structural and Biophysical Chemistry, Global Discovery Chemistry.
authors.forename: Dirksen E
authors.initials: DE
authors.lastname: Bussiere
authors.affiliation: Structural and Biophysical Chemistry, Global Discovery Chemistry, xiaolei.ma@novartis.com.
authors.forename: Xiaolei
authors.initials: X
authors.lastname: Ma
mesh_terms: D002151:Calorimetry; D018360:Crystallography, X-Ray; D005470:Fluorometry; D009980:Influenza A virus / Q000201:enzymology; D009981:Influenza B virus / Q000201:enzymology*; D008958:Models, Molecular; D018583:Pliability; D021122:Protein Subunits / Q000737:chemistry / Q000378:metabolism*; D012314:RNA Cap Analogs / Q000378:metabolism; D012315:RNA Caps / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012996:Solutions; D014764:Viral Proteins / Q000737:chemistry / Q000378:metabolism*
chemical_list: C502893:PB2 protein, influenza virus; D021122:Protein Subunits; D012314:RNA Cap Analogs; D012315:RNA Caps; D012333:RNA, Messenger; D012996:Solutions; D014764:Viral Proteins; C017516:7-methylguanosine triphosphate
keywords: DSF; PB2; biophysics; cap-binding domain; crystal structure; influenza virus; isothermal titration calorimetry (ITC); ligand-binding protein; mRNA cap analog