Tarendeau, F. et al. Structure and nuclear import function of the C-terminal domain of influenza virus polymerase PB2 subunit. Nat. Struct. Mol. Biol. 14, 229-233

European Molecular Biology Laboratory (EMBL) Grenoble Outstation, 6 rue Jules Horowitz, BP181, 38042 Grenoble Cedex 9, France.
Nature Structural & Molecular Biology (Impact Factor: 13.31). 04/2007; 14(3):229-33. DOI: 10.1038/nsmb1212
Source: PubMed


The trimeric influenza virus polymerase, comprising subunits PA, PB1 and PB2, is responsible for transcription and replication of the segmented viral RNA genome. Using a novel library-based screening technique called expression of soluble proteins by random incremental truncation (ESPRIT), we identified an independently folded C-terminal domain from PB2 and determined its solution structure by NMR. Using green fluorescent protein fusions, we show that both the domain and the full-length PB2 subunit are efficiently imported into the nucleus dependent on a previously overlooked bipartite nuclear localization sequence (NLS). The crystal structure of the domain complexed with human importin alpha5 shows how the last 20 residues unfold to permit binding to the import factor. The domain contains three surface residues implicated in adaptation from avian to mammalian hosts. One of these tethers the NLS-containing peptide to the core of the domain in the unbound state.

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    • "3.4. CIP2A-ArmRP can form similar interactions as other ArmRP proteins Crystallized ArmRP proteins exhibit a highly conserved binding mode (Reichen et al., 2014), where an extended peptide from the interacting proteins is bound into the central groove of the ArmRP proteins through a combination of electrostatic and backbone interactions (PDB 3QHE, 4OIH, 3L6X/3L6Y, 2JDQ, 1JDH; Graham et al., 2001; Ishiyama et al., 2010; Morishita et al., 2011; Roman et al., 2013; Tarendeau et al., 2007). The bound peptides run antiparallel to the ArmRP motifs and the hydrogen bonds between the conserved Asn residues in the H3 α-helices of ArmRP and the peptide backbone keep the peptide in an extended conformation (Andrade et al., 2001; Conti et al., 1998), while other residues in the binding groove confer specificity by interacting with the side chains of the bound peptide (Reichen et al., 2014). "
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    • "In the past decade, several importin-a structures in complex with NLS peptides have been solved (Catimel et al., 2001; Chen et al., 2005; Conti and Kuriyan, 2000; Conti et al., 1998; Cutress et al., 2008; Dias et al., 2009; Fontes et al., 2000, 2003a,b; Giesecke and Stewart, 2010; Hirano and Matsuura, 2011; Kobe, 1999; Matsuura and Stewart, 2005; Mynott et al., 2011; Pumroy et al., 2012; Takeda et al., 2011; Tarendeau et al., 2007; Yang et al., 2010). Based on structural homologies of the bound peptide, five peptide classes have been defined, represented by (i) the bipartite peptide nucleoplasmin (Np1), and (ii) the monopartite peptides cmyc (Myc), bound to major and minor site; (iii) pCN, a subgroup of c-myc; (iv) aIBB, bound only to the major site and (v) Nup50, bound only to the minor site (Fig. 2A). "
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