title: Assessing induced folding within the intrinsically disordered C-terminal domain of the Henipavirus nucleoproteins by site-directed spin labeling EPR spectroscopy.
abstract: This work aims at characterizing structural transitions within the intrinsically disordered C-terminal domain of the nucleoprotein (NTAIL) from the Nipah and Hendra viruses, two recently emerged pathogens gathered within the Henipavirus genus. To this end, we used site-directed spin labeling combined with electron paramagnetic resonance spectroscopy to investigate the α-helical-induced folding that Henipavirus NTAIL domains undergo in the presence of the C-terminal X domain of the phosphoprotein (PXD). For each NTAIL protein, six positions located within four previously proposed molecular recognition elements (MoREs) were targeted for spin labeling, with three of these positions (475, 481, and 487) falling within the MoRE responsible for binding to PXD (Box3). A detailed analysis of the impact of the partner protein on the labeled NTAIL variants revealed a dramatic modification in the environment of the spin labels grafted within Box3, with the observed modifications supporting the formation of an induced α-helix within this region. In the free state, the slightly lower mobility of the spin labels grafted within Box3 as compared to the other positions suggests the existence of a transiently populated α-helix, as already reported for measles virus (MeV) NTAIL. Comparison with the well-characterized MeV NTAIL-PXD system, allowed us to validate the structural models of Henipavirus NTAIL-PXD complexes that we previously proposed. In addition, this study highlighted a few notable differences between the Nipah and Hendra viruses. In particular, the observation of composite spectra for the free form of the Nipah virus NTAIL variants spin labeled in Box3 supports conformational heterogeneity of this partly pre-configured α-helix, with the pre-existence of stable α-helical segments. Altogether these results provide insights into the molecular mechanisms of the Henipavirus NTAIL-PXD binding reaction.
authors.affiliation: CNRS, Aix Marseille Université, IMM FR 3479, BIP UMR 7281, 13402 Marseille, France.
authors.forename: Marlène
authors.initials: M
authors.lastname: Martinho
authors.forename: Johnny
authors.initials: J
authors.lastname: Habchi
authors.forename: Zeina
authors.initials: Z
authors.lastname: El Habre
authors.forename: Léo
authors.initials: L
authors.lastname: Nesme
authors.forename: Bruno
authors.initials: B
authors.lastname: Guigliarelli
authors.forename: Valérie
authors.initials: V
authors.lastname: Belle
authors.forename: Sonia
authors.initials: S
authors.lastname: Longhi
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D002942:Circular Dichroism; D004578:Electron Spin Resonance Spectroscopy; D045404:Hendra Virus; D057927:Hydrophobic and Hydrophilic Interactions; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D045405:Nipah Virus; D009698:Nucleoproteins / Q000737:chemistry* / Q000235:genetics; D011485:Protein Binding; D017510:Protein Folding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D014764:Viral Proteins / Q000737:chemistry* / Q000235:genetics
chemical_list: D009698:Nucleoproteins; D014764:Viral Proteins