Dynamics of the intrinsically disordered C-terminal domain of the nipah virus nucleoprotein and interaction with the X domain of the phosphoprotein as unveiled by NMR spectroscopy

We provide an atomic-resolution description based on NMR spectroscopy, of the intrinsically disordered C-terminal domain of the Nipah virus nucleoprotein (NTAIL), both in its isolated state and within the nucleocapsid (NC). Within the NC the second half of NTAIL retains conformational behavior similar to that of isolated NTAIL, whereas the first half of NTAIL becomes much more rigid. In spite of the mostly disordered nature of NTAIL, chemical shifts and relaxation measurements show a significant degree of α-helical sampling in the molecular recognition element (MoRE) involved in binding to the X domain (XD) of the phosphoprotein, with this preconfiguration being more pronounced than in the NTAIL domain from the cognate Hendra virus. Outside the MoRE, an additional region exhibiting reduced flexibility was identified within NTAIL and found to be involved in binding to the XD. 1H- and 13C-detected titration NMR experiments support a highly dynamic binding of NTAIL at the surface of the XD.