The C-terminal domain of the measles virus nucleoprotein is intrinsically disordered and folds upon binding to the C-terminal moiety of the phosphoprotein.
The nucleoprotein of measles virus consists of an N-terminal moiety, N(CORE), resistant to proteolysis and a C-terminal moiety, N(TAIL), hypersensitive to proteolysis and not visible as a distinct domain by electron microscopy. We report the bacterial expression, purification, and characterization of measles virus N(TAIL). Using nuclear magnetic resonance, circular dichroism, gel filtration, dynamic light scattering, and small angle x-ray scattering, we show that N(TAIL) is not structured in solution. Its sequence and spectroscopic and hydrodynamic properties indicate that N(TAIL) belongs to the premolten globule subfamily within the class of intrinsically disordered proteins. The same epitopes are exposed in N(TAIL) and within the nucleoprotein, which rules out dramatic conformational changes in the isolated N(TAIL) domain compared with the full-length nucleoprotein. Most unstructured proteins undergo some degree of folding upon binding to their partners, a process termed "induced folding." We show that N(TAIL) is able to bind its physiological partner, the phosphoprotein, and that it undergoes such an unstructured-to-structured transition upon binding to the C-terminal moiety of the phosphoprotein. The presence of flexible regions at the surface of the viral nucleocapsid would enable plastic interactions with several partners, whereas the gain of structure arising from induced folding would lead to modulation of these interactions. These results contribute to the study of the emerging field of natively unfolded proteins.
Longhi
Sonia
S
Architecture et Fonction des Macromolécules Biologiques, UMR 6098 CNRS et Université Aix-Marseille I et II, ESIL, Campus de Luminy, 13288 Marseille Cedex 09, France. longhi@afmb.cnrs-mrs.fr
Receveur-Bréchot
Véronique
V
Karlin
David
D
Johansson
Kenth
K
Darbon
Hervé
H
Bhella
David
D
Yeo
Robert
R
Finet
Stéphanie
S
Canard
Bruno
B
D002850:Chromatography, Gel; D002942:Circular Dichroism; D000939:Epitopes; D004926:Escherichia coli / Q000378:metabolism; D008027:Light; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D019590:Nucleocapsid Proteins; D009698:Nucleoproteins / Q000737:chemistry* / Q000378:metabolism; D010957:Plasmids / Q000378:metabolism; D011233:Precipitin Tests; D011485:Protein Binding; D017510:Protein Folding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D012542:Scattering, Radiation; D014764:Viral Proteins / Q000737:chemistry* / Q000378:metabolism; D014965:X-Rays
D000939:Epitopes; D019590:Nucleocapsid Proteins; D009698:Nucleoproteins; D014764:Viral Proteins; C058314:nucleoprotein, Measles virus