The C-terminal domain of measles virus nucleoprotein belongs to the class of intrinsically disordered proteins that fold upon binding to their physiological partner.
The nucleoprotein of measles virus consists of an N-terminal domain, N(CORE) (aa 1-400), resistant to proteolysis, and a C-terminal domain, N(TAIL) (aa 401-525), hypersensitive to proteolysis and not visible by electron microscopy. Using two complementary computational approaches, we predict that N(TAIL) belongs to the class of natively unfolded proteins. Using different biochemical and biophysical approaches, we show that N(TAIL) is indeed unstructured in solution. In particular, the spectroscopic and hydrodynamic properties of N(TAIL) indicate that this protein domain belongs to the premolten globule subfamily within the class of intrinsically disordered proteins. The isolated N(TAIL) domain was shown to be able to bind to its physiological partner, the phosphoprotein (P), and to undergo an induced folding upon binding to the C-terminal moiety of P [J. Biol. Chem. 278 (2003) 18638]. Using a computational analysis, we have identified within N(TAIL) a putative alpha-helical molecular recognition element (alpha-MoRE, aa 488-499), which could be involved in binding to P via induced folding. We report the bacterial expression and purification of a truncated form of N(TAIL) (N(TAIL2), aa 401-488) devoid of the alpha-MoRE. We show that N(TAIL2) has lost the ability to bind to P, thus supporting the hypothesis that the alpha-MoRE may play a role in binding to P. We have further analyzed the alpha-helical propensities of N(TAIL2) and N(TAIL) using circular dichroism in the presence of 2,2,2-trifluoroethanol. We show that N(TAIL2) has a lower alpha-helical potential compared to N(TAIL), thus suggesting that the alpha-MoRE may be indeed involved in the induced folding of N(TAIL).
Bourhis
Jean-Marie
JM
Architecture et Fonction des Macromolécules Biologiques, UMR 6098 CNRS et Université Aix-Marseille I et II, ESIL, Campus de Luminy, Cedex 09 13288, Marseille, France.
Johansson
Kenth
K
Receveur-Bréchot
Véronique
V
Oldfield
Christopher J
CJ
Dunker
Keith A
KA
Canard
Bruno
B
Longhi
Sonia
S
D002942:Circular Dichroism; D019295:Computational Biology; D008459:Measles virus / Q000737:chemistry*; D019590:Nucleocapsid Proteins; D009698:Nucleoproteins / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D010750:Phosphoproteins / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation; D017510:Protein Folding; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D017384:Sequence Deletion; D014764:Viral Proteins / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*
D019590:Nucleocapsid Proteins; D009698:Nucleoproteins; C055859:P protein, Sendai virus; D010750:Phosphoproteins; D011994:Recombinant Proteins; D014764:Viral Proteins; C058314:nucleoprotein, Measles virus