title: Effect of pH on the structure of the recombinant C-terminal domain of Nephila clavipes dragline silk protein.
abstract: Spider silk proteins undergo a complex series of molecular events before being converted into an outstanding hierarchically organized fiber. Recent literature has underlined the crucial role of the C-terminal domain in silk protein stability and fiber formation. However, the effect of pH remains to be clarified. We have thus developed an efficient purification protocol to obtain stable native-like recombinant MaSp1 C-terminal domain of Nephila clavipes (NCCTD). Its structure was investigated as a function of pH using circular dichroism, fluorescence and solution NMR spectroscopy. The results show that the NCCTD structure is very sensitive to pH and suggest that a molten globule state occurs at pH 5.0 and below. Electronic microscopy images also indicate fiber formation at low pH and coarser globular particles at more basic pH. The results are consistent with a spinning process model where the NCCTD acts as an aggregation nucleus favoring the β-aggregation of the hydrophobic polyalanine repeats upon spinning.
authors.affiliation: Department of Chemistry, Regroupement Québécois de Recherche sur la Fonction, la Structure et l'Ingénierie des Protéines (PROTEO), Centre de Recherche sur les Matériaux Avancés (CERMA), Centre Québécois sur les Matériaux Fonctionnels (CQMF), and ‡Department of Biochemistry, Microbiology and Bioinformatics, Institut de Biologie Intégrative et des Systèmes (IBIS), PROTEO, Université Laval , Québec, QC Canada , G1V 0A6.
authors.forename: Martin
authors.initials: M
authors.lastname: Gauthier
authors.forename: Jérémie
authors.initials: J
authors.lastname: Leclerc
authors.forename: Thierry
authors.initials: T
authors.lastname: Lefèvre
authors.forename: Stéphane M
authors.initials: SM
authors.lastname: Gagné
authors.forename: Michèle
authors.initials: M
authors.lastname: Auger
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002942:Circular Dichroism; D003001:Cloning, Molecular; D006863:Hydrogen-Ion Concentration; D009682:Magnetic Resonance Spectroscopy; D050606:Mannose-Binding Protein-Associated Serine Proteases / Q000737:chemistry; D046529:Microscopy, Electron, Transmission; D008969:Molecular Sequence Data; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000737:chemistry*; D047011:Silk / Q000737:chemistry*; D013112:Spiders
chemical_list: D011994:Recombinant Proteins; D047011:Silk; D050606:Mannose-Binding Protein-Associated Serine Proteases