Nearly complete 1H, 13C and 15N chemical shift assignment of monomeric form of N-terminal domain of Nephila clavipes major ampullate spidroin 2

Spider dragline silk is well recognized due to its excellent mechanical properties. Dragline silk protein mainly consists of two proteins, namely, major ampullate spidroin 1 (MaSp1) and major ampullate spidroin 2 (MaSp2). The MaSp N-terminal domain (NTD) conformation displays a strong dependence on ion and pH gradients, which is crucial for the self-assembly behavior of spider silk. In the spider major ampullate gland, where the pH is neutral and concentration of NaCl is high, the NTD forms a monomer. In contrast, within the spinning duct, where pH becomes more acidic (to pH ~ 5) and the concentration of salt is low, NTD forms a dimer in antiparallel orientation. In this study, we report near-complete backbone and side chain chemical shift assignment of the monomeric form of NTD of MaSp2 from Nephila clavipes at pH 7 in the presence of 300 mM NaCl. Our NMR data demonstrate that secondary structure of monomeric form of NTD MaSp2 consists of five helix regions.