Molecular Dynamics of Synthetic Flagelliform Silk Fiber Assembly (vol 306, 2000530, 2021)

In order to better understand the relationship between flagelliform (Flag) spider silk molecular structural organization and the mechanisms of fiber assembly, the Nephilengys cruentata Flag spidroin analogue rNcFlag2222 is designed and produced. The recombinant proteins are composed by the elastic repetitive glycine-rich motifs (GPGGX/GGX) and the spacer region, rich in hydrophilic charged amino acids, present at the native silk spidroin. Using different approaches for nanomolecular protein analysis, the structural data of rNcFlag2222 recombinant proteins are compared in their fibrillar and fully solvated states. Based on the results, it is possible to identify the molecular structural dynamics of NcFlag2222 prior to and after fiber formation. Overall rNcFlag2222 shows a mixture of semiflexible and rigid conformations, characterized mostly by the presence of polyproline type II helix (PPII), beta-turn, and beta-sheet. These results agree with previous studies and bring insights about the molecular mechanisms that might drive Flag silk fibers assembly and elastomeric behavior.