Synthetic Spider Silk Provides New Insights into the Mechanisms of Flagelliform Silk Fiber Assemble and Elastomeric Behavior

In order to better understand the relationship between the elastomeric behavior of Flagelliform (Flag) spider silks and its molecular structure, it was designed and produced the Nephilengys cruentata Flageliform (Flag) spidroin analogue rNcFlag2222. 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 were compared in its fibrillar and in its fully solvated states. Based on the results and previous published data, it was possible to propose a model for the molecular dynamics of Flag spidroins’ repetitive core, during gland storage and fiber formation, and their contribution to its exceptional mechanoelastic properties. This model assumes that the Flag silk proteins acquire elastomeric behavior through a mechanism similar to collagen proteins, with the repetitive glycine-rich and the spacer regions, together with water, playing important roles in fiber assemble and elastomeric behavior.