Conformation Transitions of Recombinant Spidroins via Integration of Time-Resolved FTIR Spectroscopy and Molecular Dynamic Simulation

Current trends in biomaterial designs require a detailed understanding of structure function relationships to efficiently address specific utilities. As a prototype, spider silk has been widely studied with diversified characterization or simulation methods, exploiting the integration of experimental and modeling approaches to gain insight into structure function relationships. However, the assembly mechanisms of spider silk in natural and non-natural environments remain incompletely understood. In the present study, experimental and simulation approaches were utilized to study assembly mechanisms of recombinant spider silks. Two spider silk constructs, H(AB)(12) and H(AB)(12)NtSp, were produced and studied. Deconvoluted Fourier transform infrared spectroscopy (FTIR) spectra and molecular dynamics simulations, before and after ethanol treatment, were analyzed to quantify secondary structures, and a higher helix content was observed in H(AB)(12)NtSp compared with that in H(AB)(12). Time-resolved FTIR analysis was used to monitor conformation transitions. A higher rate of beta-sheet formation was found in H (AB)(12)NtSp compared with that in H(AB)(12). These results suggest that the N-terminal domain accelerates self-assembly of recombinant spidroins under ethanol treatment. The approaches used in this study provide insights into the function of the N-terminal domain in conformational transitions of spider silks under non-natural conditions as well as fiber formation. This approach should enable more efficient design, synthesis, and preparation of new recombinant spidroin materials with tunable mechanical properties.