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)₁₂NtSp, 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)₁₂NtSp compared with that in H(AB)₁₂. Time-resolved FTIR analysis was used to monitor conformation transitions. A higher rate of β-sheet formation was found in H(AB)₁₂NtSp 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.