Bi-terminal fusion of intrinsically-disordered mussel foot protein fragments boosts mechanical strength for protein fibers

Abstract

Microbially-synthesized protein-based materials are attractive replacements for petroleum-derived synthetic polymers. However, the high molecular weight, high repetitiveness, and highly-biased amino acid composition of high-performance protein-based materials have restricted their production and widespread use. Here we present a general strategy for enhancing both strength and toughness of low-molecular-weight protein-based materials by fusing intrinsically-disordered mussel foot protein fragments to their termini, thereby promoting end-to-end protein-protein interactions. We demonstrate that fibers of a ~60 kDa bi-terminally fused amyloid-silk protein exhibit ultimate tensile strength up to 481 ± 31 MPa and toughness of 179 ± 39 MJ*m−3, while achieving a high titer of 8.0 ± 0.70 g/L by bioreactor production. We show that bi-terminal fusion of Mfp5 fragments significantly enhances the alignment of β-nanocrystals, and intermolecular interactions are promoted by cation-π and π-π interactions between terminal fragments. Our approach highlights the advantage of self-interacting intrinsically-disordered proteins in enhancing material mechanical properties and can be applied to a wide range of protein-based materials.

Genetically Engineered Protein-Based Bioadhesives with Programmable Material Properties

“…We used our rapid cloning strategy and synthetic biology platform to produce these proteins. ,− All proteins were produced and purified to high purities (>90%) (Figure d). Purified proteins were used to fabricate hydrogels following published methods for 8xKLV-Mfp (Figure c) .…”

Blending recombinant amyloid silk proteins generates composite fibers with tunable mechanical properties

“…Moreover, these hybrid proteins boast relatively higher yield compared to recombinant silk and other proteins, due to reduced repetitiveness of their protein sequences (Table S1, ESI †). 32 Additionally, the large library of diverse amyloid zipper-forming peptides offers extensive design possibilities. Each amyloid-silk protein was individually expressed in Escherichia coli shake flask cultures and purified (Fig.…”

Biomimetic Structural Proteins: Modular Assembly and High Mechanical Performance

“…In the modular assembly process, DB24C8 derivatives provided electrostatic interactions via carboxyl groups, host−guest interactions via crown ethers, cation−π interactions via phenyl groups, and π−π interactions between phenyl groups in themselves (Figure 5C). 32 Such adhesives achieved remarkable lap-shear strength of 22 MPa on a steel substrate, maintaining strong adhesion under extreme 29 [128xFGAILSS], 41 [ N M-16xFGA-C M(YtoS)], 42 [TIO spidroins(BSD)], 43 [WS-PSD-3x], 44 [TuSp1-N2RPC:TuSp2-RP], 45 [NS4C], 46 conditions, even from −196 to 200 °C, due to these additional driving forces. Some protein biomaterials can reversibly respond to surrounding stimuli like chemical, electrical, light, temperature, and mechanical forces.…”

“…Summary of the mechanical performances of biomimetic protein fibers among representative research. [T3-eSRT-T3], [SRT-ELP Cys-36mer], [UHMW Titin], [RLP-SUP], [NTD-eADF3/4-CTD­(in vivo)], [192-mer N. clavipes dragline], [128xFGAILSS], [ N M-16xFGA- C M­(YtoS)], [TIO spidroins­(BSD)], [WS-PSD-3x], [TuSp1-N2RPC:TuSp2-RP], [NS4C], and [N16C] in the Ashby plot are recombinant protein fibers. [CNF/K144-EDC/NHS] belongs to protein-nanocellulose composite fibers.…”