Genetically Encoded Design and Biomanufacturing of Mechanical Protein Materials

ConspectusNatural protein materials such as spider silks, fibroins, and mussel foot proteins epitomize the pinnacle of mechanical performance in biological matter. Their unparalleled strength-to-weight ratios, inherent biocompatibility, and precise programmability at the amino acid level make them ideal blueprints for next-generation structural biomaterials. However, these advantages are counterbalanced by inherent limitations: scarce natural availability, limited functional diversity in native sequences, and challenges in scalable processing and reproduction. Recent advances in gene editing and synthetic biology have enabled the de novo design of artificial mechanical proteins, bypassing these constraints. By modularly integrating mechanical, metal-coordinating (e.g., LanM and amyloid motifs), and bioactive domains (e.g., antifreeze and epidermal growth factor modules) from phylogenetically diverse species, researchers now exert unprecedented control over the protein sequence, hierarchical architecture, and macroscopic behavior. These engineered variants have already led to advanced biomedical products, including surgical sutures, hernia meshes, and hemostatic sealants, that outperform conventional synthetic polymers in both functionality and biocompatibility.Nonetheless, scalable biomanufacturing remains hindered by the structural features that underpin mechanical superiority: highly repetitive motifs and high molecular weights often promote aggregation, proteolytic instability, and low recombinant yields in conventional expression systems. To overcome these bottlenecks, extensive efforts have focused on optimizing chassis cells, such as E. coli and C. glutamicum, through glycyl-tRNA enrichment, CRISPRi-enabled secretion screening, codon scrambling, and signal peptide engineering. Moreover, the fidelity of supramolecular assembly critically determines the ultimate performance of the material, necessitating precise control over the processing conditions. This Account provides a critical review of recent advances in modular protein strategies for fabricating high-performance biomaterials, organized around three synergistic pillars: (i) rational modular design, which combines rigid β-sheet domains (e.g., SRT or spidroins), flexible linkers (e.g., ELP or resilin), metal-binding motifs, and functional peptides to orthogonally tailor strength, toughness, and bioactivity; (ii) chassis cell optimization through transcriptional, translational, and post-translational engineering to enhance the synthesis and secretion of repetitive proteins; and (iii) biomimetic assembly techniques, such as microfluidic spinning and liquid–liquid phase separation, enabling the precise alignment of β-sheet nanocrystals and multiforce-directed cross-linking into hierarchical fibers and glues with toughness exceeding 200 MJ/m3 and adhesive strength over 30 MPa.Looking forward, we advocate for the integration of these experimental approaches with AI-driven design loops that combine de novo sequence generation, mechanical property prediction, and automated process optimization. Such closed-loop, data-driven frameworks promise to drastically compress development timelines, improve production yields, and enable scalable, sustainable manufacturing of protein materials tailored for cutting-edge applications in biomedicine, soft robotics, and sustainable materials.