Design and expression strategies for the production of repetitive proteins (e.g., silk, SRT, elastin, collagen) that comprise one or more tandem copies of a single unit have been an interested for the last couple of decades. Tandem repetition intrinsically promotes stability through the periodic recurrence of favorable interactions; hence modular reuse allows for a stepwise increase in functionality in the biomaterial design. However, the design of highly repetitive sequences for structural proteins present challenges for protein engineering. For example, the construction of the synthetic genes encoding them can fail or generate nonspecific products. Recently, we developed a novel technique (see Figure) combining ultrafast laser-probing spectroscopy and protein in-vivo assays to study directed evolution of tandem repeat proteins. Our technique enables screening of a large library of structural polypeptide sequences for protein assembly in hours, a feat that would be impossible to achieve with existing screening tools such as fluorescence, immunostaining, or functional assays. Using this technique we created tandem repeat protein fibers. These materials can be shaped into various geometries such as fibers, colloids, and thin films. Moreover, their molecular structure provides a rich architecture that can micro-phase-separate to form periodic nanostructures (e.g., lamellar and cylindrical repeating phases). In this talk, we focus on directed evolution of protein-based programmable fibers, with applications to textile.

Directed evolution of tandem repeat protein fibers

2019 Spring National Meeting

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