Self-Assembling Protein Materials with Genetically Programmable Morphology and Size

Materials are challenging to synthetically program down to the atom level. Nature, however, excels at creating hierarchical materials from nanoscale building blocks, a feat that remains a major challenge in synthetic systems. A deeper understanding of the molecular rules governing self-assembly would unlock the potential for designing genetically programmable materials with atomic precision. Hexameric bacterial microcompartment (BMC-H) proteins offer a powerful model system for exploring this question. These sequence-defined proteins naturally assemble into complex architectures and can be expressed biologically, making them ideal candidates for studying how minor sequence variations influence supramolecular structure. In this work, we leverage cell-free protein synthesis (CFPS) alongside immunostaining and super-resolution microscopy to investigate the self-assembly behavior of two BMC-H proteins, PduA and PduJ. We find that both proteins form micron- to millimeter-scale structures when expressed in vitro. Further, we demonstrate how single-point mutation changes lead PduA and PduJ to form significantly different supramolecular structures when produced using CFPS. These studies support the future exploration of self-assembling proteins as programmable scaffolds in broad materials applications.